Characteristics of 125I-iodocyanopindolol binding to beta-adrenergic and serotonin-1B receptors of rat brain: selectivity of beta-adrenergic agents.
The present study was designed to examine the specificity of beta-adrenergic antagonists for beta 1-, beta 2-adrenergic and 5HT1B-serotonergic receptors by the competitive interaction with 125I-iodocyanopindolol (125I-ICYP) as a radioligand. The beta 1-adrenoceptors were preferred by acebutolol, atenolol, betaxolol, practolol, and l-, dl- and d-metoprolol, while butoxamine and lCl-118,551 preferred beta 2-adrenoceptors. The selectivities of these beta 1- and beta 2-antagonists are well-known, but alprenolol which is known as a non-selective antagonist was 7.2-fold more selective for the beta 2-adrenoceptors in the present study. All beta-antagonists used were more selective towards beta-adrenoceptors as compared with 5HT1B-receptors. Good correlations were observed between the potencies of beta-adrenoceptor antagonists for inhibition of 125I-ICYP binding to beta 1- and beta 2-adrenoceptor sites and their potencies for inhibiting the binding of the same radioligand to 5HT1B-serotonergic receptor sites. These results suggest that beta-adrenoceptor antagonists can bind to beta-adrenoceptors and 5HT1B-receptors.
Tsuchihashi
H
H
Department of Pharmacology, Niigata College of Pharmacy, Japan.
Nakashima
Y
Y
Kinami
J
J
Nagatomo
T
T
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D020120:Iodocyanopindolol; D007700:Kinetics; D008297:Male; D010869:Pindolol / Q000031:analogs & derivatives* / Q000378:metabolism; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D011985:Receptors, Serotonin / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D007457:Iodine Radioisotopes; D011943:Receptors, Adrenergic, beta; D011985:Receptors, Serotonin; D020120:Iodocyanopindolol; D010869:Pindolol