Effect of actinomycin D on the pituitary response to LH-RH.
The effect of Actinomycin D (Act D) on the release of LH and FSH induced by LH-RH was investigated in rats. Immature male rats received an iv infusion over a period of 3-4 h or a quick iv injection of synthetic LH-RH. Infusion of LH-RH significantly increased serum LH and FSH levels at 1, 2, 3 and 4 h after the initiation of infusion. Pre-treatment with 100 mug/100 g.b.w. Act D failed to affect the rise of serum LH and FSH levels 1 h after the infusion but significantly suppressed the response at 2, 3 and 4 h. The increase in serum LH and FSH levels after a quick injection of LH-RH was unaffected by pre-treatment with Act D whether the antibiotic was injected 1 or 2 h before LH-RH. The results suggest that the initial phase of the pituitary response to LH-RH does not require DNA-dependent RNA synthesis, whereas that in the later period does. RNA synthesis may be necessary only to maintain the increased secretion of both LH and FSH during a continuous stimulation with LH-RH.
D000818:Animals; D003609:Dactinomycin / Q000494:pharmacology*; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D013268:Stimulation, Chemical; D013997:Time Factors
D003609:Dactinomycin; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone