Spinal microglia and neuropathic pain in young rats - PubMed (original) (raw)

. 2007 Apr;128(3):215-224.

doi: 10.1016/j.pain.2006.09.018. Epub 2006 Nov 15.

Affiliations

Spinal microglia and neuropathic pain in young rats

Andrew Moss et al. Pain. 2007 Apr.

Abstract

Neuropathic pain behaviour is not observed in neonatal rats and tactile allodynia does not develop in the spared nerve injury (SNI) model until rats are 4 weeks of age at the time of surgery. Since activated spinal microglia are known to play a key role in neuropathic pain, we have investigated whether the microglial response to nerve injury in young rats differs from that in adults. Here we show that dorsal horn microglial activation, visualised with IBA-1 immunostaining, is significantly less in postnatal day (P) 10 rat pups than in adults, 7 days after SNI. This was confirmed by qPCR analysis of IBA-1 mRNA and mRNA of other microglial markers, integrin-alpha M, MHC-II DMalpha and MHC-II DMbeta. Dorsal horn IBA-1+ve microglia could be activated, however, by intraspinal injections of lipopolysaccharide (LPS) or N-methyl-d-aspartate (NMDA) at P10, although the increase in the levels of mRNA for all microglial markers was less than in the adult rat. In addition, P10 rats developed a small but significant mechanical allodynia in response to intrathecal LPS. Intrathecal injection of cultured ATP-activated microglia, known to cause mechanical allodynia in adult rats, had no behavioural effect at P10 and only began to cause allodynia if injections were performed at P16. The results clearly demonstrate immaturity of the microglial response triggered by nerve injury in the first postnatal weeks which may explain the absence of tactile allodynia following peripheral nerve injury in young rats.

PubMed Disclaimer

Similar articles

Cited by

References

    1. Anand P, Birch R. Restoration of sensory function and lack of long-term chronic pain syndromes after brachial plexus injury in human neonates. Brain. 2002;125:113-122.
    1. Boisse L, Mouihate A, Ellis S, Pittman QJ. Long-term alterations in neuroimmune responses after neonatal exposure to lipopolysaccharide. J Neurosci. 2004;24:4928-4934.
    1. Boisse L, Spencer SJ, Mouihate A, Vergnolle N, Pittman QJ. Neonatal immune challenge alters nociception in the adult rat. Pain. 2005;119:133-141.
    1. Cahill CM, Dray A, Coderre TJ. Enhanced thermal antinociceptive potency and anti-allodynic effects of morphine following spinal administration of endotoxin. Brain Res. 2003;960:209-218.
    1. Colburn RW, DeLeo JA, Rickman AJ, Yeager MP, Kwon P, Hickey WF. Dissociation of microglial activation and neuropathic pain behaviors following peripheral nerve injury in the rat. J Neuroimmunol. 1997;79:163-175.

Publication types

MeSH terms

LinkOut - more resources