Articles: hyperalgesia.
-
Human experimental pain models play an important role in studying neuropathic pain mechanisms. The objective of the present study was to test the reproducibility of the topical menthol model over a 1-week period. ⋯ For an observation period of 1 week, the signs of cold and mechanical hyperalgesia were reproducible with a highly significant correlation of about r = 0.8 and good agreement except for the area size of mechanical pin-prick hyperalgesia. These results demonstrate that the topical menthol pain model is suitable for pharmacological interventions repeated within an observation period of 1 week.
-
We investigated both the efficacy and the sub-chronic toxicity of Tephrosia toxicaria Pers. in the zymosan-induced temporomandibular joint (TMJ) inflammatory hypernociception in rats evaluating the possible role of heme oxygenase-1 (HO-1). ⋯ T. toxicaria did not produce any signs of toxicity and effectively decreased zymosan-induced TMJ inflammatory hypernociception dependent, at least in part, upon the HO-1 pathway integrity.
-
Brain Behav. Immun. · Oct 2014
Decrease in neuroimmune activation by HSV-mediated gene transfer of TNFα soluble receptor alleviates pain in rats with diabetic neuropathy.
The mechanisms of diabetic painful neuropathy are complicated and comprise of peripheral and central pathophysiological phenomena. A number of proinflammatory cytokines are involved in this process. Tumor necrosis factor α (TNF-α) is considered to be one of the major contributors of neuropathic pain. ⋯ Diabetic animals exhibited changes in threshold of mechanical and thermal pain perception compared to control rats and also demonstrated increases in TNFα in the DRG, spinal cord dorsal horn, sciatic nerve and in the foot skin, 6 weeks after the onset of diabetes. Therapeutic approaches by HSV mediated expression of p55 TNF soluble receptor significantly attenuated the diabetes-induced hyperalgesia and decreased the expression of TNFα with reduction in the phosphorylation of p38MAPK in the spinal cord dorsal horn and DRG. The overall outcome of this study suggests that neuroinflammatory activation in the peripheral nervous system may be involved in the pathogenesis of painful neuropathy in Type 1 diabetes which can be alleviated by local expression of HSV vector expressing p55 TNF soluble receptor.
-
Quantitative sensory testing (QST) has been used to elucidate the peripheral and central mechanisms that underlie changes in pain sensitivity associated with low back pain (LBP). However, it remains unclear to what degree peripheral and central changes contribute to the generation and maintenance of LBP. The aim of this study was to compare thermal pain sensitivity, measured using QST, in participants with acute LBP, chronic LBP, and pain-free controls. ⋯ We found evidence for localized and generalized cold hyperalgesia in chronic, but not acute LBP. We might speculate that hyperalgesia develops as a consequence of long-lasting LBP, but prospective studies are needed to confirm this assumption.
-
Comparative Study
The Anti-Hyperalgesic Effects of a Novel TRPM8 Agonist in Neuropathic Rats: A Comparison with Topical Menthol.
Menthol has historically been used topically to alleviate various pain conditions. At low concentrations, this non-selective TRPM8 agonist elicits a cooling sensation, however higher concentrations result in cold hyperalgesia in normal subjects and paradoxically analgesia in neuropathic patients. Through behavioural and electrophysiological means, we examined whether this back-translated into a pre-clinical rodent model. ⋯ In addition, M8-Ag attenuated behavioural hypersensitivity to innocuous cooling but not mechanical stimulation. These data suggest that menthol induced hyperalgesia is not consistently replicable in the rat and that the analgesic properties are revealed by injury. Systemic TRPM8 agonists might be beneficial in neuropathy without affecting normal cold sensitivity.