Effect Of Lactic Acid On Enrofloxacin Disposition In Eriocheir Sinensis And Its Mechanism

As a representative acidifier,lactic acid（LA）is widely used in the diets of aquatic animals.Lactic acid can be directly absorbed by the animals for energy metabolism.Enrofloxacin（ENR）is a prescribed drug for farming animals in China.At present,there is limited information about the effects of organic acids on the metabolism and residue of drugs in aquatic animals and their mechanisms.This study was designed to explore the effect of lactic acid on ENR pharmacokinetics,the effect of lactic acid on the expression of drug metabolic enzymes gene（such as CYP2A,CYP3 and GST）and other genes related ENR metabolism and the effect of lactic acid on the histology of hepatopancreas and intestine in Eriocheir sinensis.It provides theoretical guidance for understanding the mechanism of drug metabolism in crustaceans.The main contents of this study are as follows:This first part investigated the effects of different levels of lactic acid on the ENR pharmacokinetics in E.sinensis.The concentrations of ENR in the hemolymph,hepatopancreas and muscle were determined by HPLC after a single oral dose of 10 mg kg^-1.The results showed that LA had a significant effect on the peak ENR concentrations(C_max)in all the tissues（P<0.05）by One-way ANOVA analysis.With the increase of lactic acid level,the peak concentration time points(T_max),T_1/2β（elimination half-life）and AUC_（0-∞）were shortened,and C_maxax of ENR were increased in hemolymph and other tissues.Taken together,0.3%LA might enhanced biotransformation of ENR in the hepatopancreas and might be effective in changing ENR pharmacokinetics in E.sinensis.This second part explored the effect of lactic acid on the expression of drug metabolism genes and other genes related ENR metabolism in E.sinensis,understanding the molecular mechanism of drug metabolism in crustacean.ENR metabolism is closely related to drug metabolic enzymes（such as CYP450 and GST）and energy metabolism process.The gene relative expression levels of drug metabolizing enzymes（CYP2A,CYP3 and GST）and energy metabolizing enzymes（SDH and PEPCK）by RT-qPCR.The results showed that the expression of CYP2A,CYP3 and GST in ENR+0.3%LA group were inhibited at T_max（1h）,while CYP3 in ENR group was induced by ENR;0.3%LA level could not significantly affect the expression of CYP2A,but in the elimination process of ENR,the expression of CYP3and GST were significantly induced by LA.The effects of LA on energy metabolism enzymes were as follows:at T_max（1h）,lactic acid induced the expression of PEPCK and inhibited the expression of SDH;the expression of both genes was significantly inhibited by lactic acid during enrofloxacin elimination.It can be speculated that LA can accelerate the elimination of enrofloxacin in the hepatopancreas of this crabs by inducing the expression of CYP3 and GST and enhance the detoxification of hepatopancreas;LA changes the energy metabolism pathway at T_maxax and LA make cells...