Effect of Treatment for 1 Year with a Luteinizing Hormone-Releasing Hormone Agonist on Ovarian, Thyroidal, and Adrenal Function and Menstruation in the Stumptailed Monkey (Macaca arctoides)

Publisher Website
Google Scholar
Abstract
Nine adult stumptailed macaque monkeys with regular menstrual cycles were treated daily for 11–16 months with a LHRH agonist (5 μg D-Ser-(But)6-des Gly10 LHRH ethylamide). This produced various degrees of inhibition of ovarian function, which could be divided into three types. In the most suppressed state, as represented by three of nine monkeys, ovulation was inhibited, and serum concentrations of estradiol fluctuated between levels associated with the early to midfollicular phase of the normal cycle, never reaching late follicular phase values. These animals became virtually amenorrheoic during treatment. In another three monkeys, the agonist also inhibited ovulatory cycles, but serum concentrations of estradiol occasionally rose to values associated with the late follicular phase, indicating that follicular maturation was not as completely suppressed. In one of these animals, ovulation occurred early in treatment, and one of the later episodes of follicular maturation was followed by a small rise in serum progesterone, suggesting the formation of a luteinized follicle. The other two animals, which also showed periodic follicular maturation, actually had one and three breakthrough ovulations during treatment, respectively. These animals demonstrated irregular patterns of menstruation. In the remaining three monkeys, the 5-μg dose of LHRH agonist failed to suppress ovulation, which generally appeared normal apart from a possible inadequate luteal phase in one animal and a possible luteinized follicle in another. Increasing the dose of LHRH agonist to 20 μg/day suppressed ovulation in two of the animals and reduced the number of cycles in the remaining animal; cycles in the last animal were eventually suppressed when the agonist was administered in a dose of 10 Hg twice daily. In all animals, serum concentrations of androstenedione during agonist treatment remained within the range observed in a normal cycle. Compared to the equivalent pretreatment control period, the duration of menstruation was reduced in all monkeys treated with the agonist. At the end of treatment, the monkeys ovulated within 2–4 weeks, except for one animal in the most suppressed group; cycles failed to return in this monkey. Chronic LHRH treatment had no marked effect on adrenal function, as serum cortisol concentrations remained unaltered, but there was a slight rise in serum T4 concentrations, perhaps due to changes in ovarian estrogen secretion. During and after agonist treatment, sera from all animals were tested to see if antibodies to the agonist had developed, but none was able to bind 125I-labeled LHRH agonist.

This publication has 27 references indexed in Scilit: