Browsing Center for Research in Reproduction and Contraception by Issue Date
Now showing items 41-60 of 220
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Corpus luteum insufficiency induced by a rapid gonadotropin-releasing hormone-induced gonadotropin secretion pattern in the follicular phase
(Endocrine Society, 1987-09)The pulse frequency of LH and FSH (and by inference, GnRH) is a major determinant of the relative baseline plasma levels of LH and FSH. Luteal phase deficiency has been reported to be associated with increased ... -
The effects of aging in normal men on bioavailable testosterone and luteinizing hormone secretion: response to clomiphene citrate
(Endocrine Society, 1987-12)Serum testosterone (T) levels in men decline with age while serum LH levels, as measured by RIA, increase. To assess if the decline in serum T levels in healthy aging men is paralleled by an age-related decline ... -
The corpus luteum: determinants of progesterone secretion in the normal menstrual cycle
(Elsevier, 1988-05)Fourteen normal volunteers were studied during one menstrual cycle. Follicular development, the luteinizing hormone (LH) surge, and the relationship between LH and progesterone secretion in the luteal phase ... -
Decreased serum inhibin levels in normal elderly men: evidence for a decline in Sertoli cell function with aging
(Endocrine Society, 1988-09)Compared to young men, normal elderly men have decreased sperm production despite elevated serum gonadotropin levels. To determine whether the seminiferous tubule defect in elderly men includes decreased ... -
Statistical evaluation of coincident prolactin and luteinizing hormone pulses during the normal menstrual cycle
(Endocrine Society, 1988-10)The purpose of this work was 2-fold. First, we sought to develop statistical criteria by which it could be established that the coincident occurrence of pulses of two different hormones exceeds that which ... -
Follicle-stimulating hormone is required for quantitatively normal inhibin secretion in men
(Endocrine Society, 1988-12)Inhibin is a glycoprotein hormone produced by the testis and ovary which is postulated to be an important regulator of pituitary FSH secretion. Animal data indicate that inhibin is produced by the Sertoli ... -
Stimulation of serum inhibin concentrations by gonadotropin-releasing hormone in men with idiopathic hypogonadotropic hypogonadism
(Endocrine Society, 1988-12)Inhibin is a gonadal hormone thought to be important in FSH regulation. We investigated the effects of the hypogonadotropic state and subsequent GnRH-induced increases in gonadotropin levels on inhibin ... -
Genetically haploid spermatids are phenotypically diploid
(Nature Publishing Group, 1989-01-26)Because chromosomal homologues segregate from one another during meiosis, spermatids are genetically different. Post-meiotic gene expression could lead to gametic differences, some of which might lead to ... -
Testosterone administration inhibits gonadotropin secretion by an effect directly on the human pituitary
(Endocrine Society, 1989-02)Testosterone (T) administration slows LH pulse frequency in man, presumably by an effect on the hypothalamic GnRH pulse generator, but it also may have a direct action on the pituitary. To determine if T ... -
Pubertal changes in gonadotropin-releasing hormone and proopiomelanocortin gene expression in the brain of the male rat
(Endocrine Society, 1989-04)Pubertal development in mammals is in part attributable to a brain-dependent process, whereby increased pulsatile GnRH secretion leads to the awakening of the entire reproductive system. However, the brain ... -
The importance of luteinizing hormone in the control of inhibin and progesterone secretion by the human corpus luteum
(Endocrine Society, 1989-06)Serum inhibin levels rise markedly during the luteal phase of the human menstrual cycle and are closely correlated with serum progesterone (P) levels, suggesting that the corpus luteum (CL) secretes inhibin. ... -
Sexual dimorphism and testosterone-dependent regulation of somatostatin gene expression in the periventricular nucleus of the rat brain
(Endocrine Society, 1989-07)Gender differences in hypothalamic somatostatin (SS) secretion may account in part for the sexually dimorphic patterns of GH secretion in rats. Since males have lower baseline serum GH levels than females, ... -
A comparison of the suppressive effects of testosterone and a potent new gonadotropin-releasing hormone antagonist on gonadotropin and inhibin levels in normal men
(Endocrine Society, 1989-07)GnRH antagonists have been developed in large part because of their potential use as contraceptive agents, particularly in men. Specifically, it was hoped that GnRH antagonists combined with testosterone (T) ... -
Circadian variation in testosterone, sex hormone-binding globulin, and calculated non-sex hormone-binding globulin bound testosterone in healthy young and elderly men
(American Society of Andrology, 1989-09)The circadian pattern in levels of serum total testosterone (T) in men becomes blunted with normal aging. However, because T not bound to sex hormone-binding globulin (non-SHBG-T) is felt to be a better ... -
Luteal phase deficiency: characterization of reproductive hormones over the menstrual cycle
(Endocrine Society, 1989-10)The recurrent deficiency of progesterone (P) secretion by the corpus luteum has been associated with infertility and habitual abortion and given the clinical diagnosis of luteal phase deficiency (LPD). There ... -
Stimulation of Sertoli cell inhibin secretion by the testicular paracrine factor PModS
(Elsevier, 1989-10)The testicular paracrine factor PModS is produced by peritubular myoid cells under androgen control and modulates Sertoli cell function and differentiation. The observation that luteinizing hormone (LH) ... -
Luteal phase deficiency: abnormal gonadotropin and progesterone secretion patterns
(Endocrine Society, 1989-10)Luteal phase deficiency (LPD) is a reproductive disorder associated with infertility and spontaneous abortion. This study was undertaken to determine whether LPD might be related to an abnormal pattern of ... -
Recombinant human activin-A stimulates basal FSH and GnRH-stimulated FSH and LH release in the adult male macaque, Macaca fascicularis
(Endocrine Society, 1989-11)Activin-A is a homodimer of the beta A inhibin subunit that stimulates FSH secretion by pituitary cells in vitro; however, the physiological relevance of this effect is unknown. We have examined whether ... -
Serum inhibin levels during the periovulatory interval in normal women: relationships with sex steroid and gonadotrophin levels
(Blackwell Publishing, 1990-01)Inhibin is a gonadal glycoprotein believed to be important in the regulation of pituitary FSH secretion and/or to function as a paracrine factor within the ovary and testis. We studied serum levels of inhibin, ... -
Sperm counts and reproductive hormones in male marathoners and lean controls
(Elsevier, 1990-04)In women, chronic and intense endurance exercise is frequently associated with menstrual cycle alterations. In men, the effects of similar amounts of exercise are less well-studied. We tested the hypothesis ...