Reduced stress responses by MS‐222 in juvenile silver pomfret (Pampus argenteus)

Abstract

AbstractThe silver pomfret, Pampus argenteus is a major economically important marine fish in China. However, P. argenteus is sensitive to many stress factors and susceptible to injury. This problem could be resolved using anesthesia. We determined the lowest effective dose (LED) of tricaine methanesulfonate (MS‐222) and assessed the longest safe deep anesthesia time and effect after chasing. P. argenteus juveniles were exposed to six concentrations of MS‐222 (10, 25, 50, 75, 100, and 125 mg/L); LED was established at 75 mg/L. The juveniles were exposed to different deep anesthesia times (4, 7, 10, 12, and 15 min) at 75 mg/L; the longest safe deep anesthesia time under LED was 10 min. Finally, the juveniles were randomly divided into four groups: Control (no treatment at all) group (CG), Draining stress without MS‐222 group (DG), draining + chasing stress with MS‐222 (MS + DCG), and draining + chasing stress without MS‐222 (DCG). Plasma cortisol levels in the DCG, MS + DCG, DG, and CG groups were 38.739 ± 1.065 (highest), 25.083 ± 0.587, 28.644 ± 0.612, and 22.620 ± 0.836 ng/ml (lowest). When superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), and catalase (CAT) activities of the DCG group were compared with those of the other three groups, a significant increase (p < .05) was observed. However, the DG and MS + DCG groups showed no significant increase (p > .05) in SOD, MDA, GSH, and CAT activities. The MS + DCG group showed significantly (p < .05) higher GSH, SOD, CAT, and MDA activities than the control before stress. Before aquaculture treatment, HSP70, HSP90, GR1, and GR2 mRNA levels showed no significant differences (p > .05), whereas HSP70, HSP90, GR1, and GR2 mRNA levels in the DCG group increased sharply. GR1 and GR2 mRNA levels in the MS + DCG group also increased significantly, whereas HSP70 and HSP90 mRNA levels showed no significant differences. Thus, MS‐222 can reduce oxidative damage, stress reaction, and resistance to aquaculture treatment stresses in P. argenteus.