[Sex hormone receptors in pituitary prolactinomas].

An attempt was made to interpret the mechanism responsible for the occurrence of pituitary tumors - prolactinoma in persons of different sex. The presence or absence of androgenic receptors in the tumors was studied. Analysis of the concentration of nuclear receptors, estrogen ones in particular, showed their higher concentration in prolactin-positive pituitary adenomas than in inactive pituitary adenomas. Androgen receptors were detected in the gonadotropic and lactotropic cells of the Intact pituitary. Analysis of the concentration of nuclear testosterone receptors in different morphological types of pituitary adenomas revealed no differences in the luteinizing hormone/follicle-stimulating hormone-positive and prolactin-positive tumors.

Role of sex hormones in development of pituitary adenoma.

Role of sex hormones in the development of pituitary adenomas was investigated by analyzing the content of nuclear estradiol and testosterone receptors in different tumors of the anterior pituitary: prolactinomas, meningiomas, growth hormone-producing adenomas, astrocytomas, neurinomas, and ependymomas. The concentration of nuclear estrogen and androgen receptors in prolactin-secreting pituitary adenomas was much higher than in growth hormone-producing adenomas and other pituitary tumors.

Luteinizing hormone-releasing hormone in thymus and hypothalamus of rat fetuses: suppressing effect of antagonist and of antibodies on concanavalin A-induced proliferation of thymocytes.

The effect of endogenous luteinizing hormone-releasing hormone (LHRH) on the proliferation induced by concanavalin A (Con A) in rat fetal thymocytes was studied. A selective antagonist (2 microg per fetus) or antibodies to LHRH (20 microl per fetus) were injected in utero into 20-day-old rat fetuses, and this resulted in a two- or fivefold decrease in the Con A-induced proliferation of thymocytes, respectively. In combined culture of the antagonist (10-5-10-6 M) with fetal thymocytes, the proliferative response was not decreased. The concentration of LHRH was determined by radioimmunoassay in tissues of immunocompetent organs and in blood serum of 18- and 21-day-old fetuses, and the hormone was found in the hypothalamus, thymus, and peripheral blood. The initially low level of LHRH in the thymus increased by 65 and 40%, respectively, on the first day after birth and became similar to the level in the hypothalamus. In the fetal blood serum, the LHRH level was significantly higher than in the thymus and hypothalamus of fetuses of the same age. The hormone concentration was greatest in the 18-day-old fetuses, and it decreased twofold by the 21st day. The findings indicate that LHRH is involved in regulation of T-cell immunity even during prenatal ontogenesis.

Neuroendocrine control of the gonadotropic function of the hypophysis in experimental diabetes.

The stability of the function of the reproductive system depends on a multitude of factors of the internal and external milieux. Serious disturbances in its function, with alterations in carbohydrate homeostasis, underlie such diseases as diabetes mellitus. Disturbances to the functional activity of the reproductive system in laboratory animals with diabetes are known to be associated not only with destructive changes in the gonads, but also with dysfunction of the hypothalamo-hypophyseal complex [9, 11]. Published data show that these lesions have different severities in male and female individuals [7, 8]. The question of the extent to which lesions due to the diabetic state depend on the level of sex steroids and insulin in the body thus far remains unanswered. Unlike the situation in males, females are characterized by cyclic changes in the activity of the reproductive system. Thus, it is possible that differences in the regulation of gonadotropic function in male and female rats, observed in normal animals, could explain their different sensitivities to diabetes. Thus, we elected to carry out various studies of the functional activity of the hypothalamo-hypophyseal-gonadal system in male and female rats with experimental diabetes induced by administration of streptozotocin (STZ).

Disturbance of neuroendocrine regulation of sexual behavior of male rats with streptozotocin diabetes.

Sexual behavior is a constituent of the reproductive function of the organism. In sexually mature individuals the synchronization of the level of sexual activity with the reaction of the hypothalamo-hypophyseo-gonadal system to the relevant environmental stimuli is a necessary condition for the preservation of the species. In this context, the study of the neuroendocrine mechanisms shaping a specific level of activity of sexual behavior is an important problem for investigators. The dependence of the level of sexual activity on the integrity of certain CNS structures (first of all, the olfactory bulbs, amygdala, hypothalamus, and hypophysis) has been established. It has been demonstrated that label sex steroids accumulate selectively, and the regulation of the function of the gonads on the negative feedback principle is also accomplished in these regions precisely. In addition to the participation of the sex steroids in the formation of a specific level of sexual activity, an important role has been established at the present time for luliberin (LHRH) producing system and the neurotransmitters. The stability of the functioning of the reproductive system depends on a multiplicity of factors of the internal and external milieu. Serious disturbances in its function are associated with the alteration in carbohydrate homeostasis underlying a disease such as diabetes mellitus. This is manifested in a reduction in the weight of the accessory sex glands, steroidogenic activity and spermatogenesis, in a change in the secretion of gonadotropins, as well as in a diminution of fertility and sexual behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between changes in LH-RH content in the synaptosomal fraction of the olfactory bulb and some hypothalamic zones and level of sexual activity in male rats.

We have studied the level of LH-RH in the synaptosomal fraction of the olfactory bulbs, preoptic area, and mediobasal hypothalamus, and the blood level of HL in adult male rats with sexual activity after noradrenergic denervation of the preoptic area using 6-oxydopamine. A neurotoxic effect of a 0.1% solution of ascorbic acid, preventing 6-oxydopamine disintegration was observed. Both sexual activity and level of LH-RH in synaptosomes of the preoptic area were reduced in male rats with noradrenergic denervation of the preoptic area. The maximum blood level of LH was observed during exposure to a recipient female rat, the LH-RH concentration in the synaptosomal fraction of the olfactory bulbs being raised, and that in the mediobasal hypothalamus being decreased. The results showed that LH-RH synthesizing cerebral neurons with terminals in the olfactory bulbs, preoptic area, and mediobasal hypothalamus are involved in the regulation of sexual behavior and the interaction of LH-RH-containing terminals with noradrenergic nerve endings at the level of the preoptic area.