Plasticity of spinal nicotinic acetylcholine receptors following spinal nerve ligation

• Published in: Neuroscience research 2004-02, Vol.48 (2), p.139-145
• Main Authors: Vincler, Michelle, Eisenach, James C
• Format: Article
• Language: English
• Subjects: Animals; Chronic pain; Ligation; Male; Mechanical allodynia; Neuronal Plasticity - physiology; Neuropathic pain; Posterior Horn Cells - metabolism; Posterior Horn Cells - physiology; Rats; Rats, Sprague-Dawley; Receptors, Nicotinic - analysis; Receptors, Nicotinic - biosynthesis; Receptors, Nicotinic - genetics; Spinal Nerves - metabolism; Spinal Nerves - physiology
• ISSN: 0168-0102; 1872-8111
• DOI: 10.1016/j.neures.2003.10.007

The nicotinic cholinergic system is known to be important in the processing of nociceptive information. In the spinal cord, nicotinic receptors are expressed on primary afferent terminals, inhibitory interneurons and descending noradrenergic and serotoninergic fibers. Following peripheral nerve injury, the expression of numerous receptors involved in nociceptive processing is altered in the superficial dorsal horn of the spinal cord. However, the expression of nicotinic acetylcholine receptor subunits in the lumbar spinal cord following peripheral nerve injury has not been investigated. We examined the expression of the α3, α4, α5, α7, β2, β3 and β4 nicotinic subunits in the spinal cord of normal and spinal nerve ligated rats using immunocytochemistry. Two nicotinic subunits were found to have an increased expression following spinal nerve ligation. The number of cells expressing the α3 subunit in the dorsal horn increased bilaterally following spinal nerve injury. Also, the number of α5 immunoreactive fibers increased significantly ipsilateral to ligation. The expression of the α4, α7, β2, β3 and β4 subunits was unchanged. We propose that the increased expression of the α3 and α5 nicotinic subunits may contribute to the mechanical hypersensitivity observed following spinal nerve ligation.