Neuroscience letters
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Neuroscience letters · Apr 1999
Clinical TrialSensory threshold changes without initial pain or alterations in cutaneous blood flow, in the area of secondary hyperalgesia caused by topical application of capsaicin in humans.
Changes in von Frey hair perception, pricking pain, and vibration thresholds were examined in six healthy human adults, in the zone of secondary hyperalgesia, 45 min following the topical application of capsaicin at concentrations of 0.05 and 0.1 mg/ml. In two of these subjects, cutaneous blood flow was monitored at 10-min intervals, before, during and after capsaicin application, using laser Doppler perfusion imaging. ⋯ However, there was no visible skin flare, and no change in cutaneous blood flow at these doses of capsaicin. The effects on von Frey perception threshold and vibration threshold have not been demonstrated previously, and may be indicative of central changes, initiated by afferent fibres (presumably C fibres) that are not vasoactive.
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Neuroscience letters · Apr 1999
N-methyl-D-asparate receptor antagonists abolish the maintenance phase of self-sustaining status epilepticus in rat.
We examined the effects of blockers of N-methyl-D-asparate (NMDA) and +/- -alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptors on the maintenance of self-sustaining status epilepticus (SSSE) induced in rats by brief intermittent electrical stimulation of the perforant path (PPS). Blocking of NMDA receptor at the PCP site by MK-801 (0.5 mg/kg, i.p.) or ketamine (10 mg/kg, i.p.) as well as at the glycine allosteric site by intrahippocampal 5,7-dichlorokynurenic acid (5,7-DCK, 10 nmol), rapidly and irreversibly aborted both behavioral and electrographic manifestation of SSS. Intrahippocampal injection of the AMPA/kainate receptor blocker 6-cyano7-nitroquinixaline-3-dione (CNQX, 10 nmol) transiently suppressed seizures, which reappeared 4-5 h later. We suggest that the maintenance phase of SSSE depends on activation of NMDA receptors and that NMDA receptor blockers may be a promising class of compounds for the treatment of status epilepticus.