Endogenous Hydrogen Sulfide Promotes Apoptosis via Mitochondrial Pathways in the Livers of Broilers with Selenium Deficiency Exudative Diathesis Disease

Abstract

Hydrogen sulfide (H₂S), an endogenous gasotransmitter, plays an important role in apoptosis. Exudative diathesis (ED) disease is associated with dietary selenium (Se) deficiency in broilers. The liver is one of the target organs of Se deficiency; however, little is known about the effect of H₂S on apoptosis via mitochondrial pathways in the livers of broilers with ED disease. In the present study, we aimed to investigate the correlation between endogenous H₂S and mitochondrial-mediated apoptosis in the livers of broilers with ED disease, as induced by Se deficiency. One hundred twenty healthy, 1-day-old broilers were randomly assigned to one of two groups (60 each) based on diet: Basal diet (control group, 0.2 mg/kg Se) or a low-Se diet (−Se group, 0.033 mg/kg Se). At day 20, 15 broilers of a similar weight were sacrificed from the control group, while the same number of broilers were euthanatized from the −Se group when displaying typical symptoms of ED between days 18 and 25. The livers were collected, and apoptosis was measured using a TUNEL assay. Additionally, H₂S concentration, the expression of H₂S synthases of cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST), as well as mitochondrial apoptosis-related genes of Bcl-2, Bax, Bak, Cyt-C, Caspase-9, Caspase-3, and p53, were examined in livers. The results indicated that Se deficiency could induce apoptosis in the livers of broilers. Swelling, fractures, and vacuolization were visible in the mitochondrial cristae in the livers of the −Se group. The expression of H₂S synthase-related genes and H₂S concentration was significantly enhanced (P < 0.05) in the livers of the −Se group compared to controls. Moreover, a low-Se diet downregulated (P < 0.05) the level of Bcl-2 and upregulated (P < 0.05) the levels of Bax, Bak, Cyt-C, Caspase-9, Caspase-3, and p53. These results suggest that an H₂S increase in the livers of ED broilers, which was induced by Se deficiency, is related to apoptosis mediated by mitochondrial pathways.

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