Articles: hyperalgesia.
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British medical bulletin · Jan 2009
ReviewVisceral pain hypersensitivity in functional gastrointestinal disorders.
Functional gastrointestinal disorders (FGIDs) are a highly prevalent group of heterogeneous disorders whose diagnostic criteria are symptom based in the absence of a demonstrable structural or biochemical abnormality. Chronic abdominal pain or discomfort is a defining characteristic of these disorders and a proportion of patients may display heightened pain sensitivity to experimental visceral stimulation, termed visceral pain hypersensitivity (VPH). ⋯ Tangible progress will only be made in the treatment of VPH when we begin to individually characterize patients with FGIDs based on their clinical phenotype, genetics and visceral nociceptive physiology.
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Studies in animals and humans suggest that neonatal and early infant pain or stress experiences can induce long-term alterations in somatosensory and pain processing. We studied pain and sensory sensitivity in school-aged children (9-16 years) who had suffered moderate (N=24) or severe (N=24) burn injuries in infancy (6-24 months of age) and 24 controls. Quantitative sensory testing entailing detection and pain thresholds for thermal and mechanical stimuli and perceptual sensitization to tonic heat and repetitive mechanical stimuli was performed. ⋯ In these children, mechanical pain sensitivity and detection thresholds were not consistently altered. This differential pattern of altered sensory and pain sensitivity may reflect differences in experienced stress, pain and analgesic treatment between moderately and severely burned children. Most importantly, our findings suggest that early traumatic and painful injuries, such as burns, can induce global, long-term alterations in sensory and pain processing.
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TrpV1, the receptor for capsaicin, contributes to nociception in animals but appears to be much more important for signaling increased behavioral sensitivity in the injured state. The current study examined the relationship between the marked reduction in heat hyperalgesia after incision in TrpV1 knockout (KO) mice and the activity of the nociceptors in these same mice. Also, the role of TrpV1 in spontaneous activity (SA) of afferents after incision was examined. ⋯ We conclude that a distinct class of afferents outside the mechano-heat-sensitive afferent population likely contributes to heat hypersensitivity after plantar incision. KO of TrpV1 influences SA in these unclassified afferents in incised skin. SA in these afferents is perhaps a manifestation of heat sensitization.
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Lidocaine produces analgesia by inhibiting excitation of nerve endings or blocking impulse conduction in peripheral nerves. This study was performed to determine whether intrathecal or intravesical administration of lidocaine prior, or subsequent, to induction of chemical cystitis in rats would block referred mechanical hyperalgesia. ⋯ These results indicate that pre-treatment with lidocaine attenuates referred hyperalgesia associated with cystitis. Lidocaine treatment 4 hr after induction of cystitis failed to prevent referred hyperalgesia despite a similar decrease in bladder NGF. Neurourol. Urodynam. (c) 2009 Wiley-Liss, Inc.
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Neuroscience research · Jan 2009
Comparative StudyEffects of intrathecal administration of newer antidepressants on mechanical allodynia in rat models of neuropathic pain.
Antidepressants, especially tricyclic antidepressants (TCAs) are widely used for the treatment of various types of chronic and neuropathic pain. The antinociceptive effects of TCAs are, however, complicated. Therefore, two kinds of newer antidepressants whose functions have been more fully clarified were selected, milnacipran, a serotonin and noradrenaline reuptake inhibitor (SNRI) and paroxetine and fluvoxamine, which are selective serotonin reuptake inhibitors (SSRIs). ⋯ The intrathecal administration of milnacipran had an antiallodynic effect in both CCI and STZ-induced diabetic rats in a dose-dependent manner. On the other hand, the intrathecal administration of either paroxetine or fluvoxamine elicited little antiallodynic effect in CCI rats, while both SSRIs had antiallodynic effects in the STZ-induced diabetic rats in a dose-dependent manner. These results indicate a considerable difference to exist in the development and/or maintenance between these two animal models of neuropathic pain and suggest that each of these three antidepressants may be effective for the treatment of diabetic neuropathic pain.