Emulsified isoflurane alleviates rat islet beta cell RIN-m5F apoptosis induced by glucose via inhibiting endoplasmic reticulum stress

Abstract

Background Diabetes mellitus (DM) is a critical disease that considered a detriment to the health of people all over the world. Endoplasmic reticulum stress (ERS) is the response cause by endoplasmic reticulum misfolded and unfolded protein aggregation, which induces cell apoptosis. Our previous work showed that EIso could alleviate ERS in lung reperfusion injury. This study aimed to elucidate whether Emulsified isoflurane (EIso) could alleviate apoptosis induced by glucose in rat islet beta cell RIN-m5F via inhibiting ERS. Methods RIN-m5F cells were divided into five groups: Control group, cultured in 0.1M glucose for 24h (0.1G group), culture in 0.3M glucose for 24h (0.3G group), culture in 0.3M glucose with 57uM EIso for 24h (0.3G+57E group), and culture in 0.3M glucose with 76uM EIso for 24h (0.3G+76E group). First, the cellular proliferation was measured by MTT assay, and the level of insulin secretion was measured with ELISA kit. Second, the expression of Bax and Bcl-2 were detected by Western blotting. The level of caspase-3 activity was assessed by colorimetric method. Finally, the CHOP and GRP78 expression were detected by Western blotting. The level of ATF6, Xbp1 and eIF2α mRNA were assessed by qRT-PCR after treated with EIso for 24h. Results High glucose induced significant loss of RIN-m5F cell viability, and stimulated the secretion of insulin; EIso improved the survival and protected the function of RIN-m5F. Compare to 0.3G group, treatment with EIso inhibited the activity of caspase-3, decreased the expression of Bax and increased the expression of Bcl-2. The expression of CHOP and GRP78 were inhibited by EIso at 24 h after treatment, and decrement of CHOP and GRP78 expression were correlated with EIso concentration. The level of ATF6, Xbp1 and eIF2α mRNA of RIN-m5F were enhanced culture with high glucose, but only eIF2α mRNA was decreased by EIso treatment. Conclusion High glucose induces rat islet beta cell RIN-m5F apoptosis and aggravates the function of beta cells. EIso protects beta cells from glucose-induced apoptosis, and anti-apoptosis is mediated, at least in part, by inhibiting ERS.