EFFECTS OF TESTOSTERONE AND ITS METABOLITES ON LHRH AND LH GENE-EXPRESSION IN CASTRATED ADULT-RATS

To examine alterations in LHRH and LK gene expression in response to t estosterone (T), dihydrotestosterone (DHT) and estradiol (E), LHRH mRN A level in the hypothalamus, and alpha and LH beta subunit mRNA levers in the anterior pituitary were simultaneously determined. T and other steroids were administered s.c. to castrated (two weeks) rats, and LH RH, alpha and LH beta mRNA levels were,determined by RNA-blot hybridiz ation with appropriate probes. All of the three steroids, T, DHT and E efficiently suppressed alpha and LH beta mRNA levels in the anterior pituitary, which were accompanied by parallel change in serum LH level s. However, DHT was only effective in decreasing LHRH mRNA level, wher eas neither T nor E altered LHRH mRNA levers. The present study indica tes that T and its metabolites differentially regulate LHRH and LH gen e expression.