CSF-contacting and other somatostatin-immunoreactive neurons in the brains of Anguilla anguilla, Phoxinus phoxinus, and Salmo gairdneri (Teleostei).
A system of somatostatin-immunoreactive neurons was demonstrated in the brains of the eel, Anguilla anguilla, the European minnow, Phoxinus phoxinus, and the rainbow trout, Salmo gairdneri, by means of the light-microscopic indirect immunoperoxidase technique. In the anterior periventricular nucleus, somatostatin-immunoreactive cerebrospinal fluid (CSF)-contacting neurons display intensely stained intraventricular dendritic protrusions, perikarya, and axonal processes. The latter taper into a somatostatin-immunoreactive fiber plexus extending to the infundibulum, the proximal neurohypophysis, and the lateral and mammillary recesses. In addition, somatostatin-immunoreactive neurons were demonstrated in the magnocellular preoptic, entopeduncular and dorsolateral thalamic nuclei, further in the pretectal area and the ventrolateral tegmentum. Somatostatin-immunoreactive fiber bundles project via the stria medullaris toward the habenular nucleus; they also course in the dorsomedial-ventrolateral direction at the level of the pretectal-tegmental area, and within the ventral and dorsal tegmentum. The presence of somatostatin in a variety of different neurons of the teleost brain is discussed in connection with their tentative inhibitory function. The CSF-contacting neurons of the anterior periventricular nucleus are supposed to function as sensors that pass information from the CSF to the somatostatin system of the hypothalamus and/or other components of the neuroendocrine apparatus.
D000818:Animals; D001923:Brain Chemistry; D003530:Cyprinidae / Q000502:physiology; D004027:Diencephalon / Q000032:analysis; D004524:Eels / Q000502:physiology; D005399:Fishes / Q000502:physiology*; D007124:Immunoenzyme Techniques; D008636:Mesencephalon / Q000032:analysis; D009474:Neurons / Q000032:analysis; D013004:Somatostatin / Q000032:analysis* / Q000134:cerebrospinal fluid; D013045:Species Specificity; D014337:Trout / Q000502:physiology
D013004:Somatostatin