Efflux of 5-hydroxytryptamine from synaptosomes of rat cerebral cortex.
The efflux of 3H-5-HT from a crude synaptosome preparation of the cerebral cortex of reserpinized rats was examined. The synaptosomes were loaded with 3H-5-HT by pre-incubation of the homogenate in presence of pargyline and desipramine in order to inhibit deamination of 5-HT and uptake into noradrenergic neurons. The synaptosomes were collected by centrifugation, washed and resuspended in 0.25 M sucrose. No spontaneous efflux of 5-HT was detectable at 0 degrees C but marked efflux was observed at 27 degrees C and 37 degrees C. 4-Chloroamphetamine, low external Na+ concentration, ouabain and the depolarizing agent veratridine markedly accelerated the initial (5 min) efflux. Inhibitors of the neuronal 5-HT uptake, e.g. chlorimipramine, H 102/09 and A 23189, antagonized the 5-HT efflux evoked by these means, whereas desipramine, which is a poor inhibitor of the 5-HT uptake, had only slight effect on the 5-HT efflux. It is suggested that 5-HT can be actively transported out from the synaptosomes by the reversed 5-HT uptake mechanism.
D000409:Alanine / Q000031:analogs & derivatives / Q000494:pharmacology; D000499:Allylamine / Q000031:analogs & derivatives / Q000494:pharmacology; D000662:Amphetamines / Q000494:pharmacology; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D002997:Clomipramine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D010293:Pargyline / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects; D012110:Reserpine / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D012702:Serotonin Antagonists; D013574:Synaptosomes / Q000378:metabolism*; D013696:Temperature
D000662:Amphetamines; D011725:Pyridines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D012701:Serotonin; D000499:Allylamine; D010042:Ouabain; D012110:Reserpine; D010293:Pargyline; D002997:Clomipramine; D000409:Alanine; D003891:Desipramine