Regulation of cytochrome P450 aromatase gene expression in adult rat Leydig cells: comparison with estradiol production

Abstract

Regulation of aromatase gene expression in purified rat Leydig cells has not yet been investigated. Therefore, using a highly specific quantitative RT-PCR method, we have measured the amount of cytochrome P450 aromatase (P450arom) mRNA and aromatase activity in mature rat Leydig cells submitted to various treatments during 24 h. Estradiol production was enhanced in a dose-related manner in the presence of testosterone, the maximum (28% increase) being obtained with 200 ng/ml. Related to the P450arom mRNA levels, a decrease was observed in the presence of low concentrations (50 and 100 ng/ml) of testosterone, then a 20% increase of the amount of transcripts was recorded for the higher concentrations (200-500 ng/ml). The same result was obtained in the presence of 5 -dihydrotestosterone (an androgen resistant to aromatase activity). The addition of ovine LH (oLH; 0·1-50 ng/ml) to the Leydig cell culture medium induced a dose-related augmentation of estradiol output up to 10 ng/ml oLH, although a decrease was observed with 50 ng/ml when compared with maximal values. mRNA levels slightly decreased in the presence of low concentrations (0·1-1 ng/ml) of oLH, an effect that was abolished by the addition of testosterone; mRNA levels were increased by oLH (5-10 ng/ml) 35 and 75% respectively in the absence and presence of testosterone (when compared with Leydig cells incubated without treatment). With 50 ng/ml oLH, a large augmentation (twofold) of the P450arom mRNA level either without or with testosterone was observed. Dibutyryl cyclic AMP (1 mM) mimicked the effect of oLH. The half-life of the P450arom mRNAs was twofold increased in the presence of testosterone and oLH when compared with the half-life in the absence of treatment (5·8 0·6 h). Taken together, our data have demonstrated that, in freshly isolated Leydig cells from mature rat testes, the regulation of aromatase expression and enzymatic activity is under LH (through cyclic AMP) and steroid control; moreover seminiferous tubule-secreted factor(s) are also involved. Therefore, rat Leydig cell aromatase is controlled at both transcriptional and post-transcriptional steps by endocrine and/or locally produced modulators.

Down‐regulation of serum gonadotropins is as effective as estrogen replacement at improving menopause‐associated cognitive deficits

“…2006) and the brain (Ye and Leung 2008) as such our findings are in accordance with these data. Furthermore, LH/hCG has been shown to increase p450 aromatase transcription in extra‐gonadal tissues (Shayu and Rao 2006) and in mature Leydig cells (Genissel et al. 2001), therefore down‐regulation of p450 aromatase by LA, is consistent with this previously published work.…”

Myricitrin and bioactive extract ofAlbizia amaraleaves: DNA protection and modulation of fertility and antioxidant-related genes expression

“…The aromatase is present in both Leydig cells and seminiferous tubules, predominantly in spermatids in male as well as in the granulosa cells of the oocytes of female. Leydig cell aromatase activity is under luteinizing hormone (LH) control and that paracrine factors of Sertoli cell origin are also involved (Carreau & Levallet 2000;Genissel et al 2001). In addition, Gupta et al (2005) reported that A. lebbeck inhibited the fertility of male rats which suppressed the function of Leydig cells and Sertoli cells and inhibited sperm production.…”

Phytoestrogens and their low dose combinations inhibit mRNA expression and activity of aromatase in human granulosa-luteal cells

“…In contrast the half-life of mRNA arom has been reported to range from 10 to 30 h depending on tissue investigated [31,32 and Simpson E (personal communication)]. Whilst estimates for the half-lives of both aromatase and its mRNA vary widely, generally speaking the half life of mRNA arom is very much shorter than that of the protein.…”