Effect of different doses of propofol on cognitive function after chronic cerebral ischemia-induced injury in aged rats

Objective To investigate the effects of different doses of propofol on cognitive function after chronic cerebral ischemia-induced injury in aged rats. Methods Eighty male SD rats, aged 18 months, weighing 400-500 g, were randomly divided into 4 groups ( n = 20 each): shame operation group (group S), chronic cerebral ischemia group (group I), two propofol groups (groups P1 and P2 ). The chronic cerebral ischemia was induced by permanent occlusion of bilateral common carotid arteries. On 1 day after operation, intraperitoneal normal saline 2.5 ml was injected twice a day for7 consecutive days in groups S and I, and intraperitoneal propofol 10 and 50 mg/kg in 2.5 ml of normal saline were injected twice a day for 7 consecutive days in groups P1 and P2 respectively. On 3rd and 33rd days after the last injection (T1.2), 10 rats in each group underwent Morris water maze test to assess the cognitive function. After the test was completed, the rats were sacrificed and the hippocampi were removed and sliced (450-500 μm thick). Schaffer lateral branch in CA1 region was stimulated to induce long-term potentiation (LTP). Results Compared with group S, the escape latency was significantly prolonged, the number of animals' swimming across the platform, the ratio of the swimming time spent in the forth quadrant to the total swimming time, and the success rate of LTP induction were significantly decreased at T1 and T2 in groups I, P1 and P2 (P ＜ 0.05). Compared with group I, the escape latency was significantly prolonged, the number of animals' swimming across the platform, the ratio of the swimming time spent in the forth quadrant to the total swimming time, and the success rate of LTP induction were significantly decreased at T1 in groups P1 and P2, and at T2 in group P2 ( P ＜ 0.05). Conclusion Propofol aggravates the damage to cognitive function while it attenuates the chronic cerebral ischemia-induced injury in aged rats, especially the high dose. Key words: Propofol;  Cerebral ischemia;  Cognition disorders;  Aged