EFFECTS OR
OF
NUCLEUS
BILATERAL
LESIONS
ACCUMBENS
ACTIVITY
OF
Takeshi
ON
IN
THE
and
Hideaki
STRIATUM
CATALEPTOGENIC
NEUROLEPTICS
HONMA
THE
IN
RATS
FUKUSHIMA
Research and Development Center, Pharmaceuticals Division, Sumitomo Chemical Co., Ltd., 4-2-1, Takatsukasa, Takarazuka, Hyogo 665, Japan Accepted
November
10,
1977
Abstract-To investigate the role of the striatum and nucleus accumbens in neuroleptic induced catalepsy, bilateral electrocoagulations were made or microinjections of 6hydroxydopamine (6-OHDA) were given to rats in these brain regions, and the cata leptogenic activity of neuroleptics was measured. Electrocoagulation in these regions caused a highly specific destruction of brain tissue, and 6-OHDA decreased the levels of dopamine in the injected region with little effect on these levels in other regions. The cataleptogenic activity of haloperidol was enhanced by the electrocoagulation in the striatum at 2 days after the operation, but was weakened from 7 days on. The elec trocoagulation weakened the catalepsy induced by chlorpromazine, thioridazine, and ID-4708 (a new butyrophenone derivative), but enhanced that by clozapine at 2 weeks after the operation. Microinjection of 6-OHDA into the striatum enhanced the catalepsy induced by the five neuroleptics used. The lesions in the nucleus accum bens had fewer effects on catalepsy than did those in the striatum. It was concluded that the striatum more than the nucleus accumbens is involved in producing cata lepsy with neuroleptics, and that the enhancement of catalepsy by electrocoagula tion in the striatum is characteristic of clozapine.
Pharmacological, neuroleptics produce
block
catalepsy
and produce
in rats.
catalepsy
of DA receptors terminals
biochemical dopamine
and
electrophysiological
(DA) receptors Reserpine
(4, 5).
investigations
in the brain
and tetrabenazine
(1-3). reduce
of the activity
are localized in the striatum
of DA neurons
and nucleus accumbens
may be induced by the effect of drugs on these brain regions.
and
nucleus
the contribution
accumbens
system)
togenic activity of several neuroleptics
ID-4708
accumbens
or nucleus accumbens
(a new butyrophenone
Effects of microinjection
(8, 9).
derivative),
of 6-hydroxydopamine
on the cataleptogenic
contents
DA containing Therefore,
nerve
the catalepsy
The present study was under
to the catalepsy
There are data as to the effects of electrocoagulation
lation in the striatum
(7).
that
is the result of blockade
(6).
of DA neurons in the striatum
(mesolimbic
showed
all neuroleptics
the monoamine
These facts suggest that the catalepsy
or the reduction
taken to investigate
Almost
(extrapyramidal
system)
induced
by neuroleptics.
in the caudate-putamen
on the catalep
We investigated
the effects of electrocoagu
on the cataleptogenic chlorpromazine, (6-OHDA)
activity
thioridazine
of haloperidol, and clozapine.
into the striatum
activity of these five neuroleptics
or nucleus
were also investigated.
MATERIALS AND METHODS Animals Male Wistar rats, weighing 150-170 g at the time of operation, were allowed free access to food and water except during the experiments.
Rats were housed in groups at 25±1'C
and 55+5 % humidity. Microinjection of 6-OHDA into the striatum or nucleus accumbens Rats were anesthetized with sodium pentobarbital standard stereotaxic instrument (Takahashi Shoten).
(40 mg/kg i.p.) and placed on a
The skull was exposed.
A stainless
steel cannula (0.3 mm in outer diameter) was attached to the stereotaxic instrument and placed on a predetermined position on the skull. A small opening was made with a dental drill. The injection cannula was inserted into the brain tissue through this opening. The solution of 6-OHDA was injected through the injection cannula which was connected with a motor-driven microsyringe (Stoelting Co., U.S.A.)
Three injections in each side of the
striatum of each animal were given with anterior, lateral and vertical coordinates 6.8, 3.5, ±0.0; 7.5, 2.5, ±0.5; 8.4, 2.6, -}-1.0 according to the brain atlas of Konig and Klippel (10). The coordinates used for the bilateral injections of 6-OHDA into the nucleus accumbens were 9.4, 1.0, -0.9.
A 4 ,ug of 6-OHDA was dissolved in 2 /el of physiological saline containing
0.1 % ascorbic acid and was injected into the brain tissue at the rate of 1 'al/min.
After
the injection of 6-OHDA, the injection cannula was left in the place for 1 min to allow for adequate diffusion of the solution.
Total amounts of 6-OHDA injected to each rat were
24 ag into the striatum or 8 ,ug into the nucleus accumbens.
Sham operations were made
by the injection of the same volume of the vehicle into the brain tissue in the same way as used for the injection of 6-OHDA.
DA contents were measured according to the method
of Chang (11) at the end of experiments. Electrocoagulation in the rat brain Rats were anesthetized with sodium pentobarbital and placed on a standard stereotaxic instrument.
Electrocoagulation
was caused by passing a current of 0.5 mA for 30 min
through a bipolar indwelling stainless steel electrode (0.5 mm in diameter).
The coordinates
used for the coagulation in the striatum or nucleus accumbens were the same as used for the injection of 6-OHDA into these regions.
Sham operations were performed in exactly
the same way as used in the electrocoagulation the electrode.
except that no current was passed through
Size of the coagulated area was measured in histological examinations at
the end of experiments.
The rats were again anesthetized with pentobarbital and perfused
with saline through the heart.
After blood was washed out, the brains were fixed with
Bouin's solution, and then cut in 100 /im thick sections, stained with hematoxylin and eosin, and the size of coagulated areas measured. Assessment of catalepsy The intensity of catalepsy was measured according to the method of Wirth et al. (12) with slight modification.
Both front paws of rats were placed on a horizontal metal bar,
8.8 cm in height, and the rats were forced to rest on hind legs only.
The duration (in sec)
of this more
abnormal than
position
was
300 sec, the catalepsy
regarded score
as a catalepsy was
regarded
score.
When
catalepsy
lasted
for
as 300.
Drugs All neuroleptics
used were micronized
prior to use and suspended
or dissolved
gum arabic solution before the administration. Haloperidol, clozapine new butyrophenone derivative (13), were synthesized in our laboratory.
and ID-4708, a Chlorpromazine
(Yoshitomi Seiyaku), thioridazine (Sankyo) and 6-hydroxydopamine hydrobromide were commercially purchased. Dosage of the drug is expressed in terms of base. Statistical
in 5
(Sigma)
evaluation
The catalepsy Mann-Whitney
score
was compared
between
control
and
operated
groups
using
the
U-test. RESULTS
Time-course of the effect of lesions in the striatum or nucleus accumbens on the cataleptogenic activity of haloperidol The cataleptogenic
activity
of haloperidol
(2 mg/kg s.c.) was measured
in each rat at
FIG. 1. Effects of bilateral elect rocoagulations in the striatum or nucleus accumbens and bilateral injections of 6-OHDA into the striatum or nucleus accumbens on the intensity of catalepsy induced by haloperidol in rats. The cataleptogenic activity of haloperidol (2 mg; kg s.c.) was measured at 2, 7, 14 and 21 days after the operation. The catalepsy score was measured at 6 hr after the administration, and the means and S.E.M. were calculated. unopcrated control (N=7). microinjection of 6-OHDA into the striatum (N=8). microinjection of 6-OHDA into the nucleus accumbens (N=8). A A: electrocoagulation in the striatum (N--7). A-- --A: elect rocoagulat ion in the nucleus accumbens (N-8). Vertical bars represent S.E.M. Statistical comparisons between control and operated rats were performed with U-test. *P
OF
NUCLEUS
BILATERAL
LESIONS
ACCUMBENS
ACTIVITY
OF
Takeshi
ON
IN
THE
and
Hideaki
STRIATUM
CATALEPTOGENIC
NEUROLEPTICS
HONMA
THE
IN
RATS
FUKUSHIMA
Research and Development Center, Pharmaceuticals Division, Sumitomo Chemical Co., Ltd., 4-2-1, Takatsukasa, Takarazuka, Hyogo 665, Japan Accepted
November
10,
1977
Abstract-To investigate the role of the striatum and nucleus accumbens in neuroleptic induced catalepsy, bilateral electrocoagulations were made or microinjections of 6hydroxydopamine (6-OHDA) were given to rats in these brain regions, and the cata leptogenic activity of neuroleptics was measured. Electrocoagulation in these regions caused a highly specific destruction of brain tissue, and 6-OHDA decreased the levels of dopamine in the injected region with little effect on these levels in other regions. The cataleptogenic activity of haloperidol was enhanced by the electrocoagulation in the striatum at 2 days after the operation, but was weakened from 7 days on. The elec trocoagulation weakened the catalepsy induced by chlorpromazine, thioridazine, and ID-4708 (a new butyrophenone derivative), but enhanced that by clozapine at 2 weeks after the operation. Microinjection of 6-OHDA into the striatum enhanced the catalepsy induced by the five neuroleptics used. The lesions in the nucleus accum bens had fewer effects on catalepsy than did those in the striatum. It was concluded that the striatum more than the nucleus accumbens is involved in producing cata lepsy with neuroleptics, and that the enhancement of catalepsy by electrocoagula tion in the striatum is characteristic of clozapine.
Pharmacological, neuroleptics produce
block
catalepsy
and produce
in rats.
catalepsy
of DA receptors terminals
biochemical dopamine
and
electrophysiological
(DA) receptors Reserpine
(4, 5).
investigations
in the brain
and tetrabenazine
(1-3). reduce
of the activity
are localized in the striatum
of DA neurons
and nucleus accumbens
may be induced by the effect of drugs on these brain regions.
and
nucleus
the contribution
accumbens
system)
togenic activity of several neuroleptics
ID-4708
accumbens
or nucleus accumbens
(a new butyrophenone
Effects of microinjection
(8, 9).
derivative),
of 6-hydroxydopamine
on the cataleptogenic
contents
DA containing Therefore,
nerve
the catalepsy
The present study was under
to the catalepsy
There are data as to the effects of electrocoagulation
lation in the striatum
(7).
that
is the result of blockade
(6).
of DA neurons in the striatum
(mesolimbic
showed
all neuroleptics
the monoamine
These facts suggest that the catalepsy
or the reduction
taken to investigate
Almost
(extrapyramidal
system)
induced
by neuroleptics.
in the caudate-putamen
on the catalep
We investigated
the effects of electrocoagu
on the cataleptogenic chlorpromazine, (6-OHDA)
activity
thioridazine
of haloperidol, and clozapine.
into the striatum
activity of these five neuroleptics
or nucleus
were also investigated.
MATERIALS AND METHODS Animals Male Wistar rats, weighing 150-170 g at the time of operation, were allowed free access to food and water except during the experiments.
Rats were housed in groups at 25±1'C
and 55+5 % humidity. Microinjection of 6-OHDA into the striatum or nucleus accumbens Rats were anesthetized with sodium pentobarbital standard stereotaxic instrument (Takahashi Shoten).
(40 mg/kg i.p.) and placed on a
The skull was exposed.
A stainless
steel cannula (0.3 mm in outer diameter) was attached to the stereotaxic instrument and placed on a predetermined position on the skull. A small opening was made with a dental drill. The injection cannula was inserted into the brain tissue through this opening. The solution of 6-OHDA was injected through the injection cannula which was connected with a motor-driven microsyringe (Stoelting Co., U.S.A.)
Three injections in each side of the
striatum of each animal were given with anterior, lateral and vertical coordinates 6.8, 3.5, ±0.0; 7.5, 2.5, ±0.5; 8.4, 2.6, -}-1.0 according to the brain atlas of Konig and Klippel (10). The coordinates used for the bilateral injections of 6-OHDA into the nucleus accumbens were 9.4, 1.0, -0.9.
A 4 ,ug of 6-OHDA was dissolved in 2 /el of physiological saline containing
0.1 % ascorbic acid and was injected into the brain tissue at the rate of 1 'al/min.
After
the injection of 6-OHDA, the injection cannula was left in the place for 1 min to allow for adequate diffusion of the solution.
Total amounts of 6-OHDA injected to each rat were
24 ag into the striatum or 8 ,ug into the nucleus accumbens.
Sham operations were made
by the injection of the same volume of the vehicle into the brain tissue in the same way as used for the injection of 6-OHDA.
DA contents were measured according to the method
of Chang (11) at the end of experiments. Electrocoagulation in the rat brain Rats were anesthetized with sodium pentobarbital and placed on a standard stereotaxic instrument.
Electrocoagulation
was caused by passing a current of 0.5 mA for 30 min
through a bipolar indwelling stainless steel electrode (0.5 mm in diameter).
The coordinates
used for the coagulation in the striatum or nucleus accumbens were the same as used for the injection of 6-OHDA into these regions.
Sham operations were performed in exactly
the same way as used in the electrocoagulation the electrode.
except that no current was passed through
Size of the coagulated area was measured in histological examinations at
the end of experiments.
The rats were again anesthetized with pentobarbital and perfused
with saline through the heart.
After blood was washed out, the brains were fixed with
Bouin's solution, and then cut in 100 /im thick sections, stained with hematoxylin and eosin, and the size of coagulated areas measured. Assessment of catalepsy The intensity of catalepsy was measured according to the method of Wirth et al. (12) with slight modification.
Both front paws of rats were placed on a horizontal metal bar,
8.8 cm in height, and the rats were forced to rest on hind legs only.
The duration (in sec)
of this more
abnormal than
position
was
300 sec, the catalepsy
regarded score
as a catalepsy was
regarded
score.
When
catalepsy
lasted
for
as 300.
Drugs All neuroleptics
used were micronized
prior to use and suspended
or dissolved
gum arabic solution before the administration. Haloperidol, clozapine new butyrophenone derivative (13), were synthesized in our laboratory.
and ID-4708, a Chlorpromazine
(Yoshitomi Seiyaku), thioridazine (Sankyo) and 6-hydroxydopamine hydrobromide were commercially purchased. Dosage of the drug is expressed in terms of base. Statistical
in 5
(Sigma)
evaluation
The catalepsy Mann-Whitney
score
was compared
between
control
and
operated
groups
using
the
U-test. RESULTS
Time-course of the effect of lesions in the striatum or nucleus accumbens on the cataleptogenic activity of haloperidol The cataleptogenic
activity
of haloperidol
(2 mg/kg s.c.) was measured
in each rat at
FIG. 1. Effects of bilateral elect rocoagulations in the striatum or nucleus accumbens and bilateral injections of 6-OHDA into the striatum or nucleus accumbens on the intensity of catalepsy induced by haloperidol in rats. The cataleptogenic activity of haloperidol (2 mg; kg s.c.) was measured at 2, 7, 14 and 21 days after the operation. The catalepsy score was measured at 6 hr after the administration, and the means and S.E.M. were calculated. unopcrated control (N=7). microinjection of 6-OHDA into the striatum (N=8). microinjection of 6-OHDA into the nucleus accumbens (N=8). A A: electrocoagulation in the striatum (N--7). A-- --A: elect rocoagulat ion in the nucleus accumbens (N-8). Vertical bars represent S.E.M. Statistical comparisons between control and operated rats were performed with U-test. *P
