beta-Adrenoceptor stimulation-induced increase in the number of alpha 2-adrenoceptors of cerebral cortical membranes in rats.
Effects of pre-treatment of synaptic membranes with beta-adrenoceptor agonists and cholera toxin on [3H]clonidine and [3H]yohimbine binding were examined in rat cerebral cortex. Pre-incubation of cerebral cortical membranes with isoproterenol (10 or 200 microM) or dobutamine (1, 10 or 200 microM) at 37 degrees C for 40 min caused a significant elevation of specific [3H]clonidine binding but treatment with salbutamol (10 or 200 microM) did not. Scatchard analysis showed that 200 microM isoproterenol treatment resulted in a significant elevation of high affinity component of [3H]clonidine binding which was significantly decreased by the addition of 10 microM GTP. A significant elevation in high affinity [3H]clonidine binding was observed by treatment with 100 micrograms/ml cholera toxin, while a significant decrease in low affinity one was by the treatment. Specific [3H]yohimbine binding was also elevated by 10 or 200 microM isoproterenol treatment. It is suggested that stimulation of beta-receptors, presumably beta 1-subtype, could elevate the number of agonist and antagonist binding sites in alpha 2-receptors in synaptic membranes by partially mediated by stimulatory and/or inhibitory GTP binding regulatory proteins.
Kitamura
Y
Y
Nomura
Y
Y
D000818:Animals; D002540:Cerebral Cortex / Q000032:analysis* / Q000378:metabolism; D002772:Cholera Toxin / Q000494:pharmacology; D003000:Clonidine / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D013570:Synaptic Membranes / Q000032:analysis; D015016:Yohimbine / Q000378:metabolism
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D015016:Yohimbine; D006160:Guanosine Triphosphate; D002772:Cholera Toxin; D007545:Isoproterenol; D003000:Clonidine