[Influences of repeated propofol anesthesia on hippocampal apoptosis and long-term learning and memory abilities of neonatal rats].

OBJECTIVE: To investigate the influences of repeated propofol anesthesia on the hippocampal apoptosis and the long-term learning and memory abilities of neonatal rats.

METHODS: In the study, 45 male Sprague-Dawley rats, aged 7 days, were randomly divided into 3 group (n=15 each): control group (C group) that received intralipid 7.5 mL/kg intraperitioneal (IP) once a day×7 days; group propofol 1 (P1) that received propofol 75 mg/kg IP once a day×7 days; group propofol 2 (P2) that received intralipid 7.5 mL/kg IP once a day×6 days+propofol 75 mg/kg IP on the 7th day. In each group, 5 animals were chosen and arterial blood samples were obtained immediately after the animals were fully awake for blood gas analysis. Learning and memory abilities were assessed using Morris water maze when the other rats were 4 weeks old. The animals were decapitated after the tests. The hippocampi were isolated for detection of neuron-specific nucleoprotein (NeuN) expression by immunohistochemistry method and the expression of caspase-3 using the Western blot.

RESULTS: There was no significant difference in the indexes of blood gas analysis among the 3 groups. Morris water maze test: compared with group C, the escape latency and the length of searching on the 5th day were significantly prolonged, and the searching time in target quadrant and platform crossing on the 6th day were significantly decreased in group P1 (P<0.05) but not in group P2. Compared with group C, NeuN-positive neurons were decreased, and the expression of caspase-3 was increased in the rats of group P1 (P<0.05) but not in group P2.

CONCLUSION: Repeated propofol anesthesia may destroy long-term learning and memory abilities by inducing apoptosis of hippocampal neurons in neonatal rats, while single dose of propofol has no obvious effect on the hippocampal apoptosis and long-term learning and memory of neonatal rats.