Beta-adrenergic binding is increased by melatonin and alpha-adrenergic compounds.
Binding of the beta-adrenergic ligands [3H]dihydroalprenolol and [125I]cyanopindolol to pineal particulate fractions was increased 1- to 3.5-fold by addition of low concentrations of melatonin, alpha-adrenergic agonists, or alpha-adrenergic antagonists. Minimum concentrations of melatonin or alpha-adrenergic compounds which increased beta-adrenergic binding were between 1 pM and 0.1 nM. The increased binding of [3H]dihydroalprenolol caused by melatonin (0.1 muM) was attributed to a major increase in Bmax, which persisted in protein fractions after removal of melatonin. Melatonin enhancement of [3H]dihydroalprenolol binding was apparent after 5 to 7 min (30(0], was was optimal between 20 and 40 min, and decreased at longer times. Alpha-Adrenergic receptors are unchanged during beta-receptor enhancement.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D004082:Dihydroalprenolol / Q000378:metabolism; D020120:Iodocyanopindolol; D007700:Kinetics; D008550:Melatonin / Q000494:pharmacology*; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D010870:Pineal Gland / Q000378:metabolism*; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol; D020120:Iodocyanopindolol; D010869:Pindolol; D008550:Melatonin