Effect of aging on the substance P receptor, NK-1, in the spinal cord of rats with peripheral nerve injury.
*Peripheral Nerve Injuries; Aging/*physiology; Animals; Computer-Assisted; Hot Temperature; Image Processing; Immunohistochemistry; Inbred BN; Inbred F344; Neurokinin-1/*metabolism; Rats; Receptors; Spinal Cord/*metabolism; Thermosensing/physiology; Touch/physiology
Substance P (SP) levels in the spinal cords of very old rats are less than the levels in younger rats (Bergman et al., 1996). After injury to a peripheral nerve in young rats, immunoreactivity (ir) to the SP receptor, NK-1 (neurokinin-1), increases in the spinal cord ipsilateral to the injury and the increases are correlated with the development of thermal hyperalgesia (Goff et al., 1998). Thus we postulated that aged rats might display an increased sensitivity to thermal stimulation before peripheral nerve injury and that they might respond differently to injury than do younger rats. To test this hypothesis, we used the Bennett and Xie model (1988) of chronic constriction injury (CCI) to the sciatic nerve to induce a neuropathic pain condition. We investigated the effect of age on changes in NK-1 ir in superficial layers of the dorsal horn and on numbers of NK ir cells in deeper laminae at the L4-L5 levels of the spinal cord after CCI.
Cruce W L; Lovell J A; Crisp T; Stuesse S L
Somatosensory & Motor Research
2001
2001
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1080/08990220020021366" target="_blank" rel="noreferrer noopener">10.1080/08990220020021366</a>
Neuropathic pain in aged rats: behavioral responses and astrocytic activation.
Aging/*physiology; Animal; Animal/*physiology; Animals; Astrocytes/*metabolism; Behavior; Cell Count; Disease Models; Functional Laterality/physiology; Glial Fibrillary Acidic Protein/metabolism; Hyperalgesia/physiopathology; Immunohistochemistry; Inbred F344; Lumbar Vertebrae; Male; Nerve Crush/methods; Neuralgia/*metabolism/pathology/physiopathology; Pain Measurement; Peripheral Nervous System Diseases/*metabolism/pathology/physiopathology; Posterior Horn Cells/*metabolism; Rats; Thermosensing/physiology; Touch/physiology; Up-Regulation/*physiology
We used the Bennett and Xie (1988) model of chronic neuropathic pain to study the effect of age on thermal and tactile sensitivity and on astrocytic activation in the dorsal horn of the spinal cord after nerve injury. Fischer 344 FBNF1 hybrid rats in three age groups, 4-6, 14-16, and 24-26 months, were studied. Rats were either unligated (day 0, control) or the left sciatic nerve was loosely ligated to cause a chronic constriction injury (CCI). CCI causes a neuropathic pain condition characterized by tactile allodynia and thermal hyperalgesia. Rats were behaviorally assessed for tactile and thermal sensitivity of their ligated and unligated hind paws up to 35 days postligation. Rats were sacrificed before or at various days postligation, and activated astrocytes were identified at the L4-L5 levels of their spinal cords by use of an antibody to glial fibrillary acid protein (GFAP). The number of GFAP-ir astrocytes in the dorsal horn of the spinal cord in the control, uninjured condition decreased with age (P \textless or = 0.001) but increased after CCI in all three age groups. After CCI, astrocytic activation in the cord was less robust in aged rats than in younger ones (P \textless or = 0.01). Not all the CCI rats displayed hyperalgesia to touch and to heat. Rats with an increased sensitivity to heat had increased levels of GFAP-ir in their cords; however, rats with decreased thermal sensitivity also displayed increased
Stuesse S L; Crisp T; McBurney D L; Schechter J B; Lovell J A; Cruce W L
Experimental brain research
2001
2001-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1007/s002210000630" target="_blank" rel="noreferrer noopener">10.1007/s002210000630</a>