Salidroside Alleviates Lipid Metabolism Disorder and Inflammatory Response, and Promotes Hepatocyte Proliferation in Fatty Liver-Hemorrhagic Syndrome of Laying Hens

Abstract

Background: Fatty liver hemorrhagic syndrome (FLHS) is a chronic hepatic disease which occurs when there is a disorder in lipid metabolism. This disease is often observed in caged laying hens and characterized by a decrease in egg production and dramatic increase of mortality. Salidroside (SDS) is an herbal drug which has shown numerous pharmacological activities, such as protective effects on mitochondrial function, attenuates cell apoptosis and inflammation, and promotes strong antioxidant defense system. We aimed to determine the therapeutic effects of SDS on FLHS in laying hens and investigate the underlying mechanisms through which SDS operates these functions. We constructed oleic acid (OA)-induced fatty liver model in vitro and high-fat diet-induced FLHS of laying hens in vivo.Results: Results indicated that SDS inhibited OA-induced lipid accumulation in chicken primary hepatocytes, increased hepatocyte activity, elevated the mRNA expression of proliferation related genes PCNA, CDK2, and cyclinD1 and increased the protein levels of PCNA and CDK2, as well as decreased the cleavage levels of Caspase-9, Caspase-8, and Caspase-3 and apoptosis in hepatocytes. Moreover, SDS promoted the phosphorylation levels of PDK1, AKT, and Gsk3-β, while inhabited the PI3K inhibitor. Additionally, we found that high-fat diet-induced FLHS of laying hens in vivo resulted in heavier body weight, liver weight, and abdominal fat weight, and severer steatosis in histology, compared with the control group (Con). However, SDS maintained lighter body weight, liver weight, and abdominal fat weight and alleviate hepatic steatosis in Model+SDS group. In addition, high-fat diet-induced FLHS (Model) of laying hens had higher total cholesterol (TC), triglyceride (TG), alanine transaminase (ALT), and aspartate aminotransferase (AST) levels in serum than Con group, while SDS maintained low TC, TG, ALT, and AST levels and high Superoxide dismutase (SOD) activity in Model+SDS group. Moreover, SDS decreased the mRNA expression abundances of PPARγ, SCD, and FAS in liver, whereas increased those of PPARα and MTTP, and decreased the mRNA expression of TNF-α, IL-1β, IL-6, and IL-8 in Model+SDS group.Conclusions: Generally, SDS attenuated OA-induced ROS generation, inhibited lipid accumulation and hepatocyte apoptosis, and promoted hepatocyte proliferation by targeting the pathway PI3K/AKT/Gsk3-β in OA-induced fatty liver model in vitro, and alleviated high-fat diet-induced hepatic steatosis, oxidative stress, and inflammatory response in laying hens in vivo.