Scandinavian journal of rheumatology. Supplement
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Repetitive synaptic excitation or the application of L-glutamate into the vicinity of multireceptive neurons in the dorsal horn of the spinal cord and corresponding structures of the trigeminal nucleus increases neuronal excitability, which is then reflected by an expansion of the receptive field (Fig. 1). Similar alterations of the receptive field of neurons have been observed in various other brain regions. The receptive fields of multireceptive neurons also expand their size following mechanical, chemical, inflammatory or nerve injuries. ⋯ There is evidence from recent research that this facilitatory effect on glutamatergic synaptic transmission involves membrane receptor phosphorylation, and enhances activity-dependent gene expression (Fig. 3). In order to investigate the time-dependent processing of ongoing afferent noxious stimulation in the central nervous system we recently employed the quantitative autoradiographic 14C-2-deoxyglucose technique in a model of chronic monoarthritic pain in the rat. A synopsis of these most recent experimental data and results from previous electrophysiological in vivo and in vitro studies suggests that dorsal horn neurons and probably also other neurons in pain-related structures become spontaneously active and can maintain their activity without further noxious peripheral input.
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Scand. J. Rheumatol. Suppl. · Jan 2000
Clinical TrialResults of the intravenous administration of tropisetron in fibromyalgia patients.
The observed effects on the symptoms of fibromyalgia of daily oral administration of 5 mg of the 5-HT3 receptor antagonist, tropisetron, for 10 days, could be maintained or exceeded with intravenous administration of only 2 mg of the formulation. Following a single i.v. injection of 2 mg tropisetron, a more rapid and profound reduction in pain was achieved than with 5 mg oral tropisetron per day. ⋯ A more favourable and persistent effect on pain, combined with a simultaneous significant improvement in various vegetative and functional symptoms was achieved with five days treatment with 2 mg tropisetron i.v. per day. The results outlined and the possibility for rapid improvements with drug treatment of fibromyalgia should be confirmed in randomised, placebo controlled trials.
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Scand. J. Rheumatol. Suppl. · Jan 2000
The use of 5-HT3 receptor antagonists in various rheumatic diseases--a clue to the mechanism of action of these agents in fibromyalgia?
In a pilot study, the action of the 5-HT3 receptor antagonist, tropisetron, on different types of local rheumatic pain and inflammatory effects was studied. With intra-articular injection of tropisetron, an improvement in inflammation and pain was obtained in inflammatory rheumatic diseases and activated osteoarthrosis. ⋯ The effect of the 5-HT3 receptor antagonists is probable primarily to limit the release of substance P, which acts as a pain and inflammatory mediator, and is itself released by the neurogenic inflammation that occurs after the binding of serotonin to its corresponding receptor. These results should be backed up with placebo controlled studies, which if confirmed, might imply that 5-HT3 receptor antagonists could supplement or replace the local administration of corticosteroids.