Some biochemical effects of insulin and steroid hormones on the rat prostate in organ culture

The effect of various steroids and insulin on expiants of the ventral prostate of adult rats in organ culture was investigated. Testosterone activated the incorporation of labeled precursors into RNA and protein and the formation of ¹⁴CO₂ from ¹⁴C-glucose by expiants. All these effects were mimiced by insulin. The testosterone action was suppressed by cyproterone in vitro. In addition to androgens, glucocorticoids activated the incorporation of ³H-uridine into RNA. Simultaneous addition of testosterone with hydrocortisone or insulin produced an augmented effect on the incorporation of ³H-uridine into RNA which exceeded that resulting from a simple summation of the individual hormone responses. Insulin facilitated likewise the action of testosterone on the incorporation of ¹⁴C-amino acids into protein. When all three hormones were added simultaneously to the culture medium the stimulation of the three biochemical parameters was maximal. It was therefore concluded that all three hormones are necessary for an adequate maintenance of the ventral prostate of the rat.     

Effects of steroid sex hormones on chick embryo gonads in organ culture, with special reference to hormonal control of gonadal sex differentiation

At the initial stages of sex differentiation (7.5 and 8.5 days of incubation), chick embryo gonads were treated directly with testosterone or estradiol-17 beta in organ cultures. Chemically-defined media containing cholesterol as a steroid precursor were used. The differentiation of gonads in the 10 to 12-day controls, cultured in media containing no hormones, was close to that of gonads of equivalent age in ovo. Testosterone added to the medium exerted an inhibitory effect on the cortex of the female gonad and a masculinizing one on its medulla. The results of estradiol treatment confirmed the known feminizing effect of that hormone on the male gonad, the meiotic prophase in the genetically male germ cells being initiated in the induced cortex. These data may be interpreted in favour of a bihormonal theory of gonadal sex differentiation in birds, where the predominantly-synthesized male or female hormone in the gonad determines the male or female pattern of development of the corresponding gonad.     

Development of fetal rat ovaries responsiveness to LH during organ culture.

The responsiveness of fetal neonatal rat ovaries to LH was investigated in vitro using three complementary approaches. First, steroid production was assessed after culture. In control media, detectable levels of estrogens (estradiol and estrone) and progesterone were only observed from day 6 postpartum and during the second week of life respectively. In the presence of LH (100 ng/ml) ovaries produced both estrogens and progesterone from day 4 postpartum and the response to LH was enhanced with IBMX supplementation in the medium. Second, 3 beta-HSD activity was measured with either LH or (Bu)2 cAMP (1mM). Irrespective to the time-period studies (Bu)2 cAMP stimulated this enzyme whereas the stimulation with LH occurred only from day 5 postpartum Third, specific hCG binding was assessed and we found that it occurred only on days 7 and 10. However, when fetal ovaries were pretreated for 48 h with (Bu)2 cAMP, a specific hCG binding could be detected and progesterone production was enhanced in response to LH. An effect of the nucleotide via a stimulation of the neuraminidase activity did not seem to be involved. Lastly treatment of 18-day-old fetal ovaries with cholera toxin (10nM) or forskolin (1 microM) was found to stimulate progesterone production and VIP (0.1 to 1 microM) stimulated both the 3-HSD activity and the estradiol production. These data suggest that the absence of steroidogenic response to LH before day 4 postpartum could be explained by the absence of receptors, though the LH transmembrane signal-transduction system is functional in fetal ovaries.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of sex steroid hormones on differentiation of adipose precursor cells in primary culture

The effects of estradiol-17 beta and progesterone on multiplication, differentiation and lipid filling of adipose precursor cells were examined in primary cell cultures of cells prepared from adipose tissue of both male and ovariectomized female rats. Progesterone down to a concentration of 10(-7) mol/liter, alone or in the presence of estradiol-17 beta stimulated the development of glycerophosphate dehydrogenase and lipoprotein lipase activity. Estradiol-17 beta alone had no effects. These effects were essentially parallel to increases in the rate of lipid filling of the cells. Furthermore, the formation of cells with a lipid vacuole greater than 20 micron was markedly stimulated, suggesting that new fat cells were formed by the stimulation of differentiation of the adipose precursor cells. No effects of the sex steroid hormones were seen on the rate of multiplication. These results suggest a role of sex steroid hormones in the regulation of triglyceride storage capacity in adipose tissue by facilitating the differentiation of precursor cells to form new adipocytes.     

Augmentation of aromatase activity by FSH in ovaries of fetal and neonatal mice in organ culture

The stimulative effect of FSH on aromatase activity was investigated in ovaries of fetal (on days 17 and 18 of gestation) and neonatal mice (on days 0, 3, 6 and 9 after birth). Two to six ovaries were cultured for 48 h in 2 ml of Medium 199 supplemented with insulin (5 μg/ml) and [1α, 2α, 6α, 7α, β-³H]4-adrostene-3,17-dione (0.35 μM) in the presence or absence of porcine FSH (0.5 units/ml) and the amount of [³H]oestradiol-17β and [³H]oestrone produced was estimated. In the presence of FSH, aromatase activity per ovary, which was found in all fetal and neonatal ovaries examined, increased with age. In the absence of FSH, however, the production of oestrogens could be demonstrated only in ovaries from 3- to 9-day old mice. FSH increased the aromatase activity by up to 10-fold. In spite of the stimulative effect of FSH on aromatase activity, FSH exerted no significant effect on DNA synthesis of the ovaries. The formation of primordial follicles could not be observed histologically in ovaries of fetal mice on day 17 of gestation, although the ovaries of 6- and 9-day old mice contained multilayered follicles. These results show that FSH stimulates the aromatase activity of the mouse ovary even before the formation of primordial follicles and that the stimulative effect of FSH on ovarian aromatase is not due to the proliferation of ovarian cells.     

Effects of peptides and steroid hormones on cell kinetic parameters of normal human breast tissue in organ culture

Summary Several studies have shown the importance of different hormones in the regulation of mammary tsssue growth. The use of organ culture techniques has shown tremendous value for the knowledge of cell proliferation in human breast tissue. Therefore, the purpose of these studies was to analyze the length of the cell cycle, DNA-labeling index, mitotic index, and growth fraction under the effects of insulin, hydrocortisone, and 17-β estradiol in 5-d organ culture. Normal tissues obtained from patients who underwent breast surgery for benign lesions were individually cultured at 37°C (95% air:5% CO₂ in Medium 199). Autoradiographic studies indicated that the hormones shortened the length of cell cycle of normal breast tissue in 5-d organ cultures. From the growth fraction studies we concluded that the hormones may have stimulated the cells to reenter the cell cycle from G₀ because these values were increased by the hormones used. Estrogen can alter the S phase duration with a consequent increase in the rate of DNA synthesis which may explain the high DNA-labeling index observed in the present studies. Supported by Public Health Service grant CA38921 from the National Cancer Institute, Bethesda, MD, and by an Institutional grant from the United Foundation of Greater Detroit.     

Influence of sex steroid hormones on cerebrovascular function.

The cerebral vasculature is a target tissue for sex steroid hormones. Estrogens, androgens, and progestins all influence the function and pathophysiology of the cerebral circulation. Estrogen decreases cerebral vascular tone and increases cerebral blood flow by enhancing endothelial-derived nitric oxide and prostacyclin pathways. Testosterone has opposite effects, increasing cerebral artery tone. Cerebrovascular inflammation is suppressed by estrogen but increased by testosterone and progesterone. Evidence suggests that sex steroids also modulate blood-brain barrier permeability. Estrogen has important protective effects on cerebral endothelial cells by increasing mitochondrial efficiency, decreasing free radical production, promoting cell survival, and stimulating angiogenesis. Although much has been learned regarding hormonal effects on brain blood vessels, most studies involve young, healthy animals. It is becoming apparent that hormonal effects may be modified by aging or disease states such as diabetes. Furthermore, effects of testosterone are complicated because this steroid is also converted to estrogen, systemically and possibly within the vessels themselves. Elucidating the impact of sex steroids on the cerebral vasculature is important for understanding male-female differences in stroke and conditions such as menstrual migraine and preeclampsia-related cerebral edema in pregnancy. Cerebrovascular effects of sex steroids also need to be considered in untangling current controversies regarding consequences of hormone replacement therapies and steroid abuse.     

Masculinizing effect of testes on developing rat ovaries in organ culture

Masculinizing effect of testes on developing rat ovaries was shown in vitro by culturing testes from 17.5-day-old fetuses in contact with female genital tracts from 14.5-day-old rat fetuses. The testes induced the differentiation of epithelial cells staining for cytokeratin in the ovarian blastema. These cells formed seminiferous cord-like structures delineated by a basement membrane, in a way that resembles early stages of testicular organogenesis. In addition to the morphological masculinization, functional masculinization was obtained since the ovaries produced the anti-Müllerian hormone as shown by bioassay and immunohistochemical procedures. Across a distance, testes from 17.5-day-old fetuses failed to induce masculinization. These results suggest that testes from 17.5-day-old fetuses produce a locally diffusible factor interfering with the development and the differentiation of the fetal ovaries. The possibility that the anti-Müllerian hormone secreted by the testes may be the factor involved is discussed comparing these results with those obtained with testes from different stages and with bibliographic data.     

Neonatal steroid exposure increases in vitro aromatization ability of peripubertal hamster ovaries

Neonatal female hamsters were exposed to doses of testosterone propionate or estradiol benzoate that would lead to behavioral masculinization and defeminization at adulthood. At Days 20, 30, or 40 of life, ovaries were removed and incubated in Kreb's Ringer bicarbonate for 4 h with or without the addition of 1 X 10(-9) M testosterone as a substrate. Incubation medium was assayed by radioimmunoassay (RIA) for the accumulation of estradiol. Ovaries from steroid-exposed animals aromatized testosterone to estradiol at a greatly increased rate compared to ovaries from oil-injected control animals. Serum from treated animals contained androgen, which could act as substrate for aromatization in vivo. Neonatally estrogenized females exhibited elevated circulating estradiol levels. Increased aromatizing ability could be due to early antral follicle formation as a result of elevated luteinizing hormone (LH) and/or follicle-stimulating hormone (FSH). Implications of increased aromatization ability of ovaries in the process of behavioral sexual differentiation are discussed.     

Direct transcriptional targets of sex steroid hormones in bone

The sex steroid hormones, androgens and estrogens, via their respective nuclear receptors, regulate bone mineral density in humans and mice. Very little is known about the direct targets of the androgen and estrogen receptors in bone cells. First, models of hormone and receptor deficiency in mouse and human bone are discussed. This review then focuses on the direct targets of the receptors in osteoblasts and osteoclasts. A direct target of a NR is defined here as a gene that is regulated by NR binding to the DNA (either through DNA binding or association with a DNA binding protein) at an enhancer or promoter of that gene. The experimental evidence that illustrates androgen and estrogen gene regulation in osteoblasts and osteoclasts will be summarized and compared with the phenotype of the hormones in vivo.     

Influence of sex steroid hormones on spatial memory in a songbird

In mammals, sex steroid hormones influence spatial learning and memory abilities but there are few data regarding such effects in birds. We investigated whether non-invasive sex steroid hormone treatment would affect spatial memory task performance of great tits (Parus major). For five consecutive days, birds were fed wax moth larvae injected with either 80 μg testosterone or 80 μg estradiol carried in peanut oil immediately prior to behavioral testing. During the 5 days prior to and the 5 days following hormone treatment, birds were fed vehicle-injected larvae. Both hormone manipulations resulted in an elevation of circulating hormone levels within 5 min of larva ingestion. This elevation was sustained for at least 30 min but had no short-term (<1 day) effect on spatial memory performance. However, performance tended to increase during the first 5 days of vehicle treatment and during both sex steroid treatments whereas it decreased during the 5 days of vehicle treatment following either hormone treatment. These results suggest that both hormones led to some improvement in spatial memory that declined once treatment ended. The great tit hippocampus was found to express androgen and estrogen receptors which would provide a direct site of sex steroid action.     

Bone and cartilage responsiveness to sex steroid hormones.

Gonadal steroids influence the skeletal growth and metabolism both during the pubertal growth spurt and in adulthood with aging. It is now generally agreed that sex steroid effect on skeletal tissues is due to indirect and direct actions. In this presentation, in vitro effects of sex steroids on cartilage cells are reported by comparison with those observed on bone cells.