Serum Levels of Prolactin and Luteinizing Hormone (LH) in the Ewe at Various Stages of the Estrous Cycle

Jerry J. Reeves, Akira Arimura, Andrew V. Schally

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

Estrus activity was checked daily in three whitefaced, cross-bred, yearling ewes and jugular blood samples were collected daily during five estrous cycles. Serum prolactin and LH levels were determined by double radioimmunoassays. Prolactin levels were significantly higher during proestrus, (49 mμg/ml) and Day 1 estrus (40 mμg/ml) than during Day 2 estrus (11 mμg/ml), metestrus (15 mμg/ml) and diestrus (14 mμg/ml). LH levels were elevated on Day 1 estrus in only two of the five estrous cycles observed. The mean LH level for all five of the Day 1 estrus observations was 56 mμg/ml. This level was significantly higher than that during Day 2 estrus (1.9 mμg/ml), metestrus (1.6 mμg/ml), diestrus (1.1 mμg/ml) and proestrus (1.4 mμg/ml). These data suggest that the duration of the rise in prolactin levels is longer and precedes the elevated LH value at estrus. Serum prolactin levels did not seem to be correlated with the rise in LH, even though the increase in LH occurs at a time when serum prolactin levels are still high.

Original languageEnglish (US)
Pages (from-to)938-942
Number of pages5
JournalProceedings of the Society for Experimental Biology and Medicine
Volume134
Issue number4
DOIs
StatePublished - Sep 1970
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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