Gonadal and sex steroid feedback regulation of gonadotrophin mRNA levels and secretion in neonatal male and female rats.
Serum and pituitary LH and FSH, and their pituitary mRNA levels, were measured in neonatal male and female rats after gonadectomy and after gonadectomy with sex steroid replacement. The animals were gonadectomized on day 3 of life, and those given sex steroid replacement were implanted with silicone elastomer capsules containing testosterone for males and diethylstilboestrol for females. Sham-operated rats served as controls. The animals were killed 4 or 8 days latter and the sera and pituitaries collected. Pituitary contents of mRNAs for the alpha subunit, FSH-beta and LH-beta were determined by blot hybridization using corresponding cDNAs. Distinct sex differences were found in the mRNA responses to gonadectomy and steroid replacement. In the males, gonadectomy increased all mRNA levels at 7 days of age. In the females, a rise on day 7 was detected only for FSH-beta; the other mRNAs were increased on day 11 of age. The steroid replacements reversed all the post-gonadectomy increases of mRNAs in both sexes. Moreover, the common alpha and LH-beta mRNAs of the male animals were consistently suppressed below control levels. The serum concentrations of gonadotrophins increased after gonadectomy on day 7 in the males but only on day 11 in the females. The steroid replacements also suppressed the post-gonadectomy increases in serum gonadotrophins, but only the serum concentration of FSH in the females was reduced below controls. Pituitary gonadotrophin concentrations were not affected by gonadectomy, but the steroids suppressed LH in the males and FSH in the females.(ABSTRACT TRUNCATED AT 250 WORDS)
Pakarinen
P
P
Department of Physiology, University of Turku, Finland.
Huhtaniemi
I
I
D000818:Animals; D000831:Animals, Newborn; D002369:Castration; D004054:Diethylstilbestrol / Q000494:pharmacology; D005246:Feedback; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006065:Gonadotropins, Pituitary / Q000235:genetics*; D007986:Luteinizing Hormone / Q000097:blood / Q000235:genetics / Q000378:metabolism; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012727:Sex Characteristics; D013739:Testosterone / Q000494:pharmacology
D006065:Gonadotropins, Pituitary; D012333:RNA, Messenger; D013739:Testosterone; D004054:Diethylstilbestrol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone