Chlorella vulgaris supplementation effects on performances, oxidative stress and antioxidant genes expression in liver and ovaries of New Zealand White rabbits

Abstract

Oxidative stress is an exclusive biochemical complication affecting reproduction; hence, dietary antioxidant supplementation for its attenuation is a required nutrition - reproduction improvement strategy. On this background, Chlorella vulgaris (a natural antioxidant) was supplemented to grower female rabbits to maturity. The rabbits were thirty-five in number randomly distributed into five experimental groups in a completely randomized design. Control group was fed only basal feed while treatment groups were fed diets containing 40 %, 60 %, 80 % and 100 % Chlorella vulgaris biomass as T1, T2, T3 and T4 respectively at 500 mg per animal body weight (kg) along with the basal feed daily. Performance records were obtained, blood was collected, and at the end uterus, ovaries and liver were removed from sacrificed animals for analysis. Serum, uterus and liver oxidative stress status were determined while RNA isolated from liver and ovaries samples were used for antioxidant genes expression analysis. Oxidative stress status and antioxidant enzymes activities were determined using chemical assays while antioxidant gene expression levels were determined using real-time quantitative PCR system. There was significant difference in feed intake (p < 0.014), final body weights (p < 0.008), empty carcass weights (p < 0.001) and commercial carcass weights (p < 0.001) of the rabbits as results of the microalgae supplementation. There was also significant difference in malondialdehyde (MDA) concentrations (p < 0.050), total antioxidant capacity (TAC) (p < 0.050) and protein carbonyl (PCO) concentrations (p < 0.050) due to the supplementation of the microalgae; in addition, supplementation of the microalgae significantly improved activities of superoxide dismutase (SOD) (p < 0.050), catalase (CAT) (p < 0.050) and reduced glutathione (GSH) concentration (p < 0.050). Furthermore, there was significant difference in relative expression of primary antioxidant genes sod1 (p < 0.050) and gpx1 (p < 0.050); however, there was no significant difference in relative expression of bre (p > 0.050) and ucp1 (p > 0.050). The study concluded from the outcomes stated above that supplementation of microalgae Chlorella vulgaris improved performances of rabbits through attenuation of oxidative stress, enhancement of antioxidant enzymes activities as well as up-regulation of primary antioxidant genes. Hence, it was recommended as dietary supplement for protection against oxidative stress and improved productivity in rabbits and other food producing mammalian species. In addition, further studies into assessment of its effects on expression of transcripts and immune modulation genes in rabbits and other animals is warranted as future studies in order to established its potential as beneficial nutraceutical for animals and human.

Keywords: Agriculture; Antioxidant enzymes; Biotechnology; Cancer research; Chlorella vulgaris; Genetics; Molecular biology; Oxidative stress; Physiology; Toxicology; Zoology; gpx1; sod1.

Fig. 1

Relative expression of primary antioxidant genes in liver of the rabbits. Bars with different labels are significantly different in expression of the genes determined (p < 0.05). Control - group without supplement diet. T1 - group supplemented with 200 mg/kg BW Chlorella vulgaris biomass. T2 - group supplemented with 300 mg/kg BW Chlorella vulgaris biomass. T3 - group supplemented with 400 mg/kg BW Chlorella vulgaris biomass. T4 - group supplemented with 500 mg/kg BW Chlorella vulgaris biomass.

Fig. 2

Relative expression of primary antioxidant genes in ovaries of the rabbits. Bars with different labels are significantly different in expression of the genes determined (p < 0.05). Control - group without supplement diet. T1 - group supplemented with 200 mg/kg BW Chlorella vulgaris biomass. T2 - group supplemented with 300 mg/kg BW Chlorella vulgaris biomass. T3 - group supplemented with 400 mg/kg BW Chlorella vulgaris biomass. T4 - group supplemented with 500 mg/kg BW Chlorella vulgaris biomass.

Fig. 3

Comparative expression of primary antioxidant genes in the rabbits' liver and ovaries (*p < 0.05). Control - group without supplement diet. T1 - group supplemented with 200 mg/kg BW Chlorella vulgaris biomass. T2 - group supplemented with 300 mg/kg BW Chlorella vulgaris biomass. T3 - group supplemented with 400 mg/kg BW Chlorella vulgaris biomass. T4 - group supplemented with 500 mg/kg BW Chlorella vulgaris biomass.

Fig. 4

Functional enrichment analysis of superoxide dismutase gene expression biological impacts in the rabbits.