Combined medetomidine, midazolam, and butorphanol anesthesia in mice has a central stress-relieving effect similar to that of isoflurane anesthesia.

Although the combination of medetomidine, midazolam, and butorphanol (Me/Mi/Bu) is a commonly used surgical anesthetic for small laboratory animals, the effects of Me/Mi/Bu on the central nervous system remain to be confirmed, and some researchers have questioned the use of Me/Mi/Bu as a surgical anesthetic. Herein we employed cFos-immunohistochemistry to assess the stress-relieving effects of Me/Mi/Bu and isoflurane on the murine brain in response to restraint stress. The results demonstrated that the number of cFos-immunopositive cells in the paraventricular nucleus was significantly lower in the mice anesthetized with Me/Mi/Bu or isoflurane compared to those that were not anesthetized. These findings suggest that Me/Mi/Bu exerts an effect on the brain that is similar to that of isoflurane in alleviating the response to surgical procedures.