Evidence against the existence of GABA-B receptor sites in rat cerebrovascular tree.
By the use of combined radioreceptor binding and autoradiographic techniques we attempted to analyse the biochemical characteristics and the anatomical localization of GABA-B receptors in sections of rat circle of Willis and pialarachnoid arteries. 3H-GABA in the presence of 40 microM isoguvacine and 2.5 mM CaCl2 was used to label GABA-B receptor sites. Sections of rat cerebellar cortex were also processed as a reference tissue. No specific 3H-GABA binding was detectable either in radioreceptor binding or autoradiographic experiments. In contrast, the ligand was bound to sections of cerebellar cortex in a manner consistent with the labelling of GABA-B receptor sites. These findings indicate that cerebrovascular physiological responses to GABA are not linked, in the rat cerebrovascular tree, to the activation of GABA-B receptors.
Napoleone
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P
Dipartimento di Scienze Neurologiche, Università La Sapienza, Roma, Italy.
Ferrante
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F
Amenta
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F
D000818:Animals; D001099:Arachnoid / Q000098:blood supply; D001345:Autoradiography / Q000379:methods; D001665:Binding Sites; D002122:Calcium Chloride / Q000494:pharmacology; D002525:Cerebellar Cortex / Q000378:metabolism / Q000648:ultrastructure; D002536:Cerebral Arteries / Q000648:ultrastructure*; D002941:Circle of Willis / Q000648:ultrastructure; D007539:Isonicotinic Acids / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000378:metabolism*; D014316:Tritium; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D007539:Isonicotinic Acids; D011963:Receptors, GABA-A; D014316:Tritium; D005680:gamma-Aminobutyric Acid; D002122:Calcium Chloride; C015300:isoguvacine