Abstract： Objective To investigate the expression and relationship of programmed cell death 5(PDCD5) and cell apoptosis in the parotid gland after leading duct ligation in rat and elucidate the role of PDCD5 on the atophy of parotid glad.Methods The Wistar rat model of leading duct ligation was established,and the samples of parotid gland were obtained from different time point (0,1,3,5,7,14,21,30,60,90 and 120 d).The expression of PDCD5 protein was examined by immunohistochemistry.Cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL).Results The distribution of PDCD5 protein in normal parotid was in cytoplasm with uniformity.The expression of PDCD5 protein was significantly increased and reached the peak at 3 d(1.261 ±0.048)following main duct ligation.PDCD5 was located both in cytoplasm and nuclear of parotid gland cells.The PDCD5 density in acinar cells was higher than that in duct cells at day 1 and 3 after duct ligation(P ＜0.01).The apoptotic cells were obviously upregulatcd at 3 d after duct ligation.The apoptosis index observed in acinar cells[(21.750 ± 0.119) ％] was more than that in duct cells [(5.720 ± 0.205) ％].The difference of apoptosis index between acinar cells and duct cells was statistically significant (P ＜ 0.01).The increased PDCD5 levels were positively correlated with cell apoptosis induced by duct ligation.Conclusions The expression of PDCD5 is associated with the atophy of the parotid glad after rat parotid duct ligation,indicating that PDCD5 might play an important role in apoptotic pathways after parotid duct ligation.