Infusion of alpha-2-adrenergic agents into the paraventricular and arcuate nuclei of the hypothalamus in the Siberian hamster: opposing effects on basal prolactin

Neuroendocrinology
J C Dodge, L L Badura

Abstract

Although the alpha(2)-adrenergic receptor subtype has been shown to have a significant influence on circulating levels of prolactin (PRL), its exact role remains unclear. A multitude of studies have demonstrated that blockade of the alpha(2)-receptor can either elevate or decrease circulating levels of PRL. Alpha(2)-receptor-mediated control of both stimulatory and inhibitory arms of the PRL regulatory system may explain this discrepancy. Activation of the alpha(2)-receptor has been shown to inhibit the activity of its target cell, and therefore antagonism of the alpha(2)-receptor within a stimulatory component (e.g., paraventricular nucleus (PVN) of the hypothalamus) would theoretically have the opposite effect that it would have within an inhibitory component (arcuate nucleus of the hypothalamus). Thus, the purpose of this study was to investigate the functional role of the alpha(2)-adrenergic receptor in modulating circulating levels of PRL both at the level of the PVN and arcuate using reverse microdialysis of alpha(2)-adrenergic agents coupled with serial blood sampling in the male Siberian hamster. Male hamsters were fitted with a jugular cannula for serial blood sampling, and an indwelling microdialysis probe for intrahy...Continue Reading

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