Objective: This experiment was designed to explore the possible mechanism of the brain injury caused by ketamine.
Methods: Thirty-five adult SD rats randomly divided into a control group and 6 experiment groups were given intrapertioneal injections of normal saline, 20.0, 40.0, 60.0, 80.0, 100.0, 120.0 mg/kg of ketamine respectively. Another 35 SD rats at 0-10, 11-20, 21-30, 31-45, 46-60, 61-90, 91-120 days old were allocated to 7 corresponding age groups and were given intrapertioneal injection of ketamine 80.0 mg/kg. Immunocytochemistry was used to detect HSP70 expression in rat hippocampus, and MIAS-2000 photography analytic software was chosen to analyze HSP70 expression.
Results: Ketamine induced HSP70 expression in adult rat hippocampus. Below the dose of 80.0 mg/kg, ketamine induced higher level of HSP70 expression as the dose increased; however, above the dose of 80.0 mg/kg, ketamine induced lower level of HSP70 expression as the dose increased. Ketamine did not induce HSP70 expression in the rats under 20 days of age; it induced the same HSP70 expression in rats of 90 days and over; and analyses of the rats of 20-90 days revealed that the elder the rat is, the higher the HSP70 expression will be.
Conclusion: Ketamine injures the neurons of rat hippocampus and induces the expression of HSP70, and the higher the dose is given, the more serious the injury is seen; and ketamine induces higher level of HSP70 expression in adult rats than in infant rats.