Beta-adrenergic binding and secretory responses of the anterior pituitary.
Our studies demonstrated that beta-adrenergic agonists stimulate the release of GH from rat anterior pituitary (AP) cells in vitro. Concentration-response experiments with beta-adrenergic agonists demonstrated that beta 2-adrenergic receptors mediated this phasic GH release, while having no apparent effect on PRL or LH release. The ACTH response to beta-adrenergic agonists was equivocal. Half-maximal stimulation of GH release occurred at 14 +/- 2 (+/-SE) nM isoproterenol, 160 +/- 30 nM epinephrine, and over 1 microM l-norepinephrine (n = 4). Direct binding studies in membrane particulates of rat AP confirmed receptors of the beta 2-subtype. Iodocyanopindolol binding to beta-adrenergic receptors of rat AP yielded a dissociation constant of 4.6 +/- 0.1 pM and a maximal capacity of 1.9 +/- 0.4 fmol/mg protein (n = 3). In contrast, porcine AP contained beta 1-adrenergic receptors. These results support the hypothesis that the endogenous beta 2-adrenergic agonist l-epinephrine may be a GH-releasing factor of physiological significance in the rat.
Perkins
S N
SN
Evans
W S
WS
Thorner
M O
MO
Gibbs
D M
DM
Cronin
M J
MJ
D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D013004:Somatostatin / Q000494:pharmacology; D013552:Swine
D011943:Receptors, Adrenergic, beta; D013004:Somatostatin; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine