Trending Articles
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Comparative Study
Nerve growth factor selectively decreases activity-dependent conduction slowing in mechano-insensitive C-nociceptors.
Nerve growth factor (NGF) induces acute sensitization of nociceptive sensory endings and long-lasting hyperalgesia. NGF modulation of sodium channel expression might contribute to neurotrophin-induced hyperalgesia. Here, we investigated NGF-evoked changes of the activity-dependent slowing of conduction in porcine C-fibers. ⋯ Accordingly, the number of fibers with pronounced ADS decreased but more units with pronounced ADS were mechano-sensitive. Spontaneously active C-fibers were increased above the control level (1%) by NGF 8 μg (8%). The results demonstrate that NGF changes the functional axonal characteristics of mechano-insensitive C-fibers and enhances spontaneous activity thereby possibly contributing to hyperalgesia.
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Mild brain hypothermia (32°-34°C) after human neonatal asphyxia improves neurodevelopmental outcomes. Astrocytes but not neurons have pyruvate carboxylase and an acetate uptake transporter. C nuclear magnetic resonance spectroscopy of rodent brain extracts after administering [1-C]glucose and [1,2-C]acetate can distinguish metabolic differences between glia and neurons, and tricarboxylic acid cycle entry via pyruvate dehydrogenase and pyruvate carboxylase. ⋯ Starting mild hypothermia simultaneously with oxygen-glucose deprivation, compared with delayed starting or no hypothermia, has higher pyruvate carboxylase throughput, suggesting that better glial integrity is one important neuroprotection mechanism of earlier hypothermia.
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Comparative Study
Eugenol reverses mechanical allodynia after peripheral nerve injury by inhibiting hyperpolarization-activated cyclic nucleotide-gated (HCN) channels.
Mechanical allodynia is a common symptom found in neuropathic patients. Hyperpolarization-activated cyclic nucleotide-gated channels and their current, I(h), have been suggested to play an important role in neuropathic pain, especially in mechanical allodynia and spontaneous pain, by involvement in spontaneous ectopic discharges after peripheral nerve injury. Thus, I(h) blockers may hold therapeutic potential for the intervention of mechanical allodynia under diverse neuropathic conditions. ⋯ Eugenol-induced I(h) inhibition was not mediated by G(i/o)-protein activation, but was gradually diminished by an increase in intracellular cAMP concentration. Eugenol also inhibited I(h) from injured TG neurons which were identified by retrograde labeling with DiI and reversed mechanical allodynia in the orofacial area after chronic constriction injury of infraorbital nerve. We propose that eugenol could be potentially useful for reversing mechanical allodynia in neuropathic pain patients.
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Case Reports Randomized Controlled Trial Comparative Study
Drug-induced liver injury following a repeated course of ketamine treatment for chronic pain in CRPS type 1 patients: a report of 3 cases.
Studies on the efficacy of ketamine in the treatment of chronic pain indicate that prolonged or repetitive infusions are required to ensure prolonged pain relief. Few studies address ketamine-induced toxicity. Here we present data on the occurrence of ketamine-induced liver injury during repeated administrations of S(+)-ketamine for treatment of chronic pain in patients with complex regional pain syndrome type 1 as part of a larger study exploring possible time frames for ketamine re-administration. ⋯ In all patients, the ketamine infusion was promptly terminated and the liver enzymes slowly returned to reference values within 2 months. Our data suggest an increased risk for development of ketamine-induced liver injury when the infusion is prolonged and/or repeated within a short time frame. Regular measurements of liver function are therefore required during such treatments.
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Pain and focal dystonias have been associated with chronic pain conditions such as complex regional pain syndrome. Corneal pain, frequently known as "dry eye", may be a neuropathic pain condition with abnormalities of the nerve plexus. Here we present 5 case histories of patients with defined corneal pain (with associated neuropathic features) and objective measures of changes in the nerve plexus and associated blepharospasm. A putative relationship between pain and blepharospasm suggests potential involvement of the basal ganglia in both these conditions.