Lipid metabolism disorders, often exacerbated by high-fat diets (HFD), are a significant concern in aquaculture, impacting fish health and the sustainability of the industry. Researchers at Jimei University in Xiamen, China, recently conducted a study evaluating the regulatory effects of Astragalus membranaceus polysaccharides (AMP) on lipid metabolism disorders in spotted sea bass (Lateolabrax maculatus) .
Study Overview
The study involved 375 spotted sea bass divided into five groups, each housed in separate tanks. The fish were fed different diets over 56 days: a normal diet containing 10% lipids, a high-fat diet containing 15% lipids, and three experimental diets combining the HFD with varying levels of AMP (0.06%, 0.08%, 0.10%). The goal was to determine whether AMP could mitigate the negative effects of the HFD on lipid metabolism.
Key Findings
The high-fat diet induced significant lipid metabolism disorders in the fish, evidenced by elevated serum lipids, increased malonaldehyde levels (a marker of oxidative stress), and severe liver damage. However, the addition of AMP to the HFD showed promising results in alleviating these disorders:
Reduction in Liver Lesions and Oxidative Stress: AMP reduced the severity of liver lesions and malonaldehyde levels, indicating less oxidative stress and liver damage.
Improved Lipid Profile: AMP lowered low-density lipoprotein cholesterol (LDL-C) levels.
Gene Expression Modulation: AMP modulated the expression of key genes involved in lipid metabolism, such as down-regulating fatty acid synthase (FAS) and up-regulating peroxisome proliferator-activated receptor alpha (PPAR-α).
Significance of the Findings
These results suggest that AMP could be a valuable dietary supplement in aquaculture to counteract the adverse effects of high-fat diets, thus improving fish health and potentially enhancing the sustainability of aquaculture practices. This aligns with previous research highlighting the importance of managing lipid metabolism in aquaculture species. For instance, a study on Acanthopagrus schlegelii demonstrated that fenofibrate, another lipid-regulating agent, reduced fat deposition and inflammation caused by HFD by up-regulating PPAR-α and silent information regulator 1 (SIRT1) . The current study supports these findings by showing that AMP similarly influences lipid metabolism through the regulation of PPAR-α.
Oxidative Stress and Liver Health
The study’s focus on oxidative stress and liver health is consistent with earlier findings on the impact of high-fat diets on aquatic species. Research on Macrobrachium rosenbergii indicated that high-fat diets induce oxidative stress and liver damage, which can be mitigated by dietary antioxidants like vitamin E . The current study expands on this by demonstrating that AMP, a natural polysaccharide, can also reduce oxidative stress and liver damage in fish.
Economic and Environmental Benefits
The potential economic and environmental benefits of using AMP in aquaculture are substantial. Non-alcoholic fatty liver disease (NAFLD) and related metabolic disorders are a growing concern in both humans and animals, representing a significant economic burden due to the lack of inexpensive and reliable diagnostic methods . By improving fish health and reducing the need for costly medical interventions, AMP could contribute to more sustainable and cost-effective aquaculture practices.
Conclusion
The study by Jimei University highlights the potential of Astragalus membranaceus polysaccharides as a dietary supplement to mitigate lipid metabolism disorders induced by high-fat diets in aquaculture. By reducing oxidative stress, liver damage, and modulating key lipid metabolism genes, AMP offers a promising solution to enhance fish health and support the sustainability of the aquaculture industry. These findings pave the way for further research into the application of natural supplements like AMP in aquaculture, potentially leading to healthier fish and more resilient farming practices.
Future Implications
The implications of this study extend beyond aquaculture. Understanding how natural extracts like AMP can improve lipid metabolism and reduce oxidative stress could inform dietary interventions in other species, including humans. As aquaculture continues to grow as a vital source of global protein, innovations that enhance the health and sustainability of farmed fish will become increasingly important. This study sets a precedent for exploring the benefits of natural compounds in improving the resilience and productivity of aquaculture systems.