ANDROGEN REGULATION OF GENE-EXPRESSION IN THE SYRIAN-HAMSTER HARDERIAN-GLAND

The androgenic control of sexual dimorphism has been studied in the Ha rderian gland from Syrian hamster and compared to rat Harderian gland, a system without dimorphism. Hybridization in situ with a rat cDNA cl one has revealed the presence of androgen receptor mRNA in all secreto ry cells from male and female hamster glands. Testosterone or 5-alpha- dihydrotestosterone administration to females both caused a 60% decrea se in the levels of 5-aminolevulinate synthase mRNA after 1 day of tre atment, but the resulting patterns of in vitro translation using RNA f rom glands treated, with the two androgens are different. Testosterone alters the mRNA levels for androgen receptor and 5-aminolevulinate sy nthase in the glands only 6 h after its implantation in females, and t he action is maintained up to 10 days of treatment. Finally, androgen administration to females or deprivation in males alter androgen recep tor but not 5-aminolevulinate synthase mRNA levels in rat Harderian gl ands. Our results suggest that the androgen receptor from Harderian gl ands is responsible for the sexual dimorphism found in Syrian hamsters , whereas the lack of sexual dimorphism in rat seems to be due to a re stricted effect of androgens in the glands.