Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Release of prolactin is independent of the secretion of thyrotrophin-releasing hormone into hypophysial portal blood of sheep

Release of prolactin is independent of the secretion of thyrotrophin-releasing hormone into... ABSTRACTIn order to determine whether pituitary prolactin release was directly related to the secretion of TRH into hypophysial portal blood, serial portal and jugular venous blood samples were collected from seven lactating and three non-lactating ewes. In another experiment, samples were collected from five ovariectomized ewes while being exposed to an audio-visual stress and then later administered with chlorpromazine. Secretion of TRH was pulsatile in all ewes and independent of prolactin secretion; TRH pulses coincided with significant increases in prolactin secretion in only 15% of cases and only 29% of prolactin pulses were associated with TRH pulses. Sixty-seven per cent of suckling bouts were associated with increases in prolactin secretion, but only 22% of these were associated with significant increases in TRH secretion. Chlorpromazine increased prolactin levels fourfold but did not affect portal concentrations of TRH. Audio-visual stress was not a reliable method of causing prolactin release in this model. Mean portal concentrations of TRH and jugular concentrations of prolactin were not significantly correlated. These results show that hypothalamic TRH and pituitary prolactin are secreted independently in the sheep, implying that increases in prolactin release caused by suckling or chlorpromazine are not the direct result of increased TRH secretion.J. Endocr. (1988) 117, 115–122 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Endocrinology Bioscientifica

Release of prolactin is independent of the secretion of thyrotrophin-releasing hormone into hypophysial portal blood of sheep

Download PDF
8 pages

Loading next page...
 
/lp/bioscientifica/release-of-prolactin-is-independent-of-the-secretion-of-thyrotrophin-etmlujKoOx

References

References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.

Publisher
Bioscientifica
Copyright
Copyright © 1988 The Authors. All Rights Reserved.
ISSN
0022-0795
eISSN
1479-6805
DOI
10.1677/joe.0.1170115
Publisher site
See Article on Publisher Site

Abstract

ABSTRACTIn order to determine whether pituitary prolactin release was directly related to the secretion of TRH into hypophysial portal blood, serial portal and jugular venous blood samples were collected from seven lactating and three non-lactating ewes. In another experiment, samples were collected from five ovariectomized ewes while being exposed to an audio-visual stress and then later administered with chlorpromazine. Secretion of TRH was pulsatile in all ewes and independent of prolactin secretion; TRH pulses coincided with significant increases in prolactin secretion in only 15% of cases and only 29% of prolactin pulses were associated with TRH pulses. Sixty-seven per cent of suckling bouts were associated with increases in prolactin secretion, but only 22% of these were associated with significant increases in TRH secretion. Chlorpromazine increased prolactin levels fourfold but did not affect portal concentrations of TRH. Audio-visual stress was not a reliable method of causing prolactin release in this model. Mean portal concentrations of TRH and jugular concentrations of prolactin were not significantly correlated. These results show that hypothalamic TRH and pituitary prolactin are secreted independently in the sheep, implying that increases in prolactin release caused by suckling or chlorpromazine are not the direct result of increased TRH secretion.J. Endocr. (1988) 117, 115–122

Journal

Journal of Endocrinology – Bioscientifica

Published: Apr 1, 1988

There are no references for this article.