GENDER-ASSOCIATED DIFFERENCES IN THE DEVELOPMENT OF 5-AMINOLEVULINATESYNTHASE GENE-EXPRESSION IN THE HARDERIAN-GLAND OF SYRIAN-HAMSTERS

The mRNA levels for aminolevulinate synthase (ALV-S), the rate-limitin g enzyme in porphyrin synthesis, were studied in male and female Syria n hamsters during postnatal development. Sex-associated differences in the expression of ALV-S gene were evident at the end of the third wee k of postnatal development. Serum levels of luteinizing hormone (LH), testosterone, cortisol, thyroid hormones and insulin-like growth facto r were also studied in order to correlate their concentrations with th e mRNA levels for ALV-S. Among these hormones, serum LH levels showed a positive correlation with the ALV-S mRNA levels. However, the expect ed negative correlation with testosterone levels was not clearly obser ved. Thus, in order to test the effects of testosterone on ALV-S gene expression, 11-day-old male and female Syrian hamsters and adult femal e hamsters were injected with 50 mug of testosterone for 4 days. Testo sterone administration decreased the levels of ALV-S mRNA in the adult females but did not influence those of young females. The possible ex planation for the insensitivity to testosterone during these postnatal stages might involve the maturational state of androgen receptors in the Harderian glands.