Reproductive Function In Men Research Articles

Sperm counts and reproductive hormones in male marathoners and lean controls

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 that endurance exercise in men is also associated with alterations in reproductive function. We studied 12 marathon runners and 12 age-matched, lean controls; serum and semen samples were collected every 2 weeks for 12 weeks. Sperm counts, sperm morphologies, and mean levels of testosterone (T), free T, sex hormone binding globulin, cortisol, follicle-stimulating hormone, and biologically active luteinizing hormone (LH) were similar in the two groups. Mean levels of immunologically active LH were somewhat higher in the marathoners. We conclude that this level of strenuous, long-term endurance exercise does not have major adverse effects on reproductive function in men.

Cocaine effects on pulsatile secretion of anterior pituitary, gonadal, and adrenal hormones.

Pulse frequency analysis of LH, PRL, testosterone, and cortisol was carried out with the Cluster Analysis Program in eight male cocaine abusers and eight aged-matched normal men. Four of the eight cocaine abusers had hyperprolactinemia (range, 22.08-44.65 micrograms/L). Cocaine users as a group had significantly higher mean peak height (P less than 0.02) than control subjects. Cocaine users with hyperprolactinemia had higher mean peak height than control subjects or cocaine users with normal PRL levels (P less than 0.01). Cocaine users with hyperprolactinemia also had higher mean amplitude increments than control subjects (P less than 0.02). Cocaine users with hyperprolactinemia had a higher mean valley than controls (P less than 0.01) and cocaine users with normal PRL levels (P less than 0.03). However, there were no significant differences in PRL peak frequency, peak duration, or interpulse intervals between cocaine users with or without hyperprolactinemia and control subjects. There were minimal differences between cocaine users and control subjects in pulse frequency analysis of LH parameters; the small differences in mean LH levels and average interpulse interval were not in the abnormal range and were probably not biologically significant. No differences between cocaine users and controls were detected for pulse frequency analysis of testosterone or cortisol. Cocaine-induced hyperprolactinemia may contribute to disorders of sexual and reproductive function in men who abuse the drug, and recent reports that PRL modulates immune function suggest that cocaine-induced derangements of PRL secretion may also contribute to cocaine-related comorbidity in infectious disease. Since cocaine users with hyperprolactinemia had a higher mean valley as well as a higher peak pulse PRL height than control subjects, but did not have greater PRL pulse frequencies, we conclude that hyperprolactinemia in these men may be due to a cocaine-induced derangement of dopaminergic inhibition of basal PRL secretion.

Immunoreactive Somatostatin in Male Reproductive System in Humans*

Somatostatin-like immunoreactivity is distributed widely in humans; the highest concentration is in the central nervous system, gastrointestinal tract, and pancreas. To determine if somatostatin is present in the male reproductive system, we analyzed human testis, epididymis, prostate, and semen. Somatostatin-like immunoreactivity was detectable in acid extracts of human testis, epididymis, and prostate (n = 6 each) in concentrations of 4.0 +/- 1.4 (+/- SD), 14.7 +/- 3.2, and 27.5 +/- 5.1 pmol/g wet wt, respectively. Considerable amounts of immunoreactive somatostatin also were detectable in semen; the mean value was 3.8 +/- 1.3 nmol/L (n = 6). This value was 200-fold higher than that in peripheral plasma. The somatostatin immunoreactivity in these tissues was characterized by gel filtration chromatography. Two peaks of somatostatin immunoreactivity, one coeluting with somatostatin-14 and the other with somatostatin-28, were found in the testis, epididymis, prostate, and hypothalamus. The amounts of the two sizes were nearly equal in the testis; somatostatin-14 predominated in the epididymis, prostate, and hypothalamus; whereas only somatostatin-28 was detected in semen. The presence of somatostatin in the male reproductive system suggests that somatostatin may play a role in the regulation of reproductive function in men.

The effects of exercise on reproductive function in men.

Physical activity has a range of effects on male reproductive function depending upon the intensity and duration of the activity and the fitness of the individual. In general, it appears that relatively short, intense exercise increases serum testosterone levels, but there is debate to what degree haemoconcentration, decreased clearance and/or increased synthesis are involved. It is clear from the promptness of the testosterone increment that the mechanism does not involve gonadotrophin stimulation of the testes. There is suppression of serum testosterone levels during and subsequent to more prolonged exercise (and to some extent in the hours following intense short term exercise). Again the mechanisms are not clear: a variety of systems could influence the decrease of testosterone synthesis, including decreased gonadotrophin, increased cortisol, catecholamine or prolactin levels, or perhaps even an accumulation of metabolic waste materials. Endurance training induces changes in the function of the reproductive axis in men in a manner which appears similar to the changes in women. As in women, there is a subclinical inhibition of normal reproductive function but it is unclear whether clinical expression of reproductive suppression is common in men. The long term, physiological suppression of the hypothalamic-pituitary-gonadal axis in men is probably not of major significance but it is clear that further investigation in several areas is essential to provide continuing reassurance that 'exercise is good for you'.

Long-Term Administration of Gonadotropin-Releasing Hormone in Men with Idiopathic Hypogonadotropic Hypogonadism

The effect of long-term administration of gonadotropin-releasing hormone (GnRH) for induction and maintenance of sexual maturation was characterized in 23 men with idiopathic hypogonadotropic hypogonadism. Twenty-two men achieved normal adult male serum testosterone concentrations (575 +/- 33 ng/dL; p less than 0.0001 compared with the baseline mean of 61 +/- 6 ng/dL) that were sustained in 21 men for up to 36 months with bolus doses of GnRH varying from 25 to 300 ng/kg body weight administered every 2 hours. Pulsatile luteinizing hormone (LH) secretion occurred in all 23 men, with mean levels of LH (14.7 +/- 1.3 mlU/mL) and follicle-stimulating hormone (11.3 +/- 1.3 mlU/mL) within or above the normal range for adult men. Mature sperm were observed in the ejaculates of 20 men, with counts ranging from less than 1 X 10(6) to 96 X 10(6)/mL. Increasing responsiveness of the pituitary-gonadal axis to GnRH was shown in 6 men. Men with idiopathic hypogonadotropic hypogonadism present a useful model to study the onset and maintenance of reproductive function in men.

Fertility in aging men

A wide variety of disorders, medications, physical factors, and trauma can alter testicular function and reproductive function in men as they age. There are no precise age limits for ‘aging men’, but most studies consider 50–80-yr-old subjects. Assuming we have healthy individuals, there are still changes that occur with aging. There is progressive testicular failure as evidenced by gradually increasing levels of both gonadotropins with aging. Although basal levels of male hormone remain reasonably normal in healthy older men, the ability of the Leydig cells to respond to acute stimulation with LH is reduced. There are changes in the penis, prostate, and seminal vesicle which occur with aging. Potency tends to be reduced with age. Sperm production per testis falls off with aging. The amount of capsular tissue increases in the testis with advancing years. There is very limited data about men in extreme old age (80 yr and older). Of older men who produce spermatozoa in their ejaculates, sperm motility, a manifestation of viability and fertilizing capacity, tends to be reduced. The ability of men to impregnate their wives gradually reduces from age 25 onward. Using the zona pellucida-free hamster egg, penetration by spermatozoa from aged healthy men appears to be as good as that from younger fathers. This test cannot guarantee equal fertility. but it is the best test available and correlated reasonably well with fertility. Thus, if an older man can get an erection, can ejaculate, and can produce an ejaculate with a reasonable number of motile sperm, the likelihood is that he is fertile.

Basis and Development of Reproduction. Basic Reproductive Medicine, Volume 1.David Hamilton , Frederick NaftolinReproductive Function in Men. Basic Reproductive Medicine, Volume 2.David Hamilton , Frederick Naftolin

Previous articleNext article No AccessNew Biological BooksBasis and Development of Reproduction. Basic Reproductive Medicine, Volume 1. David Hamilton , Frederick Naftolin Reproductive Function in Men. Basic Reproductive Medicine, Volume 2. David Hamilton , Frederick Naftolin R. V. ShortR. V. Short Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 58, Number 1Mar., 1983 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/413188 Views: 1Total views on this site Copyright 1983 Stony Brook Foundation, Inc.PDF download Crossref reports no articles citing this article.

BOOK REVIEWS

Book reviews in this article: Progress in Obstetrics and Gynaecology. Vol. 2 edited by J. Studd. Techniques microchirurgicales de la sterilite edited by E. Cornier. Topics in Perinatal Medicine. 2. Perinatal Perspectives edited by B. Wharton. The Ovary by Hannah Peters & Kenneth P. McNatty. Management of Complications in Gynaecologic Oncology edited by G. Delgado & J. P. Smith. Color Atlas of Cancer Cytology. 2nd Edn by M. Takahashi. Follicular Maturation and Ovulation International Congress Series 560 edited by R. Rolland, E. V. van Hall, S. G. Hillier, K. P. McNatty & J. Schoemaker. Books received some of which will be reviewed at a later date Basic Reproductive Medicine. Vol. 2. Reproductive Function in Men edited by D. Hamilton & F. Naftolin. Disturbances in Male Fertility edited by K. Bandhauer & J. Frick. Changing Childbirth. Family Birth in the Hospital by D. Young The Incontinent Woman Proceedings of a Scientijic Meeting of the Ro‐yal College of Obstetricians and Gynaecologists, February 1981 edited by J. A. Jordan & S. L. Stanton.

The Effects of Hyperprolactinemia on Sexual and Reproductive Function in Men

The Effects of Hyperprolactinemia on Sexual and Reproductive Function in Men