Concentrations of intracellular sex steroids in human spermatozoa

Occurrence and reproductive roles of hormones in seminal plasma

Only 2-5% of seminal fluid is composed of spermatozoa, while the rest is seminal plasma. The seminal plasma is a rich cocktail of organic and inorganic compounds including hormones, serving as a source of nutrients for sperm development and maturation, protecting them from infection and enabling them to overcome the immunological and chemical environment of the female reproductive tract. In this review, a survey of the hormones found in human seminal plasma, with particular emphasis on reproductive hormones is provided. Their participation in fertilization is discussed including their indispensable role in ovum fertilization. The origin of individual hormones found in seminal plasma is discussed, along with differences in the concentrations in seminal plasma and blood plasma. A part of review is devoted to methods of measurement, emphasising particular instances in which they differ from measurement in blood plasma. These methods include separation techniques, overcoming the matrix effect and current ways for end-point measurement, focusing on so called hyphenated techniques as a combination of chromatographic separation and mass spectrometry. Finally, the informative value of their determination as markers of male fertility disorders (impaired spermatogenesis, abnormal sperm parameters, varicocele) is discussed, along with instances where measuring their levels in seminal plasma is preferable to measurement of levels in blood plasma.

Expression of cytochrome P450 aromatase transcripts in buffalo (Bubalus bubalis)-ejaculated spermatozoa and its relationship with sperm motility

The cytochrome P450 aromatase (aromP450) deficient mice are infertile due to an impairment of spermatogenesis associated with a decrease in sperm motility and inability to fertilize oocytes. The sperm analysis showed decreased sperm motility in humans, having Cyp19 gene mutations. Further, in human, it was hypothesized that aromatase could be used as marker of sperm quality, particularly in the acquisition of its motility. However, there is no information regarding the expression of aromP450 in spermatozoa of farm animals including cattle and buffalo. In the present study, the expression of aromP450 in ejaculated buffalo spermatozoa and its relationship with sperm motility of ejaculated spermatozoa was studied by RT-PCR using total RNA isolated from buffalo-ejaculated spermatozoa. The results showed that conventional RT-PCR could not amplify aromatase transcript, while a nested PCR detected the presence of P450arom mRNA in buffalo-ejaculated spermatozoa. RT reaction followed by nested PCR was performed to compare the expression of aromatase transcripts in buffalo-ejaculated spermatozoa of two category semen graded on the basis of mass motility and motile and non-motile spermatozoa separated by swim-up. A higher (P<0.01) expression of aromP450 transcript was found in spermatozoa obtained from the good quality semen (higher mass motility) to that in spermatozoa of poor quality semen (low mass motility). Similarly, higher (P<0.01) expression of aromP450 mRNA was observed in the motile spermatozoa as compared to non-motile spermatozoa separated from good quality semen by swim-up. It is concluded that the present study demonstrates a positive relation between aromatase transcript and mass motility of buffalo-ejaculated spermatozoa, which could be a putative marker for the quality of semen in farm animals, particularly the acquisition of sperm motility.

Sperm analysis in growth hormone-deficient adolescents previously treated with an aromatase inhibitor: Comparison with normal controls

We performed two semen analyses in each of a small cohort of 11 GH-deficient (GHD) adolescents (mean age 18.1 +/- 0.6 yrs), previously treated (mean 29 months prior) with either GH alone or GH and an aromatase inhibitor (anastrozole) for 12 months and compared their data with those of 10 healthy controls (mean age 18.7 +/- 1.8 yrs). Although some adolescents had lower sperm parameters as compared to adult reference values, mean sperm concentrations, motility, and morphology were comparable among the 3 groups, suggestive that this small group of GHD adolescents previously treated with anastrozole has descriptively similar sperm parameters as other GHD and GH-sufficient adolescent controls.

Aromatase expression and role of estrogens in male gonad : a review

The ability of the testis to convert irreversibly androgens into estrogens is related to the presence of a microsomal enzymatic complex named aromatase, which is composed of a specific glycoprotein, the cytochrome P450 aromatase (P450arom) and an ubiquitous reductase. The aromatase gene is unique in humans and contained 18 exons, 9 of them being translated. In the rat testis we have immunolocalized the P450arom not only in Leydig cells but also in germ cells and especially in elongated spermatids. Related to the stage of germ cell maturation, we have shown that the level of P450arom mRNA transcripts decreases, it is much more abundant in pachytene spermatocytes and round spermatids than in mature germ cells whereas the aromatase activity is 2-4 fold greater in spermatozoa when compared to the younger germ cells. Using a highly specific quantitative competitive RT-PCR method we have evidenced that several factors direct the expression of the aromatase gene in Leydig cells, Sertoli cells, pachytene spermatocytes and round spermatids, and it is obvious that promoter PII is the main one but other promoters could be concerned. In the bank-vole testis we have observed a positive correlation between a fully developed spermatogenesis and a strong immunoreactivity for both P450arom and estrogen receptor beta not only in Sertoli cells but also in pachytene spermatocytes and round spermatids. Our recent data obtained from ejaculated human spermatozoa demonstrate the presence of aromatase both in terms of mRNA and protein, and in addition, we suggest that aromatase could be involved in the acquisition of sperm motility. Indeed in men the congenital aromatase deficiency is associated with severe bone maturation problems and sterility. Together with the widespread distribution of estrogen receptors in testicular cells these data clearly show that estrogens play a physiological role in the regulation of spermatogenesis in mammals.

Reproductive system: aromatase and estrogens

The cytochrome P450 aromatase (P450arom) is the terminal enzyme responsible for the formation of estrogens from androgens. In the rat testis we have immunolocalized the P450arom not only in Leydig cells but also in germ cells and especially in elongated spermatids. Related to the stage of germ cell maturation, we have shown that the level of P450arom transcripts decreases, it is much more abundant in pachytene spermatocytes (PS) than in mature germ cells whereas the aromatase activity is two- to fourfold greater in spermatozoa when compared to younger germ cell preparations. In rat germ cells, the aromatase gene expression is not only under androgen and cyclic AMP control but also subjected to cytokine (TNFalpha) and growth factor (TGFbeta) regulation. In the bank-vole testis we have evidenced a positive correlation between a fully developed spermatogenesis and a strong immunoreactivity for both P450arom and estrogen receptor (ERbeta) not only in Sertoli cells but also in PS and round spermatids (RS). Therefore, the aromatase gene expression and its translation in a fully active protein in rodent germ cells evidence an additional site for estrogen production within the testis. Our recent data showing that human ejaculated spermatozoa expressed specific transcripts for P450arom reinforced the observations reported in germ cells of other mammalian species. Together with the widespread distribution of ERs in testicular cells these data bring enlightenment on the hormonal regulation of spermatogenesis.

A delta 4-3-keto pathway for testosterone synthesis in the human spermatozoa

The ability of human spermatozoa to metabolize pregnenolone to progesterone and progesterone to testosterone was assessed. Sonicated specimens of freshly ejaculated sperm from two groups of husbands (n = 6, age 32-38 years; n = 6, age 30-51 years) of infertile couples in the range of sperm concentration between 237.5 and 568.5, 100.1 and 248.8 millions per ejaculate, were separately incubated with [7n-3H]pregnenolone and [1,2,6,7,16,17-3H]progesterone. Using the classical reverse-isotope dilution technique the desired products [3H]progesterone and [3H]testosterone formed from the respective substrates were isolated and characterized, yielding 1.4 to 12.2% and 3.1 x 10(-2) to 2.0 x 10(-1)%. Such metabolites were not evident in the controls. The results indicate that the human spermatozoa contain the enzymes necessary for the transformation of pregnenolone to testosterone via the delta 4-3-keto route.

Characterization of a delta 5-3 beta-hydroxy pathway of testosterone synthesis in the human spermatozoa

Sonicated specimens of freshly ejaculated sperm from two groups of husbands (n = 6, age 32-38 years; n = 7, age 27-38 years) of infertile couples in the range of sperm concentration between 237.5 and 568.5; 131.1 and 256.7 millions per ejaculate were separately incubated with [7n-3H]pregnenolone and [1,2,6,7(-3)H]dehydroepiandrosterone. Using the reverse-isotope dilution technique [3H]dehydroepiandrosterone and [3H]testosterone formed from the respective substrates were isolated and characterized, yielding 1.2 x 10(-2) to 4.6 x 10(-20/0) and 7.1 x 10(-2) to 2.5 x 10(-10/0)/ Such metabolites were not evident in the controls. These results provide evidence for metabolic transformation of pregnenolone to testosterone via the delta 5-3 beta-hydroxy route.

A relationship between sperm count and intracellular progesterone, 17 alpha-hydroxyprogesterone, and cortisol concentrations in human spermatozoa

In an attempt to determine whether human spermatozoa contain steroid hormones, in this study we have measured the immunoreactive levels of P, 17 alpha-OHP, and F in the extracts of sonicated specimens of sperms obtained as ejaculates from husbands of infertile couples. The results of this study demonstrate for the first time that human spermatozoa contain definite amounts of the measured steroids and suggests an association between steroid levels and sperm count. These steroids identified intracellularly in the haploid germ cells may play a role in the molecular events associated with fertilization.