Effects of cocaine- and amphetamine-regulated transcript peptide, leptin and orexins on hypothalamic serotonin release

We have studied the effects of cocaine- and amphetamine-regulated transcrip t (CART) peptide-(55-102), leptin, orexin-A and orexin-B on basal and depol arization (K+ 15 mW)-induced serotonin (5-hydroxytryptamine, 5-HT) release from rat hypothalamic neuronal endings (synaptosomes) in vitro. We have fou nd that leptin and CART peptide-(55-102) have no effect on 5-HT release, wh ile orexin-A and orexin-B inhibit depolarization-stimulated serotonin relea se. We can conclude that leptin and CART peptide-(55-102), which play a phy siological role as feeding inhibitors, do not acutely affect 5-HT release f rom hypothalamic synaptosomes; on the other hand, feeding induced by orexin -A and orexin-B could be partially explained by decreased 5-HT release. (C) 2001 Elsevier Science B.V. All rights reserved.