Background: Hydrogen sulfide (H2S) can protect against hepatic ischemia-reperfusion injury (HIR). However, it is unknown whether it can protect against HIR in insulin resistance. This study investigated the protective effects of silymarin against HIR in a rat model of insulin resistance and the possible involvement of endogenous H2S.
Materials and methods: Insulin resistance was first established using 10% fructose in drinking water for 10 weeks. HIR was conducted in fructose-fed rats treated with saline or silymarin (100 mg/kg), 15 min before HIR (30 min ischemia, followed by 1 h reperfusion). Insulin resistance and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), total nitrites (NO2(-)), and H2S were measured. Hepatic malondialdehyde (MDA), reduced glutathione (GSH), hydroxyproline, H2S synthesizing activity, and mRNA expression of cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE) were determined. Additionally, histopathological examination involved H&E, Sirius red, and caspase-3 immunostaining.
Results: Fructose-induced insulin resistance increased serum ALT, TNF-α, H2S and H2S synthesizing activity, and hepatic MDA, hydroxyproline, and CSE mRNA and decreased NO2(-) and GSH. These changes exacerbated the HIR injury in which endogenous H2S production was auxiliary increased. Silymarin preconditioning decreased ALT, AST, MDA, NO2(-), TNF-α, and TNF-α/IL-10 ratio, increased GSH, IL-10, improved hepatic architecture, and lowered caspase-3 immunostaining. Serum H2S, its hepatic synthesizing activity, and CSE and CBS mRNA expressions were all suppressed by silymarin pretreatment.
Conclusions: The increases in endogenous H2S exacerbate HIR injury, whereas silymarin preconditioning protected against HIR in insulin resistant rats via powerful antioxidant, anti-inflammatory, and antiapoptotic effects along with suppressing H2S production.
Keywords: CSE; Hepatic ischemia-reperfusion; Hydrogen sulphide; Insulin resistance; Silymarin.
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