M)?X-3~S~79:0901-0723102.W
Npun~pkur~~~r,l~?. Vol. 18. pp. 723 to 725 Q Pergamon Press Ltd lY7Y. Printed m Great Britain
0
A SIMPLE DEVICE TO MEASURE STEREOTYPED REARING OF THE RAT IN AN OBJECTIVE AND QUANTITATIVE WAY L.
DECSI,
E. Glics, KATALINZ.bm6 and JULIA NAGY
Institute of Pharmacotogy,
University Medical School, H-7443, Hungary
(Accepted
14 March 1979)
~mmary-An
inexpensive and simple device is described which measures stereotyped rearing of the rat automatically. The apparatus works on the principle of capacitance changes of an oscillator system, these changes being caused by postural changes, in this case by the rearing of the animal. Whenever the rat is standing on the hind feet with the head over a constant, but deliberately adjustable level, the change in capacitance starts a digital counter which measures and totalizes the time spent in this position with a freely-chosen accuracy (0.1 set in the present case). The efficiency of the method has been checked by measuring the stereotypy caused by various doses of intraneritoneal anomornhine and the dose-related inhibition of this effect by bilateral intracaudate pretreatment with thperidol.
Drug-effects on the function of the nigrostriatal system have been the subject of a vast amount of investigation during the last 10-15 years. Disregarding the rotatory responses the most often used pharmacological method is probably the study of so-called stereotyped behaviour of animals evoked by dopaminergic and/or direct or indirect adrenergic stimulation of the nigrostriatal system. This stereotypy consists of several components, out of which the rearing response is very characteristic of the rat. For this reason it
“anything” is the rat; it is placed between two metal plates (which actually is the condenser). Whenever the rat is standing on the hind feet with the head over a constant, but deliberately adjustable level, the change in capacitance reaches such a degree as to alter the frequency of an oscillator connected to the condenser system. This alteration is the input signal to a digital counter; thus, when the animal is in a rearing posture the counter measures and totalizes the time spent in this position with an accuracy of 0.1 set (this can he 0.01 or even 0.001 set: depending on the construction). This accuracy (0.1 set) is more than enough, for the inevitable hysteresis of the apparatus (i.e. the delay of switching-0~ lies in about this order of ma~itude.
is surprising how few attempts have been made to measure this stereotypy, or some components of it,
in an objective and quantitative way. Most of the authors are satisfied to use subjective and, so, only ~miquantitative methods (e.g. scoring by gross ob~rvat~on). A very good approach to make the investigations objective and quantitative is that of Kotasiewin and Wolfarth (1973, who developed a simple, but very reliable method to measure one of the components, i.e. the gnawing, of stereotyped behaviour in the rabbit. In the rat, a very characteristic component, of stereotyped behaviour is the rearing of the animal. It is the aim of the present paper to describe a simple and inexpensive device that allows measurement of the rearing response automatically and, thus, in a fully objective and quantitative manner. A similar method has been used by Bryan and Ellison (1975); the first application of the principle of the procedure to be described dates back to Zucker and Howard (1968). The method is based on the principle that the capacitance of a surface-condenser system will be changed when the distance between the two plates changes or, when anything conducting electricity is placed between them. The more close this “anything” to the two condenser plates the greater is the change in the capacitance of the system. In the present case the
DESCRIIWON
OF APPARATUS
(Fig. la, b) The rat is put in a cage the bottom and top walls of which are made of metal plate (steel, copper or aluminium; the latter being more practical) while the other ones are of insulating material (wood and/or plexiglas). Thus, the bottom and top plates make a capacitive system, the capacitance of which depends on the geometric data (C,) of the cage, including the posture of the animal within the cage (AC,). Thus, the total capacitance is C, + AC,, plus the dielectric con: stant of the cage. Whenever the rat takes a rearing posture component AC, will change. This C, + AC, capacitance is a part of the oscillator capacitance of a Clapp-oscillator built of transistor T,. From this it follows that any change in C, + AC, will after the oscillation frequency, too. The signal level, i.e. the height of rearing that starts to alter this frequency can be adjusted by means of the trimming capacitance C, which is parallet connected to C,. Thus, the digital display system receives the
123
L. DECSI,E. Grits, KATALINZAt& and
KILIA NAGY
t.timer 0
Fig. I(a). Block diagram of the apparatus. 0
Fig. I(b). Circuit
0
diagram of the apparatus.
input signal only in the case when the ascillator’s frequency (which is a function of AC, + C,, when the constant Cb is disregarded) is within the range of the hand-pass filter. Thus, the principb of measurement is that changes in AC, cause an alteration in the master oscillator’s frequency, which alteration will then be detected by the digitai display system. The frequency of the oscillator is: 1 Wg = L,(Cb t C, + AC, + CJ where: c, = capacitance of the empty cage
C, = adjustable capacitance AC, = capacitance change depending on the posture of the animal in the cage C, = sum of the dispersed capacitances LI = inductance of the oscillator EXAMPLES ~EMUNSTRATING
circuit THE
EFFICIENCY OF THE APPARA~I.~~ i[t is common-pear that systemic a~rn~r~hi~e (APO) ap~i~ation evokes stereotyped behaviour in the rat. Tabfe 1 demonstrates the dose-dependent nature of this action. A~rnar~hi~e was injected 5 min before beginning the m~surement. R-Amster-
725
New device to measure stereotypy of rat Table 1. Stereotyped rearing after intraperitoneal apomorphine and its inhibition by intracaudate triperidol. Injection volume = 2 ~1 over 30 sec. Two groups of animal (A-G and H-L) with 10 rats each Rearing (set/l 5 mm)
Treatment
A
i.c.
i.p.
cb
Q, Physiol saline
33.8 f 11.8
#
35.9 + 12.1
B
#J
c
Solvent*
D
d,
E
#
F
cb
G
#
H
Solvent
J
6.25 figI Triperidol
K
12.50 &ig Triperidol
5.00 mg/kg APO
110.7 & 28.2
L
25.00 pg Triperidol
5.00 mgfig
52.5 i 9.0
* Distilled water; t Apomorphin~HCi on each side).
P
29.3 k 9.2
0.62 mg/kg APOt f.25 mg/kg APO 2.50 mg/kg APO 5.00 mg/kg APO 5.00 mg/kg APO 5.00 m&kg APO
APO
Difference (73
129.4 * 27.4 180.2 i: 30.2 345.3 * 4s.t 441.3 rt 55.8 447.3 + 58.5 309.6 * 47.1
+ 15.4 (vs AI $_6.2 (vs B) + 282.8 (vs B) i-433.1 (vs B) +912.4 (vs B) + 1205.6 (vs B) + 2.3 (vs G) - 30.8 (vs H)
NS (vs A or C) NS (vs A or B)
Npun~pkur~~~r,l~?. Vol. 18. pp. 723 to 725 Q Pergamon Press Ltd lY7Y. Printed m Great Britain
0
A SIMPLE DEVICE TO MEASURE STEREOTYPED REARING OF THE RAT IN AN OBJECTIVE AND QUANTITATIVE WAY L.
DECSI,
E. Glics, KATALINZ.bm6 and JULIA NAGY
Institute of Pharmacotogy,
University Medical School, H-7443, Hungary
(Accepted
14 March 1979)
~mmary-An
inexpensive and simple device is described which measures stereotyped rearing of the rat automatically. The apparatus works on the principle of capacitance changes of an oscillator system, these changes being caused by postural changes, in this case by the rearing of the animal. Whenever the rat is standing on the hind feet with the head over a constant, but deliberately adjustable level, the change in capacitance starts a digital counter which measures and totalizes the time spent in this position with a freely-chosen accuracy (0.1 set in the present case). The efficiency of the method has been checked by measuring the stereotypy caused by various doses of intraneritoneal anomornhine and the dose-related inhibition of this effect by bilateral intracaudate pretreatment with thperidol.
Drug-effects on the function of the nigrostriatal system have been the subject of a vast amount of investigation during the last 10-15 years. Disregarding the rotatory responses the most often used pharmacological method is probably the study of so-called stereotyped behaviour of animals evoked by dopaminergic and/or direct or indirect adrenergic stimulation of the nigrostriatal system. This stereotypy consists of several components, out of which the rearing response is very characteristic of the rat. For this reason it
“anything” is the rat; it is placed between two metal plates (which actually is the condenser). Whenever the rat is standing on the hind feet with the head over a constant, but deliberately adjustable level, the change in capacitance reaches such a degree as to alter the frequency of an oscillator connected to the condenser system. This alteration is the input signal to a digital counter; thus, when the animal is in a rearing posture the counter measures and totalizes the time spent in this position with an accuracy of 0.1 set (this can he 0.01 or even 0.001 set: depending on the construction). This accuracy (0.1 set) is more than enough, for the inevitable hysteresis of the apparatus (i.e. the delay of switching-0~ lies in about this order of ma~itude.
is surprising how few attempts have been made to measure this stereotypy, or some components of it,
in an objective and quantitative way. Most of the authors are satisfied to use subjective and, so, only ~miquantitative methods (e.g. scoring by gross ob~rvat~on). A very good approach to make the investigations objective and quantitative is that of Kotasiewin and Wolfarth (1973, who developed a simple, but very reliable method to measure one of the components, i.e. the gnawing, of stereotyped behaviour in the rabbit. In the rat, a very characteristic component, of stereotyped behaviour is the rearing of the animal. It is the aim of the present paper to describe a simple and inexpensive device that allows measurement of the rearing response automatically and, thus, in a fully objective and quantitative manner. A similar method has been used by Bryan and Ellison (1975); the first application of the principle of the procedure to be described dates back to Zucker and Howard (1968). The method is based on the principle that the capacitance of a surface-condenser system will be changed when the distance between the two plates changes or, when anything conducting electricity is placed between them. The more close this “anything” to the two condenser plates the greater is the change in the capacitance of the system. In the present case the
DESCRIIWON
OF APPARATUS
(Fig. la, b) The rat is put in a cage the bottom and top walls of which are made of metal plate (steel, copper or aluminium; the latter being more practical) while the other ones are of insulating material (wood and/or plexiglas). Thus, the bottom and top plates make a capacitive system, the capacitance of which depends on the geometric data (C,) of the cage, including the posture of the animal within the cage (AC,). Thus, the total capacitance is C, + AC,, plus the dielectric con: stant of the cage. Whenever the rat takes a rearing posture component AC, will change. This C, + AC, capacitance is a part of the oscillator capacitance of a Clapp-oscillator built of transistor T,. From this it follows that any change in C, + AC, will after the oscillation frequency, too. The signal level, i.e. the height of rearing that starts to alter this frequency can be adjusted by means of the trimming capacitance C, which is parallet connected to C,. Thus, the digital display system receives the
123
L. DECSI,E. Grits, KATALINZAt& and
KILIA NAGY
t.timer 0
Fig. I(a). Block diagram of the apparatus. 0
Fig. I(b). Circuit
0
diagram of the apparatus.
input signal only in the case when the ascillator’s frequency (which is a function of AC, + C,, when the constant Cb is disregarded) is within the range of the hand-pass filter. Thus, the principb of measurement is that changes in AC, cause an alteration in the master oscillator’s frequency, which alteration will then be detected by the digitai display system. The frequency of the oscillator is: 1 Wg = L,(Cb t C, + AC, + CJ where: c, = capacitance of the empty cage
C, = adjustable capacitance AC, = capacitance change depending on the posture of the animal in the cage C, = sum of the dispersed capacitances LI = inductance of the oscillator EXAMPLES ~EMUNSTRATING
circuit THE
EFFICIENCY OF THE APPARA~I.~~ i[t is common-pear that systemic a~rn~r~hi~e (APO) ap~i~ation evokes stereotyped behaviour in the rat. Tabfe 1 demonstrates the dose-dependent nature of this action. A~rnar~hi~e was injected 5 min before beginning the m~surement. R-Amster-
725
New device to measure stereotypy of rat Table 1. Stereotyped rearing after intraperitoneal apomorphine and its inhibition by intracaudate triperidol. Injection volume = 2 ~1 over 30 sec. Two groups of animal (A-G and H-L) with 10 rats each Rearing (set/l 5 mm)
Treatment
A
i.c.
i.p.
cb
Q, Physiol saline
33.8 f 11.8
#
35.9 + 12.1
B
#J
c
Solvent*
D
d,
E
#
F
cb
G
#
H
Solvent
J
6.25 figI Triperidol
K
12.50 &ig Triperidol
5.00 mg/kg APO
110.7 & 28.2
L
25.00 pg Triperidol
5.00 mgfig
52.5 i 9.0
* Distilled water; t Apomorphin~HCi on each side).
P
29.3 k 9.2
0.62 mg/kg APOt f.25 mg/kg APO 2.50 mg/kg APO 5.00 mg/kg APO 5.00 mg/kg APO 5.00 m&kg APO
APO
Difference (73
129.4 * 27.4 180.2 i: 30.2 345.3 * 4s.t 441.3 rt 55.8 447.3 + 58.5 309.6 * 47.1
+ 15.4 (vs AI $_6.2 (vs B) + 282.8 (vs B) i-433.1 (vs B) +912.4 (vs B) + 1205.6 (vs B) + 2.3 (vs G) - 30.8 (vs H)
NS (vs A or C) NS (vs A or B)
