Although cerebral and spinal metabotropic glutamate mGlu(1) receptors are thought to be involved in nociception and in the development/maintenance of chronic pain, it is still unclear to what extent mGlu(1) receptors are present in the dorsal root ganglia of peripheral sensory afferents, and whether their expression is affected during development of chronic pain. It was found in the present study that mGlu(1) receptor messenger RNA (mRNA) is present in rat L5 dorsal root ganglia and that it is strongly downregulated after unilateral axotomy of the tibial branch of the sciatic nerve, a model of chronic neuropathic pain. However, as sham-operated animals showed a similar downregulation, it is suggested that peripheral tissue damage is sufficient to result in a reduction of peripheral mGlu(1) receptor expression.