Study On The Mechanism Of Prophenoloxidase Activating System Activation Modulated By Biogenic Amines In Litopenaeus Vannamei

This paper reports the mechanism of prophenoloxidase(proPO) activating system activation modulated by biogenic amines(BA) in the White Shrimp Litopenaeus vannamei. discusses mainly the following theses:â‘ Effect of 3 BA on the total haemocyte count (THC), differential haemocyte count (DHC), proPO activity of haemocyte and phenoloxidase(PO) activity of L. vannamei;â‘¡Mechanism of dopamine(DA) effecting the haemocyte of L. vannamei;â‘¢Effect of DA and Vibrio algino1yticus injection on the BA concentration in the haemolymph and proPO activating system of L. vannamei;â‘£Effect of DA and V. algino1yticus injection on the immune response of L. Vannamei.1. Effect of 3 BA on the THC, DHC and proPO exocytosis of L. vannamei.The results show that DA, NE and 5-HT injection resulted in significant effects on the THC, DHC, proPO activity of haemocyte and PO activity released from haemocyte of L. vannamei (p<0.05), while no significant difference in the parameters is observed in the control group. THC, DHC and proPO activity of haemocyte decrease significantly after incubated 20min respectively in 0.5, 1.0 and 3.0μM DA, NE or 5-HT, whereas PO activity released from haemocyte increases significantly.Among these BA, DA has the strongest effect on these parameters , whereas 5-HT has the least.2. Way of DA effecting the haemocyte of L. vannamei.The results indicat that THC, DHC and proPO activity of haemocyte decrease significantly after incubated 20min in 1μM DA, whereas PO activity released from haemocyte increases significantly(P<0.05).10, 100, 500μM D1 receptor antagonist SCH23390 and D2 receptor antagonist Sulpiride can inhibit the effect of DA on these parameters markedly when haemocytes preincubated 20min in the antagonist(P<0.05).The changes of parameters had a positive correlation with concentration of these two antagonists. The inhibitory effct of SCH23390 is stronger than that of Sulpiride and the mixture of SCH23390 and Sulpiride has the strongest inhibitory effect.3. Effect of DA and V. algino1yticus injection on BA concentration in the haemolymph and proPO activating system of L. vannamei.The concentrations of DA, NE and 5-HT in the haemolymph, THC, DHC, serine proteases and proPO activity of haemocyte, PO and proteinase inhibitor activity in the haemolymph of L. vannamei were measured after injection individually with 50μl saline, 10^-7 mol l^-1or 10-6 mol l^-1 DA, 6.0×10⁵ cells ml^-1 or 6.0×10⁶ cells ml^-1 V. algino1yticus. Results show that DA and V. algino1yticus injection resulted in significant dose-depended effects on the parameters measured(p<0.05)except for the serine proteases activy after DA injection, while no significant difference in the parameters was observed in the control group. During the experiment, all of these immunological parameters show peak changes except for the serine proteases activy after DA injection, but the times when they reach their peaks and incline to stabilization do not synchronize.After DA and V. algino1yticus injection, 5-HT concentration in the haemolymph increase markedly before 1h,6h and 3h, whereas the concentrtion of DA reach the maxima or minima at 3h. NE concentration in the haemolymph increase markedly before 3h and 1h after DA and V. algino1yticus injection.The THC decrease significantly after injection of DA or 6.0×10⁶ cells ml^-1 V. algino1yticus, whereas the THC and DHC reach the maxima at 3h then decline tardily and became stable at 6h. The ratio of granular cells increase before 3h. All enzyme activities reach their minima or maxima in 1-6h except for the serine proteases activy after DA injection.The concentration of 5-HT after V. algino1yticus injection, the hyaline cells, semi-granular cells counts, THC after injection of DA and 6.0×10⁶ cells ml^-1 V. algino1yticus, serine proteases activy after DA injection are lower than control markedly, whereas all the other parameters returned to the value observed in the control after stable.4.Effect of DA and V. algino1yticus injection on the immune response of L. vannameiThe results show that injection of 50μl 10^-7 mol l^-1or 10^-6 mol l^-1 DA, 6.0×10⁵ cells ml^-1 or 6.0×10⁶ cells ml^-1 V. algino1yticus result in significant effects on the concentrations of DA, NE and 5-HT in the haemolymph, THC, phagocytic activity , bacteriolytic and antibacterial activities, hemocyanin in the haemolymph(p<0.05), while no significant difference in the parameters was observed in the control group.The concentration of DA, NE and 5-HT and THC are same with the result of 3. The phagocytic activity of haemocyte reach the minima or maximum at 6h or 3h respectively after injection of DA or V. algino1yticus, and have negative or positive correlations with the dosage of injection. The bacteriolytic activities reach the minima at 3h and became stable after 6h after injection of DA or 6.0×10⁶ cells ml^-1 V. algino1yticus, whereas the bacteriolytic activitiy increases markedly before 3h after injection of 6.0×10⁵ cells ml^-1 V. algino1yticus. After injection of DA or V. algino1yticus ,the PO activities reach the maximum at 6h and 1h and became stable afer 12h and 3h,whereas the hemocyanin in the haemolymph reach the maximum or minima at 6h and 3h and became stable afer 24h.All these parameters have no significantly difference with the control after stabilize except for the bacteriolytic activities are remarkably lower than the control group after injection of DA or 6.0×10⁶ cells ml^-1 V. algino1yticus and hemocyanin are remarkably higher than the control group after injection of V. algino1yticus.