Developmental characteristics of neuropathic pain induced by peripheral nerve injury of rats during neonatal period.
To gain an insight into the developmental characteristics of neuropathic pain induced by peripheral nerve injury during neonatal period, we employed three groups of rats suffering from peripheral nerve injury at different postnatal times, and compared the onset time, severity and persistency of neuropathic pain behaviors, such as mechanical and cold allodynia. The first group (P0 group) was subjected to partial injury of tail-innervating nerves within 24 h after birth, the second group (P10 group) underwent nerve injury at postnatal day (P) 10, and the third group (P60 group) was subjected to injury at P60. Although mechanical allodynia was readily detectable in the P60 group even 1 day after nerve injury, the signs of neuropathic pain were observed from 6 or 8 weeks after nerve injury in the P0 or P10 groups, respectively. Compared with the P60 group, the P0 group showed more robust mechanical and cold allodynia, whereas the P10 group exhibited rather milder pains. In addition, while the P0 and P60 groups showed long-lasting signs of mechanical allodynia, the P10 group exhibited shorter persistency. These results indicate that peripheral nerve injury during neonatal period leads to neuropathic pain with distinct developmental characteristics later in life.
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Seung Keun
SK
Medical Science Research Center and Department of Physiology, Korea University College of Medicine, 126-1 Anam-dong 5 Ga, Seongbuk-Gu, Seoul 136-705, Republic of Korea.
Kim
Myung Ah
MA
Kim
Hee Jin
HJ
Lee
Jaehee
J
Sung
Backil
B
Yoon
Youngsul
Y
Na
Heung Sik
HS
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000209:etiology; D008297:Male; D009437:Neuralgia / Q000209:etiology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D010523:Peripheral Nervous System Diseases / Q000150:complications*; D010812:Physical Stimulation / Q000009:adverse effects; D051381:Rats; D011930:Reaction Time / Q000502:physiology