Noradrenaline and dopamine regulation of prolactin secretion in sheep: role in prolactin homeostasis but not photoperiodism

Journal of Neuroendocrinology
G A Lincoln, I J Clarke

Abstract

The role of noradrenaline (NA) and dopamine (DA) in the hypothalamic control of prolactin (PRL) secretion was investigated in hypothalamic intact (control) and hypothalamo-pituitary disconnected (HPD) Soay rams. The animals were exposed to alternating 16-weekly periods of short (8 L : 16D) and long days (16 L : 8D) to induce marked cyclical changes in PRL secretion in both groups (as demonstrated previously). Selective NA and DA receptor antagonists (dose: 1.2 micromol/kg) were administered under short days (low endogenous PRL secretion), and agonists (dose: 0.0012-0.12 micromol/kg) were administered under long days (high endogenous PRL secretion). The acute changes in blood PRL concentrations were measured over 4 h as the index of responsiveness. Under short days, treatment with WB4101 (alpha-1 adenoceptor antagonist), and rauwolscine (alpha-2 antagonist), consistently increased PRL secretion in control, but not in HPD rams. The treatments produced similar acute, drug-specific behavioural effects in both groups. Propranolol (beta antagonist) had no effect on PRL secretion, while sulpiride (DA D-2 antagonist) induced a marked increase in blood PRL concentrations in control rams (> 4 h), and a transient effect in HPD rams (15 mi...Continue Reading

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Citations

Sep 27, 2003·General and Comparative Endocrinology·Jonathan D JohnstonAndrew S I Loudon
Jul 20, 2005·Annals of Medicine·Christian A Kell, Jörg H Stehle
May 20, 2008·Journal of Biological Rhythms·Duncan J Macgregor, Gerald A Lincoln
May 2, 2003·FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology·Jonathan D JohnstonAndrew S I Loudon
Nov 5, 2005·Endocrinology·Jonathan D JohnstonDavid G Hazlerigg
Feb 12, 2019·Frontiers in Endocrinology·Xiaoshuang LiuChiyuan Ma

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