Immunocytochemical localization of somatostatin in cell bodies of the rat hypothalamus

Immunohistochemical localization of somatostatin in the human hypothalamus

In order to identify clearly the nervous structures containing somatostatin in the human hypothalamus, an immunohistochemical localization of this neurohormone was performed at light-microscopic level. Using a antiserum specific to somatostatin and the unlabeled antibody peroxidase-antiperoxidase technique, we have found somatostatin in neurons with cell bodies in an area in the anterior hypothalamus corresponding to the infundibular nucleus. Somatostatin-containing fibers were also detected in the neurovascular zone of the pituitary stalk, suggesting that somatostatin is released in that region to reach the capillaries in the pituitary portal plexus. A large bundle of somatostatin fibers extending from the anterior part of the paraventricular nucleus up to the posterior portion of the mammillary bodies has also been detected. The role of these fibers still remains to be clarified.

Somatostatin: electron microscope immunohistochemical localization in secretory neurons of rat hypothalamus

Somatostatin, the hypothalamic hormone which inhibits the secretion of growth hormone by the pituitary, has been localized in the rat hypothalamus by using electron microscope immunohistochemistry. Somatostatin occurs in secretory granules (80 to 110 nm in diameter) of a few neurons located in the hypothalamic periventricular nucleus. These observations establish the identity of neurosecretory neurons involved in the regulation of adenohypophyseal secretion.

Distribution of growth hormone-release-inhibiting hormone (somatostatin) in the rat brain as observed with immunocytochemistry

The objective was to determine the distribution of growth hormone-release-inhibiting hormone (somatostatin) in the rat brain using the peroxidase-antiperoxidase immunocytochemical method with antisera prepared against unconjugated, synthetic somatostatin. Somatostatin occurred in low quantity in the organum vasculosum of the lamina terminalis. It was present throughout the full length of the median eminence and occupied the entire width between the tuberoinfundibular sulci. Most somatostatin was located in the dorsal portion of the external lamina, and the amount varied according to the mediolateral position. The bodies labeled for somatostatin were most often granules; occasionally they appeared as clusters of granules that seemed to be membrane-enclosed. Some of these bodies appeared to be portions of axons. Many of the larger bodies were arranged alongside tanycytes, but no label was distributed generally in tanycyte cytoplasm. Somatostatin was highly concentrated in the proximal one-quarter of the infundibular stem and appeared in lower concentration throughout the distal portion of the stem. It was absent from the pars nervosa and pars intermedia of the pituitary gland. The distribution of somatostatin in the median eminence differed considerably from that of gonadotropin-releasing hormone. Somatostatin was identified in the ventromedial and/or dorsomedial hypothalamic nuclei of only two animals. Here it was probably located in axons that terminated on neuronal cell bodies but also may have been present in a restricted portion of the perikaryonal cytoplasm.

Immunohistochemical localization of somatostatin, insulin and glucagon in the principal islets of the anglerfish (Lophius americanus) and the channel catfish (Ictalurus punctata) (1) (2)

Somatostatin, insulin and glucagon were localized in the principal islets of the anglerfish (Lophius americanus) and the channel catfish (Ictalurus punctata) by means of the unlabeled antibody-peroxidase-antiperoxidase immunocytochemical method. Both species showed a similar ratio of positive cells 9:6:4 (insulin:somatostatin:glucagon), but the interrelations of the three cell types differed between species. The large number of somatostatin-positive cells may be indicative of an important role for this hormone in teleost physiology. The principal islets appear to be a good source of tissue for further work on somatostatin.