Age-related decline in deciduogenic ability of the rat uterus.

To study age-related changes in uterine responsiveness to deciduogenic stimuli, virgin female rats of the T strain were ovariectomized at 4, 8, 10, or 12 mo of age and given daily s.c. injections of 3 mg progesterone for 7 days, commencing on the day after operation, and a single s.c. injection of 0.1 microgram estradiol-17 beta on the third day of the period. Endometrial stimulation was effected by either endometrial traumatization or intraluminal instillation of sesame oil or prostaglandin E2 (PGE2), applied 16 h after the injection of estradiol. Decidual response began to decrease at 8 mo of age and completely disappeared between 8 and 12 mo, regardless of the type of induction stimulus. At 8 mo of age, females formed deciduomata in response to instillation of oil or PGE2, only when they had been cycling regularly at the time of ovariectomy. In 10-mo-old rats, instillation of oil or PGE2 invariably failed to elicit a positive response, regardless of the pattern of estrous cycles at surgery. However, if an ovary was transplanted s.c. 5 or 7 mo after ovariectomy at 4 mo of age, the uteri responded positively to oil instillation at 10 and 12 mo of age, after the ovarian grafts had been removed and steroid treatments had been administered. Moreover, a 2-mo interval between ovariectomy at 8 mo of age and the commencement of the standard treatment schedule restored or maintained the uterus's ability to form deciduomata by 10 mo of age.(ABSTRACT TRUNCATED AT 250 WORDS)