THE FOLLICLE-STIMULATING-HORMONE (FSH) BETA-SUBUNITS AND COMMON ALPHA-SUBUNITS ARE EXPRESSED IN MOUSE TESTIS, AS DETERMINED IN WILD-TYPE MICE AND THOSE TRANSGENIC FOR THE FSH BETA-SUBUNIT HERPES-SIMPLEX VIRUS THYMIDINE KINASE FUSION GENE

Testicular expression of the endogenous FSH beta-subunit (FSH beta) an d common alpha-subunit (C alpha) genes, as well as a Herpes simplex Vi rus type 1 thymidine kinase (tk) transgene, driven by a 2.3-kilobase f ragment of the bovine FSH beta promoter, were studied at messenger RNA and protein level in normal and transgenic mice. A major 3.8-kb speci es of FSH beta messenger RNA was demonstrated in the normal mouse test is by Northern hybridization. This was longer than the main 1.7-kb FSH beta transcript detected in the pituitary gland. Reverse transcriptio n-polymerase chain reaction, followed by Southern hybridization, demon strated FSH beta and tk expression in the pituitary gland and gonads o f adult normal and transgenic mice, respectively. The C alpha expressi on was detected by reverse transcription-polymerase chain reaction in the pituitary gland and testis. During development, testicular transcr iption of the FSH beta and tk genes was initiated simultaneously a few days after birth. Immunocytochemistry of adult testes showed stage-sp ecific positive reaction with FSH beta, C alpha, and tk antisera in th e pachytene spermatocytes and type B spermatogonia, but not in Sertoli cells. Positive reaction with these antisera was also seen in the int erstitial tissue. These results demonstrate testicular expression of t he endogenous FSH subunit genes and confirm that the testicular expres sion of the FSH beta/tk transgene reflects genuine testicular activity of the FSH beta promoter. The findings suggest that FSH or its subuni ts play a paracrine or autocrine role in the regulation of testicular function.