Vol.31,No. 9, Pp. 843-849,1992 Printedin Great Britain.All rightsreserved Neuropharmacology
0028-3908/92 s5.00 + 0.00
Copyright0 1992PergamonPressLtd
SYSTEMIC ADMINISTRATION OF DYNORPHIN A(l-13) MARKEDLY INHIBITS DIFFERENT BEHAVIOURAL RESPONSES INDUCED BY COCAINE IN THE MOUSE M. UKAI, T. KAMIYA,T. TOYOSHIand T. KAMEYAMA Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya 468, Japan (Accepted 12 May 1992)
Summary-The effects of systemic administration (i.p.) of dynorphin A(l-13) on the cocaine-induced behavioural alterations in the mouse were determined by using multi-dimensional behavioural analyses, based upon a capacitance system. A l.Omg/kg dose of cocaine did not influence behaviour, while increasing doses to 3-30 mg/kg produced a significant increment in the frequency of behaviour, such as linear locomotion, circling, rearing and grooming. Although a 1.Omg/kg dose of dynorphin A( l- 13) alone produced a significant decrease in grooming behaviour, larger doses (3.0 and 10.0 mg/kg) of the peptide failed to affect different behaviour. The cocaine (3.0mg/kg)-induced increases in linear locomotion, circling and rearing behaviour were significantly inhibited by dynorphin A(l-13) (10.0 mg/kg). The inhibitory effects of dynorphin A(l-13) (10.0 mg/kg) were antagonized by the opioid antagonist Mr 2266 (5.6 mg/kg). It is thus possible that the systemic administration of dynorphin A(l-13) inhibits different behavioural responses induced by cocaine through the blood-brain barrier, although the instability of amino acid bonds or the relatively large molecular weight of dynorphin A(l-13), may result in the failure to demonstrate opioid activity by the peptide after systemic administration. Key words-dynorphin
A(l-13), cocaine, Mr 2266, locomotor activity, mouse.
Cocaine is one of the psychomotor stimulants which possesses prominent subjective effects, resulting in its abuse (Jaffe, 1985). Although neuropharmacological investigations suggest that various biogenic amines play an important role in rewarding or reinforcing responses to cocaine, the inhibition of the reuptake of dopamine by binding to dopamine transporters, seems to underlie the behavioural effects of cocaine (Ritz, Lamb, Goldberg and Kuhar, 1987). The behavioural effects of intracerebroventricular injections of opioid peptides have been demonstrated by using multi-dimensional behavioural analysers, based upon a capacitance system in which 9 different parameters of behaviour can be detected simultaneously (Kameyama and Ukai, 1981, 1983; Ukai and Kameyama, 1984, 1985; Ukai, Toyoshi and Kameyama, 1989a, b). For instance, a- and y-endorphins produce a marked increase in linear locomotion, without affecting other behavioural measures (Kameyama and Ukai, 1981, 1983), while p-endorphin produces a significant decrease in almost all behaviour (Kameyama and Ukai, 1983). In particular, the IEopioid agonist dynorphin A(l-13) has been reported to produce a biphasic effect, i.e. naloxonereversible marked increase in linear locomotion at smaller doses (0.3 and 1.0 pg); no marked effects at larger doses (3.0 and 10.0 pg) (Ukai and Kameyama, 1984). Moreover, previously the effects of intracerebroventricular injection of opioid peptides, selective
for various opioid receptors, have been analysed on apomorphine-induced alterations in behaviour (Ukai et al., 1989a; Ukai, Toyoshi and Kameyama, 1991). For example, the intracerebroventricular injection of dynorphin A(l-13) and DAMGO ([D-Ala’,NMePhe4,Gly(ol)S]enkephalin) produced an antagonistic effect on the apomorphine-induced increase in rearing behaviour (Ukai et al., 1989a, 1991). Dynorphin A( I- 13) also inhibited the behavioural effects of the D, dopamine agonist N-n-propyl-N-phenylethylp-(3-hydroxyphenyl)-ethylamine (RU 24213) but not those of the D, dopamine agonist 2,3,4,Stetrahydro7,8-dihydroxy-1-phenyl-lH-3-benzazepine (SKF 38393) (Ukai, Toyoshi and Kameyama, 1992). Although naloxone reportedly attenuates the locomotor-activating effect of cocaine (Houdi, Bardo and Van Loon, 1989), the involvement of opioid peptides, such as dynorphins, in different behavioural responses, induced by cocaine, remains poorly understood. In contrast, since it is possible that opioid peptides are very susceptible to enzymatic degradation and low permeability of the blood-brain barrier, after systemic administration (Goldstein, Tachibana, Lowney, Hunkapiller and Hood, 1979; Pardridge and Mietus, 1981), intracerebroventricular injections have frequently been used to evaluate the effects of opioid peptides. However, it is important to examine whether the systemic administration of opioid peptides exerts pharmacological effects through the
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M. UKAIet al.
844
blood-brain barrier (Terasaki, Hirai, Sato, Kang and Tsuji, 1989). In particular, k-selective opioid peptides, such as dynorphins, which lack dependence liability (Nakazawa, Kaneko, Yoshino, Tachibana, Goto, Taki and Yamatsu, 1991) seem to be effective in the therapy of cocaine psychosis. The present study was designed to determine the effects of systemic administration (i.p.) of the naturally-occurring opioid peptide dynorphin A( l- 13) (Cuello, 1983) on cocaine-induced behaviour by using multi-dimensional behavioural analyses. The effects of the opioid antagonist Mr 2266, with relatively high affinity for K opioid receptors (Ukai and Kameyama, 1985), were also evaluated to clarify the involvement of opioid receptors. METHODS
Animals Male ddY mice (Japan SLC, Inc.), weighing between 20-30 g, were employed in the experiments. The animals were randomly assigned to groups consisting of 8-10 mice per group. Before the experiments, the mice were given free access to food and water and individual mice were housed in a cage in a constantly illuminated room, at a temperature of 23 f 1°C and a relative humidity of 55 f 5%. The mice were used only once and were unfamiliar with the test box. The experiments were conducted between 10:00 a.m. and 6:00 p.m. in a soundattenuating room. Multi-dimensional analysis Immediately before multi-dimensional behavioural analyses, mice were selected according to the number of revolutions (range from 125 to 150 per 10 min for criterion) employing wheel cages to exclude animals having behavioural abnormalities, as much as possible. About 30% of the mice purchased were discarded for failing the criterion in the first measurement. The mice discarded were repeatedly put into wheel cages for selection on different days.
Fiild
Side View Iinternal
TopView
Finally, almost all of the mice purchased could be used in the study. Although behaviour was observed over a 30 min test period, divided into two portions, the data of the former 15 min period were solely displayed, because most of the behavioural responses were not markedly influenced during the latter 15 min period. The Animex II, equipped with an electronic microcomputer, was used for measuring the behaviour (Kameyama and Ukai, 198 1,1983; Ukai and Kameyama, 1984, 1985). The sensor consisted of three pairs of electrodes and formed a capacitor bridge. Once a mouse was placed in the space (150 x 210 x 140 mm) between the electrodes connected to field detectors, the value of the capacitor then depended upon the location of the mouse within that space. When converting the analogue signal, received by the detectors to a digital form, the d.c. voltage movement spectrum analyser classified the movement into 9 degrees (l/l, l/2, l/4, l/8, l/16, l/32, l/64, l/128 and l/256) (Fig. 1). The surface areas of the cage, in which mice could show behavioural responses (ambulation, rearing and circling) were 490 mm in distance. The 490 mm distance consisted of the length of the bottom of the cage (210 mm) and the walls of the cage (140mm x 2). Thus, the counters corresponded to the following sizes of movements: l/l ( x 490.0 mm) = 490.0 mm, l/2 ( x 490.0 mm) = 245.0 mm, l/4 ( x 490.0 mm) = l/S (x490.0mm)=61.3mm, l/16 122.5 mm, ( x 490.0 mm) = 30.6 mm, l/32 ( x 490.0 mm) = l/64 ( x 490.0 mm) = 7.7 mm, l/128 15.3 mm, ( x 490.0 mm) = 3.8 mm and l/256 ( x 490.0 mm) = 1.9 mm. The movement of greatest magnitude was principally registered on the l/l counter and the movement of the smallest magnitude, such as tremor, on the l/256 counter. Specific patterns of behaviour, induced by a drug, were registered on the counters as follows, linear locomotion on l/l, circling on l/4, rearing on l/16 and grooming on l/64 (Fig. 2). The sensitivity (%) of the device was adjusted according to the body weight (g) as follows, 20-21 g = 27%, 22-23 g = 26%, 24-25 g = 25%, 26-28 g = 24% and
Dotaotor
(internal1
Fig. 1. Block diagram of Animex II. A field detector gives d.c.-voltage changes, reflecting the shifted positions of an animal in a cage. A movement spectrum analyser can separate and classify the movements of the animal into 9 degrees. A microcomputer within the device provides instantaneous mean and SE calculations. This diagram has already been published elsewhere (Kameyama and Ukai, 1983).
Dynorphin A@-13) and cocaine-induced behaviour 160
a
220
+!! .a 8
100
k
60
2 3
40
80
20
20 Count for l/t
size of movements
40
60
80 100 120 140 160
Count for
I/4
size of movements
fO0
600,
[Df
90
540.
Y = 4.522X + 106.624 r = 0.762
80
580.
‘3 420.
40
10 20 30 40 50 60 70 80 90 100 Count for l/l6
p < 0.05 “=I6
20
30
Count for I/64
size of movements
40
50
60
70
80
size of movements
Fig. 2. Relationships between four sizes of movements and actual behavioural responses such as linear locomotion, circling, rearing and grooming. Linear locomotion (A), circling (B), rearing (C) and grooming (D) are highly correlated with the following movement sizes of l/i, l/4,1/16 and 1164,respectively. Among them, the data about 114(8) and f/i6 (C)sizes of movements have akeady been published efsewhere (Ukai et ai., I989b, 1991).
29-30 g = 23%. Each value in the tables was labelled “ratio (number of movements) = {value of drugtreated ~jrnals)/~rn~n value ofcontrols)". Additionally, a continuous recording of behaviour of the animal was made with X-Y recorders (Watanabe Inc., Japan), connected to the field detectors of the Animex II.
Cocaine hydro~hlo~de (Shionogi Pharmaceutical Co., Ltd, Japan), dynorphin A(l-13) (Peptide fnstitute Inc., Japan) and 5,9-diethyl-2-(3.furylmethyl)Zhydroxyd,7benzomorphan (Mr 2266, Boehringer lngelheim KG, Germany) were employed throughout. Cocaine was dissolved in isotonic saline (0.9% NaCl, pII 7.5). The Mr 2266 was dissolved in I .Oml 5% w/v ( + )-tartaric acid and the volume was made up with 0.9% saline. Cocaine (s.c.) and Mr 2266 (s.c.) were administered 25 and 15 min before the start of the behavioural measurements, respectively. Dynorphin A( l-13), dissolved in sterile isotonic saline in
polypropylene containers, was injected toneally 5min before the start. AnaIysis
intraperi-
of data
Data for actual values were analysed statistically by means of a one-factor analysis of variance (ANGVA). Post hoc analysis for between-group differences was carried out by the Newman-Keuls method for muhiple comparisons (Zar, 1984). Effects were considered statistically significant if P < 0.05. Data in the figures indicate ratios derived from actual values for the clearer presentation of results.
The drug (lO.Omg/kg) effects on ~3.~m~kg)
Mr 2266 (5.6 mg/kg), dynorphin A( l- f 3) or their combinations had no marked behavioural traces (Fig. 3). Cocaine produced a prominent increase in
M. UKAI et al.
846
SAL + SAL + DYN
COCA + Mr + SAL
SAL+SAL+SAL
SAL+Mr+SAL
SAL+Mr+DYN
COCA + SAi + SAL
COCA + SAL + DYN
COCA+Mr+ DYN
Fig. 3. Behavioural traces for each of the mice, treated with dynorphin A(l-13), cocaine, Mr 2266 and their combinations, within 15 min after the start of behavioural measurements. Top left-hand part of the figures shows: A, cage bottom; B, cage walls; SAL, 0.9% saline (s.c. or i.p.); DYN, dynorphin A(l-13) 10.0 mg/kg (i.p.); COCA, cocaine 3.0 mg/kg (s.c.); Mr, Mr 2266 5.6 mg/kg (s.c.).
horizontal and vertical movements, while dynorphin A( 1- 13) (10.0 mg/kg) decreased these movements induced by cocaine (3.0mg/kg). The effects of dynorphin A( I-13) were fully reversed by a 5.6 mg/kg dose of Mr2266 (Fig. 3). Effects of cocaine Analysis of variance showed a significant relationship (P < 0.01): F(4,45) = 25. 31 in linear locomotion, F(4,45) = 27.75 in circling, F(4,45) = 6. 77 in rearing and F(4,45) = 6.31 in grooming (Fig. 4). A 1.0 mg/kg dose of cocaine had no effects on
behaviour, whereas larger doses (3.0-30.0 mg/kg) of the drug produced a marked increase in linear locomotion, circling, rearing and grooming (Fig. 4). Effects of dynorphin A(l-13) Analysis of variance revealed a significant relationship (P < 0.05): F(3,36) = 4.04 in grooming. A 1.Omg/kg dose of dynorphin A( l-l 3) produced a significant decrease in grooming, although the peptide (3.0 and lO.Omg/kg) did not affect any behavioural patterns such as linear locomotion, circling, rearing or grooming (Table 1).
--- : Ball118 (ac) E : Cocaine 3 1 m@tg mm (S.C.) (8~) ::
Linear kmmotion
circling
R-m
:
30 10 NW manta(W c.a
Grooming
Fig. 4. Movements of mice after the administration of cocaine (l.O-30.0mg/kg). Values represent the means + SE for 10 mice. *Denotes signiticant difference from saline control, P < 0.05.
Dynorphin
A( l-i 3) and cocaine-induced behaviout
Table 1. Movements of mice after the administration A(I-13) (I&lO.Omg/kg)
of dynorphin
13) (10.0 mg/kg) were clearly reversed by Mr 2266 (5.6 mg/kg) (Fig. 6). DISCUSSION
Ikhaviour TraatmCItts (m&kit, i.p.) DYNi 3 IO
Linear locomotion
Circling
Rearing
Grooming
0.7*0.1 l.Of0.3 1.2kO.3
0.5*0.2 0.9 f 0.2 0.6kO.l
0.6f0.i 0.8 * 0.1 0.7kO.l
0.5*0.1+ 0.8 * 0.1 0.7fO.I
Values represent the means k SE for 10 mice. *Denotes significant difference from saline contro1, P < 0.05.
Eflects of dynor~hi~ A{l-13) behaoiour
847
on cocaine-creed
Analysis of variance revealed a significant reiationship (P < 0.05 or P < 0.01): F(4,55) = 7.55 in linear locomotion, F(4,55) = 6.88 in circling, F(4,55) = 3.91 in rearing and F(4,SS) = 2.86 in grooming. Cocaine (3.0 mgjkg) again produced a significant increase in linear locomotion, circling, rearing and grooming behaviours. Although dynorphin A(l-13) (1.0 and 3.0mg/kg) had no significant effects on cocaine (3.0 mg/kg)-induced behaviour, a 10.0 mg/kg dose of such peptide significantly attenuated the cocaine (3.0 mg/kg)-indu~ increase in different ~haviourai responses (Fig. 5). Eflects of iUr 2266 Analysis of variance showed a significant relationship (P < 0.01): F(7,104) = 18.0 in linear locomotion, F(7,104) = 9.35 in circling, F(7,104) = 16.59 in rearing and f;(7,104) = 4.0 in grooming. Dynorphin Afl13) (10.0 mg/kg), Mr 2266 (5.6 mg/kg) and their combinations did not significantly influence behaviour in the mice. Dynorphin A(l-13) (10.0 mg/kg) again prevented the cocaine (3.0 mg/kg)-induced increase in linear locomotion, circling and rearing behaviour. The inhibitory effects of dynorphin A(l-
The multi-dimensional behaviourai analyses were employed to determine the behavioural interaction of opioid peptides with dopamine neurones, by using multi-dimensional behaviourai analysers (Kameyama and Ukai, 1981, 1983; Ukai et al., 1989a). This apparatus can simultaneously analyse and record 9 different dimensions of behaviour in the mouse, based upon a capacitance system, demonstrating the close relationship between actual number of behavioural responses, such as linear locomotion, circling, rearing and grooming, observed by experimenters and counts for sizes of movements (Fig. 2). Thus the present study dealt with 4 kinds of behavioural patterns, mentioned above. A smaller dose (1 .Omg/kg) of the naturaliy-occurring opioid peptide dynorphin A(l-13) (Cueiio, 1983) produced a marked decrease in grooming behaviour, although larger doses (3.0 and lO.Omg/kg) of the peptide had no influence on any behaviour. iSimilarly, tram-( f )-3,4dichloro-N-methyl-N[2-( pyrroiidinyl)cyclohexyl] benzenacetamide emethane sulphonate (U-50,488H, i.p.), a nonpeptide K opioid compound, inhibited grooming behaviour (Ukai and Kameyama, 1985). Since the in~a~~brovent~c~ar injection of dynorphin A(l-13) (0.1-10.0 pg) has been reported to affect linear locomotion and rearing but not grooming behaviour (Ukai and Kameyama, 1984), the decrease in grooming may be mediated through peripheral K opioid receptors. There is evidence that cocaine binds to multiple receptor sites and interacts with several neuronal
--;
: Saline (s.c.) + Saline (i.p.) : Cooaine 3 mg&cg(8.c) + Saline (1.p.) + DYN 1 mgilq (i.p.) : + DYN 3 m@q (Lp.) 8: + DYN 10 mgikg (Lp.) 8:
Linearlocmohn
Circling
-mll
Grooming
Fig. 5. Movements of mice after the administration of cocaine (3.0 mg/kg), dynorpbin A(l-13) (DYN) (10.0 mg/kg) and their combinations. Values represent the means f SE for 12 mice. *Denotes significant difference from saline control, P c 0.05. Wenotes significant differen= from cocaine (3.0 mg/kg).
848
M. WAI et al.
- - - : sslhls (SE.) + ssurm (S.C.)+ sshs (hp.) : cocaifm 3 m!@cg (S.C.)+ Sam (8.C.)+ saine (I.P.)
+ Ml2263 5.6 m&kg (8.c.) + saline (1.P.) + Salha (s.c.) + DYN 10 trqlq (Lp.) + Mt2266 5.6 m@q (OS.) + DYN 10 mgtlq (19.)
Linear locomotion
Circling
Rearing
Grooming
Fig. 6. Movements of mice after the administration of cocaine (3.0 mg/kg), dynorphin A(l-13) (DYN) (10.0 mg/kg), Mr 2266 (5.6 mg/kg) and their combinations. Values represent the means f SE for 14 mice. *Denotes significant difference from saline control, P < 0.05. *Denotes significant difference from cocaine (3.0 mg/kg), P < 0.05. #Denotes significant differr;,t;m cocaine (3.0 mg/kg) plus DYN (10.0 mg/kg),
systems, that could modulate any of its behavioural effects (Johanson and Fischman, 1989). However, there is general agreement that the ability of cocaine to block the reuptake of dopamine by binding to dopamine transporters, plays a major role in its motor-activating effects (Johanson and Fischman, 1989; Ritz et al., 1987). Although the discriminative stimulus effects of cocaine are mediated through both D, and D, dopamine receptors (Callahan, Appel and Cunningham, 1991), it is possible that the motoractivating effects of cocaine are mediated through D, dopamine receptors, because it has been demonstrated that methamphetamine-induced behaviour, similar to that induced by cocaine, is exclusively mediated through D, dopamine receptors (Toyoshi, Ukai and Kameyama, 1991). It was demonstrated that the systemic administration of dynorphin A( 1- 13) (10.0 mg/kg) inhibited the marked increase in linear locomotion, circling and rearing behaviour induced by cocaine (3.0 mg/kg), while Houdi et al. (1989) have demonstrated that naloxone inhibited cocaine-induced hyperactivity and reinforcement. In addition, the effects of dynorphin A(l-13) (10.0 mg/kg, i.p.) were almost completely antagonized by Mr 2266 (5.6 mg/kg). It thus appears that the behavioural effects of cocaine are inhibited by endogenous K opioid peptides. Furthermore, the effects of dynorphin A( 1-13) would be centrally-mediated, because the intracerebroventricular injection of dynorphin A(l-13) (12.5 pg) likewise inhibits different behavioural responses such as linear locomotion, circling, rearing and grooming, induced by cocaine (3.0 mg/kg) (unpublished observation), although the possible involvement of peripheral effects of dynorphin A( l- 13) in the attenuation of cocaine-induced behavionr remains to be determined.
It was demonstrated that the non-specific dopamine agonist apomorphine (0.56 and 1.0 mg/kg)induced increase in rearing behaviour was completely inhibited by dynorphin A(l-13) (10.0 gg) (Ukai et al., 1989a). The inhibitory effects of dynorphin A( l- 13) (10.0 pg) are entirely reversed by the opioid antagonist Mr 2266 (Ukai et al., 1989a). The inhibitory effects of dynorphin A( l-13) on behaviour, induced by apomorphine, are considered to be elicited through D, dopamine receptors, inasmuch as it has been reported that dynorphin A(l-13) inhibits behavioural responses induced by the D, but not D, dopamine agonists (Ukai et al., 1992). Therefore, it appears that the preferential effects of dynorphin A( 1-13) on behaviour, through the mediation of D2 dopamine receptors, results in the inhibition of behavioural responses, induced by cocaine. Finally, this provides one of the new strategies that have been recently developed for the systemic administration of neuropeptides through the bloodbrain barrier (Terasaki et al., 1989). Dynorphin A( 1-13) would be one of the peptides, as potential neuropharmaceuticals in the therapy of cocaine abuse.
Acknowledgements-The authors thank Boehringer Ingelheim KG for the generous gift of Mr 2266. The secretarial work of Tetsuya Kobayashi is greatly appreciated.
REFERENCES Callahan P. M., Appel J. B. and Cunningham K. A. (1991) Dopamine D, and D, mediation of the discriminative stimulus properties of d-amphetamine and cocaine. Psychopharmacology 103: SO-55 Cue110A. C. (1983) Central distribution of opioid peptides. Br. Med. Bull. 39: 11-16.
Dynorphin A(l-13) and cocaine-induced behaviour Goldstein A., Tachibana S., Lowney L. I., Hunkapiller M. and Hood L. (1979) Dynorphin-(l-13), an extraordinary potent opioid peptide. Proc. nurn. Acud. Sci. U.S.A. 76: 6666-6670.
Houdi A. A., Bardo M. T. and Van Loon G. R. (1989) Opioid mediation of cocaine-induced hyperactivity and reinforcement. Brain Res. 497: 195198. Jaffe J. (1985) Drug addiction and drug abuse. In: The Pharmkolo&al Basis of Therapeutics(Gilman A. G., Goodman L. S.. Rall T. W. and Murad F.. Eds). pp. 532-58 1. Macmillan, New York. Johanson C.-E. and Fischman M. W. (1989) The pharmacology of cocaine related to its abuse. Pharmac. Rev. 41: I,
3-52.
Kameyama T. and Ukai M. (1981) Multi-dimensional analyses of behavior in mice treated with a-endorphin. Neuropharmacology 20: 247-250.
Kameyama T. and Ukai M. (1983) Multi-dimensional analyses of behavior in mice treated with morphine, endorphins and [destyrosine’l-y-endorphin. Pharmac. Biochem. Behav. 19, 671-677.
Nakaxawa T., Kaneko T., Yoshino H., Tachibana S., Goto M., Taki T. and Yamatsu K. (1991) Physical dependence liability of dynorphin A analogs in rodents. Eur. J. Pharmac. 201: 185-189. Pardridge W. M. and Mietus L. J. (1981) Enkephalin and blood-brain barrier: studies of binding and degradation in isolated brain microvessels. Endocrinology 109: 1138-1143. Ritz M. C., Lamb R. J., Goldberg S. R. and Kuhar M. J. (1987) Cocaine receptors on dopamine transporters are related to self-administration of cocaine. Science, Wash. DC 237: 1219-1224. Terasaki T., Hirai K.-I., Sato H., Kang Y. S. and Tsuji A. (1989) Absorptive-mediated endocytosis of a dynorphin-
849
like analgesic peptide, E-2078, into the blood-brain barrier. J. Pharmac. exp. Ther. 251: 351-357. Toyoshi T., Ukai M. and Kameyama T. (1991) Effects of dynorphin A(l-13) on the methamphetamine-induced behaviors in the mouse, using multi-dimensional behavioral analyses. Jap. J. Phurmac. 55: Suppl. I, 210P. Ukai M. and Kameyama T. (1984) The antagonistic effects of naloxone on hypermotility in mice induced by dynorphin A(l-13) using a multi-dimensional behavioral analysis. Neuropharmacology 23: 165-168. Ukai M. and Kameyama T. (1985) Multi-dimensional analyses of behavior in mice treated with U-50,488H, a purported kappa (non-mu) opioid agonist. Brain Res. 337: 352-356.
Ukai M., Toyoshi T. and Kameyama T. (1989a) Dynorphin A( l-l 3) modulates apomorphine-induced behaviors using multi-dimensional behavioral analyses in the mouse. Brain Res. 499: 299-304.
Ukai M., Toyoshi T. and Kameyama T. (1989b) Multidimensional analysis of behavior in mice treated with the delta opioid agonists DADL (D-Ala*-o-Leur-enkephalin) and DPLPE (D-Pen’-L-Pen’-enkenhalin). Neurooharma. cology UI: 1033-1039. Ukai M., Toyoshi T. and Kameyama T. (1991) DAGO ([o-Ala’,N-MePhe4, Gly(ol)]enkephalin) specifically mverses apomorphine-induced increase in rearing and grooming behaviors in the mouse. Brain Res. 557: I
77-82.
Ukai M., Toyoshi T. and Kameyama T. (1992) Dynorphin A( I-13) preferentially inhibits behaviors induced by the D, donamine agonist RU 24213 but not by the D, dopamme agonist SKF 38393. Pharmac. Biochek. Behav: In press. Zar J. H. (1984) Biostatistical Analysis, 2nd edn, pp. 190-191. Prentice-Hall, Englewood Cliffs.
0028-3908/92 s5.00 + 0.00
Copyright0 1992PergamonPressLtd
SYSTEMIC ADMINISTRATION OF DYNORPHIN A(l-13) MARKEDLY INHIBITS DIFFERENT BEHAVIOURAL RESPONSES INDUCED BY COCAINE IN THE MOUSE M. UKAI, T. KAMIYA,T. TOYOSHIand T. KAMEYAMA Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya 468, Japan (Accepted 12 May 1992)
Summary-The effects of systemic administration (i.p.) of dynorphin A(l-13) on the cocaine-induced behavioural alterations in the mouse were determined by using multi-dimensional behavioural analyses, based upon a capacitance system. A l.Omg/kg dose of cocaine did not influence behaviour, while increasing doses to 3-30 mg/kg produced a significant increment in the frequency of behaviour, such as linear locomotion, circling, rearing and grooming. Although a 1.Omg/kg dose of dynorphin A( l- 13) alone produced a significant decrease in grooming behaviour, larger doses (3.0 and 10.0 mg/kg) of the peptide failed to affect different behaviour. The cocaine (3.0mg/kg)-induced increases in linear locomotion, circling and rearing behaviour were significantly inhibited by dynorphin A(l-13) (10.0 mg/kg). The inhibitory effects of dynorphin A(l-13) (10.0 mg/kg) were antagonized by the opioid antagonist Mr 2266 (5.6 mg/kg). It is thus possible that the systemic administration of dynorphin A(l-13) inhibits different behavioural responses induced by cocaine through the blood-brain barrier, although the instability of amino acid bonds or the relatively large molecular weight of dynorphin A(l-13), may result in the failure to demonstrate opioid activity by the peptide after systemic administration. Key words-dynorphin
A(l-13), cocaine, Mr 2266, locomotor activity, mouse.
Cocaine is one of the psychomotor stimulants which possesses prominent subjective effects, resulting in its abuse (Jaffe, 1985). Although neuropharmacological investigations suggest that various biogenic amines play an important role in rewarding or reinforcing responses to cocaine, the inhibition of the reuptake of dopamine by binding to dopamine transporters, seems to underlie the behavioural effects of cocaine (Ritz, Lamb, Goldberg and Kuhar, 1987). The behavioural effects of intracerebroventricular injections of opioid peptides have been demonstrated by using multi-dimensional behavioural analysers, based upon a capacitance system in which 9 different parameters of behaviour can be detected simultaneously (Kameyama and Ukai, 1981, 1983; Ukai and Kameyama, 1984, 1985; Ukai, Toyoshi and Kameyama, 1989a, b). For instance, a- and y-endorphins produce a marked increase in linear locomotion, without affecting other behavioural measures (Kameyama and Ukai, 1981, 1983), while p-endorphin produces a significant decrease in almost all behaviour (Kameyama and Ukai, 1983). In particular, the IEopioid agonist dynorphin A(l-13) has been reported to produce a biphasic effect, i.e. naloxonereversible marked increase in linear locomotion at smaller doses (0.3 and 1.0 pg); no marked effects at larger doses (3.0 and 10.0 pg) (Ukai and Kameyama, 1984). Moreover, previously the effects of intracerebroventricular injection of opioid peptides, selective
for various opioid receptors, have been analysed on apomorphine-induced alterations in behaviour (Ukai et al., 1989a; Ukai, Toyoshi and Kameyama, 1991). For example, the intracerebroventricular injection of dynorphin A(l-13) and DAMGO ([D-Ala’,NMePhe4,Gly(ol)S]enkephalin) produced an antagonistic effect on the apomorphine-induced increase in rearing behaviour (Ukai et al., 1989a, 1991). Dynorphin A( I- 13) also inhibited the behavioural effects of the D, dopamine agonist N-n-propyl-N-phenylethylp-(3-hydroxyphenyl)-ethylamine (RU 24213) but not those of the D, dopamine agonist 2,3,4,Stetrahydro7,8-dihydroxy-1-phenyl-lH-3-benzazepine (SKF 38393) (Ukai, Toyoshi and Kameyama, 1992). Although naloxone reportedly attenuates the locomotor-activating effect of cocaine (Houdi, Bardo and Van Loon, 1989), the involvement of opioid peptides, such as dynorphins, in different behavioural responses, induced by cocaine, remains poorly understood. In contrast, since it is possible that opioid peptides are very susceptible to enzymatic degradation and low permeability of the blood-brain barrier, after systemic administration (Goldstein, Tachibana, Lowney, Hunkapiller and Hood, 1979; Pardridge and Mietus, 1981), intracerebroventricular injections have frequently been used to evaluate the effects of opioid peptides. However, it is important to examine whether the systemic administration of opioid peptides exerts pharmacological effects through the
843
M. UKAIet al.
844
blood-brain barrier (Terasaki, Hirai, Sato, Kang and Tsuji, 1989). In particular, k-selective opioid peptides, such as dynorphins, which lack dependence liability (Nakazawa, Kaneko, Yoshino, Tachibana, Goto, Taki and Yamatsu, 1991) seem to be effective in the therapy of cocaine psychosis. The present study was designed to determine the effects of systemic administration (i.p.) of the naturally-occurring opioid peptide dynorphin A( l- 13) (Cuello, 1983) on cocaine-induced behaviour by using multi-dimensional behavioural analyses. The effects of the opioid antagonist Mr 2266, with relatively high affinity for K opioid receptors (Ukai and Kameyama, 1985), were also evaluated to clarify the involvement of opioid receptors. METHODS
Animals Male ddY mice (Japan SLC, Inc.), weighing between 20-30 g, were employed in the experiments. The animals were randomly assigned to groups consisting of 8-10 mice per group. Before the experiments, the mice were given free access to food and water and individual mice were housed in a cage in a constantly illuminated room, at a temperature of 23 f 1°C and a relative humidity of 55 f 5%. The mice were used only once and were unfamiliar with the test box. The experiments were conducted between 10:00 a.m. and 6:00 p.m. in a soundattenuating room. Multi-dimensional analysis Immediately before multi-dimensional behavioural analyses, mice were selected according to the number of revolutions (range from 125 to 150 per 10 min for criterion) employing wheel cages to exclude animals having behavioural abnormalities, as much as possible. About 30% of the mice purchased were discarded for failing the criterion in the first measurement. The mice discarded were repeatedly put into wheel cages for selection on different days.
Fiild
Side View Iinternal
TopView
Finally, almost all of the mice purchased could be used in the study. Although behaviour was observed over a 30 min test period, divided into two portions, the data of the former 15 min period were solely displayed, because most of the behavioural responses were not markedly influenced during the latter 15 min period. The Animex II, equipped with an electronic microcomputer, was used for measuring the behaviour (Kameyama and Ukai, 198 1,1983; Ukai and Kameyama, 1984, 1985). The sensor consisted of three pairs of electrodes and formed a capacitor bridge. Once a mouse was placed in the space (150 x 210 x 140 mm) between the electrodes connected to field detectors, the value of the capacitor then depended upon the location of the mouse within that space. When converting the analogue signal, received by the detectors to a digital form, the d.c. voltage movement spectrum analyser classified the movement into 9 degrees (l/l, l/2, l/4, l/8, l/16, l/32, l/64, l/128 and l/256) (Fig. 1). The surface areas of the cage, in which mice could show behavioural responses (ambulation, rearing and circling) were 490 mm in distance. The 490 mm distance consisted of the length of the bottom of the cage (210 mm) and the walls of the cage (140mm x 2). Thus, the counters corresponded to the following sizes of movements: l/l ( x 490.0 mm) = 490.0 mm, l/2 ( x 490.0 mm) = 245.0 mm, l/4 ( x 490.0 mm) = l/S (x490.0mm)=61.3mm, l/16 122.5 mm, ( x 490.0 mm) = 30.6 mm, l/32 ( x 490.0 mm) = l/64 ( x 490.0 mm) = 7.7 mm, l/128 15.3 mm, ( x 490.0 mm) = 3.8 mm and l/256 ( x 490.0 mm) = 1.9 mm. The movement of greatest magnitude was principally registered on the l/l counter and the movement of the smallest magnitude, such as tremor, on the l/256 counter. Specific patterns of behaviour, induced by a drug, were registered on the counters as follows, linear locomotion on l/l, circling on l/4, rearing on l/16 and grooming on l/64 (Fig. 2). The sensitivity (%) of the device was adjusted according to the body weight (g) as follows, 20-21 g = 27%, 22-23 g = 26%, 24-25 g = 25%, 26-28 g = 24% and
Dotaotor
(internal1
Fig. 1. Block diagram of Animex II. A field detector gives d.c.-voltage changes, reflecting the shifted positions of an animal in a cage. A movement spectrum analyser can separate and classify the movements of the animal into 9 degrees. A microcomputer within the device provides instantaneous mean and SE calculations. This diagram has already been published elsewhere (Kameyama and Ukai, 1983).
Dynorphin A@-13) and cocaine-induced behaviour 160
a
220
+!! .a 8
100
k
60
2 3
40
80
20
20 Count for l/t
size of movements
40
60
80 100 120 140 160
Count for
I/4
size of movements
fO0
600,
[Df
90
540.
Y = 4.522X + 106.624 r = 0.762
80
580.
‘3 420.
40
10 20 30 40 50 60 70 80 90 100 Count for l/l6
p < 0.05 “=I6
20
30
Count for I/64
size of movements
40
50
60
70
80
size of movements
Fig. 2. Relationships between four sizes of movements and actual behavioural responses such as linear locomotion, circling, rearing and grooming. Linear locomotion (A), circling (B), rearing (C) and grooming (D) are highly correlated with the following movement sizes of l/i, l/4,1/16 and 1164,respectively. Among them, the data about 114(8) and f/i6 (C)sizes of movements have akeady been published efsewhere (Ukai et ai., I989b, 1991).
29-30 g = 23%. Each value in the tables was labelled “ratio (number of movements) = {value of drugtreated ~jrnals)/~rn~n value ofcontrols)". Additionally, a continuous recording of behaviour of the animal was made with X-Y recorders (Watanabe Inc., Japan), connected to the field detectors of the Animex II.
Cocaine hydro~hlo~de (Shionogi Pharmaceutical Co., Ltd, Japan), dynorphin A(l-13) (Peptide fnstitute Inc., Japan) and 5,9-diethyl-2-(3.furylmethyl)Zhydroxyd,7benzomorphan (Mr 2266, Boehringer lngelheim KG, Germany) were employed throughout. Cocaine was dissolved in isotonic saline (0.9% NaCl, pII 7.5). The Mr 2266 was dissolved in I .Oml 5% w/v ( + )-tartaric acid and the volume was made up with 0.9% saline. Cocaine (s.c.) and Mr 2266 (s.c.) were administered 25 and 15 min before the start of the behavioural measurements, respectively. Dynorphin A( l-13), dissolved in sterile isotonic saline in
polypropylene containers, was injected toneally 5min before the start. AnaIysis
intraperi-
of data
Data for actual values were analysed statistically by means of a one-factor analysis of variance (ANGVA). Post hoc analysis for between-group differences was carried out by the Newman-Keuls method for muhiple comparisons (Zar, 1984). Effects were considered statistically significant if P < 0.05. Data in the figures indicate ratios derived from actual values for the clearer presentation of results.
The drug (lO.Omg/kg) effects on ~3.~m~kg)
Mr 2266 (5.6 mg/kg), dynorphin A( l- f 3) or their combinations had no marked behavioural traces (Fig. 3). Cocaine produced a prominent increase in
M. UKAI et al.
846
SAL + SAL + DYN
COCA + Mr + SAL
SAL+SAL+SAL
SAL+Mr+SAL
SAL+Mr+DYN
COCA + SAi + SAL
COCA + SAL + DYN
COCA+Mr+ DYN
Fig. 3. Behavioural traces for each of the mice, treated with dynorphin A(l-13), cocaine, Mr 2266 and their combinations, within 15 min after the start of behavioural measurements. Top left-hand part of the figures shows: A, cage bottom; B, cage walls; SAL, 0.9% saline (s.c. or i.p.); DYN, dynorphin A(l-13) 10.0 mg/kg (i.p.); COCA, cocaine 3.0 mg/kg (s.c.); Mr, Mr 2266 5.6 mg/kg (s.c.).
horizontal and vertical movements, while dynorphin A( 1- 13) (10.0 mg/kg) decreased these movements induced by cocaine (3.0mg/kg). The effects of dynorphin A( I-13) were fully reversed by a 5.6 mg/kg dose of Mr2266 (Fig. 3). Effects of cocaine Analysis of variance showed a significant relationship (P < 0.01): F(4,45) = 25. 31 in linear locomotion, F(4,45) = 27.75 in circling, F(4,45) = 6. 77 in rearing and F(4,45) = 6.31 in grooming (Fig. 4). A 1.0 mg/kg dose of cocaine had no effects on
behaviour, whereas larger doses (3.0-30.0 mg/kg) of the drug produced a marked increase in linear locomotion, circling, rearing and grooming (Fig. 4). Effects of dynorphin A(l-13) Analysis of variance revealed a significant relationship (P < 0.05): F(3,36) = 4.04 in grooming. A 1.Omg/kg dose of dynorphin A( l-l 3) produced a significant decrease in grooming, although the peptide (3.0 and lO.Omg/kg) did not affect any behavioural patterns such as linear locomotion, circling, rearing or grooming (Table 1).
--- : Ball118 (ac) E : Cocaine 3 1 m@tg mm (S.C.) (8~) ::
Linear kmmotion
circling
R-m
:
30 10 NW manta(W c.a
Grooming
Fig. 4. Movements of mice after the administration of cocaine (l.O-30.0mg/kg). Values represent the means + SE for 10 mice. *Denotes signiticant difference from saline control, P < 0.05.
Dynorphin
A( l-i 3) and cocaine-induced behaviout
Table 1. Movements of mice after the administration A(I-13) (I&lO.Omg/kg)
of dynorphin
13) (10.0 mg/kg) were clearly reversed by Mr 2266 (5.6 mg/kg) (Fig. 6). DISCUSSION
Ikhaviour TraatmCItts (m&kit, i.p.) DYNi 3 IO
Linear locomotion
Circling
Rearing
Grooming
0.7*0.1 l.Of0.3 1.2kO.3
0.5*0.2 0.9 f 0.2 0.6kO.l
0.6f0.i 0.8 * 0.1 0.7kO.l
0.5*0.1+ 0.8 * 0.1 0.7fO.I
Values represent the means k SE for 10 mice. *Denotes significant difference from saline contro1, P < 0.05.
Eflects of dynor~hi~ A{l-13) behaoiour
847
on cocaine-creed
Analysis of variance revealed a significant reiationship (P < 0.05 or P < 0.01): F(4,55) = 7.55 in linear locomotion, F(4,55) = 6.88 in circling, F(4,55) = 3.91 in rearing and F(4,SS) = 2.86 in grooming. Cocaine (3.0 mgjkg) again produced a significant increase in linear locomotion, circling, rearing and grooming behaviours. Although dynorphin A(l-13) (1.0 and 3.0mg/kg) had no significant effects on cocaine (3.0 mg/kg)-induced behaviour, a 10.0 mg/kg dose of such peptide significantly attenuated the cocaine (3.0 mg/kg)-indu~ increase in different ~haviourai responses (Fig. 5). Eflects of iUr 2266 Analysis of variance showed a significant relationship (P < 0.01): F(7,104) = 18.0 in linear locomotion, F(7,104) = 9.35 in circling, F(7,104) = 16.59 in rearing and f;(7,104) = 4.0 in grooming. Dynorphin Afl13) (10.0 mg/kg), Mr 2266 (5.6 mg/kg) and their combinations did not significantly influence behaviour in the mice. Dynorphin A(l-13) (10.0 mg/kg) again prevented the cocaine (3.0 mg/kg)-induced increase in linear locomotion, circling and rearing behaviour. The inhibitory effects of dynorphin A(l-
The multi-dimensional behaviourai analyses were employed to determine the behavioural interaction of opioid peptides with dopamine neurones, by using multi-dimensional behaviourai analysers (Kameyama and Ukai, 1981, 1983; Ukai et al., 1989a). This apparatus can simultaneously analyse and record 9 different dimensions of behaviour in the mouse, based upon a capacitance system, demonstrating the close relationship between actual number of behavioural responses, such as linear locomotion, circling, rearing and grooming, observed by experimenters and counts for sizes of movements (Fig. 2). Thus the present study dealt with 4 kinds of behavioural patterns, mentioned above. A smaller dose (1 .Omg/kg) of the naturaliy-occurring opioid peptide dynorphin A(l-13) (Cueiio, 1983) produced a marked decrease in grooming behaviour, although larger doses (3.0 and lO.Omg/kg) of the peptide had no influence on any behaviour. iSimilarly, tram-( f )-3,4dichloro-N-methyl-N[2-( pyrroiidinyl)cyclohexyl] benzenacetamide emethane sulphonate (U-50,488H, i.p.), a nonpeptide K opioid compound, inhibited grooming behaviour (Ukai and Kameyama, 1985). Since the in~a~~brovent~c~ar injection of dynorphin A(l-13) (0.1-10.0 pg) has been reported to affect linear locomotion and rearing but not grooming behaviour (Ukai and Kameyama, 1984), the decrease in grooming may be mediated through peripheral K opioid receptors. There is evidence that cocaine binds to multiple receptor sites and interacts with several neuronal
--;
: Saline (s.c.) + Saline (i.p.) : Cooaine 3 mg&cg(8.c) + Saline (1.p.) + DYN 1 mgilq (i.p.) : + DYN 3 m@q (Lp.) 8: + DYN 10 mgikg (Lp.) 8:
Linearlocmohn
Circling
-mll
Grooming
Fig. 5. Movements of mice after the administration of cocaine (3.0 mg/kg), dynorpbin A(l-13) (DYN) (10.0 mg/kg) and their combinations. Values represent the means f SE for 12 mice. *Denotes significant difference from saline control, P c 0.05. Wenotes significant differen= from cocaine (3.0 mg/kg).
848
M. WAI et al.
- - - : sslhls (SE.) + ssurm (S.C.)+ sshs (hp.) : cocaifm 3 m!@cg (S.C.)+ Sam (8.C.)+ saine (I.P.)
+ Ml2263 5.6 m&kg (8.c.) + saline (1.P.) + Salha (s.c.) + DYN 10 trqlq (Lp.) + Mt2266 5.6 m@q (OS.) + DYN 10 mgtlq (19.)
Linear locomotion
Circling
Rearing
Grooming
Fig. 6. Movements of mice after the administration of cocaine (3.0 mg/kg), dynorphin A(l-13) (DYN) (10.0 mg/kg), Mr 2266 (5.6 mg/kg) and their combinations. Values represent the means f SE for 14 mice. *Denotes significant difference from saline control, P < 0.05. *Denotes significant difference from cocaine (3.0 mg/kg), P < 0.05. #Denotes significant differr;,t;m cocaine (3.0 mg/kg) plus DYN (10.0 mg/kg),
systems, that could modulate any of its behavioural effects (Johanson and Fischman, 1989). However, there is general agreement that the ability of cocaine to block the reuptake of dopamine by binding to dopamine transporters, plays a major role in its motor-activating effects (Johanson and Fischman, 1989; Ritz et al., 1987). Although the discriminative stimulus effects of cocaine are mediated through both D, and D, dopamine receptors (Callahan, Appel and Cunningham, 1991), it is possible that the motoractivating effects of cocaine are mediated through D, dopamine receptors, because it has been demonstrated that methamphetamine-induced behaviour, similar to that induced by cocaine, is exclusively mediated through D, dopamine receptors (Toyoshi, Ukai and Kameyama, 1991). It was demonstrated that the systemic administration of dynorphin A( 1- 13) (10.0 mg/kg) inhibited the marked increase in linear locomotion, circling and rearing behaviour induced by cocaine (3.0 mg/kg), while Houdi et al. (1989) have demonstrated that naloxone inhibited cocaine-induced hyperactivity and reinforcement. In addition, the effects of dynorphin A(l-13) (10.0 mg/kg, i.p.) were almost completely antagonized by Mr 2266 (5.6 mg/kg). It thus appears that the behavioural effects of cocaine are inhibited by endogenous K opioid peptides. Furthermore, the effects of dynorphin A( 1-13) would be centrally-mediated, because the intracerebroventricular injection of dynorphin A(l-13) (12.5 pg) likewise inhibits different behavioural responses such as linear locomotion, circling, rearing and grooming, induced by cocaine (3.0 mg/kg) (unpublished observation), although the possible involvement of peripheral effects of dynorphin A( l- 13) in the attenuation of cocaine-induced behavionr remains to be determined.
It was demonstrated that the non-specific dopamine agonist apomorphine (0.56 and 1.0 mg/kg)induced increase in rearing behaviour was completely inhibited by dynorphin A(l-13) (10.0 gg) (Ukai et al., 1989a). The inhibitory effects of dynorphin A( l- 13) (10.0 pg) are entirely reversed by the opioid antagonist Mr 2266 (Ukai et al., 1989a). The inhibitory effects of dynorphin A( l-13) on behaviour, induced by apomorphine, are considered to be elicited through D, dopamine receptors, inasmuch as it has been reported that dynorphin A(l-13) inhibits behavioural responses induced by the D, but not D, dopamine agonists (Ukai et al., 1992). Therefore, it appears that the preferential effects of dynorphin A( 1-13) on behaviour, through the mediation of D2 dopamine receptors, results in the inhibition of behavioural responses, induced by cocaine. Finally, this provides one of the new strategies that have been recently developed for the systemic administration of neuropeptides through the bloodbrain barrier (Terasaki et al., 1989). Dynorphin A( 1-13) would be one of the peptides, as potential neuropharmaceuticals in the therapy of cocaine abuse.
Acknowledgements-The authors thank Boehringer Ingelheim KG for the generous gift of Mr 2266. The secretarial work of Tetsuya Kobayashi is greatly appreciated.
REFERENCES Callahan P. M., Appel J. B. and Cunningham K. A. (1991) Dopamine D, and D, mediation of the discriminative stimulus properties of d-amphetamine and cocaine. Psychopharmacology 103: SO-55 Cue110A. C. (1983) Central distribution of opioid peptides. Br. Med. Bull. 39: 11-16.
Dynorphin A(l-13) and cocaine-induced behaviour Goldstein A., Tachibana S., Lowney L. I., Hunkapiller M. and Hood L. (1979) Dynorphin-(l-13), an extraordinary potent opioid peptide. Proc. nurn. Acud. Sci. U.S.A. 76: 6666-6670.
Houdi A. A., Bardo M. T. and Van Loon G. R. (1989) Opioid mediation of cocaine-induced hyperactivity and reinforcement. Brain Res. 497: 195198. Jaffe J. (1985) Drug addiction and drug abuse. In: The Pharmkolo&al Basis of Therapeutics(Gilman A. G., Goodman L. S.. Rall T. W. and Murad F.. Eds). pp. 532-58 1. Macmillan, New York. Johanson C.-E. and Fischman M. W. (1989) The pharmacology of cocaine related to its abuse. Pharmac. Rev. 41: I,
3-52.
Kameyama T. and Ukai M. (1981) Multi-dimensional analyses of behavior in mice treated with a-endorphin. Neuropharmacology 20: 247-250.
Kameyama T. and Ukai M. (1983) Multi-dimensional analyses of behavior in mice treated with morphine, endorphins and [destyrosine’l-y-endorphin. Pharmac. Biochem. Behav. 19, 671-677.
Nakaxawa T., Kaneko T., Yoshino H., Tachibana S., Goto M., Taki T. and Yamatsu K. (1991) Physical dependence liability of dynorphin A analogs in rodents. Eur. J. Pharmac. 201: 185-189. Pardridge W. M. and Mietus L. J. (1981) Enkephalin and blood-brain barrier: studies of binding and degradation in isolated brain microvessels. Endocrinology 109: 1138-1143. Ritz M. C., Lamb R. J., Goldberg S. R. and Kuhar M. J. (1987) Cocaine receptors on dopamine transporters are related to self-administration of cocaine. Science, Wash. DC 237: 1219-1224. Terasaki T., Hirai K.-I., Sato H., Kang Y. S. and Tsuji A. (1989) Absorptive-mediated endocytosis of a dynorphin-
849
like analgesic peptide, E-2078, into the blood-brain barrier. J. Pharmac. exp. Ther. 251: 351-357. Toyoshi T., Ukai M. and Kameyama T. (1991) Effects of dynorphin A(l-13) on the methamphetamine-induced behaviors in the mouse, using multi-dimensional behavioral analyses. Jap. J. Phurmac. 55: Suppl. I, 210P. Ukai M. and Kameyama T. (1984) The antagonistic effects of naloxone on hypermotility in mice induced by dynorphin A(l-13) using a multi-dimensional behavioral analysis. Neuropharmacology 23: 165-168. Ukai M. and Kameyama T. (1985) Multi-dimensional analyses of behavior in mice treated with U-50,488H, a purported kappa (non-mu) opioid agonist. Brain Res. 337: 352-356.
Ukai M., Toyoshi T. and Kameyama T. (1989a) Dynorphin A( l-l 3) modulates apomorphine-induced behaviors using multi-dimensional behavioral analyses in the mouse. Brain Res. 499: 299-304.
Ukai M., Toyoshi T. and Kameyama T. (1989b) Multidimensional analysis of behavior in mice treated with the delta opioid agonists DADL (D-Ala*-o-Leur-enkephalin) and DPLPE (D-Pen’-L-Pen’-enkenhalin). Neurooharma. cology UI: 1033-1039. Ukai M., Toyoshi T. and Kameyama T. (1991) DAGO ([o-Ala’,N-MePhe4, Gly(ol)]enkephalin) specifically mverses apomorphine-induced increase in rearing and grooming behaviors in the mouse. Brain Res. 557: I
77-82.
Ukai M., Toyoshi T. and Kameyama T. (1992) Dynorphin A( I-13) preferentially inhibits behaviors induced by the D, donamine agonist RU 24213 but not by the D, dopamme agonist SKF 38393. Pharmac. Biochek. Behav: In press. Zar J. H. (1984) Biostatistical Analysis, 2nd edn, pp. 190-191. Prentice-Hall, Englewood Cliffs.
