Neuropathic Pain Behaviors and the Change of Spinal Neuropeptides following Peripheral Nerve Injury in Neonatal Rats.

Yoon, Young Sul; Back, Seung Keun; Kim, Hee Jin; Na, Heung Sik

Original Article

Journal of Korean Neurosurgical Society 2006;39(1): 52-57.

Young Sul Yoon, Seung Keun Back, Hee Jin Kim, Heung Sik Na

¹Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
²Department of Physiology, Medical Science Research Center, Korea University College of Medicine, Seoul, Korea. hsna@korea.ac.kr
³Department of Life Science, Yonsei University Wonju Campus College of Science, Wonju, Korea.

ABSTRACT

OBJECTIVE
It has been suggested that the occurrence of persistent pain signal during the early postnatal period may alter an individual's response to pain later in life. The aim of this study is to assess whether neonatal nerve injury resulted in long-lasting consequences on nociceptive system in the rat.
METHODS
We examined whether neuropathic pain behaviors and the changes of spinal neuropeptides (SP, CGRP, VIP and VIP) induced by peripheral nerve injury within 1 day after birth (Neonate group) were different from those at 8 weeks after birth (Mature group).
RESULTS
The Neonate group showed more robust and long-lasting pain behaviors than the Mature group. Immunohistochemical findings demonstrated that spinal SP- & CGRP-immunoreactivities(ir) of the ipsilateral to the contralateral side increased in the Neonate group, whereas those decreased in the Mature group. In addition, increase in spinal VIP- & NPY-ir of the ipsilateral to the contralateral side was more robust in the Mature group than in the Neonate group.
CONCLUSION
These results suggest that peripheral nerve injury in the early postnatal period may result in long-lasting and potentially detrimental alterations in nociceptive pathways.

Key Words: Peripheral nerve injury; Neuropathic pain; Neonatal; Allodynia; Spinal neuropeptides