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Elongation of oestrous cycle in the guinea‐pig following subcutaneous or intra‐uterine administration of indomethacin
Author(s) -
HORTON E. W.,
POYSER N. L.
Publication year - 1973
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1973.tb08271.x
Subject(s) - corpus luteum , estrous cycle , luteal phase , uterus , uterine horns , prostaglandin , endocrinology , guinea pig , medicine , luteolysis , biology , hormone , chemistry
Summary1 Guinea‐pigs injected subcutaneously with 10 mg indomethacin twice daily, from day 7 of the oestrous cycle, had their oestrous cycles significantly lengthened (P < 0·001) by about 3 days. 2 When the indomethacin was incorporated into a slow‐release preparation and placed in the uterus (33 mg per horn), the oestrous cycle lengths of these guinea‐pigs were greatly prolonged and approached that produced by hysterectomy. 3 The measurement of corpora luteal size and progesterone levels in some of the guinea‐pigs autopsied on day 47 of the extended cycle showed functional corpora lutea to be present. 4 It was apparent that indomethacin had prolonged the life span of the corpus luteum. This would account for the increase in the length of the oestrous cycle. 5 Recent investigations suggest that normal corpora luteal regression, with the termination of the oestrous cycle, is induced by prostaglandin F 2α released from the uterus on day 15. Since indomethacin prevents prostaglandin biosynthesis, it is probable in these experiments that this drug had prevented luteal regression by inhibiting the biosynthesis by, and release from, the uterus of prostaglandin F 2α in luteolytic concentrations. 6 These results provide further evidence that the uterine luteolytic hormone in guinea‐pigs is prostaglandin F 2α .