Abstract
Summary
Serum concentrations of pro-lactin, LH, and estradiol-17β (E2) were measured on Day 1 (Day 8-17 of the menstrual cycle) at 30 and 0 min before and 10, 30, 60, 120, and 180 min after coitus in five intact female rhesus monkeys. Blood samples were also collected on a similar schedule on the following 2 days when the females were placed for 30 min in the mating cage alone (Day 2) or in the presence of a male in a separate cage (Day 3). None of the females showed an increase in serum prolactin or E2 levels on any of the 3 days. Serum LH levels increased (P < 0.05) in two of the three monkeys in which they were monitored. However, of these two monkeys, one showed a similar LH increase when she was left alone in the mating cage. In three females which refused copulation, serum prolactin, LH, and E2 levels remained unchanged.
The effect of copulation on serum LH was further investigated in eight additional females which were allowed to copulate on Days 5, 12, and 22 of the menstrual cycle and in two long-term ovariectomized E2-treated females. Serum LH increased within 30 min after coitus in one female on each of the 3 days, but remained unchanged or showed inconsistent fluctuations in the remaining seven intact females and in the two ovariectomized E2-treated females. We conclude that copulation per se does not influence serum prolactin, LH, or E2 levels nor do changing ratios of circulating estrogen and progesterone before coitus account for occasional postcoital LH fluctuations in captive female rhesus monkeys after pairing with a sexually active male.
We thank Terry Oyama and Margaret Stobie for excellent technical assistance and Lois Hasebe for typing the manuscript. Special appreciation is due to Dr. Charles Phoenix for use of the copulation room.
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