Hypothalamo-pituitary portal blood concentrations of beta-endorphin during suckling in the ewe.
K Gordon, M B Renfree, R V Short, I J Clarke
Index: J. Reprod. Fertil. 79(2) , 397-408, (1987)
Full Text: HTML
Abstract
Matched hypothalamo-pituitary portal and jugular blood samples were collected over about 6 h from 7 lactating Corriedale ewes penned with their lambs, and a careful record was kept of ewe/lamb behaviour. Hypothalamo-pituitary portal blood concentrations of beta-endorphin were measured by radioimmunoassay and the secretion rates were calculated; these were related to peripheral plasma prolactin and LH concentrations, and the sucking bouts of the lambs. Basal LH concentrations remained less than 1 ng/ml with 0-2 pulses of 1.5-3.5 ng/ml amplitude per 6-h collection period. Prolactin secretion was episodic with individual baselines varying from 24 to 286 ng/ml, and peak concentrations of 50-631 ng/ml. Portal beta-endorphin was secreted in an episodic pattern with individual baseline secretion rates varying from 0.125 to 0.495 ng/min, and peak secretion rates of 0.768 to 3.216 ng/min. A close correlation was seen between sucking bouts and the secretion of portal beta-endorphin and peripheral prolactin; 86% of sucking bouts resulted in a significant release of beta-endorphin, and 46% of sucking bouts resulted in a significant release of prolactin. These results show that hypothalamic beta-endorphin is released in response to the sucking stimulus. This provides support for the hypothesis that, during lactation, beta-endorphin acts within the hypothalamus to reduce GnRH release and hence depress pituitary gonadotrophin secretion.
Related Compounds
Related Articles:
1998-03-01
[Jpn. J. Pharmacol. 76 , 233-253, (1998)]
Beta-endorphin and the immune system--possible role in autoimmune diseases.
1995-01-01
[Autoimmunity 21 , 161-171, (1995)]
1995-05-01
[Naunyn Schmiedebergs Arch. Pharmacol. 351 , 464-468, (1995)]
Proopiomelanocortin signaling system is operating in mast cells.
2006-09-01
[J. Invest. Dermatol. 126(9) , 1934-6, (2006)]
Regulation of human epidermal melanocyte biology by beta-endorphin.
2003-06-01
[J. Invest. Dermatol. 120(6) , 1073-80, (2003)]