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[3H]5-methyl-urapidil labels 5-HT1A receptors and alpha 1-adrenoceptors in the rat CNS. In vitro binding and autoradiographic studies.

Abstract : The tritiated derivative of the potent antihypertensive agent, 5-methyl-urapidil, was used as a radioligand in binding studies with rat brain membranes and tissue sections. Serotonin and prazosin inhibited [3H]5-methyl-urapidil binding to membranes from the rat hippocampus, cerebral cortex and brainstem biphasically, leading to the definition of serotonin high-affinity and prazosin high-affinity [3H]5-methyl-urapidil binding sites. Comparison of these serotonin-sensitive [3H]5-methyl-urapidil binding sites with the 5-HT1A sites labelled by [3H]8-hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT) revealed striking similarities regarding pharmacological properties, respective densities and regional distribution. On the other hand, the prazosin-sensitive [3H]5-methyl-urapidil binding sites should correspond to the alpha 1A-subtype of adrenoceptors which has recently been defined. Detailed autoradiographic investigations allowed the detection of 5-HT1A sites labelled by both [3H]5-methyl-urapidil and [3H]8-OH-DPAT in the posterior raphe nuclei (pallidus and obscurus) which are possibly involved in the hypotensive action of 5-methyl-urapidil. These data demonstrate that [3H]5-methyl-urapidil is a useful radioligand for the visualization and quantification of both 5-HT1A serotonin receptors and alpha 1A-adrenoceptors in the central nervous system.
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https://hal.inrae.fr/hal-02711945
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Submitted on : Monday, June 1, 2020 - 6:00:15 PM
Last modification on : Wednesday, June 16, 2021 - 11:46:04 AM

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Anne Marie Laporte, Lee E Schechter, Francisco Bolaños-Jiménez, Daniel Vergé, Michel Hamon, et al.. [3H]5-methyl-urapidil labels 5-HT1A receptors and alpha 1-adrenoceptors in the rat CNS. In vitro binding and autoradiographic studies.. European Journal of Pharmacology, Elsevier, 1991, 198 (1), pp.59-67. ⟨10.1016/0014-2999(91)90562-5⟩. ⟨hal-02711945⟩

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