Jc. Winter et Ra. Rabin, DISCRIMINATIVE STIMULUS PROPERTIES OF M-CHLOROPHENYLPIPERAZINE, Pharmacology, biochemistry and behavior, 45(1), 1993, pp. 221-223
Stimulus control was established in a group of 10 rats using a dose of
m-chlorophenylpiperazine (MCPP) of 0.8 mg/kg, administered IP, 15 min
before training. A two-lever operant task using a fixed-ratio 10 sche
dule of sweetened milk reinforcement was used. Based upon a criterion
for the presence of stimulus control of five consecutive sessions duri
ng which 83% or more of all responses were on the appropriate lever, a
mean of 27 sessions was required to reach criterion performance. Resp
onse rates were significantly suppressed by the training dose of MCPP
(14 responses/min) as compared with saline sessions (38 responses/min)
. Subsequent to the establishment of stimulus control, tests of genera
lization were conducted with m-trifluoromethylphenylpiperazine (TFMPP)
, 6-chloro-2-(1-piperazinyl)-pyrazine (MK-212), and 5-methoxy-3-(1,2 3
,6-tetrahydro-4-pyridinyl)-1H-indole (RU-24969). MCPP generalized comp
letely to MK-212 and TFMPP at doses of the latter drugs of 0.7 and 1.0
mg/kg, respectively. Maximum generalization to RU-24969 was 67% at a
dose of 1.0 mg/kg but only 4 of 10 subjects completed the test session
. The present results indicate that MCPP is efficacious as a discrimin
ative stimulus. In addition, because of MCPP's relative selectivity fo
r the 5-hydroxytryptamine c(5-HT,c) receptor subjects trained with MCP
P may prove valuable in assessing the respective functional contributi
ons of 5-HT sites to the actions of a variety of serotonergic agents.