High- and Low-Affinity Binding of [3H]Imipramine in Rat Hypothalamus |
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Authors: | C. Moret M. Briley |
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Affiliation: | Department of Biochemical Pharmacology, Centre de Recherche Pierre Fabre, Castres, France |
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Abstract: | In the rat hypothalamus [3H]imipramine binding is inhibited by tricyclic and nontricyclic antidepressant drugs in a complex manner, with biphasic curves and Hill coefficients less than 1.0. 5-Hydroxytryptamine (serotonin) inhibited with high affinity a decreasing proportion of the [3H]imipramine binding sites as the [3H]imipramine concentration was raised. In the absence of sodium ions, IC50 values for the inhibition by tricyclic and nontricyclic antidepressants were increased by approximately 1,000-fold, and the inhibition curves became classically monophasic with Hill coefficients close to 1.0. These data are interpreted as suggesting that [3H]imipramine binds to two independent sites in the rat hypothalamus. One site is sodium-dependent with a high affinity for the drugs tested; the other is sodium-independent and has a low affinity for these drugs. |
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Keywords: | [3H]Imipramine binding Tricyclic and nontricyclic antidepressants Complex inhibition of binding 5-Hydroxytryptamine (serotonin) Sodium dependence |
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