Seventy-two male SD rats weighing 200-250 g were randomly divided into 3 groups( n=24 each group) sham operation group (sham group), focal cerebral I/R group (I/R group), and oxycodone hydrochlorideinjection group (Oxy group). Focal cerebral I/R was induced by middle cerebral artery occlusion for 2 h followed by reperfusion. In the Oxy group, oxycodone hydrochloride 0.5 mg/kg was injected iv at 5 min before ischemia. While the same volume of saline (1 mL) was injected in the sham group and I/R group. The neurological deficit score (NDS) was assessed at 24 h of reperfusion, the rats were then sacrificed, and their brains were immediately removed for determination of brainwater content and the infarct volume, and the histopathological changes were observed after HE staining. The levels of cytokines (TNF-α, IL-1β and IL-10) in the ischemia cortex were quantified by ELISA. MPO activity in the ischemia cortex was assessed. Western blot was used to detect the expression of NF-κB in the ischemia cortex. The data were analyzed using SPSS 20.0 software, multiple-group comparisons were performed using one-way ANOVA, and LSD- t test was used for pairwise comparison between groups. A P<0.05 was considered statistically significant different.
Results:
Compared with the sham group, NDS, brainwater content, relative infarction volume and rate of nerve cellnecrosis were significantly increased in the I/R and Oxy groups (all P<0.05). Levels of TNF-α, IL-1β, IL-10, NF-κB and the activities of MPO were increased in the ischemia cortex (all P<0.05). Compared the Oxy group with the I/R group, NDS, brainwater content, relative infarction volume and rate of nerve cellnecrosis were significantly decreased [(1.7±0.9) vs (2.6±1.1);(79.2±2.4)% vs (84.7±4.2)%; (23.0±5.4)% vs (34.8±6.0)%; (25.2±12.4)% vs (54.8±14.8)%, all P<0.05]. The levels of TNF-α, IL-1β, relative expression of NF-κB, and the activities of MPO were significantly decreased in the ischemia cortex [(4.4±1.2) pg/mg vs (6.5±1.2) pg/mg; (5.4±0.7) pg/mg vs (7.8±0.8) pg/mg; (0.83±0.11) vs (1.23±0.33); (0.27±0.09) U/g vs (0.36±0.14) U/g, all P<0.05] , while the concentration of IL-10 was significantly increased [(20.9±4.5) pg/mg vs (9.2±1.6) pg/mg, t=6.036, P=0.000 1].