125I-LSD autoradiography confirms the preferential localization of caudate-putamen S2 receptors to the caudal (peripallidal) region.
The in vitro binding of 125I-lysergic acid diethylamide (LSD) to horizontal sections of rat brain was quantified with computer-assisted autoradiography. Specific binding of 125I-LSD to D2 and S2 sites, defined with 5 microM (+)-butaclamol, was 65-94% of the total binding. Identification of S2 sites with 50 nM ketanserin showed that over 90% of the butaclamol-displaced 125I-LSD binding in the frontal, cingulate and parietal neocortex was to S2 sites (22-55 fmol/mg protein). 125I-LSD also labeled a dense population of S2 sites (16 fmol/mg protein) in the caudal caudate-putamen at the level of the globus pallidus which exceeded by 5-fold the concentration of S2 sites (3 fmol/mg protein) in more rostral portions of the caudate-putamen. The peripallidal distribution of S2 sites was identical to that observed previously with the less selective S2 label, [3H]spiperone. The dense concentration of S2 sites in the caudal caudate-putamen and their overlap with D2 binding sites indicates that the peripallidal neostriatum may play an important role in interactions between dopamine and serotonin.
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D000818:Animals; D001345:Autoradiography; D002069:Butaclamol / Q000378:metabolism; D002421:Caudate Nucleus / Q000378:metabolism*; D005625:Frontal Lobe / Q000378:metabolism; D007457:Iodine Radioisotopes; D007650:Ketanserin; D008238:Lysergic Acid Diethylamide / Q000378:metabolism*; D008297:Male; D010880:Piperidines / Q000378:metabolism; D011699:Putamen / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000032:analysis*; D012701:Serotonin / Q000378:metabolism*
D007457:Iodine Radioisotopes; D010880:Piperidines; D011985:Receptors, Serotonin; D012701:Serotonin; D008238:Lysergic Acid Diethylamide; D007650:Ketanserin; D002069:Butaclamol