Pain
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The acid sensing ion channel 3 (ASIC3) is critical for the development of secondary hyperalgesia as measured by mechanical stimulation of the paw following muscle insult. We designed experiments to test whether ASIC3 was necessary for the development of both primary and secondary mechanical hyperalgesia that develops after joint inflammation. We used ASIC3 -/- mice and examined the primary (response to tweezers) and secondary hyperalgesia (von-Frey filaments) that develops after joint inflammation comparing to ASIC3 +/+ mice. ⋯ ASIC3 was found, however, in synoviocytes of the knee joint of uninflamed mice. In ASIC3 +/+ mice with joint inflammation, ASIC3 co-localized with PGP 9.5 or CGRP in joint afferents innervating the synovium. We conclude that the decreased pH that occurs after inflammation would activate ASIC3 on primary afferent fibers innervating the knee joint, increasing the input to the spinal cord resulting in central sensitization manifested behaviorally as secondary hyperalgesia of the paw.
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Significant decreases in the protein levels of potassium-chloride co-transporter 2 (KCC2) were detected in the ipsilateral spinal dorsal horn 4h following loose ligation of the sciatic nerve. These decreases were associated with a change in hindlimb weight distribution suggestive of pain behavior. In contrast, no changes in GABA-A receptor subunit alpha-1 levels were detected. ⋯ These data suggested that TrkB-dependent reduction in KCC2 protein levels in the spinal dorsal horn was an early consequence of peripheral nerve injury. This decrease in KCC2 may have elicited an early increase in overall dorsal horn neuronal excitability perhaps through a loss of GABA inhibition which is critically dependent on KCC2 activity. The increased neuronal excitability may in turn have caused enhanced and exaggerated communication between primary afferents and dorsal horn neurons to contribute to the early behavioral signs of pain.
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Randomized Controlled Trial Multicenter Study
Laser acupuncture in children with headache: a double-blind, randomized, bicenter, placebo-controlled trial.
To investigate whether laser acupuncture is efficacious in children with headache and if active laser treatment is superior to placebo laser treatment in a prospective, randomized, double-blind, placebo-controlled trial of low level laser acupuncture in 43 children (mean age (SD) 12.3 (+/-2.6) years) with headache (either migraine (22 patients) or tension type headache (21 patients)). Patients were randomized to receive a course of 4 treatments over 4 weeks with either active or placebo laser. The treatment was highly individualised based on criteria of Traditional Chinese medicine (TCM). ⋯ The mean number of headaches per month decreased significantly by 6.4 days in the treated group (p<0.001) and by 1.0 days in the placebo group (p=0.22). Secondary outcome measures headache severity and monthly hours with headache decreased as well significantly at all time points compared to baseline (p<0.001) and were as well significantly lower than those of the placebo group at all time points (p<0.001). We conclude that laser acupuncture can provide a significant benefit for children with headache with active laser treatment being clearly more effective than placebo laser treatment.