Angiotensin II promotes development of neurophysin neurons in dissociated culture

Dissociated cultures of retrochiasmatic hypothalamus of 18-day-old rat embryos were continuously treated with 2 X 10(-9) M angiotensin II (ang II) from the third day in vitro on. Cultivation was terminated at days 9 and 16 in vitro, respectively. Neurons immunoreactive for neurophysin, arg-vasopressin and oxytocin were visualized by immunocytochemistry, using the unlabeled antibody technique, and counted. Large, well-differentiated magnocellular neurons and small, probably immature cells could be distinguished. A certain number of large neurons were, in addition, immunoreactive for either vasopressin or oxytocin whereas the small cells were devoid of such staining. Ang II treatment brought about a modest increase in neurophysin-immunoreactive (NEU-IR) cell numbers at day 9 and a drastic augmentation of both large and small NEU-IR cells at day 16 in vitro, without appreciably affecting the total counts of neurons per culture.