title: Rubus occidentalis alleviates hyperalgesia induced by repeated intramuscular injection of acidic saline in rats.
abstract: BACKGROUND
  The purpose of this study was to evaluate the antinociceptive effect of black raspberry (Rubus occidentalis) fruit extract (ROE) in a rat model of chronic muscle pain and examine the mechanisms involved.
  
  
  METHODS
  Adult male Sprague-Dawley rats were used, and chronic muscle pain was induced by two injections of acidic saline into one gastrocnemius muscle. For the first experiment, 50 rats were randomly assigned to five groups. After the development of hyperalgesia, rats were injected intraperitoneally with 0.9 % saline or ROE (10, 30, 100, or 300 mg/kg). For the second experiment, 70 rats were randomly assigned to seven groups. Rats were injected intraperitoneally with saline, yohimbine, dexmedetomidine, prazosin, atropine, mecamylamine, or naloxone after the development of hyperalgesia. Ten minutes later, ROE (300 mg/kg) was administered intraperitoneally. For both experiments, the mechanical withdrawal threshold (MWT) was evaluated with von Frey filaments before the first acidic saline injection, 24 h after the second injection, and at 15, 30, 45, 60, 80, 100, and 120 min, 24 and 48 h after the drug administration.
  
  
  RESULTS
  Compared with the control group, the MWT significantly increased up to 45 min after injection of ROE 100 mg/kg and up to 60 min after injection of ROE 300 mg/kg, respectively. Injection of ROE together with yohimbine or mecamylamine significantly decreased the MWT compared with the effect of ROE alone, while ROE together with dexmedetomidine significantly increased the MWT.
  
  
  CONCLUSIONS
  ROE showed antinociceptive activity against induced chronic muscle pain, which may be mediated by α2-adrenergic and nicotinic cholinergic receptors.
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06911, Republic of Korea.
authors.forename: Geun Joo
authors.initials: GJ
authors.lastname: Choi
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06911, Republic of Korea. roman00@naver.com.
authors.forename: Hyun
authors.initials: H
authors.lastname: Kang
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Won Joong
authors.initials: WJ
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06911, Republic of Korea.
authors.forename: Chong Wha
authors.initials: CW
authors.lastname: Baek
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06911, Republic of Korea.
authors.forename: Yong Hun
authors.initials: YH
authors.lastname: Jung
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06911, Republic of Korea.
authors.forename: Young Cheol
authors.initials: YC
authors.lastname: Woo
authors.affiliation: Gochang Berry & Bio Food Research Institute, Gochang-gun, Jeollabuk-do, Korea.
authors.forename: Ji Wung
authors.initials: JW
authors.lastname: Kwon
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D059350:Chronic Pain / Q000188:drug therapy*; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000188:drug therapy*; D007273:Injections, Intramuscular; D008297:Male; D010936:Plant Extracts / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D065856:Rubus / Q000737:chemistry*
chemical_list: D010936:Plant Extracts
keywords: Antinociception; Black raspberry; Chronic pain; Rubus occidentalis