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Titolo:
GHRP-6-induced changes in electrical activity of single cells in the arcuate, ventromedial and periventricular nucleusriventricular nuclei of a hypothalamic slice preparation in vitro
Autore:
Hewson, AK; Viltart, O; McKenzie, DN; Dyball, REJ; Dickson, SL;
Indirizzi:
Univ Cambridge, Dept Physiol, Cambridge CB2 3EG, England Univ Cambridge Cambridge England CB2 3EG iol, Cambridge CB2 3EG, England Univ Cambridge, Dept Anat, Cambridge, England Univ Cambridge Cambridge England mbridge, Dept Anat, Cambridge, England
Titolo Testata:
JOURNAL OF NEUROENDOCRINOLOGY
fascicolo: 12, volume: 11, anno: 1999,
pagine: 919 - 923
SICI:
0953-8194(1999)11:12<919:GCIEAO>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
HORMONE-RELEASING PEPTIDE; CENTRAL SOMATOSTATIN ACTION; GROWTH-HORMONE; SECRETAGOGUE-RECEPTOR; FACTOR NEURONS; RAT; HEXAPEPTIDE; EXPRESSION; PITUITARY; SECRETION;
Keywords:
growth hormone secretagogues; growth hormone-releasing hormone; somatostatin; growth hormone-releasing peptide;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Dickson, SL Univ Cambridge, Dept Physiol, Downing St, Cambridge CB2 3EG, England Univ Cambridge Downing St Cambridge England CB2 3EG , England
Citazione:
A.K. Hewson et al., "GHRP-6-induced changes in electrical activity of single cells in the arcuate, ventromedial and periventricular nucleusriventricular nuclei of a hypothalamic slice preparation in vitro", J NEUROENDO, 11(12), 1999, pp. 919-923

Abstract

Previously, we demonstrated that systemic injection of the growth hormone secretagogue, growth hormone-releasing peptide (GHRP)-6, selectively activated cells in the hypothalamic arcuate nucleus, as reflected by increased electrical activity and induction of the immediate early gene c-fos. The growth hormone secretagogue receptor distribution is not confined to the arcuate nucleus, suggesting that additional sites of action may exist. In the present study we characterized the electrophysiological responses of cells in the arcuate nucleus, ventromedial nucleus and periventricular nucleus in anin-vitro hypothalamic slice preparation, following bath application of GHRP-6. Additionally, since central somatostatin administration has been shownto attenuate the induction of the c-fos gene by GHRP-6, we sought to determine whether the arcuate cells activated by GHRP-6 are also somatostatin-sensitive. Male Wistar rats (100-150 g body weight (BW)) were anaesthetized (urethane; 1.2 g/kg BW) and the brains removed. Coronal sections (400 mu m thickness) were cut through a block of hypothalamus and were transferred to a slice chamber perfused with artificial cerebrospinal fluid. Forty-one arcuate nucleus cells were tested with bath application of 15 mu m GHRP-6 for 10 min, 16 of which were tested subsequently (> 30 min later) with application of 10 mu M somatostatin. Following GHRP-6 administration, 19 cells (46.3%) showed a significant increase in firing rate during the 15-min period after GHRP-6 application (P < 0.001), 17 cells (41.5%) did not respond and the remaining five cells (12.2%) were significantly inhibited. Six of the eight arcuate nucleus cells that were excited by GHRP-6 were significantly inhibited by somatostatin. By contrast, five of the six arcuate nucleus cellsthat were unresponsive to GHRP-6 were also unresponsive to somatostatin. In the ventromedial nucleus, of 19 cells tested, eight cells (42.1%) were excited by GHRP-6, eight cells (42.1%) were unresponsive and the remaining three cells (15.8%) were significantly inhibited. Of 19 cells recorded in theperiventricular nucleus, 13 (68.4%) were unresponsive to GHRP-6 and six (31.6%) were significantly inhibited. Thus, electrophysiological studies in vitro suggest that: (1) neurones in the hypothalamic arcuate nucleus, ventromedial nucleus and periventricular nucleus show changes in electrical activity in response to GHRP-6; and (2) the arcuate nucleus cells excited by GHRP-6 are also subject to inhibitory control by somatostatin.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/08/20 alle ore 19:19:02