title: Specific release of a novel pituitary polypeptide, 7B2, from rat anterior pituitary cells in vitro by luteinizing hormone-releasing hormone.
abstract: We have recently purified a novel pituitary polypeptide, designated 7B2. Subsequently, we developed a sensitive and specific radioimmunoassay (RIA) for this novel polypeptide. Our aim in the present study was to investigate the release of 7B2 from rat pituitary induced by various hypothalamic factors [luteinizing hormone-releasing factor (LH-RH), corticotropin-releasing factor (CRF), and growth hormone-releasing factor (GRF)]. The anterior pituitaries were removed from rats and immediately dispersed enzymatically (a mixture of collagenase/dispase/deoxyribonuclease/chicken serum) and plated on collagen-coated multiwell plates in culture medium containing 10% fetal bovine serum. After 2 days of attachment period, the medium was replaced with fresh medium every 24 h. The primary cell culture was incubated with various concentrations of LH-RH, CRF or GRF. Subsequently, the concentrations of IR-7B2, IR-LH, IR-FSH, and IR-ACTH released into the medium were quantified by specific RIA. LH-RH, at a concentration as low as 7.5 ng/ml (6 X 10(9) M: dose range 7.5-60 ng/ml) stimulated the release of IR-7B2, IR-LH, and IR-FSH, by 2- to 3-fold, 17- to 18-fold, and 3-fold, respectively, over basal levels. No significant increase of IR-7B2 was observed when stimulated by CRF or GRF at doses as high as 100 ng/ml. In addition, K+ (50 mM) stimulated the release of all the peptides measured. In conclusion, our studies suggest that the novel peptide 7B2 is under LH-RH control and indirectly confirm the immunohistochemical results of its cellular co-localization in FSH and LH cells.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D013006:Growth Hormone / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins; D051859:Neuroendocrine Secretory Protein 7B2; D009479:Neuropeptides / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism*; D010908:Pituitary Hormones, Anterior; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009419:Nerve Tissue Proteins; D051859:Neuroendocrine Secretory Protein 7B2; D009479:Neuropeptides; D010446:Peptide Fragments; D010907:Pituitary Hormones; D010908:Pituitary Hormones, Anterior; C497680:Scg5 protein, rat; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone; D003346:Corticotropin-Releasing Hormone; D013007:Growth Hormone-Releasing Hormone