Articles: hyperalgesia.
-
Dioscorea bulbifera var sativa is a medicinal plant commonly used in Cameroonian traditional medicine to treat pain and inflammation. ⋯ Present demonstrate the antinociceptive activities of Dioscorea bulbifera both in inflammatory and neuropathic models of pain and these effects may result, at least partially, from its ability to activate the NO-cGMP-ATP-sensitive potassium channels pathway.
-
Neuroscience letters · Apr 2010
Behavioral evidence of thermal hyperalgesia and mechanical allodynia induced by intradermal cinnamaldehyde in rats.
TRPA1 agonists cinnamaldehyde (CA) and mustard oil (allyl isothiocyanate=AITC) induce heat hyperalgesia and mechanical allodynia in human skin, and sensitize responses of spinal and trigeminal dorsal horn neurons to noxious skin heating in rats. TRPA1 is also implicated in cold nociception. We presently used behavioral methods to investigate if CA affects sensitivity to thermal and mechanical stimuli in rats. ⋯ CA significantly reduced mechanical withdrawal thresholds of the injected paw that peaked sooner (3 min) and was more profound (44.4% of baseline), with no effect contralaterally. Bilateral intraplantar injections of CA resulted in a significant cold hyperalgesia (cold plate test) and a weak enhancement of innocuous cold avoidance (thermal preference test). The data are consistent with roles for TRPA1 in thermal (hot and cold) hyperalgesia and mechanical allodynia.
-
The possible antiallodynic effect of phosphodiesterase 5 inhibitor sildenafil and nitric oxide donor glyceryl trinitrate as well as the changes in phosphodiesterase 5A2 mRNA expression in dorsal root ganglion and spinal cord of allodynic diabetic rats was assessed. Diabetes was induced by streptozotocin (50mg/kg, i.p.) in male Wistar rats. Streptozotocin injection produced hyperlglycemia, polydipsia, polyphagia and polyuria as well as long-term tactile allodynia (12 weeks) and a reduction of phosphodiesterase 5A2 mRNA expression in spinal cord of diabetic rats. ⋯ Moreover, both drugs reversed streptozotocin-induced phosphodiesterase 5A2 mRNA expression reduction. Our results indicate that glyceryl trinitrate and sildenafil reduce tactile allodynia in diabetic rats suggesting that nitric oxide and cyclic GMP supply is an important step in their mechanism of action of these drugs in diabetic animals. Data suggest that nitric oxide donors (as glyceryl trinitrate) and drugs which increase cyclic GMP levels (as sildenafil) could have a role in the pharmacotherapy of tactile allodynia in diabetic patients.
-
Neuropathic pain syndromes are characterised by the occurrence of spontaneous ongoing and stimulus-induced pain. Stimulus-induced pain (hyperalgesia and allodynia) may result from sensitisation processes in the peripheral (primary hyperalgesia) or central (secondary hyperalgesia) nervous system. The underlying pathophysiological mechanisms at the nociceptor itself and at spinal synapses have become better understood. ⋯ These mechanisms include reorganisation of cortical somatotopic maps in sensory or motor areas (highly relevant for phantom limb pain and CRPS), increased activity in primary nociceptive areas, recruitment of new cortical areas usually not activated by nociceptive stimuli and aberrant activity in brain areas normally involved in descending inhibitory pain networks. Moreover, there is evidence from PET studies for changes of excitatory and inhibitory transmitter systems. Finally, advanced methods of structural brain imaging (voxel-based morphometry, VBM) show significant structural changes suggesting that chronic pain syndromes may be associated with neurodegeneration.
-
Clinical rheumatology · Apr 2010
Evidence for generalized hyperalgesia in chronic fatigue syndrome: a case control study.
Several studies provided evidence for generalized hyperalgesia in fibromyalgia or whiplash-associated disorders. In chronic fatigue syndrome, however, pain is a frequently reported complaint, but up to now, evidence for generalized hyperalgesia is lacking. The aim of this study is to examine whether the pressure pain thresholds (PPTs) at both symptomatic and asymptomatic sites differ in chronic fatigue syndrome (CFS) patients with chronic pain, compared to healthy controls. ⋯ No confounding factors responsible for the observed differences, as, e.g., catastrophizing and depression, could be revealed. These findings provide evidence for the existence of hyperalgesia even in asymptomatic areas (generalized secondary hyperalgesia). The generalized hyperalgesia may represent the involvement of a sensitized central nervous system.