ADRENOCORTICOTROPIC HORMONE INFLUENCES THE

M. VOLOSLN, L. M. CANCELA, C. LAINO, M. MASSEX AND V. A. MOLINA

NEUROPHARMACOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1991 vol. 30 p. 719 - 725

0028-3908

Sammary--The influence of adrenocorticotropic hormone (ACTH) in the adaptive changes on central dopaminc (DA) autoreceptors following chronic administration of desipramine (DMI) has been examined in rats. Dopamine had an inhibitory effect on basal and K+-induced release of [3H]DA from slices of striatum and n. accumbens of rats treated chronically (10 days) with ACTH (50 IU/kg, s.c.), DMI (10 mg/kg, i.p.) or the combination of ACTH and DMI. In slices of n. accumbens, but not in slices of striatum of rats exposed to the combined treatment of ACTH and DMI, a significant decrease in the inhibitory effect of exogenous DA on stimulated release of [3H]DA was observed. Chronic administration of ACTH or DMI alone had no effect. The effect of the combined treatment with both agents, on the reactivity of these DA receptors was evaluated by means of apomorphinc-induced hypoactivity. The administration of ACTH and DMI (5 mg/kg, i.p.) reduced the hypoactivity induced by apomorphinc, as compared to hypoactivity in rats treated with ACTH or DMI alone. Experiments with ACTH,q 0 revealed that the peptide modified biochemical and behavioural parameters of dopaminergic function, which may implicate a direct action of the peptide on the brain, rather than on the release of adrenal hormones. These findings suggest that ACTH a~,elerates the onset of DMI-induced adaptive changes on dopamine in the mesolimbic area. However, because the effect of ACTH4_m0 on release of adrenocortical hormone was not investigated, the possibility cannot be disregarded that the effect of the peptide was secondary to an enhancement of release of adrenal hormone.