Heavy metals and neuroimmunomodulation in Mytilus edulis

Immunocytes of mussels are the chief immune defense in these organisms. Whe n an immunocyte becomes activated there is a conspicuous change in its morp hology (i.e., from round to amoeboid) that can be quantified using image an alytical tools. Active immunocytes will typically show larger perimeters an d areas and a smaller shape factor. Immunocytes exposed to heavy metals bec ome inactive (Cd, Hg and Ph) thus with smaller perimeters (e.g., Pb-2ppm(2): P = 69.72 mu) and areas (e.g., Pb2+ (2ppm): A = 270 mu(2)) and larger sh ape factors (Pb2+ (2 ppm): SF = 0.65) than the unexposed control cells (alp ha = 0.05). Xenobiotics may also interfere with neuroimmunomodulation proce sses such as nitric oxide (NO) release. The release of NO is catalyzed by a calcium dependent constitutive nitric oxide synthase (cNOS). Presently, we are exploring the effects of heavy metals and other pollutants on cNOS act ivity, measured as real time NO release, in immunocytes and pedal ganglia f rom M. edulis. Preliminary results suggest that immunocytes exposed to Pb2 (5 ppm) cause NO release and does not seem to inhibit further NO release i n the presence of morphine. The possible implications of NO mediated Pb2+ n eurotoxicity are also explored.