ON DIFFERENCES BETWEEN THE PREOVULATORY LUTEINIZING HORMONE SURGES OF 4- AND 5-DAY CYCLIC RATS

in Journal of Endocrinology
Authors:
G. A. SCHUILING
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J. DE KONING
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A. F. ZÜRCHER
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SUMMARY

Preovulatory LH surges were studied in rats with ovarian cycles of 4 days (4d-rats) and 5 days (5d-rats). In 5d-rats the maximal peak height was about twice that observed in 4d-rats, whereas in 4d-rats peaks occurred about 1·5 h later than in 5d-rats and were much less consistently timed.

From experiments in which LH releasing hormone (LH-RH) was infused into pentobarbitone-blocked pro-oestrous rats, it was concluded that (a) differences between the two types of preovulatory LH surges originate within the central nervous system, and (b) prooestrous LH-RH secretion may not be restricted to the period in which increased LH levels in blood were found, but may exceed this period for a considerable time.

 

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