Inhibitory effect of neural transections of dorsal raphe nucleus on induction of nocturnal prolactin surge by vaginal stimulation in ovariectomized rats

The effect of complete (CC), anterior (AC) or posterior (PC) cut of the dor sal raphe nucleus (DRn) on induction of the nocturnal prolactin (PRL) surge by electrical vaginal stimulation (VS) was investigated in ovariectomized rats. Plasma level of PRL was measured by radioimmunoassay before and after VS. The data revealed that PRL levels increased in early morning on the da y following VS in the rats without brain surgery or with sham-operation. In contrast, the nocturnal PRL surge did not occur in the CC, AC, or PC rats. These results suggest that both the anterior and the posterior fibers of t he DRn plays an important role in induction of nocturnal PRL surge by VS in ovariectomized rats. (C) 1998 Elsevier Science B.V. All rights reserved.