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Ethanol Fails to Modify [ 3 H]GR65630 Binding to 5‐HT 3 Receptors in NCB‐20 Cells and in Rat Cerebral Membranes
Author(s) -
Hellevuo Kaisa,
Hoffman Paula L.,
Tabakoff Boris
Publication year - 1991
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1991.tb00599.x
Subject(s) - agonist , receptor , membrane , 5 ht receptor , serotonin , chemistry , antagonist , ethanol , mechanism of action , biophysics , medicine , endocrinology , in vitro , biochemistry , biology
Low concentrations of ethanol have been found to enhance the electrophysiologic effect of serotonin (5‐HT) acting at 5‐HT 3 receptors on NCB‐20 cells. To determine whether this action of ethanol reflects a change in the agonist‐receptor interaction, the effect of ethanol (100 mm) on agonist and antagonist binding to 5‐HT 3 receptor was studied in vitro in membranes from NCB‐20 cells and from cortex plus hippocampus of rat. The antagonist [ 3 H]GR65630 was used to label 5‐HT 3 , recognition sites. Ethanol did not change the characteristics of saturable [ 3 H]GR65630 binding in either membrane preparation. In competition studies, the agonists 5‐HT and 2‐methyl‐5‐HT completely inhibited the binding of [ 3 H]GR65630 to NCB‐20 cell membranes, while in brain membranes the maximum displacement of specific [ 3 H]GR65630 binding by 5‐HT was approximately 30%. Ethanol decreased the affinity of the receptor for 2‐methyl‐5‐HT, but not to 5‐HT in NCB‐20 cells, and had no effect on agonist binding in brain membranes. The results indicate that enhancement of 5‐HT responses at 5‐HT 3 receptors by ethanol is not a result of changes in the equilibrium binding characteristics of the agonist.