Antioxidant and immune responses of common carp (Cyprinus carpio) anesthetized by cineole: Effects of anesthetic concentration

In the present study, the effects of anesthesia with 1,8-cineole (cineole) were investigated on the antioxidant, innate immune and inflammatory responses of common carp (Cyprinus carpio). The anesthetic efficacy of cineole was determined using 200, 400, 600, 800, 1000 and 1200 mu l/l concentrations. The results showed that concentrations of 400-1200 mu l/l induced all stages of anesthesia in the fish. The time range for stages 1, 2, 3 and 4 were 58.6-13.1, 110-42, 270-80 and 460-140 s, respectively; at cineole concentrations of 400-1200 mu l/l. In the second experiment, fish were anesthetized with 400 and 1000 mu l/l cineole and were sampled immediately, and again, 24 h after anesthesia. Anesthesia with 400 mu l/l cineole led to immediate increase in plasma cortisol and glucose levels. Hepatic SOD, CAT, and GPx activities significantly increased; whereas GSH significantly decreased after anesthesia, depending on both the cineole concentration and sampling time. In general, 1000 mu l/l cineole pronounced more significant effects on these parameters, 24 h after anesthesia. Fish hepatic MDA levels presented significant elevation, and both lysozyme and bactericidal activity increased 24 h after anesthesia with 1000 mu l/l cineole. The fish anesthetized with 400 mu l/l cineole showed immediate, significant increase in plasma bactericidal activity, as well as 24 h after anesthesia. Anesthesia had no significant effects on plasma complement activity. The 400 mu l/l cineole significantly down-regulated the gene expression of tnf alpha and il1 beta immediately after the anesthesia. In conclusion, anesthesia with 1000 mu l/l cineole proved suitable for rapid sampling, yet not for practical aquaculture. Moreover, anesthesia led to an apparent increase in innate immune responses, which may be a defensive response to anesthesia-induced stress.