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Titolo:
Cells of the arcuate nucleus and ventromedial nucleus of the ovariectomized ewe that respond to oestrogen: A study using Fos immunohistochemistry
Autore:
Clarke, IJ; Pompolo, S; Scott, CJ; Rawson, JA; Caddy, D; Jakubowska, AE; Pereira, AM;
Indirizzi:
Prince Henrys Inst Med Res, Clayton, Vic 3168, Australia Prince Henrys Inst Med Res Clayton Vic Australia 3168 Vic 3168, Australia Monash Univ, Dept Physiol, Clayton, Vic 3168, Australia Monash Univ Clayton Vic Australia 3168 siol, Clayton, Vic 3168, Australia
Titolo Testata:
JOURNAL OF NEUROENDOCRINOLOGY
fascicolo: 11, volume: 13, anno: 2001,
pagine: 934 - 941
SICI:
0953-8194(200111)13:11<934:COTANA>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
GONADOTROPIN-RELEASING-HORMONE; LUTEINIZING-HORMONE; NEUROPEPTIDE-Y; BETA-ENDORPHIN; TYROSINE-HYDROXYLASE; ESTROGEN-RECEPTORS; PREOPTIC AREA; LH SURGE; HYPOTHALAMUS; NEURONS;
Keywords:
gonadotropin releasing hormone; female; reproduction; endocrinology; sheep;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
35
Recensione:
Indirizzi per estratti:
Indirizzo: Clarke, IJ Prince Henrys Inst Med Res, POB 5152, Clayton, Vic 3168, Australia Prince Henrys Inst Med Res POB 5152 Clayton Vic Australia 3168
Citazione:
I.J. Clarke et al., "Cells of the arcuate nucleus and ventromedial nucleus of the ovariectomized ewe that respond to oestrogen: A study using Fos immunohistochemistry", J NEUROENDO, 13(11), 2001, pp. 934-941

Abstract

Oestrogen produces a positive feedback effect on the secretion of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) when implanted into the ventromedial/arcuate nucleus of the ovariectomized (OVX) ewe. This has led to the belief that it is in this area of the hypothalamus that oestrogen causes the preovulatory surge in GnRH/LH. To date, however, the cell types that are integral to this response have not been identified. The present study aimed to examine cellular responsiveness to oestrogen in this region of the brain using Fos immunohistochemistry and further aimed to determine the cell type that shows an acute response to oestrogen. OVX ewes (n=4-6 per group) were given i.m. injections of oestradiol benzoate or oil (vehicle) and were killed 1-6 h later. Brains were perfused for immunohistochemistry. The number of cells in the arcuate nucleus which were immunopositive for Fos was greater (two- to fourfold) in the oestradiol benzoate-treated OVX ewes (n=5) 1 h after injection. The number of Fos-positive cells in the ventromedial hypothalamic nucleus was 10-fold greater in the oestradiol benzoate-treated ewes 1 h after injection. Because there were high levels of Fos-immunoreactive cells in oil-treated ewes, we repeated the experiment with i.v. injection of 50 mug oestrogen or vehicle (n=5). With this latter procedure, we found that oestrogen injection caused a significant increase in the number of Fos immunoreactive cells in the arcuate nucleus within 1 h, but there was no response in the ventromedial hypothalamus. To further characterize the types of cells that might respond to oestrogen, we double-labelled cells for Fos and either adrenocorticotropin hormone, neuropeptide Y ortyrosine hydroxylase (a marker for dopaminergic cells). These cell types could account for less than 30% of the total number of cells that were Fos-positive and oestrogen treatment did not cause an increase in the Fos labelling of any of these types of cell. These data show that oestrogen activatescells of the arcuate/ventromedial hypothalamus within 1 h of injection andthat this response could relate to the feedback effects of this gonadal hormone. The majority of cells that produce Fos following oestrogen injectionare of unknown phenotype. The data further suggest that induction of cellsof the ventromedial hypothalamic nucleus require more prolonged oestrogen stimulus than cells of the arcuate nucelus.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 22/01/20 alle ore 06:58:27