Effect of co-administration of caffeine and cotinine on antioxidant enzyme activities of rainbow trout (Oncorhynchus mykiss)

Caffeine is found in coffee, tea, and cacao. Cotinine is a metabolite of nicotine. Nicotine is found in tobacco. We are exposed to both of these chemicals in our daily lives. The effects of these chemicals have not been well known in fish. In this study, our aim was to determine the effect of caffeine and cotinine on glutathione S-transferase (GST), catalase (CAT), glutathione peroxidase and glutathione reductase (GR) activities in rainbow trout (Oncorhynchus mykiss). For this purpose, 48 fish were taken from fish farm and they were treated with individually or in combinations of 50 µg/L of caffeine and cotinine for 48 hours. Fish were separed according to gender. Livers were taken and cytosols were prepared from each liver tissues. GST activities of male cotinine treatment and co-administration groups were significantly different from the fish in the male control group. Catalase activities of male fish treated with caffeine was significantly different from the male co-administration group. Glutathione peroxidase activities of male fish treated with cotinine was significantly different from the male control group. These was no significant difference in female groups in these measured activities. There was no significant difference in the glutathione reductase activities in male and female groups. The results of this study indicated that caffeine and cotinine modified some of the antioxidant enzyme activities in male fish. However, they did not alter any of the measured enzyme activities in female fish. It is clear that there is a gender difference in respose to these chemicals at this dose in acute study in fish.