RESUMO
BACKGROUND: Naloxone has a significant arousal effect on many types of comas. It is usually believed that this is because its inhibition on endogenous opioid peptides. But depth of coma is not necessarily positively correlated to endorphin (EP).OBJECTIVE: Based on existing findings on direct stimulating effect of naloxone on cerebral cortex, further studies need to be done to explore whether it is dose-dependent or not.DESIGN: Single-factor design based on cells.SETTING: Neurology department in a university hospital and the neurology department in a hospital of a military medical university of Chinese PLA.MATERIALS: This study was completed in the Laboratory Center of Tongji Medical College, Huazhong University of Science and Technology. Thirty healthy new born Wistar rats, regardless of their gender, aging 8 - 12 days and weighing 150 -250 g, were selected.METHODS: The experiment was performed at room temperature. The perfusion slot were placed on the microscope stage, and cells with smooth surfaces, triangle or pyramidal shapes, strong refraction and more than one neurites were selected for patch clamp experiment. Patch clamp whole-cell recording technique was used to measure the pyramidal cells of the frontal lobe immediately after separated from the Wistar rats, and to investigate the fluctuations of their membrane potential of cerebral cortex neurons and the frequencies of their spontaneous electric activities after administration of naloxone at different doses.MAIN OUTCOME MEASURES: The neural excitatory reaction rate, depolarization amplitude and increasing rate of spontaneous electric activities after administration of different doses of naloxone were selected as main outcome measurements.RESULTS: The excitatory reaction rates of cerebral cortex neurons immediately after separation to doses of naloxone(100, 50, 10, 1, 0. 1 μmol/L)were 83%, 67%, 86%, 71% and 33%; while the depolarization amplitude of them were 9. 8, 9.6, 8.4, 5.2 and 1. 3 mV respectively; and the corresponding spontaneous electric activity were increased by 587% , 375% ,291%, 125% and 69%.CONCLUSION: Naloxone can induce excitatory reactions in cerebral cortex neurons directly, and the reactions have proved to be dose-dependent.