Characteristics of 125I-iodocyanopindolol binding to beta-adrenergic and serotonin-1B receptors of rat brain: selectivity of beta-adrenergic agents

Jpn J Pharmacol. 1990 Feb;52(2):195-200. doi: 10.1254/jjp.52.195.


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.

MeSH terms

  • Adrenergic beta-Agonists / pharmacology*
  • Adrenergic beta-Antagonists / pharmacology*
  • Animals
  • Brain Chemistry / drug effects*
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / metabolism
  • In Vitro Techniques
  • Iodine Radioisotopes
  • Iodocyanopindolol
  • Kinetics
  • Male
  • Pindolol / analogs & derivatives*
  • Pindolol / metabolism
  • Rats
  • Receptors, Adrenergic, beta / metabolism*
  • Receptors, Serotonin / metabolism*


  • Adrenergic beta-Agonists
  • Adrenergic beta-Antagonists
  • Iodine Radioisotopes
  • Receptors, Adrenergic, beta
  • Receptors, Serotonin
  • Iodocyanopindolol
  • Pindolol