Nociceptive behaviours evoked by intrathecal (R, S)-3,5-dihydroxyphenylglycine to rats with neuropathic and inflammatory pain conditions

• Main Author: Duckworth, Phoebe E.
• Format: Others
• Language: en
• Published: McGill University 2006
• Subjects: Nociceptors.; Pain.
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99369

Spontaneous nociceptive behaviours (SNBs) are an important but under-studied component of chronic pain conditions. The group I metabotropic glutamate receptor (mGluR) agonist DHPG produces SNBs when injected intrathecally and group I mGluR antagonists are effective at reducing symptoms of neuropathic and inflammatory pain. The present experiments tested whether rats with sciatic nerve injury or persistent inflammation exhibit greater SNBs following intrathecal DHPG compared with control animals. SNBs were observed following intrathecal injection of DHPG between the L4 and L5 vertebrae. When DHPG was injected in rats with chronic constriction injury (CCI) of the sciatic nerve, they showed increased paw stamping behaviour compared to DHPG-injected sham controls. Results of the complementary experiment in rats with complete Freund's adjuvant (CFA)-induced inflammation did not show significant effects. Both CCI and CFA rats injected with DHPG showed increased paw licking and biting behaviour in the ipsilateral paws. These results provide evidence for behaviourally relevant contributions of group I mGluRs to SNBs in models of neuropathic and inflammatory pain.