Effects of leucine-enkephalin on alpha-naphthyl acetate esterase and myeloperoxidase activity in haemolymph of the scallop Chlamys farreri

The study was designed to investigate the effects of leucineenkephalin (L-ENK) on the activity of alpha-naphthyl acetate esterase ( ANAE) and myeloperoxidase (MPO) in haemolymph of the scallop Chlamys farreri. Our results indicate that MPO activity with DAB and DEA substrate solution was induced when the concentration of L-ENK was 5 and 50 mu g/ml, and the intracellular and extracellular MPO activity with two substrate solutions was highest when the concentration of L- ENK was 50 mu g/ ml. However, both the intracellular and extracellular MPO activity of 1 mu g/ ml group was significantly lower than that of control group. It was also found that the intracellular and extracellular ANAE activity was induced by L- ENK. The supernatant ANAE activity was highest when the concentration of L- ENK was 50 mu g/ ml, but the resultant HLS ANAE activity was highest when the concentration of L- ENK was 5 mu g/ ml. Overall, the data suggests an involvement of L- ENK in the regulation of the defense systems of the scallop Chlamys farreri. L- ENK may function as messengers in the bidirectional interaction between the neuroendocrine and the immune systems.