Astragaloside Inhibites Cadmium-Induced Apoptpsis And Connexin43 Expression And Function Of Gap Junction Intercellular Communication Decrease In TM3 Cells

Objective:To investigate the toxicity of Cadmium (Cd) on gap junction intercellular communication (GJIC), Connexin43 (Cx43) expression and apoptosis rate of TM3 cells, as well as the protective effect of astragaloside (As).Method:The best protective concentration of As on TM3 cell after Cd treatment was selected by MTT cell viability experiment. The apoptosis rate of TM3 cells was measured by Flow cytometry. The expression of Cx43 was detected by immunohistochemistry. The morphological changes of TM3 cells were observed by electron microscopy. The real-time quantitative PCR and western blot were used to detect the expression levels of Cx43 mRNA and protein respectively. Furthermore, the GJIC was estimated by scrape-loading and dye transfer (SLDT).Results:The viability of TM3 cells both control and As group was not significantly difference after 24h or 48h, but it was significantly decreased in Cd group. However, the viability of TM3 cells in Cd+As group was higher than that in Cd group(P<0.01). Flow cytometry showed there was no significant difference in the apoptosis rate of TM3 cells between the control and As group after 24h, but it has obviously increased with the Cd concentration. The apoptosis rate of Cd+As group was lower than that in Cd group(P<0.01). Immunohistochemistry demonstrated that the average optical density (AOD) of positive product of Cx43 in Cd-treated TM3 cells was obviously decreased (P< 0.01), but the average gray value (AGV) was significantly increased when compared with the control group (P<0.01). Positive product of Cd+As group was higher than that in Cd group (P< 0.01). The ultrastructural changes of TM3 cells were obvious after Cd-treated, but those in Cd+As group were improved when compared with Cd group. There was not significantly difference in the expression levels of mRNA and protein of Cx43, as well as the function of GJIC between control group and As group. However, compared with the control group, the expression levels of Cx43 mRNA and protein, as well as function of GJIC of Cd group and Cd+As group were significantly decreased (P< 0.01), but the Cd+As group expressed higher of Cx43 and enhanced the function of GJIC comparing with the Cd group (P< 0.01).Conclusion:Cd decreases expression of Cx43, damages function of GJIC of TM3 cells, and increases apoptosis rate of TM3 cells; As has protective effect on Cd-induced TM3 cell injury.