Reproductive Hormonal Status Research Articles

Thymocyte maturity in male and female hypogonadal mice and the effect of preoptic area brain grafts

Hypogonadal mice with a genetic deficiency of gonadotropin-releasing hormone (GnRH) have low levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and gonadal steroids. In this study we found differences from normal mice in many aspects of thymic development. Thymus weights and cellularity were higher in hypogonadal than in normal male mice but lower in hypogonadal than in normal females. Although all normal mice had higher proportions of mature, single staining thymocytes (CD8 + or CD4 +) than seen in hypogonadal mice, there was a sex difference in the basis for this shift. Significantly more double-staining (CD8 +, CD4 +) thymocytes were seen in hypogonadal males than in normal males while both groups had similar single-staining populations. However, in females, both single-staining CD8 + and CD4 + thymocytes were more numerous in normal than in hypogonadal females while numbers of double-staining cells were similar in the two groups. These studies indicate that a mature thymocyte profile may be arrived at through differential effects of reproductive hormones in males and females. When brain grafts containing GnRH cells were used to correct reproductive deficits in hypogonadal mice, there were higher splenocyte counts in males with grafts, a similar trend in females, and a lower ratio of single staining CD4 + to CD8 + thymocytes in all females with grafts vs. all females without, regardless of whether or not the grafts corrected the reproductive hormone status of the recipients, indicating an effect of the graft surgery on the immune system.

Exaggerated gonadotropin response to luteinizing hormone-releasing hormone in amenorrheic runners

Most studies of exercise-induced amenorrhea have compared amenorrheic athletes (usually runners) with sedentary control subjects. Such comparisons will identify hormonal changes that develop as a result of exercise training but cannot determine which of these changes play a role in causing amenorrhea. To obviate this problem, we assessed reproductive hormone status in a group of five amenorrheic runners and compared them to a group of six eumenorrheic runners matched for body fatness, training intensity, and exercise performance. Compared to the eumenorrheic runners, the amenorrheic runners had lower serum estradiol concentrations, similar basal serum luteinizing hormone and follicle-stimulating hormone concentrations, and exaggerated responses of serum gonadotropins after administration of luteinizing hormone-releasing hormone (100 μg intravenous bolus). Serum prolactin levels, both basally and after thyrotropin-releasing hormone administration (500 μg intravenous bolus) or treadmill exercise, was similar in the two groups, as were serum thyroid function tests (including thyrotropin response to thyrotropin-releasing hormone). Changes in serum cortisol levels after short-term treadmill exercise were simiiar in both groups, and serum testosterone levels increased after exercise only in the eumenorrheic group. In neither group did such exercise change serum luteinizing hormone, follicle-stimulating hormone, or thyrotropin levels. We conclude that exercise-induced amenorrhea is not solely related to the development of increased prolactin output after exercise training. The exaggerated gonadotropin response to luteinizing hormone-releasing hormone seen in amenorrheic runners in comparison with matched eumenorrheic runners is consistent with a hypothalamic etiology for the menstrual dysfunction, analogous to that previously described in “stress-induced” or “psychogenic” amenorrhea.

Recognition of H-2 types in relation to the blocking of pregnancy in mice.

Inbred BALB/c females were mated and subsequently exposed in a divided cage to "stimulus" males or females whose H-2 type was similar or dissimilar to the stud male's. The incidence of pregnancy blocking was considerably higher when stud and stimulus males differed in H-2 type than when they did not. Similar results were obtained with urine samples of H-2 identical and nonidentical males. Females exposed after mating to other females whose H-2 type differed from the stud male, under the same experimental conditions, also showed an appreciable incidence of pregnancy block. It is therefore concluded that chemosensory recognition of H-2 types affects the reproductive hormonal status of the pregnant female.

Dose-response effects of prostaglandin F 2α on the rabbit oviduct: Reproductive endocrine influence and tachyphylaxis

The dose-response effect of PGF 2α on the perfused oviduct of estrous and ovariectomized rabbits was determined. The oviducts of ovariectomized rabbits were more sensitive to the contractile effects of PGF 2α than those of estrous rabbits. This was demonstrated by a significant difference in the slope of the dose-response curves and in the magnitude of the maximum responses between the two groups. Blood pressure responses (depressor) to PGF 2α were not affected by the reproductive hormonal status of the rabbits. The oviduct (estrous rabbits) developed tachyphylaxis to the effect of PGF 2α. It was concluded that the response of the rabbit oviduct to PGF 2α is dependent on the reproductive hormone status of the animal and that the oviduct becomes insensitive to the effects of PGF 2α with repeated administration.