Meeting Abstract

P2.124  Thursday, Jan. 5  A Study of GABA in Bivalve Molluscs BROWN, C.*; SADCHLA, M.; MATTHEW, K.; COCHRAN, T.; CARROLL, M.A.; CATAPANE, E.J.; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY; Medgar Evers College, Brooklyn, NY catapane@mec.cuny.edu

The nervous systems of most studied bivalves contain serotonin and dopamine in their ganglia that serve as neurotransmitters regulating various physiological functions such as heart rate, foot movement, reproduction and gill lateral cilia beating. GABA (gamma aminobutyric acid) is a major inhibitory neurotransmitter found in the CNS of vertebrates and the ganglia of many invertebrates. Its presence and functions have not been well studied in bivalve molluscs. In this study we used a HPLC method with pre-column derivatization and fluorescence detection to look for GABA in ganglia of Crassostrea virginica, Mercenaria mercenaria and Mytilus edulis. We also examined effects of GABA on beating of gill lateral cilia in C. virginica and M. edulis. GABA was detected in low ng amounts in each of the ganglia of each of the bivalves. In C. virginica and M. edulis GABA had no direct effect on lateral cilia activity whether superfused to the cerebral ganglia or applied directly on the gill. However, in C. virginica when serotonin was applied to the cerebral ganglia, the presence of GABA, whether applied prior to or after serotonin, blocked the normal excitatory response of serotonin on the beating of the cilia. Furthermore, the GABA antagonist bicuculline methchloride blocked the effects of GABA in the cerebral ganglia of C. virginica. Similar experiments with M. edulis did not demonstrate that GABA had a serotonin blocking effect at the cerebral ganglia. This study is showing that GABA is present and has a neurophysiological role in bivalve ganglia. This work was supported by grants 2R25GM0600309 of the Bridge Program of NIGMS, 0516041071 of NYSDOE and 0622197 of the DUE Program of NSF.