Study on antioxidant potential, immunological response, and inflammatory cytokines induction of glycyrrhizic acid (GA) in silver carp against vibriosis

Abstract

Effect of dietary with 100, 200, and 300 mg kg^-1 glycyrrhizic acid (GA) on growth enhancer, blood physiology, digestive-antioxidant enzyme ability, innate-adaptive defense, and inflammatory cytokines induction was studied in silver carp, Hypophthalmichthys molitrix against vibriosis caused by Vibrio alginolyticus. Significant weight gain (WG), specific growth rate (SGR), and 100% survival rate (SR) was attained non-infected health (NiH) fish fed in control or all GA diets on 30, 45, and 60 days. Both NiH and V. alginolyticus challenged (VaC) fish treated with 200 mg GA diet significantly (P < 0.05) exhibited an enhancement in leucocytes value on 30, 45, and 60 days. Albumin (AB) or total proteins (TP) levels were significantly (P < 0.05) better in both groups fed 200 GA on 45 and 60 days. Malondialdehyde (MDA) and superoxide dismutase (SOD) activities were also substantial (P < 0.05) in both groups fed 200 mg GA on days 30, 45, and 60; whereas glutathione peroxidase (GPx) and catalase (CAT) activities were significantly (P < 0.05) better in both groups received 200 mg GA on days 45 and 60. Phagocytic (PC) and lysozyme (Lyz) activities significantly enhanced in both groups fed 200 or 300 mg GA on 45 and 60 days. Respiratory burst (RB), reactive oxygen species (ROS) and immunoglobulin (Ig) production significantly (P < 0.05) increased in both groups administered 200 or 300 mg GA. Growth hormone (GH) mRNA was up regulated in 200 mg GA trial on 45 days and in 200 or 300 mg GA treatments on 60 days. The IL-8 cytokine mRNA expression was up-regulated in both groups 200 and 300 mg GA on days 45 and 60, whereas TNF-α mRNA expression was increased in 200 mg GA. In addition, IL-10 cytokine mRNA expression was up regulated in 200 mg GA on 45 days whereas it was increased in both 200 mg and 300 mg GA trial on 60 days. The present study revealed that feeding fish 200 mg GA per kg diet demonstrated a better growth, digestive-antioxidant activity, innate-adaptive defense, and inflammatory cytokines induction than lower or higher dosage of GA in H. molitrix against V. alginolyticus.

Keywords: Antioxidant activity; Glycyrrhizic acid (GA); Hypophthalmichthys molitrix; Innune response; Vibrio alginolyticus.