Effects of naloxone or transient weaning on secretion of LH and prolactin in lactating sows
- 1 May 1988
- journal article
- research article
- Published by Bioscientifica in Reproduction
- Vol. 83 (1), 301-308
- https://doi.org/10.1530/jrf.0.0830301
Abstract
Sows (N = 16) were infused intravenously for 8 h with saline or naloxone (200 mg/h) or their litters were transiently weaned for 8 h. Before infusion, 200 mg naloxone were administered to elevate quickly concentrations of naloxone. Blood samples were collected from sows at 15 min intervals for 24 h, beginning 8 h before and continuing until 8 h after imposition of treatments during the middle 8-h segment. Frequency of episodic release of LH and concentrations of prolactin were similar before, during and after infusion of saline. Average concentration of LH was greater during the last than during the middle 8-h segment when sows were given saline. Frequency of episodic release of LH increased and concentrations of prolactin decreased during infusion of naloxone or transient weaning; however, averge concentration of LH incrased during transient weaning, but not during infusion of naloxone. After transient weaning or infusion or naloxone, frequency of release of LH decreased, returning to pretreatment values in sows infused with naloxone but remaining above pretreatment values in sows subjected to transient weaning. At the resumption of suckling by litters in sows subjected to transient weaning, prolactin increased to levels not different from those observed during the 8-h pretreatment segment. Prolactin did not increase until 4-5 h after cessation of naloxone infusion. We conclude that continuous infusion of naloxone altered secretory patterns of LH and prolactin. Collectively these results provide evidence that the immediate effects of weaning on LH and prolactin in sows were mediated in part through a mechanism involving endogenous opioid peptides.This publication has 24 references indexed in Scilit:
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