Acute toxicity of 3,4-methylenedioxymethamphetamine in the anxious mood of rats

摘要

BACKGROUND: The long-term neurotoxicity of 3,4-methylenedioxymethamphetamine (MDMA) mainly caused by repeated exposure to MDMA or a single big dose of MDMA, which results in degeneration of serotonin terminal of central nervous system, and someone believe that the great release of serotonin transmitter in central nervous system will lead to anxious mood. OBJECTIVE: To observe the changes of anxiety related behaviors in rats after single administration of different doses of MDMA. DESIGN: A randomized control study. SETTING: Laboratory of Psychopharmacology of the Mental Health Center, West China Hospital of Sichuan University. MATERIALS: Thirty male adult Wistar rats, weighing (251.3±18.34) g, were used. MDMA were obtained from the National Institute for the Control of Pharmaceutical and Biological Products, and dissolved in saline. All the doses of the drug were administered in a volume of 1 mg/kg. METHODS: The experiment was carried out in the Laboratory of Psychopharmacology of the Mental Health Center, West China Hospital of Sichuan University in July 2003. ①The rats were randomly divided into control group (n=6) and experimental group (n=24), and then those in the latter were randomly assigned into four subgroups of MDMA 3, 5, 10 and 20 mg/kg groups, with 6 rats in each, which were administrated by single intraperitoneal injection of MDMA 3, 5, 10 and 20 mg/kg respectively, and those in the control group were administrated by single intraperitoneal injection of saline of the same volume. ② The open field test, elevated plus-maze test and social interaction test were performed immediately after administration. For the open field test, the apparatus was situated in a darkened room, illuminated by a single 60 W white light bulb located approximately 60 cm above the center of the open field. Before administration, all the rats were placed into the open field to be familiar with the open field for 5 minutes. They were observed for 45 minutes after administration. The locomotion (number of squares the rat passes), rearing response, time spent in central squares and defecation were observed, 1 minute for each time for a total of 9 times. For the elevated plus-maze test, the maze was situated in a quiet darkened room, illuminated by a single 60 W white light bulb located approximately 50 cm above the center of the maze. Arm entries were only counted when all the four paws had entered either a closed or an open arm within5 minutes, and the time spent in the arms were observed. For the social interaction test, the matched rats were put into the arena head-to-head in opposite direction, and aggressive-type behaviors, avoidance, passive and exploration were observed. ③ The one-way analysis of variance was performed with the SPSS 10.0 software. MAIN OUTCOME MEASURES: The results of open field test, elevated plus-maze test and social interaction test were observed. RESULTS: All the 30 rats were involved in the analysis of results. ① Results of open field test: After single administration of MDMA of 5, 10 and 20 mg/kg, the dose-dependent locomotors (number of squares the rat passes) in the experimental groups were obviously higher than those in the control group [(21.67±17.55), (34.44±19.47), (33.48±23.34), (7.31±6.02) s; P 0.05). ③ Results of the social international test: After acute administration of MDMA, there were no differences between the MDMA subgroups and saline group in the aggressive-type behaviors, avoidance, passive, exploration and total time of interaction (P > 0.05) CONCLUSION: The acute administration of MDMA has no obvious influence on the anxiety-related behaviors of rats.