A novel rat forelimb model of neuropathic pain produced by partial injury of the median and ulnar nerves.
The vast majority of human peripheral nerve injuries occur in the upper limb, whereas the most animal studies have been conducted using the hindlimb models of neuropathic pain, involving damages of the sciatic or lumbar spinal nerve(s). We attempted to develop a rat forelimb model of peripheral neuropathy by partial injury of the median and ulnar nerves. The halves of each nerve were transected by microscissors at about 5mm proximal from the elbow joint and behavioral signs of neuropathic pain, such as mechanical and cold allodynia, and heat hyperalgesia, were monitored up to 126 days following nerve injury. Mechanical allodynia was assessed by measuring the forepaw withdrawal threshold to von Frey filaments, and cold allodynia was evaluated by measuring the time spent in lifting or licking the forepaw after applying acetone to it. Heat hyperalgesia was also monitored by investigating the forepaw withdrawal latencies using the Hargreaves' test. After the nerve injury, the experimental animals exhibited long-lasting clear neuropathic pain-like behaviors, such as reduced forepaw withdrawal threshold to von Frey filaments, the increased response duration of the forepaw to acetone application, and the decreased withdrawal latency to radiant heat stimulation. These behaviors were significantly alleviated by administration of gabapentin (5 or 50mg/kg, i.p.) in a dose-dependent manner. Therefore, these abnormal sensitivities are interpreted as the signs of neuropathic pain following injury of the median and ulnar nerves. Our rat forelimb model of neuropathic pain may be useful for studying human neuropathic pain and screening for valuable drug candidates.
Yi
Hanju
H
Neuroscience Research Institute and Department of Physiology, Korea University College of Medicine, 126-1 Anam-dong 5 Ga, Sungbuk-Gu, Seoul 136-705, Republic of Korea.
Kim
Myung Ah
MA
Back
Seung Keun
SK
Eun
Jong Shin
JS
Na
Heung Sik
HS
D000588:Amines / Q000494:pharmacology; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D039481:CD11b Antigen / Q000378:metabolism; D003080:Cold Temperature; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology; D004195:Disease Models, Animal; D005552:Forelimb / Q000294:innervation*; D000077206:Gabapentin; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D006930:Hyperalgesia / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008475:Median Nerve / Q000293:injuries*; D009437:Neuralgia / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology*; D020671:Posterior Horn Cells / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014459:Ulnar Nerve / Q000293:injuries*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D000588:Amines; D000700:Analgesics; D039481:CD11b Antigen; D003509:Cyclohexanecarboxylic Acids; D005904:Glial Fibrillary Acidic Protein; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin