TDK conference 2019

The biotransformation of foreign matters – otherwise called xenobiotics – in the body is a multistep process where cytocrome P450 (CYP) enzymes play a defining role. Although the main place of these reactions is the liver, the detoxifying process of pollutants taken up from the environment or with the diet begins in the intestine; in the case of ruminants, even before that, in the rumen. Studying the drug metabolizing enzymes of wild animals is of special importance, since they are directly affected by pollutants in the natural environment and bioactive compounds of the ingested plants. So far limited data is available concerning detoxification processes in wild animals. Our research group has been studying the hepatic and intestinal activity of CYP enzymes in wild boars, but only limited information is available in the case of wild ruminants. Our present study deals with the comparative investigation of hepatic, ruminal and intestinal CYP enzyme activities in various deer species (roe deer, red deer and fallow deer).

Samples were freshly collected from the liver, ruminal epithelium and duodenum of 39 wild ruminants from three hunting areas of the Trans-danubian region in a period of a little more than a year. The post-mitochondrial supernatant containing CYP enzymes was isolated after homogenization of tissue samples in phosphate buffer by a multi-step differential centrifugation. Specific activity of CYP1A2 and CYP2C9 enzymes was assessed by luminometric P450-Glo assays. For standardizing the results, total protein and hemoglobin concentrations of samples were measured by BCA method and ammonia reagent, respectively.

On the basis of our results, the activity of hepatic CYP2C9 enzymes in the liver of all investigated species was significantly lower than that of the CYP1A2. The highest activity of both enzymes were discerned in roe deer. The CYP1A2 activity in the rumen was under the detection level in case of the fallow deer, while CYP2C9 was detectable, but its measure was of minor relevance. The activities of both enzymes were above the detectable level in the rumen of the roe deer and the red deer, but it was much lower compared to that of the liver. The highest level of both ruminal CYP1A2 and CYP2C9 activities were discerned in case of the red deer. CYP1A2 activity in the duodenum of the fallow deer was also under the detection level and it was just above in samples taken from the roe and the red deer. Duodenal CYP2C9 produced an outstandingly low activity in all three species.

Our research was the first to deal with the CYP enzyme activity in the rumen of wild ruminants, and to present a significant difference between the CYP1A2 and CYP2C9 enzyme in all three species. Our results provide highly important information on environmental pollutants wild ruminants are exposed to, and on the consequent presence of toxic residues in game meat.