Rapid changes in rat pineal beta-adrenergic receptor: alterations in l-(3H)alprenolol binding and adenylate cyclase.

摘要: Abstract The properties of the beta-adrenergic receptor which regulates adenylate cyclase [ATP pyrophosphate-lyase (cyclizing)8 EC 4.6.1.1] in pineal gland are similar to sites specifically bind l-[3H]alprenolol, a potent antagonist. Stimulation results 30-fold increase activity N-acetyltransferase (= arylamine acetyltransferase; acetyl CoA:arylamine N-acetyltransferase, 2.3.1.5), an enzyme involved synthesis thepineal hormone melatonin. In normal diurnal light-dark cycle there is greater physiological stimulation during night than day. Pineals from rats kept constant light for 24 hr possess more hormone-sensitive and l-[3H]alprenolol do pineals dark overnight. When rats, exposed hr, treated with beat-adrenergic agonist isoproterenol, rapid loss both specific binding sites. There no change affinity isoproterenol or its substrate, ATP. Similarly, although fewer sites, remaining either Inhibition protein cycloheximide does not affect The data suggest that causes decrease number available receptors activity; conversely, lack these parameters. It suggested changes contribute phenomena super- subsensitivity by regulating capacity synthesize cyclic AMP response stimulation.