Changes in expression of cannabinoid receptor CB2 in the dorsal root ganglia of some rat models of neuropathic pain
| Authors | |
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| Year of publication | 2006 |
| Type | Article in Proceedings |
| Conference | FENS Abstr. |
| MU Faculty or unit | |
| Citation | |
| Field | Neurology, neurosurgery, neurosciences |
| Keywords | cannabinoid receptor CB2-dorsal root ganglia-neuropathic pain |
| Description | Cannabinoids modulate nociceptive processing in models of acute, inflammatory and neuropathic pain. These actions are mediated by both cannabinoid CB1 and CB2 receptors. In contrast to CB1 ligands, CB2 agonists do not produce unwanted central nervous system effects and so they show promise for the treatment of acute and chronic pain, especially the neuropathic pain. In the present study we evaluated the immunohistochemical distribution of CB2 receptors in the intact dorsal root ganglia (DRG) of the adult rat and its changes in rat neuropathic pain models. Twenty adult Wistar rats were divided to six groups. The neuropathic pain model was performed by unilateral ligation (n=5) or transection (n=4) of the sciatic nerve. The third group of animals (n=5) was used for ligation of the intercostal nerves (T10, 11, 12). Two groups of rats were used for sham operations of the sciatic (n=2) and intercostal nerves (n=2). The last group was represented by naive animals (n=2). All operated animals were allowed to survive for 1 or 2 weeks. Transverse cryostat sections cut simultaneously through ipsilateral and contralateral T10, T11, T12, L4 and L5 DRG of both experimental and intact animals were incubated with rabbit polyclonal antibody against CB2 receptor over night. It was followed by treatment with goat anti-rabbit antibody conjugated with rhodamine at room temperature for 90 min. The results of immunostaining were viewed and digitized in a Leica-DMBL fluorescence microscope. The CB2 receptor immunoreactivity was found not only in the ipsilateral DRG neurons corresponding with the injured nerves but also in the contralateral ones at the same level. In contrast, a lower intensity of the CB2 immunofluorescence was observed in the DRG neurons of naive rats and those from the sham-operated animals. The presence of CB2 receptors in the DRG neurons may be responsible for antinociceptive effect of CB2 selective ligands. |
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