Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Randomized Controlled Trial Controlled Clinical Trial
Effects of NGF-induced muscle sensitization on proprioception and nociception.
Temporomandibular disorders (TMDs) are associated with perturbation of proprioceptive and nociceptive function. Recent studies have shown that injection of the neurotrophic protein nerve growth factor (NGF) into the masseter muscle causes sensitization to mechanical pressure stimuli; however, it is not clear if vibration sense and jaw stretch reflexes as measures of proprioceptive function as well as glutamate-evoked pain are also altered. We tested the hypothesis that NGF-induced mechanical sensitization would be associated with changes in vibration sense and stretch reflex sensitivity as well as facilitation of glutamate-evoked pain responses. ⋯ In conclusion, this study confirms that masseter muscle injection of NGF is associated with a distinct and prolonged sensitization to mechanical stimuli, but without an effect on large-diameter mechanoreceptive and the muscle spindle afferents. Additional challenge of the NGF pretreated muscle with glutamate did not indicate a conspicuous sensitization to noxious chemical stimuli. These findings are discussed in terms of the concept of "proprioceptive allodynia".