The hypothalamic and neurohypophysial oxytocin content as influenced by desmethylimipramine in normal and pinealectomized white male rats.

Pinealectomized, sham-operated and non operated control rats were injected intracerebroventricularly (i.c.v.) with a single dose of desmethylimipramine hydrochloride (DMI; 20 micrograms, dissolved in 10 microliters of normal saline); after 4 hours they were decapitated and the hypothalamic and neurohypophysial oxytocin content was bioassayed using the milk-ejection effect in vitro. DMI decreased oxytocin content of the hypothalamus and neurointermediate lobe in non operated and sham-operated animals. In pinealectomized rats the oxytocin content of the hypothalamus and neurointermediate lobe diminished and could be further reduced by an i.c.v. DMI injection. As shown in animals pretreated with phenoxybenzamine, these events might be only partially related to an increase of alpha-adrenergic transmission.