Effect Of γ-aminobuty Ric Acid On The Immune Defense Of Chlamys Farreri

Being no acquired immune ability, the mollusk mainly depends on innate immuneresponse, consisting of the humoral immunity and cell-mediated immunity dependent on thephagocytosis of hemocytes to kill various pathogens. In this paper, we studied the distributionof GABA and its GABA receptor A and GABA receptor B in hemocytes of Chlamys Farreriwith immunohistochemical technique, and studied the impact of GABA on some humoralimmune-related enzymes with biochemical methods, studied the impact of GABA on thephagocytic rate of hemocytes and the protection carried out by GABA on the hemocytes withflow cytometry, in order to accumulate research data for shellfish immunology.Using the immunohistochemical technique, we found that large amounts of GABA-likeand GABAR-A-like immunoreactive punctuation were scattered in the hemocytes, whilethere was no GABAR-B-like immunoreaction. The result permitted the forward research onthe impact of GABA on the immune ability of hemocytes.Using the biochemical methods to detect the influences of GABA on the activities ofseveral immune related enzyme, the results showed that, when the concentrations of GABA(CGABA) were less than or equal to0.025μg/mL, the activities of acid phosphatase (ACP) andalkaline phosphatase (AKP) and catalase (CAT) and myeloperoxidase (MPO) in thehaemolymph of Chlamys Farreri were higher than that in the control group, what’s more, themaximum were occurred at the GABA concentration of0.025μg/mL. When CGABAwas equalto0.125μg/mL, the activities of ACP, AKP and CAT in the hemocytes and the activities ofACP, AKP and MPO in the haemolymph plasm were higher than that in the control group, theactivites of MPO in the hemocytes were lower than that in the control group, while there wereno significant difference between the activities of CAT in the haemolymph and in the controlgroup. When the CGABAwas equal to0.625μg/mL, both of the activities of CAT in thehemocytes and the activities of AKP in the haemolymph plasm were higher than that in thecontrol group, the activities of ACP, AKP and MPO in the hemocytes were lower than that inthe control group, while there were no significant difference between the activities of ACPand MPO in the haemolymph plasm and that in the control group. When the CGABAwas equalto3.625μg/mL, the enzymes’ activities of experimental group were lower than that in thecontrol group with the exception of AKP and CAT in the hemocytes which were detected to be higher.Using the flow cytometry to analyze the influence of GABA on the subgroups and thephagocytic rate of hemocytes, the results showed that: Three distinct hemocytes subgroupswere identified by flow cytometry, hyaline cell with little small size and little granules (HC),small granule cells with unequal size and midding granules (SGC) and the large granule cellswith large size and much granules (LGC). The proportion of large granule cell could besignificantly up-regulated, and there was an unconspicuous increasement of the proportion ofsmall granule cells while the proportion of hyaline cells was reduced; Both of the maximumof the proportion of LGC and the minimum of the proportion of HC were reached at theGABA concentration of0.025μg/mL. Increasement of phagocytic rate of hemocytes with themaximum at the GABA concentration of0.025μg/mL were also detected when there wereGABA, in addition, there were no change of the phagocytic rate as the CGABAmore than orequal to0.125μg/mL increased.Using the flow cytometry to analyze the protection of GABA on the haemocytes, theresults showed that, the GABA dose-dependent mortality rate lower than that in the controlgroup were detected in the experimental group with concentration gradient of GABA, inaddition, the significant difference between the experimental group and control group werealso detected. As well, the mortality rate of the mixed group with heavy metal ion and GABAwere all lower than that in the heavy metal goup.To sum up, GABA could influence the cell-mediated immunity and the humoralimmunity of Chlamys Farreri, as well as the protection taken on the hemocytes. Theinfluence may be carried out by the combination with the A receptors in the hemocytes.