3beta-hydroxysteroid dehydrogenase/delta5-->4-isomerase activity associated with the human 17beta-hydroxysteroid dehydrogenase type 2 isoform

The farnesoid X receptor regulates transcription of 3beta-hydroxysteroid dehydrogenase type 2 in human adrenal cells

Recent studies have shown that the adrenal cortex expresses high levels of farnesoid X receptor (FXR), but its function remains unknown. Herein, using microarray technology, we tried to identify candidate FXR targeting genes in the adrenal glands, and showed that FXR regulated 3beta-hydroxysteroid dehydrogenase type 2 (HSD3B2) expression in human adrenocortical cells. We further demonstrated that FXR stimulated HSD3B2 promoter activity and have defined the cis-element responsible for FXR regulation of HSD3B2 transcription. Transfection of H295R adrenocortical cells with FXR expression vector effectively increased FXR expression levels and additional treatment with chenodeoxycholic acid (CDCA) caused a 25-fold increase in the mRNA for organic solute transporter alpha (OSTalpha), a known FXR target gene. HSD3B2 mRNA levels also increased following CDCA treatment in a concentration-dependent manner. Cells transfected with a HSD3B2 promoter construct and FXR expression vector responded to CDCA with a 20-fold increase in reporter activity compared to control. Analysis of constructs containing sequential deletions of the HSD3B2 promoter suggested a putative regulatory element between -166 and -101. Mutation of an inverted repeat between -137 and -124 completely blocked CDCA/FXR induced reporter activity. Chromatin immunoprecipitation assays further confirmed the presence of a FXR response element in the HSD3B2 promoter. In view of the emerging role of FXR agonists as therapeutic treatment of diabetes and certain liver diseases, the effects of such agonists on other FXR expressing tissues should be considered. Our findings suggest that in human adrenal cells, FXR increases transcription and expression of HSD3B2. Alterations in this enzyme would influence the capacity of the adrenal gland to produce corticosteroids.

Beneficial effect of tibolone on mood, cognition, well-being, and sexuality in menopausal women

Tibolone is a synthetic molecule used extensively for the management of menopausal symptoms, with the proposed additional advantage of enhanced mood and libido. Tibolone, after oral administration, is rapidly converted into 3 major metabolites: 3alpha-hydroxytibolone and 3beta-hydroxytibolone, which have estrogenic effects, and the Delta(4)-isomer, which has progestogenic and androgenic effects. The tissue-selective effects of tibolone are the result of metabolism, of enzyme regulation, and of receptor activation which vary in different tissues. Tibolone seems to be effective on estrogen-withdrawal symptoms such as hot flushes, sweating, insomnia, headache, and vaginal dryness, with results generally comparable to the effects exerted by estrogen-based treatments, and the additional property of a progestogenic activity on the endometrium. As well as relieving vasomotor symptoms, tibolone has positive effects on sexual well-being and mood, and improves dyspareunia and libido. These effects may depend on both estrogenic and androgenic actions exerted at the genital level and in the central nervous system, and on a reduction of sex-hormone-binding globulin and an increase of free testosterone, without affecting Delta-5 androgens levels. Based on the evidence available, tibolone is a valuable treatment option to relieve menopausal complaints, especially in women suffering persistent fatigue, blunted motivation, and loss of sexual desire despite an adequate estrogen replacement.