Serotonin uptake and release from rat cerebellum in vitro.
Serotonin (5-HT) uptake and release were analyzed in cerebellar fractions. Cerebellar, P2 fractions and molecular layer homogenates are able to accumulate exogenous 5-HT through an Na-dependent, high-affinity transport system. Molecular layer 5-HT uptake, however, was totally dependent upon Na+, whereas the accumulation of the amine by P2 fractions from whole cerebellum was also carried out by an Na-independent transport system. Ca++-dependent release of recently accumulated 5-HT was observed in both P2 fractions and molecular layer homogenates when depolarizing conditions were used. This release was blocked by ruthenium red and Mg++, two inhibitors of the Ca++ entry to the nerve endings induced by depolarization. The molecular layer homogenates released twice as much 5-HT as did cerebellar P2 fractions, indicating that serotoninergic boutons in the cerebellar cortex might be located in the molecular layer. Our results suggest that 5-HT might play a transmitter role in the cerebellum.
D000818:Animals; D002118:Calcium / Q000502:physiology; D002525:Cerebellar Cortex / Q000502:physiology; D002531:Cerebellum / Q000378:metabolism*; D008297:Male; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism* / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism; D009435:Synaptic Transmission; D014702:Veratrine / Q000494:pharmacology
D012701:Serotonin; D011189:Potassium Chloride; D014702:Veratrine; D002118:Calcium