Meeting Abstract

P1.176  Friday, Jan. 4  Neurotoxic Effects of Manganese on GABAergic Innervation in the Bivalve Mollusc Crassostrea virginica OGUNNOIKI, J.*; JACKSON, K.; CATAPANE, E.J.; CARROLL, M.A.; Medgar Evers College; Medgar Evers College; Medgar Evers College; Medgar Evers College catapane@mec.cuny.edu

High levels of airborne manganese (Mn) cause Manganism, a neurotoxsic, Parkinsons-like disease in humans by interfering with dopaminergic neurotransmission in brain. Recent studies are showing GABAergic neurons also are damaged by Mn. C. virginica contains a dopaminergic and serotonergic innvervation of its gill. It is a simple system to study Mn toxicity. Previously we showed Mn disrupts dopaminergic innervation. We also showed the cerebral ganglia (CG) of C. virginica contains GABA and within the CG GABA inhibits serotonergic innervation of gill lateral cell cilia. Here we studied if ganglia and peripheral tissues contain GABA receptors, and if Mn has effects on GABA neurons within CG of C. virginica. We used 1° antibodies (GABAA Ra1-6 ) and 2° antibodies (IgG-FITC) to detect GABA receptors with paraformaldehye fixed, paraffin embedded tissues using a Zeiss epilume fluorescence microscope and ProgRes C3 Peltier cooled camera. We found fluorescence due to GABA receptors in CG , visceral ganglia, palps and digestive tract. We also examined effects of Mn treatments on GABAergic inhibition of serotonin (HT) neurons in CG. Beating of lateral cilia in gill cells were measured by stroboscopic microscopy. Applying HT to CG caused a dose-dependent increase in cilia beating. Applying GABA prior to HT prevented the increase. Acute applications of Mn (50 and 500 µM) prior to GABA prevented GABA from inhibiting HT. The study is showing GABA receptors are present in ganglia and peripheral tissues in C. virginica, and acute Mn treatments damage GABA neurons. C. virginica preparations are good, simple test preparation to study the GABAergic system and the mechanism underlying the neurotoxic effects of Mn.