title: Role of capsaicin in a murine model of labor and delivery.
abstract: BACKGROUND
  The objectives of this study were to develop a murine model of labor and delivery and to use this model to examine whether capsaicin diminishes labor pain and expedites delivery.
  
  
  METHODS
  To develop a murine model of labor pain, the authors identified and compared the incidence of four proposed pain behaviors in 46 mice: (1) No analgesia in labor and the postpartum period, and (2) increasing doses of an analgesic, morphine. The model was then used to examine the impact of topical cervical capsaicin on: (1) labor pain behaviors and (2) labor progress by examining its impact on the time from treatment to delivery of the first pup and on the duration of delivery per pup. The treatment was randomly allocated and the behavioral observation was blinded.
  
  
  RESULTS
  In the absence of analgesia, there was a statistically significant decrease in all four proposed pain behaviors in the postpartum period compared with labor (cumulative 55.0 ± 16.1/h vs. 16.1 ± 8.7/h; P < 0.0001). Additionally, morphine reduced their incidence during labor in a dose-dependent manner (cumulative 55.0 ± 16.1.7/h control, 46.4 ± 15.8 morphine 0.1 mg/kg/h, 34.6 ± 5.6/h, morphine 0.5 mg/kg/h; P = 0.1988, 0.0014). In addition, the incidence of identified pain behaviors was reduced by pericervical capsaicin (cumulative 55.0 ± 16.1.7/h control, 38.9 ± 15.4 capsaicin, P = 0.02).
  
  
  CONCLUSIONS
  In this pilot study, the authors developed a novel mouse model of labor and delivery. Pericervical capsaicin applied days before delivery reduces labor pain behaviors.
authors: Department of Obstetrics and Gynecology, American University of Beirut Medical Center, Beirut, Lebanon. fmirza@aub.edu.lb
authors: Fadi G
authors: FG
authors: Mirza
authors: Ayed A
authors: AA
authors: Fakhoury
authors: Thomas J
authors: TJ
authors: Rowley
authors: Pamela D
authors: PD
authors: Flood
mesh_terms: D016362:Analgesia, Obstetrical / Q000379:methods*; D000701:Analgesics, Opioid / Q000627:therapeutic use; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002211:Capsaicin / Q000494:pharmacology*; D036861:Delivery, Obstetric / Q000379:methods*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D048949:Labor Pain / Q000188:drug therapy / Q000523:psychology; D007743:Labor, Obstetric / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000627:therapeutic use; D011247:Pregnancy; D011256:Pregnancy Outcome; D040901:Proteomics; D015430:Weight Gain / Q000187:drug effects
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine; D002211:Capsaicin