Distribution of galanin receptor-2 immunoreactive neurones in the ovine hypothalamus: No evidence for involvement in the control of gonadotrophin-releasing hormone secretion

Chambers, G., Whitelaw, C.M., Robinson, J.E. and Evans, N.P. (2007) Distribution of galanin receptor-2 immunoreactive neurones in the ovine hypothalamus: No evidence for involvement in the control of gonadotrophin-releasing hormone secretion. Journal of Neuroendocrinology, 19(12), pp. 966-973. (doi:10.1111/j.1365-2826.2007.01609.x)

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Abstract

Galanin is a small neuropeptide that mediates its effects via three receptor isoforms: galanin receptor-1, galanin receptor-2 and galanin receptor-3 (Gal-R1, Gal-R2 and Gal-R3). Galanin is thought to be an important intermediate in signalling in the hypothalamic-pituitary-gonadal axis and has been widely detected in the ovine hypothalamus. The expression of galanin and Gal-R1 has been reported to fluctuate during the reproductive cycle. Although the distribution of Gal-R1 has been determined in the ovine hypothalamus, the distribution of Gal-R2 was hitherto unknown. Using immunohistological and immunofluorescence techniques, we have mapped the distribution of Gal-R2 in the ovine hypothalamus, collected during the follicular phase of the oestrous cycle and examined colocalisation of Gal-R2 with oestrogen receptor alpha (ERα) and gonadotrophin-releasing hormone (GnRH). Gal-R2 was expressed in several regions of the hypothalamus (supraoptic nucleus, paraventricular nucleus, ventromedial nucleus, arcuate nucleus) but not as widely expressed as Gal-R1. Areas of Gal-R2 expression overlapped with those reported for Gal-R1. We observed that, in certain defined regions of the hypothalamus, up to 50% of neurones that express Gal-R2 also express ERα. No neurones coexpressed Gal-R2 and GnRH. Thus, we conclude that, in follicular phase animals, this receptor plays little or no role in direct intermediary signal transmission in GnRH-mediated control of the reproductive cycle.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Robinson, Dr Jane and Whitelaw, Mrs Christine and Evans, Professor Neil
Authors: Chambers, G., Whitelaw, C.M., Robinson, J.E., and Evans, N.P.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Journal of Neuroendocrinology
ISSN:0953-8194

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