Effect of hypoxemia factor on hippocampal long-term potentiation in newborn rats undergoing propofol anesthesia

Abstract

Objective To evaluate the effect of hypoxemia factor on hippocampal long-term potentiation(LTP)in newborn rats undergoing propofol anesthesia. Methods Forty-two pathogen-free healthy Sprague-Dawley rats(21 males, 21 females), aged 7 days, weighing 14-18 g, were divided into 3 groups(n=14 each)using a random number table: propofol plus air group(group PA), propofol plus pure oxygen group(group PO)and intralipid plus pure oxygen group(group IO). Propofol 50 mg/kg was injected intraperitoneally once a day for 7 consecutive days in PA and PO groups. Intralipid 5.0 ml/kg was injected intraperitoneally once a day for 7 consecutive days in IO group. The rats were exposed to air or pure oxygen for 6 h after the end of each injection. The arterial oxygen saturation and respiratory rate were determined after administration. The rats were returned to the cage after recovery of righting reflex. Six rats in each group were selected for preparation of hippocampal slices at 24 h after the last injection on 7th day, and the electric stimulation-induced field excitatory post synaptic potential(fEPSP)and success rate of LTP induction were recorded. Morris water maze test was performed in the other rats at 2 weeks after administration to assess the cognitive function. Results Compared with group IO, the respiratory rate, amplitude of fEPSP and success rate of LTP induction were significantly decreased, and the escape latency was prolonged in group PO(P<0.05). Compared with group PO, the arterial oxygen saturation, amplitude of fEPSP and success rate of LTP induction were significantly decreased, the escape latency was prolonged, and the number of crossing the original platform was decreased in group PA(P<0.05). Conclusion Hypoxemia factor increases propofol-induced neurotoxicity in the central nervous system of newborn rats. Key words: Oxygen; Propofol; Hippocampus; Long-term potentiation; Cognition