title: Antinociceptive Effects of Ginsenoside Rg3 in a Rat Model of Incisional Pain.
abstract: BACKGROUND
  Ginsenoside Rg3 is an extract of total ginseng saponins, which accounts for 4.7% of all saponins. This study aimed to identify the mechanisms of the antinociceptive effects of ginsenoside Rg3.
  
  
  METHODS
  Rats were randomly divided into six groups, which were treated with vehicle or 0.5, 1, 1.5, 2, or 4 mg/kg of ginsenoside Rg3 intraperitoneally 2 h after a plantar incision was made. To evaluate the mechanisms of antinociceptive effects, the rats were intraperitoneally injected with naloxone 5 mg/kg, atropine 1 mg/kg, yohimbine 2 mg/kg, mecamylamine 1 mg/kg, prazosin 1 mg/kg, and dexmedetomidine 5 μg/kg. Hyperalgesia produced by the plantar incision was assessed using von Frey filaments 1 day before the incision (BI) and 2 h after the plantar incision (AP); this measurement was repeated at 15, 30, 45, 60, 80, 100 and 120 min, and 24 and 48 h after the injection of ginsenoside Rg3. Serum interleukin-1β (IL-1β) and interleukin-6 (IL-6) levels were measured 1 day before incision and 120 min, 24 h, and 48 h after the injection of ginsenoside Rg3 or vehicle.
  
  
  RESULTS
  The mechanical withdrawal threshold (MWT) significantly increased in the group that received ginsenoside Rg3. The dose-MWT response showed a curvilinear, bell-shaped relationship. The maximum MWT was found with the administration of ginsenoside Rg3 at 1.5 mg/kg; MWT decreased to 2 and 4 mg/kg. Yohimbine diminished the analgesic effect of ginsenoside Rg3. Prazosin and dexmedetomidine increased the analgesic effect of ginsenoside Rg3. IL-1β and IL-6 appeared significantly lower relative to control group.
  
  
  CONCLUSIONS
  Ginsenoside Rg3 has an analgesic effect with a curvilinear dose-response relationship. Alpha 2 adrenergic receptor appeared to be related to the analgesic effect of ginsenoside Rg3. Also, the anti-inflammatory effect of ginsenoside Rg3 could be related to its analgesic effect.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Inje University Seoul Paik Hospital, Seoul, Korea.
authors.forename: Eun Jin
authors.initials: EJ
authors.lastname: Ahn
authors.forename: Geun Joo
authors.initials: GJ
authors.lastname: Choi
authors.forename: Hyun
authors.initials: H
authors.lastname: Kang
authors.forename: Chong Wha
authors.initials: CW
authors.lastname: Baek
authors.forename: Yong Hun
authors.initials: YH
authors.lastname: Jung
authors.forename: Young Cheol
authors.initials: YC
authors.lastname: Woo
authors.forename: Si Ra
authors.initials: SR
authors.lastname: Bang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D036145:Ginsenosides / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D007660:Ketoprofen / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000970:Antineoplastic Agents; D036145:Ginsenosides; D053583:Interleukin-1beta; D015850:Interleukin-6; C097367:ginsenoside Rg3; D007660:Ketoprofen