HORMONAL-REGULATION OF FHG22 MESSENGER-RNA IN SYRIAN-HAMSTER HARDERIAN GLANDS - ROLE OF ESTRADIOL

The regulation of the FHG22 gene by sex steroids has been studied in S yrian hamster Harderian gland, an organ with sexual dimorphism in whic h the FHG22 mRNA is female-specific. Testosterone treatment of females caused irregular inhibitory effects on the FHG22 mRNA levels, whereas male castration originated transitory increases during less than 2 we eks. Treatment of 15 day-castrated males for 1 or 2 days with beta-est radiol-3-benzoate caused a marked Stimulation in the FHG22 mRNA levels . The results found in vivo may be explained considering those found i n female Harderian gland serum-free primary cell cultures. In the abse nce of hormones, the FHG22 mRNA levels decreased along the time and ne ither progesterone, testosterone or 5 alpha-dihydrotestosterone affect ed the expression. However, estradiol stimulated the FHG22 mRNA expres sion in a time and dose-dependent manner: increasing effects were dete cted between 8-96 h of treatment and the EC(50) was about 10(-9) M. Th e estradiol effect was reverted by the antiestrogen ICI 164384 or by c ycloheximide. We conclude that estradiol stimulates FHG22 mRNA express ion in Harderian gland, although other agents may also control the exp ression in vivo. Copyright (C) 1996 Elsevier Science Ireland Ltd.