Alpha-adrenergic potentiation of beta-adrenergic stimulation of rat pineal N-acetyltransferase. Studies using cirazoline and fluorine analogs of norepinephrine.
Recent evidence indicates that melatonin production is controlled by norepinephrine acting via alpha 1-and beta 1-adrenoceptors on pinealocytes; activation of alpha 1-adrenoceptors appears to potentiate the effects of beta 1-adrenoceptor activation. However, alpha-adrenergic potentiation of beta 1-adrenergic activation has been demonstrated with only one alpha-adrenergic agonist. For this reason, this issue was reinvestigated using two other alpha-adrenergic agonists, 6-fluoronorepinephrine and cirazoline. Both compounds, which were found to have a high affinity for pineal alpha 1-adrenoceptors, potentiated the stimulatory effects of isoproterenol on pineal N-acetyltransferase. 6-Fluoronorepinephrine also potentiated the stimulation of N-acetyltransferase activity produced by another beta-adrenergic agonist, 2-fluoronorepinephrine. These findings support the hypothesis that pineal N-acetyltransferase activity is regulated by norepinephrine acting through both alpha 1- and beta 1-adrenoceptors.
D000123:Acetyltransferases / Q000032:analysis*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D004357:Drug Synergism; D007093:Imidazoles / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology; D010870:Pineal Gland / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D007093:Imidazoles; D011942:Receptors, Adrenergic, alpha; C024884:6-fluoronorepinephrine; D000123:Acetyltransferases; C014282:cirazoline; D009638:Norepinephrine