Although brain amines have been suggested as neurotransmitters regulating the release of hypothalamic hormones, some conflicting evidence has still to be explained. Scapagnini, Van Loon, Moberg & Ganong (1970) have implicated brain noradrenaline in the inhibitory control of adrenocorticotrophin (ACTH) secretion, based on the results of intraperitoneal injection of α-methyl-p-tyrosine. However, we found no increase in corticosterone after oral administration of α-methyl-p-tyrosine to rats (Uchimura, Kumeda, Kawabata, Maeda, Tada, Okamoto, Ogawa & Inamori, 1972). In this study we have examined the effects of intraventricular administration of 6-hydroxydopamine (6-OHDA), a specific and long-lasting catecholamine depletor which does not cross the blood-brain barrier thus excluding the effects of serotonin, peripheral noradrenaline or peritoneal irritation. We performed the experiments 2 weeks after intraventricular administration of 6-OHDA to avoid the stress effects of the administration of 6-OHDA itself. Male Wistar rats (125–250 g), caged singly, were used. Each rat was