IN-VITRO UP-REGULATORY EFFECT OF TESTOSTERONE ON ALPHA(2)-ADRENOCEPTOR EXPRESSION IN ADIPOSE-TISSUE

Long-term in vitro exposure of deep-intraabdominal adipose tissue fragments from immature male or female hamsters to testosterone leads to an increase in fat cell alpha(2)-adrenoreceptor level. This effect was (i) dose-dependent and maximum (about onefold increase) after 48 h exposure to 10 nM free testosterone; (ii) prevented by either the androgen-receptor antagonist RU 23908 or the transcriptional inhibitor actinomycin D, and (iii) varied according to the anatomical origin of the adipose tissue, subcutaneous fat tissue being refractory to testosterone contrary to the effect in epididymal or parametrial adipose tissues. These results demonstrate that the or,adrenoreceptor up-regulation seen in hamster fat cells after testosterone treatment in vivo (Pecquery et al., 1988) is due to a direct, pretranslational and androgen-receptor dependent action of testosterone on the alpha(2)-adrenoreceptor expression in adipose tissue.