Mammalian sperm quality and aromatase expression

Abstract

In most mammalian species the aromatase is encoded by a single gene (cyp19), which contains 18 exons, 9 of them being translated. In adult rats, together with Leydig cells germ cells represent an additional source of estrogens. The amount of P450arom transcript is threefold higher in pachytene spermatocytes compared to younger cells (spermatogonia-preleptotene spermatocyte) or round spermatids; conversely, aromatase activity is more intense in haploid cells. In man besides Leydig cells, we have shown the presence of a biologically active aromatase and of estrogen receptors (ERalpha and ERss) in immature germ cells and ejaculated spermatozoa. Concerning aromatase, a 30% decrease of the amount of mRNA is observed in immotile compared to motile sperm fraction from the same sample; moreover, the aromatase activity is diminished. We have amplified aromatase mRNA by RT-real time PCR in spermatozoa from asthenospermic, teratospermic, and asthenoteratospermic men and recorded respectively 44, 52, and 67% decreases of the amount of transcripts as compared to controls. Statistical analyses between the sperm morphology and the aromatase/GAPDH ratio have revealed a high degree of correlation (r = -0.64) with the percentage of abnormal spermatozoa (especially microcephaly and acrosome malformations). Alterations of sperm number and motility have been described in men genetically deficient in aromatase, which together with our data, suggest a likely role for aromatase/estrogens in the acquisition of sperm motility. Therefore besides gonadotrophins and testosterone, estrogens produced locally should be considered as a physiologically relevant hormone involved in the regulation of mammalian spermatogenesis.

Testis morphology in rats chronically treated with letrozole, an aromatase inhibitor

“…P450arom is the member of the cytochrome P450 gene superfamily, and is a product of transcription of a single copy of the Cyp19 gene. In humans, this is located on chromosome 15 [13][14][15], in rats on chromosome 8, and in mice on chromosome 9 [16]. The enzyme is a microsomal complex composed of two proteins: specific heme-glycoprotein cytochrome P450 aromatase, which contains a steroid binding pocket, and ubiquitous NADPH-cytochrome P450 reductase [13,14].…”

“…In humans, this is located on chromosome 15 [13][14][15], in rats on chromosome 8, and in mice on chromosome 9 [16]. The enzyme is a microsomal complex composed of two proteins: specific heme-glycoprotein cytochrome P450 aromatase, which contains a steroid binding pocket, and ubiquitous NADPH-cytochrome P450 reductase [13,14]. It is known that aromatase is widely distributed in the testes of mammals, including humans [14,15].…”

“…The enzyme is a microsomal complex composed of two proteins: specific heme-glycoprotein cytochrome P450 aromatase, which contains a steroid binding pocket, and ubiquitous NADPH-cytochrome P450 reductase [13,14]. It is known that aromatase is widely distributed in the testes of mammals, including humans [14,15]. In adult men, transcripts of aromatase are found in Leydig cells and Sertoli cells [13].…”

“…In adult men, transcripts of aromatase are found in Leydig cells and Sertoli cells [13]. Latest studies have proved that human and animal germ cells within the seminiferous epithelium also have the ability to convert androgens into estrogens [14,17]. In the seminiferous epithelium of adult rats, P450arom transcripts have been detected in spermatocytes and spermatids, while the enzyme activity was more intense in haploid germ cells, especially in the elongated spermatids [13].…”

Expression of receptor advanced glycosilation end product (RAGE) and active caspase-3 of the streptozotocin-induced chronic diabetes mellitus Sprague Dawley rats’ sperm with soybean (Glycin max) powder suspension treatment

“…However, it is reported that the low in FSH, testoterone and estrogen level can cause sperm immaturity. [22][23][24] Immature spermatozoa is a source of ROS and lack of antiapoptotic factor Bcl-xl. 13 …”