Effects of anesthetics on expression of dopamine and acetylcholine receptors in the rat brain in vivo

Dopamine D2 and acetylcholine M1 receptors might be related to post-operative cognitive dysfunction. The aim of the present study is to investigate whether several anesthetics which are used for general anesthesia and/or sedation, affect expression of dopamine D2 and acetylcholine M1 receptors in the rat brain. Thirty-six male rats aged 5–9 weeks old were divided into six groups (n = 6 in each group); five groups for anesthetics and one for control. The five groups were anesthetized with either dexmedetomidine 0.4 µg/kg/min, propofol 50 mg/kg/h, midazolam 25 mg/kg/h, sevoflurane 3.3%, or nitrous oxide 75% for 4 h. Then, the rats were decapitated, and the cerebral cortex, hippocampus, corpus striatum, brain stem, and cerebellum were collected from all rats. Then, real-time polymerase chain reaction was performed to examine the expression of Drd2 (cord dopamine D2 receptor) and Chrm1 (cord acetylcholine M1 receptor). There were no significant differences among the groups regarding Drd2 and Chrm1 mRNA expression of each region of the brain. Postsynaptic changes of dopamine D2 and acetylcholine M1 receptors due to administration of dexmedetomidine, propofol, midazolam, sevoflurane, and nitrous oxide are unlikely to occur at the doses of each anesthetic used in the present study.