Immuno-electron microscopic localization of luteinizing hormone-releasing hormone in the arcuate nuclei and median eminence of the rat.

TLDR: It was concluded that the LH-RH is packaged or condensed into granules in the Golgi cisternae.

Abstract: Luteinizing hormone-releasing hormone (LH-RH) was localized in neurons of the arcuate nucleus and median eminence, and in many of the nerve fibres of the median eminence of the rat, by using antisera to synthetic LH-RH with the immunoglobulin-peroxidase technique or by using a soluble peroxidase-antiperoxidase complex at the electron microscopic level. Many of the arcuate neurons and some of the median eminence neurons contained numerous densely stained granules (diameter about 90–130 nm) associated with the Golgi complex, and scattered granules elsewhere in the cytoplasm. Similar granules, positive for LH-RH, were observed in many nerve profiles around the capillaries of the primary portal plexus of zona palisadica and zona granulosa of the median eminence, and such profiles may represent the release sites of LH-RH into the portal vessels. About 20% of the nerve profiles around the primary portal plexus were LH-RH positive and the rest of the nerve profiles were negative. The negative profiles may belong to other hypophysiotropic hormones and/or to catecholaminergic fibers. Some nerve endings at the ventricular surface of the ependymal cells, in contact with the ventricular fluid, were also LH-RH positive. These nerve endings probably release their secretion into the cerebrospinal fluid.