Neuroscience letters
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Neuroscience letters · Nov 2004
Comparative StudyAnalgesic effect of extracts of Chinese medicinal herbs Moutan cortex and Coicis semen on neuropathic pain in mice.
Neuropathic pain arising from peripheral nerve injury is a clinical disorder characterized by a combination of spontaneous pain, hyperalgesia and tactile pain (allodynia), and remains a significant clinical problem since it is often poorly relieved by conventional analgesics. To seek an analgesic compound(s) in Chinese herbs, we examined the effect of seven Chinese herbs that are routinely prescribed for pain management in two neuropathic pain models: allodynia induced by intrathecal administration of prostaglandin F2alpha (PGF2alpha) and by selective L5 spinal nerve transection. ⋯ The increase in NADPH diaphorase activity in the spinal cord associated with neuropathic pain was also blocked by these extracts. These results suggest that Moutan cortex and Coicis semen contain substances effective in neuropathic pain.
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Neuroscience letters · Nov 2004
Comparative StudyThe monosodium iodoacetate model of osteoarthritis: a model of chronic nociceptive pain in rats?
Osteoarthritis (OA) is a widespread condition affecting the elderly population. One of the most prominent features but least studied symptoms is chronic pain associated with OA. The study objective was to determine pain endpoints in rats with monosodium iodoacetate (MIA) induced OA, and to investigate the efficacy of common nociceptive agents. ⋯ Morphine (0.3-3 mg/kg, s.c.) and tramadol (3-100 mg/kg, p.o.) dose-dependently inhibited punctate allodynia and partially reversed weight bearing deficit. In conclusion, the MIA model of OA is reproducible and mimics OA pain in humans. Analgesic drug studies indicate this model may be useful for investigating chronic nociceptive pain.
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Neuroscience letters · Nov 2004
Comparative StudyMental motor imagery and the body schema: evidence for proprioceptive dominance.
Previous studies have demonstrated that both visual and proprioceptive feedback influence motor control. The relative contributions of these sensory modalities to the on-line computation of body position--that is, the body schema--remain unclear. We report a study designed to explore the roles of vision and proprioception in motor planning. ⋯ There were three conditions: a "control" condition (real hand in view), a "fake hand" condition (fake hand in view, real hand out of view), and a "proprioception" condition (no fake hand, real hand out of view). We found that proprioceptive input (that is, the subject's "felt position") had a significant influence on mental rotation whereas the visually perceived posture of the hand did not. We suggest that, at least under some circumstances, proprioceptive inflow may represent the dominant sensory input to the on-line representation of the body in space.
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Neuroscience letters · Nov 2004
Comparative StudyCloning and pharmacological characterization of mouse TRPV1.
The Transient Receptor Potential cation channel V1 (TRPV1) is expressed in peripheral nociceptive neurons and is subject to polymodal activation via various agents including capsaicin, noxious heat, low extracellular pH, and direct phosphorylation by protein kinase C (PKC). We have cloned and heterologously expressed mouse TRPV1 (mTRPV1) and characterized its function utilizing FLIPR-based calcium imaging to measure functional responses to various small molecule agonists, low pH and direct phosphorylation via PKC. The various TRPV1 agonists activated mTRPV1 with a rank order of agonist potency of (resiniferatoxin (RTX) = arvanil > capsaicin = olvanil > OLDA > PPAHV) (EC50 values of 0.15+/-0.04 nM, 0.27+/-0.07 nM, 9.1+/-1.2 nM, 3.7+/-0.3 nM, 258+/-105 nM, and 667+/-151 nM, respectively). ⋯ However, the antagonist capsazepine was only able to inhibit a capsaicin-evoked response of mTRPV1 with an IC50 of 1426+/-316 nM. Comparable results were achieved with rat TRPV1, while capsazepine blocked all modes of human TRPV1 activation. Thus, the mTRPV1 cation channel has a molecular pharmacological profile more akin to rat TRPV1 than either human or guinea pig TRPV1 and the molecular pharmacology suggests that capsazepine may be an ineffective TRPV1 antagonist for in vivo models of inflammatory pain in the mouse.