Vasopressin neurons grafted into Brattleboro rats: viability and activity.

Blocks of the anterior hypothalamus containing vasopressin neurons were grafted from normal 17-day-old rat fetuses into the median eminence of adult female rats with a congenital deficiency of vasopressin neurons (Brattleboro strain rats). Immunocytochemical staining of the transplants 40 days after grafting demonstrated the presence of magnocellular neurons which stained positively for vasopressin and neurophysin. Axons from these neurons could be traced into the median eminence and the primary capillary plexus of the hypothalamo-hypophyseal portal system. Water consumption decreased by as much as 63% in animals carrying viable grafts. The observation that water consumption decreased and remained depressed in hosts carrying viable grafts along with the immunocytochemical data suggest that the transplanted neurons are synthesizing, storing, and releasing biologically active VP.