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 μg/ml, and the intracellular and extracellular MPO activity with two substrate solutions was highest when the concentration of L-ENK was 50 μg/ml. However, both the intracellular and extracellular MPO activity of 1 μg/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 μg/ml, but the resultant HLS ANAE activity was highest when the concentration of L-ENK was 5 μg/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 Keywords: Chlamys farreri; Leucine-enkephalin; Alpha-naphthyl acetate esterase; Myeloperoxidase; Haemolymph Received: 23 September 2008 / Received in revised form: 6 October 2008, Accepted: 7 October 2008 Published online: 18 October 2008