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 araeries.3H-GABA in the presence of 40 μm 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 specific3H-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. © 1990 The Italian Pharmacological Society.