The effect of selenium and polysaccharide of Atractylodes macrocephala Koidz. (PAMK) on endoplasmic reticulum stress and apoptosis in chicken spleen induced by heat stress

Abstract

Endoplasmic reticulum (ER) stress and oxidative stress are involved in different types of stress induced injuries. The aim of the present study was to evaluate the effect of selenium (Se), polysaccharide of Atractylodes macrocephala Koidz. (PAMK), and the combination of Se and PAMK on oxidative stress, ER stress and apoptosis in chicken spleen under heat stress (HS) condition. Chickens (1 day old, n = 200) were randomly divided into two groups, the control (Con) group and the HS group. Then these chickens were treated with Se (0.3 mg kg⁻¹), PAMK (200 mg kg⁻¹) alone, and the combination of Se (0.3 mg kg⁻¹) and PAMK (200 mg kg⁻¹). The inducible NO synthase (iNOS)–NO activities (including NO content and iNOS activity), ER stress-related genes (GRP78, GRP94, ATF4, ATF6 and IRE) and apoptosis-related genes (caspase3 and Bcl-2) were examined by fluorescence quantitative PCR or western blot analysis. Apoptosis levels were also measured using ultrastructural observations. The results indicated that HS induced higher levels of NO content and the activity of iNOS which demonstrated that oxidative stress occurred in the chicken spleen. The ER stress-related genes (GRP78, GRP94, ATF4, ATF6 and IRE) and the apoptosis related gene caspase3 were increased (P < 0.05), while Bcl-2 was decreased (P < 0.05) induced by heat stress. These responses were alleviated by the treatment of Se, PAMK alone, and the combination of Se and PAMK (P < 0.05 or not). The results showed that under common conditions, Se and PAMK could improve the immune response by reducing the levels of oxidative stress, ER stress and apoptosis to proper levels; however, under HS condition, Se and PAMK could change the abnormal levels of oxidative, ER damage and apoptosis to ameliorate the injury induced by HS. In addition, there existed a synergistic effect on the modulation of these biomarkers in chicken spleen between Se and PAMK. So both Se and PAMK may play important roles in regulating the immune function in chicken.