Priming effect of luteinizing hormone releasing factor in vitro: role of protein synthesis, contractile elements, Ca2+ and cyclic AMP.
The mechanism of the priming effect of luteinizing hormone releasing factor (LH-RF) upon gonadotrophin secretion was studied using short-term incubation of hemipituitary glands from pro-oestrous rats. The dependence of the priming, but not the LH releasing action of LH-RF on protein synthesis in pituitary tissue was confirmed. Cytochalasin B failed to affect the first response to LH-RF, but abolished the priming effect, suggesting that the integrity of cellular microfilaments was essential. Colchicine and vinblastine did not modify the response to LH-RF. Neither inhibitors of DNA nor the inhibitor of RNA polymerase II, alpha-amanitin, significantly affected the priming action of LH-RF. Normal extracellular concentrations of Ca2+ were necessary for gonadotrophin release, but the priming effect was not significantly affected by low extracellular Ca2+ and could not be elicited by raising intracellular Ca2+ concentrations. Adenosine 3':5'-cyclic phosphate did not appear to act as a second messenger for either the gonadotrophin releasing or the priming action of LH-RF.
D000818:Animals; D002118:Calcium / Q000502:physiology*; D003285:Contractile Proteins / Q000502:physiology*; D000242:Cyclic AMP / Q000502:physiology*; D004261:DNA Replication; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology / Q000502:physiology*; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011247:Pregnancy; D011359:Proestrus; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D012636:Secretory Rate / Q000187:drug effects
D003285:Contractile Proteins; D007987:Gonadotropin-Releasing Hormone; D012313:RNA; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP; D002118:Calcium