Estradiol-17β-responsive A1 and A2 noradrenergic cells of the brain stem project to the bed nucleus of the stria terminalis in the ewe brain: A possible route for regulation of gonadotropin releasing hormone cells

Abstract

We have studied brain stem cells in the ewe brain that project to the bed nucleus of the stria terminalis (BNST) and determined if these cells are activated by estradiol-17β. This would predicate an indirect role in the estradiol-17β regulation of gonadotropin releasing hormone (GnRH) cells, since these receive input from the BNST. Ovariectomized ewes received 50 μg estradiol-17β benzoate (i.m.) 1 h prior to brain collection, so that activated cells could be identified by Fos immunohistochemistry. Retrograde tracer (FluoroGold; FG), was injected into the three divisions of the BNST and labeled cells were mapped to the A1 and A2 regions and the parabrachial nucleus (PBN) of the brain stem. Wi..