Intrathecal Resiniferatoxin Modulates TRPV1 in DRG Neurons and Reduces TNF-Induced Pain-Related Behavior

Figure 2

Influence of intrathecal administration of TNF and TNF + RTX on thermal hyperalgesia. (a) Administration of NaCl or RTX did not affect paw withdrawal thresholds, compared to control conditions (). (b) Two nanograms of TNF did not lead to changes in paw withdrawal thresholds 1 h, 3 h, 6 h, or 24 h after administration (). Additional administration of RTX (1.9 mg/kg) resulted in changes in withdrawal threshold over the experimental time. When TNF + RTX were administered, a significant increase of withdrawal threshold was observed after 3 (), 6 (), and 24 h (), compared to TNF administration alone. (c) Administration of TNF did not change paw withdrawal thresholds over the experimental time, compared to pretesting (). When RTX was additionally administered, paw withdrawal threshold was significantly increased (). When TNF + RTX was compared to TNF administration alone, an increase of withdrawal threshold was observed after 1 h (), 3 h (), 6 h (), and 24 h (). (d) Administration of 200 ng TNF resulted in a reduction of paw withdrawal threshold after 24 h (), while no changes were observed after 1 h, 3 h, or 6 h (). Additional RTX led to significant increase of paw withdrawal threshold 24 h after administration (). Additional RTX abolished the TNF-induced reduction of paw withdrawal threshold 24 h after administration ().

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