Spirulina supplementation improves lipid metabolism and autophagic activities in the liver and muscle of Hu lambs fed a high-energy diet

ABSTRACT

The current study aimed to examine the effects of dietary spirulina supplementation in high-energy (HE) diets on fatty acid metabolism in sheep, and preliminarily explored the potential mechanisms underlying the associated autophagy-mediated regulation of lipid metabolism. In a 2 × 3 factorial design, including six treatment combinations of two metabolisable energy diets (10 and 11 MJ/kg DM), three spirulina supplementation levels (0, 1%, and 3%) were used. Serum alanineaminotransferase (ALT) (p = 0.003) and aspartatetransaminase (AST) (p = 0.002) activities increased, whereas total PUFA content (p < 0.001) decreased in the liver of lambs fed a HE diet. With the addition of spirulina, serum ALT (p = 0.037) and AST (p = 0.014) activities decreased, whereas EPA (p = 0.004), GLA (p = 0.019), n-6 PUFA (p = 0.005), and total PUFA contents (p = 0.019) increased. Moreover, the crude protein content in the Longissimus thoracis et lumborum (LTL) increased (p = 0.013), the expression of PPARα and PPARγ was up-regulated, while ELOVL2 was down-regulated in liver and LTL (p < 0.05). Spirulina supplementation increased mRNA expression levels of autophagy-associated genes, including that of Beclin-1, AMPK, and ULK1 (p < 0.05). In conclusion, spirulina supplementation in a HE diet exerted a protective effect on the liver, increased PUFA content, and modulated expression levels of autophagy-related genes in growing lambs.

KEYWORDS:

• Autophagy
• high-energy diet
• polyunsaturated fatty acids
• sheep
• Spirulina

Acknowledgments

This study was supported by the earmarked fund for Jiangsu Agricultural Industry Technology System [grant numbers, JATS [2019] 419], and China Agricultural Research System [grant numbers CARS-38]. The authors also thank all the members of our laboratory for their technical assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Ministry of Agriculture and Rural Affairs of the People’s Republic of China [CARS-38]; Department of Agriculture and rural affairs of Jiangsu Province [JATS [2019] 419].