[Hypothalamic LH-RH neuronal modifications after prolactine intraventricular infusion in the guinea pig (author's...

Ovine prolactine injected at doses of either 31,25 to 500 microgram by lateral intraventricular route in male guinea pigs, affects LH-RH hypothalamic neurons within 2 to 24 hours. After this treatment there is an increase of LH-RH immunoreactive material in eminential terminals and in numerous small granules of hypothalamic neuronal cell bodies. This accumulation of immunoactive LH-RH in pericaryon and in terminals can be interpreted as stimulation of LH-RH synthesis. Preliminary results of radioimmunoassayed plasmatic LH level, 2 h after PRL infusion, are in agreement with this hypothesis. The probability that short feed-back by PRL or PIF secretion would simultaneously be able to check LH-RH secretion is discussed.