Pain
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Comparative Study
Thiamine, pyridoxine, cyanocobalamin and their combination inhibit thermal, but not mechanical hyperalgesia in rats with primary sensory neuron injury.
Neuropathic pain after nerve injury is severe and intractable, and current drugs and nondrug therapies offer substantial pain relief to no more than half of affected patients. The present study investigated the analgesic roles of the B vitamins thiamine (B1), pyridoxine (B6) and cyanocobalamin (B12) in rats with neuropathic pain caused by spinal ganglia compression (CCD) or loose ligation of the sciatic nerve (CCI). ⋯ Results showed that (1) intraperitoneal injection of B1 (5, 10, 33 and 100 mg/kg), B6 (33 and 100 mg/kg) or B12 (0.5 and 2 mg/kg) significantly reduced thermal hyperalgesia; (2) the combination of B1, B6 and B12 synergistically inhibited thermal hyperalgesia; (3) repetitive administration of vitamin B complex (containing B1/B6/B12 33/33/0.5 mg/kg, for 1 and 2 wk) produced long-term inhibition of thermal hyperalgesia; and (4) B vitamins did not affect mechanical hyperalgesia or normal pain sensation, and exhibited similar effects on CCD and CCI induced-hyperalgesia. The present studies demonstrate effects of B vitamins on pain and hyperalgesia following primary sensory neurons injury, and suggest the possible clinical utility of B vitamins in the treatment of neuropathic painful conditions following injury, inflammation, degeneration or other disorders in the nervous systems in human beings.
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Effective verbalization of pain requires progressive cognitive development and acquisition of social communication skills. Use of self-report in pediatric pain assessment assumes children have acquired a capacity to understand and use common words to describe pain. The current investigation documented the language most commonly used by young children to describe pain and the age of onset of use of these words. ⋯ The word-stem 'pain' was used relatively infrequently and gradually emerged in children's vocabularies. The findings indicate that young children rely on a select number of words to describe pain, with these words appearing in children's vocabularies at an early age. These results have implications for developmentally appropriate pain assessment in young children.
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The pain enhancing (hyperalgesic) effect of morphine was characterized in relation to pain stimulus (thermal, mechanical), dose, mode of administration (acute, chronic), sex and mechanism. We found that a low (subanalgesic) dose of morphine enhanced the sensitivity to thermal and mechanical noxious stimuli in a dose- and sex-related manner. Morphine hyperalgesia was inversely related to dose (0.002-0.2mg/kg) and was more pronounced in female than male rats. ⋯ Sex-related differences in morphine's analgesic action (male>female) were attenuated. Development of tolerance to the analgesic effect of morphine was delayed. The present findings may have an implication for the use of mu opioids in the clinical setting.
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Some electrophysiologic studies demonstrate new, excitatory alpha2-adrenoceptors on peripheral nociceptors and their dorsal root ganglion (DRG) cell bodies after nerve injury, yet administration of alpha2-adrenoceptor agonists at these sites reduces hypersensitivity rather than worsens it. Since TRPV-1 expressing nociceptor afferents are important in many pain states, we examined the expression of this channel and its co-expression with alpha2C-adrenoceptors in injured DRG cell bodies and the ability of alpha2-adrenoceptors to inhibit responses to stimulation. Rats underwent tight ligation of the left L5 and L6 spinal nerves, followed by behavioral testing, removal of L5 and L6 DRGs, and either immunostaining for TRPV-1 channels and alpha2C-adrenoceptors or intracellular calcium videomicroscopy in response to electrical field stimulation before and after perfusion with clonidine and capsaicin. ⋯ The proportion of clonidine inhibited cells which responded to capsaicin increased 5 fold after injury. We conclude that TRPV-1 and alpha2C-adrenoceptors are up-regulated in some injured medium and large size neurons after nerve ligation. Increased co-expression by immunocytochemistry, and increased proportion of cells inhibited by clonidine and expressing functional TRPV-1 channels suggest that these cells may play an important role in the analgesic effects of alpha2-adrenoceptor agonists in neuropathic pain.
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Randomized Controlled Trial Comparative Study Clinical Trial
Neonatal procedural pain exposure predicts lower cortisol and behavioral reactivity in preterm infants in the NICU.
Data from animal models indicate that neonatal stress or pain can permanently alter subsequent behavioral and/or physiological reactivity to stressors. However, cumulative effects of pain related to acute procedures in the neonatal intensive care unit (NICU) on later stress and/or pain reactivity has received limited attention. The objective of this study is to examine relationships between prior neonatal pain exposure (number of skin breaking procedures), and subsequent stress and pain reactivity in preterm infants in the NICU. ⋯ Among infants born