Abstract:Objective To compare the effects of oxycodone hydrochloride and morphine on postoperative analgesia and immune cell function in rats with liver cancer.Methods The liver cancer model was successfully established by intraperitoneal injection of 0.19% diethylnitrosamine (DENA) at a dose of 50 mg·kg-1 and twice a week. 18 rats were randomly divided into negative control group (NC), oxycodone hydrochloride group (OH) and morphine group (MO). After abdominal exploration, the rats were implanted with Alezt micro-pump containing normal saline, oxycodone hydrochloride and morphine for analgesia, respectively. On the 1st, 3rd and 7th day after operation, the sucrose preference test and the open field test were performed. After 7 days, blood samples were collected from the heart. The proportion of NK cells and Treg cells in peripheral blood were detected by flow cytometry.Results Compared with NC group, the sucrose preference rate was significantly increased in OH group and MO group (P<0.05). Besides, the movement distance (P<0.05) and the time spent in central area (P<0.05) in OH group and MO group were significantly increased as compared with NC group. However, there were no significant differences between OH group and MO group in sucrose preference rate, movement distance and time spent in central area (P>0.05). Moreover, the proportion of Treg cells in OH group and MO group was significantly lower than that in the NC group (P<0.05), and OH group had a significantly lower proportion of Treg cells than MO group (P<0.05). The proportion of NK cells in OH group was significantly higher than that in NC group (P<0.05). On the contrary, the proportion of NK cells in MO group was significantly lower than that in NC group (P<0.05).Conclusion Oxycodone hydrochloride and morphine showed similar effects in postoperative analgesia. However, oxycodone hydrochloride could significantly improve the anti-tumor immune system by decreasing the proportion of Treg cells and increasing the proportion of NK cells. Oxycodone hydrochloride might be a more ideal analgesic drug than morphine during perioperative period.