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High affinity [3H]zolpidem binding in the rat brain: an imidazopyridine with agonist properties at central benzodiazepine receptors

1986; Elsevier BV; Volume: 130; Issue: 3 Linguagem: Inglês

10.1016/0014-2999(86)90276-1

1879-0712

S. Arbilla, John Allen, A. K. Wick, Salomón Z. Langer,

Pharmacological Receptor Mechanisms and Effects

[3H]Zolpidem, a novel hypnotic drug posessing a chemical structure unrelated to that of benzodiazapine (BZD) was employed as a new ligand to determine its binding characteristics to membrane preparations of rat cerebral cortex and cerebellum. In both structures, the imidazopyridine [3H]zolpidem bound with high affinity to a single population of recognition sites. The cerebellum possessed a similar number of [3H]zolpidem and [3H]diazepam binding sites, while the cerebral cortex possessed a lower density of [3H]zolpidem than [3H]diazepam binding sites. In contrast to [3H]diazepam binding, [3H]zolpiem binding was not detectable in the spinal cord. In the cortex, BZDs had a similar potency to displace [3H]zolpidem and [3H]diazepam binding while non-BZDs were more potent to inhibit [3H]zolpidem binding than [3H]diazepam binding. The binding of [3H]zolpidem was enhanced by GABA to the same extent as [3H]diazepam binding. The increase in [3H]zolpidem binding caused by chloride ions was less pronounced than that in [3H]diazepam binding. It is concluded that [3H]zolpidem possesses selectivity for BZD receptors with the pharmacological characteristics and regional distribution of the BZD1 receptor subtype. [3H]Zolpidem as a radioligand offers a useful additional tool to study the mechanism of action of hypnotics acting through BZD receptor subtypes.