title: The differential effect of cyclosporine on hypnotic response and pain reaction in mice.
abstract: BACKGROUND
  The calcineurin inhibitor, cyclosporine, is widely used for preventing allograft rejection in organ transplantation. Systemically administered cyclosporine is prevented from entering into the brain by the action of P-glycoprotein, encoded by the multidrug resistant 1 (mdr1) gene. However, in many transplant recipients, cyclosporine administration causes postoperative neuropsychological side effects, such as confusion, depression, and anxiety. Recently, calcineurin-inhibitor-induced pain syndrome, characterized by severe pain in the lower limbs, has also been recognized in both organ and stem-cell transplantations.
  
  
  METHODS
  In the present study, we developed behavioral models in wild-type and mdr1a knockout mice to reveal whether peripheral or central cyclosporine alters pain reactions and hypnotic sensitivities. Cyclosporine's central actions can be better evaluated in mdr1a knockout mice that lack P-glycoprotein. After intraperitoneal administration of cyclosporine, we examined tail-flick latency in the tail immersion test, or duration of loss of righting reflex in response to pentobarbital and ketamine.
  
  
  RESULTS
  In wild-type mice, the highest dose of cyclosporine significantly prolonged the duration of loss of righting reflex in response to ketamine, but not to pentobarbital. On the other hand, the lower doses of cyclosporine significantly increased both pentobarbital- and ketamine-induced sleep durations in mdr1a knockout mice. Tail-flick latencies in the tail immersion test were significantly shortened in both wild-type and knockout mice by the administration of cyclosporine.
  
  
  CONCLUSIONS
  Our results suggest that centrally accumulated cyclosporine enhances the hypnotic response to pentobarbital and ketamine, but peripheral cyclosporine induces hyperalgesia.
authors.affiliation: Department of Anesthesiology, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan. aneyuki@jichi.ac.jp
authors.forename: Yuki
authors.initials: Y
authors.lastname: Sato
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Onaka
authors.forename: Eiji
authors.initials: E
authors.lastname: Kobayashi
authors.forename: Norimasa
authors.initials: N
authors.lastname: Seo
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology; D000818:Animals; D016572:Cyclosporine / Q000494:pharmacology* / Q000627:therapeutic use* / Q000633:toxicity; D004357:Drug Synergism; D006993:Hypnotics and Sedatives / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010146:Pain / Q000139:chemically induced* / Q000517:prevention & control*; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D018528:ATP-Binding Cassette Transporters; D006993:Hypnotics and Sedatives; D016572:Cyclosporine; C095122:multidrug resistance protein 3