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The effect of endogenous hyperprolactinemia induced by pituitary transplantation under the kidney capsule on haloperidol induced catalepsy was evaluated in male Wistar rats treated with two doses of the drug (500 gamma/kg; 2 mg/kg i.p.). Rats of 220 +/- 30 g received intraperitoneal injection of haloperidol. Every five minutes following drug administration the rats were assessed for catalepsy by placing the forepaw on a horizontal bar, and observed for two minutes. Data obtained show that hyperprolactinemia potentiates the cataleptic score in rats treated with dose of 500 gamma/kg i.p., while no significant difference was observed between hyperprolactinemic rats and control rats, at the dose of 2 mg/kg i.p. of haloperidol.

In the present study the role of amygdala in the antidepressant action of imipramine is discussed. An animal model of depression is induced, in rats, by systemic injection of low doses of apomorphine. Systemic administration of imipramine prevents, as already reported, apomorphine-induced sedation. The same effect is observed following intra-amygdaloid imipramine administration. On the contrary, local injection of imipramine in frontal cortex or caudate nucleus does not affect apomorphine-induced sedation.