Modulation of systemic antioxidant and immune responses in red abalone (Haliotis rufescens) during the recovery phase of anesthesia, in preparation for grafting surgery

The use of anesthetic agents as pre-operatory treatment to pearl seeding surgery can be stressful to organisms and activate various physiological response mechanisms. This study evaluated some parameters of the systemic antioxidant and immune responses in red abalone (Haliotis rufescens) exposed to 0.25 mL L^-1 eugenol (EUB), 3.0 mL L^-1 phenoxyethanol (PEB) and CO₂ at saturation, as well as in a control (CT) without anesthetic. Abalone were anesthetized for 45 min and, during the recovery stage, hemolymph samples were collected at 0.5, 1, 2 and 24 h. Total protein content (TP), superoxide dismutase (SOD), catalase (CAT) and myeloperoxidase (MPO) activity, as well as nitric oxide (NO) production, were evaluated in hemolymph cell-free fraction (HCF) and hemocytes lysate (HL). In addition, total hemocyte count (THC) was determined. In HCF, TP was significantly higher in abalone exposed to PEB than in the other treatments and CT at 0.5, 1 and 24 h. SOD activity in HCF was significantly higher in all treatments compared to the CT (1 h), while CAT and MPO activity was only significantly higher in abalone exposed to EUB compared to PEB at 1, 2 and 24 h. In the HL fraction, the percentage of SOD inhibition was significantly higher only in abalone anesthetized with EUB compared to the CT (0.5 h). These results suggest that the antioxidant activity of the species during the recovery phase from anesthesia was transient and restored after 24 h. Similarly, the immune response of H. rufescens at the systemic level was not altered by the anesthetics, suggesting that the species adequately tolerated the anesthesia process. This research provides evidence of the effects of anesthesia at the systemic level in red abalone for the proper selection of anesthetics for pearl culture.