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Immunocytochemical localization of somatostatin and autoradiographic distribution of somatostatin binding sites in the brain of the African lungfish, Protopterus annectens
Author(s) -
Vallarino Mauro,
Trabucchi Michele,
Masini Maria Angela,
Chartrel Nicolas,
Vaudry Hubert
Publication year - 1997
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19971124)388:3<337::aid-cne1>3.0.co;2-1
Subject(s) - somatostatin , biology , tegmentum , lungfish , endocrinology , medicine , tectum , reticular formation , anatomy , cerebellum , neuroscience , midbrain , central nervous system , fishery , fish <actinopterygii>
The anatomical distribution of somatostatin‐immunoreactive structures and the autoradiographic localization of somatostatin binding sites were investigated in the brain of the African lungfish, Protopterus annectens . In general, there was a good correlation between the distribution of somatostatin‐immunoreactive elements and the location of somatostatin binding sites in several areas of the brain, particularly in the anterior olfactory nucleus, the rostral part of the dorsal pallium, the medial subpallium, the anterior preoptic area, the tectum, and the tegmentum of the mesencephalon. However, mismatching was found in the mid‐caudal dorsal pallium, the reticular formation, and the cerebellum, which contained moderate to high concentrations of binding sites and very low densities of immunoreactive fibers. In contrast, the caudal hypothalamus and the neural lobe of the pituitary exhibited low concentrations of binding sites and a high to moderate density of somatostatin‐immunoreactive fibers. The present results provide the first localization of somatostatin in the brain of a dipnoan and the first anatomical distribution of somatostatin binding sites in the brain of a fish. The location of somatostatin‐immunoreactive elements in the brain of P. annectens is consistent with that reported in anuran amphibians, suggesting that the general organization of the somatostatin peptidergic systems occurred in a common ancestor of dipnoans and tetrapods. The anatomical distribution of somatostatin‐immunoreactive elements and somatostatin binding sites suggests that somatostatin acts as a hypophysiotropic neurohormone as well as a neurotransmitter and/or neuromodulator in the lungfish brain. J. Comp. Neurol. 388:337–353, 1997. © 1997 Wiley‐Liss, Inc.