European journal of pain : EJP
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Thyroid hormones (THs) play a crucial role in the development of several organic systems. An adequate support of maternal THs may be required to ensure a normal nociceptive function of offspring into adulthood. We investigated the impact of experimental gestational hypothyroidism (EGH) on nociceptive threshold and motor performance in the offspring at different post-natal days (PND) in both male and female rats. ⋯ EGH promotes hypersensitivity to noxious thermal but not mechanical stimulus. Moreover, motor force is similarly reduced in male and female OMTDs, whereas motor performance is reduced only in mature male OMTD, suggesting the presence of a protective factor in females.
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l-Kynurenine has antinociceptive effects in acute and inflammatory pain. This study determined the effect of l-kynurenine and its metabolite (kynurenic acid) on rats subjected to neuropathic pain. ⋯ l-Kynurenine produces its antiallodynic effect in the central nervous system through kynurenic acid. This effect may result from blockade of N-methyl-d-aspartate receptors. KAT II is expressed in dorsal root ganglion and dorsal spinal cord. Combined l-kynurenine and probenecid therapy has the potential to reduce neuropathic pain in humans.
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The chronic pain grading (CPG), a standard approach to classify the severity of pain conditions in adults, combines the characteristics of pain intensity and pain-related disability. However, in children and adolescents, the CPG has only been validated in a school sample, but not in the actual target population, i.e., clinical populations with pain. ⋯ The CPG may be applied to adolescent tertiary care samples and to assess outcomes in clinical trials. However, in this study it was not appropriate to assign adolescent patients to different treatment options. Future work should focus on developing a comprehensive assessment tool for assigning patients to different treatments.
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Slowing refers to the gradual decrease in conduction velocity evoked by repetitive electrical stimuli. The underlying mechanisms are still poorly understood, and its physiological/pathological relevance scarcely discussed; however, changes in axonal conduction properties might unmask abnormal nociceptor function and alter the encoding time window at the spinal cord. ⋯ Under our experimental conditions, slowing seems largely dependent on functional Ih . The marked decrease in slowing after axotomy in C-fibres fits with the increased expression of functional hyperpolarization-activated/HCN channel current and may underlie the analgesic effects of the specific Ih blocker ZD7288 previously described in neuropathic pain models.
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Fibromyalgia syndrome (FMS) is frequently associated with psychiatric conditions, particularly anxiety. Deficits in contingency learning during fear conditioning have been hypothesized to increase anxiety and, consequently, pain sensation in susceptible individuals. The goal of this study was to examine the relationship between contingency learning and pain experience in subjects with FMS and rheumatoid arthritis (RA). ⋯ Contingency learning deficits represent a potentially promising and specific, but largely unstudied, psychopathological factor in FMS. Deficits in contingency learning may increase anxiety and, consequently, pain sensation. These findings have the potential to contribute to the development of novel therapeutic approaches for FMS.