Abstract
A series of gangllosides and related sphingolipids were assayed for serotonin [5-hydroxytryptamine] receptor activity by 2 different methods of bloassay. The most active compound was a new gnaglioside called new G. Very much less activity was found in 3 other known gangliosldes, but no activity was present in such common ganglio-sldes as G1, G4, and the Tay-Sachs'' ganglioside. The results indicated that the serotonin receptors are definite and specific chemical substances, possibly one or more gangllosides such as new G.