In this study, we have evaluated the hypophyso-gonadal axis in three groups of men aged 60-69, 70-79 and 80-91 years by measuring the intratesticular concentrations of several steroids (pregnenolone, progesterone, DHEA, DHEA-S, testosterone, estradiol) and serum levels of FSH, LH, testosterone, estradiol and sex hormone binding globulin (SHBG). The histological examination of testes revealed no...

the present study aimed to evaluate the effects of ramadan fasting on the level of sex hormones in girls between 9-13 years before age at menarche.this study was conducted on a sample of 58 subjects (age range: 9-13 years), who were divided intotwo groups of fasting (n=31) and non-fasting (n=27). the levels of follicle-stimulating hormone(fsh), luteinizing hormone (lh), progesterone and estradi...

Wastewater from concentrated animal feeding operations (CAFOs) frequently contains high concentrations of steroid estrogenic hormones. Release of these hormones into the environment may occur when CAFO wastewater is applied to agricultural lands as a nutrient and water source for crop production. To assess the potential risk of hormone contaminants derived from animal wastewater, we investigate...

The role of endogenous sex hormones in many diseases makes understanding factors that influence levels of these hormones increasingly important. This study examined age-associated variations in total and bioavailable testosterone and estradiol levels among community-dwelling Caucasian men in Rancho Bernardo, California. Plasma samples obtained from 810 men aged 24-90 years in 1984-1987 were ana...

We investigated the effects of estradiol on bioactive luteinizing hormone (LH) release in normal men using two complementary strategies: (i) steady state intravenous infusions of estradiol at its endogenous production rate, and (ii) oral administration of the antiestrogen, tamoxifen HCl. Immunoreactive and biologically active LH were monitored by radioimmunoassay and the rat interstitial cell t...

Estrogens fluctuate across the lifespan in women, with circulating 17β-estradiol levels higher pre-menopause than estrone and circulating estrone levels higher postmenopause than 17β-estradiol. Estrone is a common component of hormone replacement therapies, but research shows that 17β-estradiol may have a greater positive impact on cognition. Previous studies show that acute estrone and 17β-est...

Epidemiologic studies have consistently reported that endogenous steroid hormone levels are associated with postmenopausal breast cancer risk, but little is known on the associations by tumor grade, hormone receptor status, or age at diagnosis. We performed a case-cohort study of naturally postmenopausal women within the Melbourne Collaborative Cohort Study that included a random sample of 857 ...

A historical perspective on estradiol's enhancement of cognitive function is presented, and research, primarily in animals, but also in humans, is reviewed. Data regarding the mechanisms underlying the enhancements are discussed. Newer studies showing rapid effects of estradiol on consolidation of memory through membrane interactions and activation of inter-cellular signaling pathways are revie...

BACKGROUND Differences in sex hormone levels among populations might contribute to the variation in breast cancer incidence across countries. Previous studies have shown higher breast cancer incidence and mortality among Japanese Brazilians than among Japanese. To clarify the difference in hormone levels among populations, we compared postmenopausal endogenous sex hormone levels among Japanese ...

A robust surge of gonadotropin-releasing hormone (GnRH) release triggers the luteinizing hormone surge that induces ovulation. The GnRH surge is attributable to estradiol feedback, but the mechanisms are incompletely understood. Voltage-gated calcium channels (VGCCs) regulate hormone release and neuronal excitability, and may be part of the surge-generating mechanism. We examined VGCCs of GnRH ...