The broad objective of this study will be to investigate whether dexamethasone, a synthetic glucocorticoid useful in chemical reproductive therapy in humans, can indirectly affect ovarian function. Specifically, such influence on ovarian function will be tested via.the uterine metabolism and the body temperature rhythm during decidualized pseudopregnancy (DCPG) in albino rats. From a health related standpoint, dexamethasone, because of its suppression of androgens,is widely used to measure hypothalamic-hypophyseal-adrenal activity, and is also utilized in the chemical therapy of reproductive functions. Moreover, the study will be concerned with reproductive and body temperature functions in a mammalian species, the rat. Experimentally, rats between 200-250 grams, of the Sprague-Dawley strain will be employed. Rats displaying at least two consistent 4 or 5 days estrous cycle (determined by vaginal lavages) will be used. After cervical stimulation with a vibrating plastic rod during proestrus and estrus, rats will undergo the induction of uterine deciduoma (implantation simulation) on the fourth day of continuous leucocytic infiltration in the vaginal lavages. This procedure will be surgically performed via laparotomy and by scratching the inner anti-mesometrial uterine membrane with a specially designed needle. During the latter portion of a 5-8 days post-operative recovery period, rats will be divided into three groups of dexamethasone treatment. Rats will be subcutaneously injected with dexamethasone (0.5, 1.0, and 1.5 mg/rat) in daily doses for days post-implantationally (Days 6-10 DCPG) between 1000 to 1200 hours. Thereafter, the ovarian protein content and the uterine metabolism by way of biochemical endpoints (wet weight, protein and glycogen contents) will be examined by standard assay procedures on Day 11 of DCPG. The body temperature circadian rhythm will be monitored and analyzed by means of a computerized biotelemetry system (Dataquest III) during Days 11-16 of DCPG. Results, presented as means + standard errors, will be tested statistically, with a p value of at least 0.05 considered significant, by the Student's t-test, by the Analysis of Variance and by Cosinor regression analysis.
