Melatonin is a hormone produced by the pineal gland. There is much controversy about its relationship to the male reproductive process. In this study, seminal plasma as well as the serum melatonin levels were studied in different infertile male groups and were correlated with their semen parameters and hormonal levels. One hundred twenty male cases subdivided into six equal groups were consecutively included; fertile normozoospermic men, oligoasthenozoospermia (OA), OA with leucocytospermia, OA with varicocele, non-obstructive azoospermia (NOA) with high serum follicle stimulating hormone (FSH) and NOA with normal FSH. Semen analysis, estimation of melatonin, FSH, testosterone (T) and prolactin (PRL) hormone was carried out. Mean level of serum melatonin was higher than its corresponding seminal concentrations in all investigated groups with a positive correlation between their levels (r = 0.532, p = 0.01). Serum and seminal plasma melatonin levels in all infertile groups were reduced significantly compared with their levels in the fertile group. The lowest concentrations were in OA with leucocytospermia group. Melatonin in both serum and semen demonstrated significant correlation with sperm motility (r = 607, 0.623 respectively, p = 0.01). Serum melatonin correlated positively with serum PRL (r = 0.611, p = 0.01). It may be concluded that melatonin may be involved in the modulation of reproductive neuroendocrine axis in male infertility. Also, low levels of melatonin in semen were observed in infertile groups having reduced sperm motility, leucocytospermia, varicocele and NOA.
Leptin is an adipocyte-secreted protein that participates in the regulation of energy homeostasis. Eighty men were investigated; fertile normozoospermia as a control (n = 30) and infertile oligozoospermia (n = 50). The patients underwent estimation of body weight (kg), height (cm), calculation of body mass index (BMI), semen analysis, serum leptin and testosterone hormones. Mean body weight was significantly higher in infertile oligozoospermia compared with controls. Mean height, BMI and serum testosterone levels showed nonsignificant differences between the two groups. Infertile oligozoospermia had significantly higher mean serum leptin level than controls (mean +/- SD; 6.88 +/- 8.65, 16.3 +/- 13.98 ng ml(-1), P < 0.01). Serum leptin demonstrated significant positive correlation with age, body weight, BMI and significant inverse correlation with serum testosterone. It had nonsignificant correlation with the height and sperm concentration. These results are suggestive of a link between the adipocyte derived hormone, leptin and male reproduction.
Induced zinc deficiency in male albino rats caused a great reduction in the testicular levels of testosterone as compared to control and zinc-supplemented (ZS) rats. Estimation of the testicular levels of follicle-stimulating hormone, luteinizing hormone and prolactin (PRL) in the zinc-deficient (ZD) rats showed higher levels in comparison with both control and zinc-supplemented rats. However, the increase in PRL levels was statistically insignificant. A great reduction in the activity of 3 beta-hydroxysteroid dehydrogenase, an important enzyme involved in testosterone biosynthesis, was demonstrated histochemically in the testes of ZD rats as compared to both control and ZS ones. These results reflect a direct action of zinc deficiency on the testicular steroidogenesis and strongly support the idea that the hypogonadal state associated with zinc deficiency results mainly from some alteration in the testicular steroidogenesis or in other words Leydig cell failure.
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