Endocrine Abstracts

Endothelin-1 has various paracrine and endocrine effects on the male reproductive system. It is supposed that the testosterone is probably responsible for the higher endothelin-1 levels in males and this may be related with the enhanced cardiovascular risk in males of reproductive age. In order to study in more detail the relationship between endothelin-1 and testosterone, we have studied 37 male patients with various forms of hypogonadism (14 with hypergonadotrophic hypogonadism and 23 with hypogonadotrophic hypogonadism). Fourteen age-matched healthy males served as controls. The study was approved by the local ethical committee. Endothelin-1 concentrations were determined in blood samples taken in the morning between 08:00 and 09:00 h after an overnight fast. The basal endothelin-1 levels in patients with hypogonadism (0.88±0.11 fmol/ml) (x±S.E.M.) were significantly higher in comparison with the controls (0.44±0.04 fmol/ml), P<0.05. The males with hypergonadotrophic hypogonadism were with significantly elevated endothelin-1 concentrations (0.83±0.14 fmol/ml), P<0.05. The same was true for those with hypogonadotrophic hypogonadism (0.91±0.16 fmol/ml), P<0.05. Twenty individuals of these patients (7 with hypergonadotrophic and 13 with hypogonadotrophic hypogonadism) received testosterone depot 250 mg i.m. every three weeks. The endothelin-1 levels, which were determined at 3 and 6 months of the medication, decreased (from 0.93±0.20 fmol/ml to 0.76±0.12 fmol/ml and to 0.71±0.21 fmol/ml, respectively), but not significantly (P>0.05).

The results of this study suggest that plasma endothelin-1 levels in males with hypogonadism are increased and they have tendency to decrease after testosterone administration. These data show that the testosterone do not enhanced the cardiovascular risk and even though may have a protective effect as far as endothelin is regarded.