Exploratory analyses of postanesthetic effects of desflurane using behavioral test battery of mice.

Halogenated ethers, such as desflurane, sevoflurane, and isoflurane, are known to exert an array of effects besides sedation. However, the postanesthetic effects of desflurane remain undiscovered as no study has explored these effects systematically. Phenotypic screening using behavioral test batteries is a powerful method to identify such effects. In the present study, we behaviorally phenotyped desflurane-treated mice to investigate postanesthetic effects. We applied comprehensive behavioral test batteries measuring sensorimotor functions, anxiety, depression, sociability, attention, and learning abilities, starting 7 days after anesthesia performed with 8.0% desflurane for 6 h. Although our previous study revealed postanesthetic effects of isoflurane in adult mice, in the current study, desflurane-treated mice exhibited no such effects in any behavioral test. To further examine whether desflurane affect behavior in more early time point, we built up a new additional test battery, which carried out 1 day or 3 days after exposure to desflurane. Mice treated with desflurane 1 day before testing showed more slips than other two groups in the first trial, suggesting mild acute side effects of desflurane on motor coordination. These results suggest the safety of desflurane in clinical settings and imply that postanesthetic effects are unique to each halogenated ether.

Comprehensive behavioral study and proteomic analyses of CRMP2-deficient mice.

Collapsin response mediator protein 2 (CRMP2) plays a key role in axon guidance, dendritic morphogenesis and cell polarization. CRMP2 is implicated in various neurological and psychiatric disorders. However, in vivo functions of CRMP2 remain unknown. We generated CRMP2 gene-deficient (crmp2-/- ) mice and examined their behavioral phenotypes. During 24-h home cage monitoring, the activity level during the dark phase of crmp2-/- mice was significantly higher than that of wild-type (WT) mice. Moreover, the time during the open arm of an elevated plus maze was longer for crmp2-/- mice than for WT mice. The duration of social interaction was shorter for crmp2-/- mice than for WT mice. Crmp2-/- mice also showed mild impaired contextual learning. We then examined the methamphetamine-induced behavioral change of crmp2-/- mice. Crmp2-/- mice showed increased methamphetamine-induced ambulatory activity and serotonin release. Crmp2-/- mice also showed altered expression of proteins involved in GABAergic synapse, glutamatergic synapse and neurotrophin signaling pathways. In addition, SNAP25, RAB18, FABP5, ARF5 and LDHA, which are related genes to schizophrenia and methamphetamine sensitization, are also decreased in crmp2-/- mice. Our study implies that dysregulation of CRMP2 may be involved in pathophysiology of neuropsychiatric disorders.

Postanesthetic effects of isoflurane on behavioral phenotypes of adult male C57BL/6J mice.

Isoflurane was previously the major clinical anesthetic agent but is now mainly used for veterinary anesthesia. Studies have reported widespread sites of action of isoflurane, suggesting a wide array of side effects besides sedation. In the present study, we phenotyped isoflurane-treated mice to investigate the postanesthetic behavioral effects of isoflurane. We applied comprehensive behavioral test batteries comprising sensory test battery, motor test battery, anxiety test battery, depression test battery, sociability test battery, attention test battery, and learning test battery, which were started 7 days after anesthesia with 1.8% isoflurane. In addition to the control group, we included a yoked control group that was exposed to the same stress of handling as the isoflurane-treated animals before being anesthetized. Our comprehensive behavioral test batteries revealed impaired latent inhibition in the isoflurane-treated group, but the concentration of residual isoflurane in the brain was presumably negligible. The yoked control group and isoflurane-treated group exhibited higher anxiety in the elevated plus-maze test and impaired learning function in the cued fear conditioning test. No influences were observed in sensory functions, motor functions, antidepressant behaviors, and social behaviors. A number of papers have reported an effect of isoflurane on animal behaviors, but no systematic investigation has been performed. To the best of our knowledge, this study is the first to systematically investigate the general health, neurological reflexes, sensory functions, motor functions, and higher behavioral functions of mice exposed to isoflurane as adults. Our results suggest that the postanesthetic effect of isoflurane causes attention deficit in mice. Therefore, isoflurane must be used with great care in the clinical setting and veterinary anesthesia.