TRIIODOTHYRONINE AND ESTRADIOL INCREASE THE SERUM LEVEL OF ANDROSTANEDIOL GLUCURONIDE BUT DO NOT INFLUENCE ANDROGEN UDP-GLUCURONYL TRANSFERASE-ACTIVITY IN THE FEMALE RAT

In this study, adult female rats were treated with either estradiol, t estosterone or triiodothyronine (T-3) The mean+/-SD for serum levels o f androstane-3 alpha, 17 beta-diol glucuronide (ADIOL-G) in rats injec ted with estradiol (31.1+/-6.1 nmol/l) and T-3 (28.7+/-6.1 nmol/l) inc reased three-fold in comparison to the controls (9.2+/-3.6 nmol/l; p<0 .01). There was no significant increase in ADIOL-G levels in rats inje cted with testosterone (12.0+/-3.4 nmol/l) even though serum testoster one levels increased more than 17-fold (1.2+/-0.3 nmol/l; p<0.01). Tes tosterone levels remained below the detection level of the assay (0.07 nmol/l) in the control and the estradiol and T-3 treattment groups. A ndrogen UDPGT activity in liver microsomes was not altered by treatmen t with testosterone, estradiol or T-3. However, the UDPGT activity for p-nitrophenol increased two-fold in estradiol and T-3-treated females (p<0.01), but was not significantly altered by testosterone treatment . These results suggest that the activity of androgen UDPGT in liver i s not the limiting factor in the increased serum levels of ADIOL-G obs erved on treatment with estradiol and T-3.