Inhibition of Mauthner Cells by Allylglycine

IN view of the possibility that glycine or glycine-like substances are inhibitory transmitters in the vertebrate central nervous system (CNS)^1,2, it is particularly interesting that the derivative, allylglycine (2-amino-4-pentenoic acid), causes convulsions when injected into mice and rats^3,4. Last year it was reported that allylglycine in vitro and in vivo reduced the synthesis of the depressant aminoacid, γ-amino-butyric acid (GABA)⁵, which has itself been suggested as a neural inhibitory substance^6,7; it seemed possible therefore that the convulsant properties of allylglycine may be due to a reduction in the concentration of GABA which it produces within the brain⁵. This communication describes an investigation of allylglycine on the Mauthner cells of goldfish, and in particular any action it may have either directly on these cells or on inhibitory pathways converging on them.