title: Growth hormone release induced by an amino acid mixture from primary cultured anterior pituitary cells of goats.
abstract: The effects of amino acids on growth hormone (GH) release and cytosolic calcium concentration ([Ca2+]i) were investigated in caprine anterior pituitary cells cultured for 3 d in Dulbecco modified Eagle medium. The addition of an amino acid mixture consisting of seven nonessential amino acids (NEAA: L-Asp, Gly, L-Ala, L-Ser, L-Pro, L-Asn, and L-Glu; concentration of each 12.5-200 mumol/l) in the medium significantly raised GH release from the cultured cells in a concentration-dependent manner with the maximum release at 200 mumol/l NEAA. Although an addition of L-Asp (0.1-100 mumol/l) caused a significant rise in GH release in a concentration-dependent manner, neither the individual amino acids contained in NEAA except L-Asp nor others (L-Leu, L-Phe, L-Gln, L-Met, and L-Arg) caused a rise in GH release when added alone to the medium. The rise in GH release induced by NEAA (200 mumol/l) and GH-releasing hormone (GHRH, 10 nmol/l) was significantly reduced by the addition of EGTA (1.8 mmol/l) and nifedipine (1 mumol/l) to the medium, respectively. The addition of NEAA (200 mumol/l) caused a rapid and transient [Ca2+]i increase, followed thereafter by a steady increase. The prior addition of nifedipine (1 mumol/l), which itself significantly reduced the basal [Ca2+]i, completely abolished the response induced by NEAA or GHRH. From these findings, we conclude that: 1) NEAA raises GH release and [Ca2+]i in cultured caprine anterior pituitary cells, and 2) Ca2+ influx from the medium may be responsible for the cellular action of NEAA.
authors.affiliation: Department of Animal Physiology, Faculty of Agriculture, Tohoku University, Sendai, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ohata
authors.forename: Y
authors.initials: Y
authors.lastname: Maruyama
authors.forename: K
authors.initials: K
authors.lastname: Katoh
authors.forename: Y
authors.initials: Y
authors.lastname: Sasaki
mesh_terms: D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D006041:Goats / Q000502:physiology*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D002121:Calcium Channel Blockers; D009842:Oligopeptides; C079956:alanyl-histidyl-(2-naphthyl)alanyl-tryptophyl-phenylalanyl-lysinamide; D004533:Egtazic Acid; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D009543:Nifedipine; D002118:Calcium