THIOREDOXIN MESSENGER-RIBONUCLEIC-ACID IS REGULATED BY ESTRADIOL IN THE RAT UTERUS

Thioredoxin is a major cellular dithiol reductant with a large number of functions in electron transport and thiol redox control of enzymes and transcription factors. To investigate the expression and regulatio n of thioredoxin in the uterus, 35 rats were ovariectomized (OVX) and treated 14 days after surgery with either growth hormone (GH), dexamet hasone (DEX), or estradiol (E-2), or combinations of these, for 24 h. Thioredoxin mRNA levels were determined by solution hybridization. The animals receiving E-2 or a combination of E-2 and DEX showed signific antly increased thioredoxin mRNA levels, by 4-fold and 5-fold, respect ively, as compared to the OVX control group. The GH or GH+DEX-treated groups did not display any difference in thioredoxin mRNA levels. Thio redoxin mRNA was also measured at different time points in uteri from OVX rats treated with daily E-2 injections and was found to be transie ntly increased, with a maximum 48 h after the initiation of the E-2 tr eatment. In contrast, the thioredoxin mRNA level in the liver of OVX r ats was about 10-fold higher than in the uterus but remained unaffecte d by the different hormone treatments. We conclude that thioredoxin mR NA is expressed in the rat uterus, and up-regulated by E-2 in a tissue -specific manner, with a maximum at 48 h after the initiation of hormo ne treatment.