Soy isoflavone effects on the adrenal glands of orchidectomized adult male rats: a comprehensive histological and hormonal study.

Genistein (G) and related soy phytoestrogens have been studied for potential usefulness in different chronic diseases, and may ameliorate signs of aging. They have a profound influence on the hypothalamo-pituitary-adrenal (HPA) axis. The present study utilized the rat model of mild andropause to thoroughly evaluate the effects of G and soy extract on the adrenal gland and related blood hormones. Adult male rats were orchidectomized (Orx) or sham operated (SO). Orx rats received daily subcutaneous injections for 3 weeks of solvent, or G (Orx+G, 30 mg/kg), or commercial soy extract (Orx+Soy, 30 mg/kg). Adrenal glands and blood were harvested at the end of the treatment for hormone analyses, histology and design-based stereology. Compared to SO rats Orx evoked significant (P<0.05) changes including: the replicating cell number in the 3 adrenocortical zones; vascularity and cortical volume and blood levels of adrenocorticotropic hormone (ACTH), aldosterone and dehydroepiandrosterone (DHEA). When comparing Orx vs. Orx+G groups the following significant (P<0.05) changes were observed: a further increase in number of replicating cells in zonas glomerulosa and reticularis, vasculature network presence, cortical and zona reticularis volumes, ACTH and corticosterone concentrations, and lower DHEA levels. Comparing Orx vs. Orx+Soy resulted in elevated (P<0.05) ACTH and corticosterone levels. Structural integrity of the adrenal gland was unchanged vs. SO rats. Overall, G and soy extract treatments resulted in proliferative activity and/or vasculature support in the adrenal cortex. The data and current literature support the impression of a beneficial effect of soy components on the homeostatic response to stress.

Effects of soy phytoestrogens on pituitary-ovarian function in middle-aged female rats.

The aim of this study was to assess the effects of genistein (G) and daidzein (D) on the histological, hormonal, and functional parameters of the pituitary-ovarian axis in middle-aged female rats, and to compare these effects with the effects of estradiol (E), commonly used in the prevention and treatment of menopausal symptoms. Middle-aged (12 month old) Wistar female rats subcutaneously received 35 mg/kg of G, or 35 mg/kg of D, or 0.625 mg/kg of E every day for 4 weeks. Each of the treated groups had a corresponding control group. An intact control group was also established. G and D did not change the intracellular protein content within gonadotropic and lactotropic cells, but vacuolization was observed in all the cell types. In contrast, E caused an inhibition of gonadotropic and stimulation of lactotropic cells. Also, ovaries of middle-aged female rats exposed to G or D have more healthy primordial and primary follicles and less atretic follicles. E treatment in the ovaries had a mostly negative effect, which is reflected by the increased number of atretic follicles in all tested classes. G and D provoked decrease in CuZnSOD and CAT activity, while E treatment increased MnSOD and decreased CuZnSOD and GSHPx activity. All the treatments increased serum estradiol and decreased testosterone levels, while D and E increased the serum progesterone level. In conclusion, soy phytoestrogens exhibited beneficial effects on pituitary-ovarian function in middle-aged female rats, as compared to estradiol.

Morpho-functional characteristics of rat fetal thyroid gland are affected by prenatal dexamethasone exposure.

Thyroid hormones (TH) and glucocorticoids strongly contribute to the maturation of fetal tissues in the preparation for extrauterine life. Influence of maternal dexamethasone (Dx) administration on thyroid glands morpho-functional characteristics of near term rat fetuses was investigated applying unbiased stereology. On the 16th day of pregnancy dams received 1.0mg/Dx/kg/b.w., followed by 0.5mg/Dx/kg/b.w. on the 17th and 18th days of gestation. The control females received the same volume of saline. The volume of fetal thyroid was estimated using Cavalieri's principle; the physical/fractionator design was applied for the determination of absolute number of follicular cells in mitosis and immunohistochemically labeled C cells; C cell volume was measured using the planar rotator. The functional activity of thyroid tissue was provided from thyroglobulin (Tg) and thyroperoxidase (TPO) immunohistochemical staining. Applying these design-based modern stereological methods it was shown that Dx treatment of gravid females led to a significant decrease of fetal thyroid gland volume in 19- and 21-day-old fetuses, due to decreased proliferation of follicular cells. The Tg and TPO immunohistochemistry demonstrated that intensive TH production starts and continues during the examined period in control and Dx-exposed fetuses. Under the influence of Dx the absolute number of C cells was lower in both groups of near term fetuses, although unchanged relation between the two populations of endocrine cells, follicular and C cells suggesting that structural relationships within the gland are preserved. In conclusion maternal glucocorticoid administration at the thyroid gland level exerts growth-inhibitory and maturational promoting effects in near term rat fetuses.

Long-term effects of somatostatin 14 on the pituitary-ovarian axis in rats.

The long-term effects of somatostatin 14 (SST-14) on the pituitary-ovarian axis were examined. Female Wistar rats received 20 µg/100g b.w. doses subcutaneously twice daily for 5 consecutive days in the infantile (from 11th to 15th day) or peripubertal (from 33rd to 37th day) period of life. Females treated as infants were killed in the peripubertal (38th day) or adult period of life (80th day), and those treated during peripuberty as adults (80th day). Pituitary follicle-stimulating (FSH), luteinizing (LH) and somatotropic (GH) cells, and ovaries were analyzed by stereology and morphometry. Serum FSH and LH concentrations were determined by RIA. FSH and LH cell volumes were significantly decreased in pituitaries of peripubertal females treated with SST-14 as infants, and in adult females treated during peripuberty. GH cell volume was decreased in all treated rats. In the ovaries, enlargement of the non-growing pool of follicles was detected in adult females treated during peripuberty. SST-14 applied to infant rats did not lead to changes in initial follicular recruitment, but it disturbed follicle growth and development at later stages. It can be concluded that SST-14 exerted long-term inhibitory effects on the pituitary-ovarian axis and GH cells in rats.