Effects of astaxanthin in diet on antioxidant capacity and molting-related genes expression of larvae giant freshwater prawn (Macrobrachium rosenbergii)

Abstract

This experiment was carried out to determine the effects of astaxanthin on reactive oxide species (ROS), antioxidant capacity as well as molting-related genes expression in larvae of giant freshwater prawn, Macrobrachium rosenbergii. A total of 90,000 larvae were assigned to five treatments with six replicates each. Astaxanthin mixed in steamed eggs with graded effective content as 0 (control, A0), 40 (A40), 80 (A80), 160 (A160) and 320 (A320) mg kg−1 were fed to larvae for 14 days. The results showed that ROS of larvae in astaxanthin treatments was significantly lower than the control (P < 0.05). T-AOC, T-SOD and GR activities under astaxanthin treatments generally showed a downward trend and decreased significantly than the control (P < 0.05). No significant difference was observed towards CAT activities among A40 and A80, but the values were markedly greater than A0, A160, A320 (P < 0.05). Larvae in A80 exhibited stronger MDA content than the other (P < 0.05). GSH-Px activity was significantly highest in A320 than the other treatments (P < 0.05). The expression of molt-inhibiting hormone (MIH) in A40 and A80 enhanced markedly than the control (P < 0.05). The elevated expression of Ecdysone receptor (EcR) was recorded only in A160 and A320 (P < 0.05). Chitinase (CHIT) expression among treatments was significantly downregulated than the control except for A40. Heat shock protein (HSP21) and chitooligosaccharidolytic beta-N-acetylglucosaminidase-like expression increased dramatically in A160 and A320 (P < 0.05). For actin 6 gene, higher expression was happened only in A40 compared to control, others presented drop expression in very low level (P < 0.05). This study provides a theoretical basis that 320 mg/kg astaxanthin was excessive level, and might decreased partial antioxidant indexes and influenced molting genes expression of larvae M. rosenbergii.