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Titolo:
IMMUNOHISTOCHEMICAL AND NEUROCHEMICAL EVIDENCE FOR GABA(A) RECEPTOR HETEROGENEITY BETWEEN THE HYPOTHALAMUS AND CORTEX
Autore:
INGLEFIELD JR; SIEGHART W; KELLOGG CK;
Indirizzi:
UNIV ROCHESTER,DEPT PSYCHOL,ROOM 186,MELIORA HALL ROCHESTER NY 14627 UNIV ROCHESTER,DEPT PSYCHOL ROCHESTER NY 14627 UNIV VIENNA,PSYCHIAT CLIN A-1090 VIENNA AUSTRIA UNIV ROCHESTER,DEPT NEUROBIOL & ANAT ROCHESTER NY 14627
Titolo Testata:
Journal of chemical neuroanatomy
fascicolo: 4, volume: 7, anno: 1994,
pagine: 243 - 252
SICI:
0891-0618(1994)7:4<243:IANEFG>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
RAT-BRAIN; BENZODIAZEPINE RECEPTORS; DORSOMEDIAL HYPOTHALAMUS; PARAVENTRICULAR NUCLEUS; DEFENSE REACTION; CHANNEL COMPLEX; MESSENGER-RNA; A RECEPTOR; ADULT-RAT; SUBUNIT;
Keywords:
BENZODIAZEPINES; CHLORIDE CHANNEL; GABA(A) RECEPTOR FUNCTION; IMMUNOHISTOCHEMISTRY; GABA(A) RECEPTOR SUBTYPES; STRESS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
54
Recensione:
Indirizzi per estratti:
Citazione:
J.R. Inglefield et al., "IMMUNOHISTOCHEMICAL AND NEUROCHEMICAL EVIDENCE FOR GABA(A) RECEPTOR HETEROGENEITY BETWEEN THE HYPOTHALAMUS AND CORTEX", Journal of chemical neuroanatomy, 7(4), 1994, pp. 243-252

Abstract

This study examined both the function of the GABA(A) receptor complexand the expression of its alpha 1, alpha 2 and alpha 3 subunits within the hypothalamus as compared to that of the cerebral cortex. A largenumber of different GABA(A) receptor subunit combinations potentiallyexist in various brain regions which, presumably, would intimate differing receptor structure and function. Here, we present evidence that the average functional characteristics of GABA(A) receptors within therat hypothalamus are considerably different from those of the cerebral cortex. We assessed two neurochemical measures of GABA(A) receptor function: namely, chloride-facilitation of [H-3]flunitrazepam binding and GABA-mediated (36)chloride uptake. [H-3]Flunitrazepam binding in the rat cortex was facilitated by increasing concentrations (12.5-500 mM) of chloride, and this facilitation was responsive to 15 min restraint. Yet, hypothalamic [H-3]flunitrazepam binding was not responsive to increasing chloride-concentration in either the basal or restraint conditions. Also, maximal facilitation of GABA-mediated (36)chloride uptake was significantly blunted in the hypothalamus relative to cortex (7.4 +/- 0.9 versus 35.8 +/- 1.5 nmoles/mg protein, respectively). Whilein vitro addition of 10 mu M diazepam shifted GABA-mediated (36)chloride uptake curves of the cortex to the left, diazepam addition appeared to be without effect in the hypothalamus. However, the blunted maximal facilitation of GABA on hypothalamic (36)chloride uptake made accurate determination of the EC(50) for the diazepam-potentiation difficult. In addition to these functional disparities between the regions, differences in subunit expression were also apparent. Distributions of alpha 1, alpha 2 and alpha 3 subunit immunoreactivities within cingulate, parietal and temporal cortices and 8 major hypothalamic regions were assessed. Staining of the alpha 1 subunit was prevalent throughout the hypothalamus and cortex, and dense in both regions. However, the alpha 2 and alpha 3 subunits, while of intermediate density in cortex, were of low density or absent alpha 3 in the hypothalamus. The alpha 2-immunoreactivity was restricted to cell bodies of the arcuate nucleus,dorsomedial nucleus and overlying dorsal area and to neuropil staining of the median eminence. Thus, functional responsiveness of the GABA(A) receptor differs in the hypothalamus relative to the cortex and this would seem related to the presence of different receptor ct subunitsin homogenate preparations of the two regions.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/04/20 alle ore 23:16:22