Protracted elevation of endothelin immunoreactivity in hypothalamo-neurohypophysial system after ischemia

In the present study we investigated the effects of brain ischemia on endothelin expression in the hypothalamo-neurohypophysial system of the rat using the post-embedding immunogold technique for electron microscopy. From 24 hours to six months after ischemia, a relatively high endothelin immunoreactivity was observed in some neurosecretory cells of the supraoptic and paraventricular nuclei as well as in endothelial cells of some microvessels of the hypothalamus and neurohypophysis. The results indicate that ischemia is a potent stimulus for increased production of endothelin. The distribution of endothelin-immunoreactive neurons in the hypothalamus was similar to that of vasopressin and oxytocin, so it seems possible that endothelin participates directly in controlling hormonal synthesis and release from vasopressinergic and oxytocinergic neurons in the hypothalamo-neurohypophysial system.