Abstract: Objective To investigate the protective effect of astragaloside(As) against cadmium(Cd) toxicity on the expression of connexin43 (Cx43) and the changes of connexin43-mediated gap junctional intercellular communication(GJIC) in TM3 cells . Method The TM3 cells were cultured, and four groups were designed : control, As(20㎎/L), Cd(10μmol/L) and Cd +As. The expression of connexin 43(Cx43) was detected by immunohistochemistry. The real-time quantitative PCR was used to detect the expression levels of Cx43 mRNA, and the Western blot was used to detect the expression levels of Cx43 protein. Furthermore, the GJIC was estimated by scrape-loading and dye transfer (SLDT). Results Compared with the control group, the average optical density ( AOD) of the positive product of Cx43 in Cd group was obviously decreased ( P＜0.01) , the expression levels of Cx43 mRNA and protein in Cd group was decreased ( P＜0.01), and the GJIC of TM3 cells was also decreased（P＜0.01）. On further analysis, the positive productives of Cx43, the expression levels of Cx43 mRNA and protein and GJIC of TM3 cells in Cd +As group were significantly higher than those in Cd group, though lower than of the control group. Conclusions As can inhibit the down-regulation of the expression levels of Cx43 and damage of GJIC of TM3 cells induced by Cd, which results in protective effects on TM3 cells function.

Key words: Key words Astragaloside , cadmium, TM3 cell, connexin43, gap junction intercellular communication