Subcellular distribution and chemical nature of the receptor for 5-hydroxytryptamine in the central nervous system

Abstract— In vitro binding experiments with 5-hydroxy¹⁴C]tryptamine (3.3 × 10^?6 M) were carried out on subcellular fractions of the cat brain. The highest specific activity was observed in some fractions of nerve-ending membranes isolated from the hypothalamus, basal ganglia, and gray areas of the mesencephalon. The specificity of this high affinity binding was demonstrated by competition with reserpine, butanolamide of lysergic acid, and desmethylimipramine. With butanol-water extraction the ¹⁴C]5-HT was found in the butanol while the gangliosides were separated in the water phase. Several experiments with thin layer and column chromatography suggest that in the organic phase the ¹⁴C]5-HT is not bound to the lipids but to a special proteolipid. This proteolipid is different from that found in myelin and has similar chromatographic properties to that previously observed in the proteolipid which binds d-¹⁴C]tubocurarine in nerve-ending membranes of the cerebral cortex.