The effect of site and type of nerve injury on the expression of brain-derived neurotrophic factor in the dorsal root ganglion and on neuropathic pain behavior

• Published in: Neuroscience Vol. 137; no. 3; pp. 961 - 970
• Main Authors: Obata, K., Yamanaka, H., Kobayashi, K., Dai, Y., Mizushima, T., Katsura, H., Fukuoka, T., Tokunaga, A., Noguchi, K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-01-2006; Elsevier
• Subjects: Animals; Behavior, Animal - physiology; Biological and medical sciences; brain-derived neurotrophic factor; Brain-Derived Neurotrophic Factor - biosynthesis; dorsal rhizotomy; dorsal root ganglion; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - injuries; Ganglia, Spinal - metabolism; Hyperalgesia - metabolism; Hyperalgesia - psychology; Immunohistochemistry; In Situ Hybridization; Male; Motor Neurons - metabolism; Motor Neurons - physiology; Neurons, Afferent - metabolism; Neurons, Afferent - physiology; neuropathic pain; Pain - etiology; Pain - metabolism; Pain - psychology; Peripheral Nervous System Diseases - complications; Peripheral Nervous System Diseases - metabolism; Peripheral Nervous System Diseases - psychology; Rats; Rats, Sprague-Dawley; Spinal Cord - cytology; Spinal Cord - drug effects; Spinal Cord - metabolism; spinal nerve transection; Spinal Nerves - injuries; ventral rhizotomy; Vertebrates: nervous system and sense organs; ventral rhizotomy; BDNF; ISHH; IR; spinal nerve transection; NGF; DR; neuropathic pain; PB; ANOVA; dorsal root ganglion; DRG; SNT; brain-derived neurotrophic factor; dorsal rhizotomy; VR; Spinal cord; Nervous system diseases; Central nervous system; Peripheral neuropathy; Spinal nerve; Pain; Spinal ganglion; Rhizotomy; Peripheral nerve disease; Behavior; Brain derived neurotrophic factor; Lesion
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2005.10.015

A number of rat neuropathy models have been developed to simulate human neuropathic pain conditions, such as spontaneous pain, hyperalgesia, and allodynia. In the present study, to determine the relative importance of injury site (proximal or distal to the primary afferent neurons) and injury type (motor or sensory), we examined pain-related behaviors and changes of brain-derived neurotrophic factor expression in the dorsal root ganglion in sham-operated rats, and in the L5 dorsal rhizotomy, L5 ventral rhizotomy, L5 dorsal rhizotomy+ventral rhizotomy, and L5 spinal nerve transection models. L5 ventral rhizotomy and spinal nerve transection produced not only mechanical and heat hypersensitivity, but also an increase in brain-derived neurotrophic factor mRNA/protein in the L5 dorsal root ganglion at 7 days after surgery. In contrast, rats in the L5 dorsal rhizotomy and dorsal rhizotomy+ventral rhizotomy groups did not show both pain behaviors at 7 days after surgery, despite brain-derived neurotrophic factor upregulation in medium- and large-size neurons in the L5 dorsal root ganglion. On the other hand, L5 spinal nerve transection, but not dorsal rhizotomy, dorsal rhizotomy+ventral rhizotomy or ventral rhizotomy, increased the expression of brain-derived neurotrophic factor in the L4 dorsal root ganglion at 7 days after surgery. Taken together, these findings suggest that the upregulation of brain-derived neurotrophic factor expression in the L4 and L5 dorsal root ganglion neurons may be, at least in part, involved in the pathophysiological mechanisms of neuropathic pain and that the selective nerve root injury models may be useful for studying the underlying mechanisms of chronic pain after nerve injury.