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Ontogeny of the somatostatin variant [Pro 2 ,Met 13 ]somatostatin‐14 in the brain, pituitary, and sensory organs of the frog Rana esculenta
Author(s) -
Vallarino Mauro,
Bruzzone Federica,
Mathieu Maura,
Chartrel Nicolas,
Vieau Didier,
Ciarlo Monica,
Fournier Alain,
Vaudry Hubert
Publication year - 2006
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/cne.20986
Subject(s) - biology , somatostatin , anterior olfactory nucleus , diagonal band of broca , preoptic area , hypothalamus , interpeduncular nucleus , ontogeny , medicine , anatomy , endocrinology , central nervous system , neuroscience , olfactory tubercle , olfactory bulb , basal forebrain , midbrain
Abstract Two forms of somatostatin are expressed in the frog brain, i.e., somatostatin‐14 (SS1) and the [Pro 2 , Met 13 ]somatostatin‐14 variant (SS2). We have previously described the ontogeny of SS1‐immunoreactive cells in the brain of Rana esculenta . In the present study, we have investigated the distribution of prepro‐SS2 (PSS2)‐expressing neurons in the brain of the same species during development by using antibodies directed against the N‐flanking region of SS2 (PSS2 54‐66 ). Immunoreactive perikarya first appeared in the ventral hypothalamus at stages IV–VII. Subsequently, positive neurons were seen in the nucleus of the diagonal band of Broca, the anterior preoptic area, the posterior tuberculum (stages VIII–XII), as well as the dorsal (stages XIII–XV) and medial (stages XIX–XX) periventricular preoptic nucleus. At metamorphic climax and in newly metamorphosed frogs, positive perikarya were found in the striatum and in the interpeduncular nucleus. PSS2 54‐66 ‐immunoreactive fibers were already widely distributed during the first stages of development, indicating that SS2 may act as a neuromodulator and/or neurotransmitter during ontogeny. The presence of PSS2 54‐66 ‐positive nerve fibers in olfactory structures suggests that, in tadpoles, SS2 may be involved in the processing of olfactory information. The occurrence of PSS2 54‐66 ‐like immunoreactivity in taste buds, and in the olfactory and vomeronasal organs indicates that SS2 may mediate the unconditioned and reinforcing properties of natural chemicals. Finally, the intenseexpression of PSS2 54‐66 ‐like immunoreactivity in melanotrope cells of the pituitary suggests that SS2 may diffuse toward the pars distalis to regulate the activity of adenohypophysial cells during tadpole development. J. Comp. Neurol. 497:717–733, 2006. © 2006 Wiley‐Liss, Inc.