Alleviation of Carbon-Tetrachloride-Induced Liver Injury and Fibrosis by Betaine Supplementation in Chickens

Figure 6

Antioxidant capacity of betaine and its role in CCl₄-induced liver fibrosis. Under CCl₄ stimulation, cytochrome P450 2E1 (CYP2E1) transforms CCl₄ to . is a free radical, which induces lipid peroxidation (LPO) and causes oxidative stress. The cellular elevated oxidative stress induces secretion of inflammatory cytokines, including interleukin-6 (IL-6). Inflammation cytokines upregulate glutathione S-transferase (GST) and transforming growth factor-beta 1 (TGF-β1). GST as an antioxidant provides the self-protective mechanism to eliminate free radicals and LPO. Hepatocyte secreted TGF-β1 activates hepatic stellate cells (Ac-HSCs) through binding with TGF-β receptors. Further, the activated HSCs process fibrogenesis and synthesize collagens, finally leading to liver fibrosis. Moreover, Ac-HSCs generate and secret the dipeptidyl-peptidase 4 (DPP4), which leads us to detect the increasing plasma DPP4 concentrations in liver fibrosis chicken. Betaine provides the antioxidant capacity to alleviate the oxidative stress, which suppresses the effects of CCl₄ in the very beginning.