Chloramphenicol influence on antioxidant enzymes with preliminary approach on microsomal CYP1A immunopositive-protein in Chamelea gallina

Chloramphenicol (CA) is a largely used antibiotic and it is an inhibitor of protein synthesis that also induces ROS production. In this work there were investigated activities and expressions in the Adriatic bivalve Chamelea gallina of some antioxidant and detoxification proteins like superoxide dismutase (Mn–SOD, Cu/Zn–SOD), catalase (CAT) and Cytochrome P450 (CYP1A). Clams exposed to 5 mg l−1 of chloramphenicol were sampled 2, 4 and 8 days after treatment (CA2, CA4 and CA8). SODs, CAT, and CYP1A activity and/or expression were detected in pooled digestive glands by Western blotting and by spectrophotometrical analysis. Enzymes activities increase during the entire antibiotic exposure. With respect to the control Cu/Zn–SOD expression increases, while Mn–SOD expression decreases significantly after 4 days. Two CYP1A immunopositive-proteins (57.7 and 59.8 kDa) were detected. The lower band significantly decreases in CA8, the upper one also in CA4 condition. High levels of Mn–SOD, CAT activity and Cu/Zn–SOD expression, indicate intense ROS production while Mn–SOD expression inhibition might be ascribable to mitochondrial alterations due to CA and indirectly to ROS. CYP1A1 action determines H2O2 production that would contribute to a CYP1A1 gene promoter down regulation, a response to oxidative stress with the antioxidant enzymes activation as a final result. This study highlights the close association, in C. gallina, in presence of chloramphenicol, between SOD/CAT and CYP system, and it appear particularly interesting to the lack of similar researches on mollusc species.