Persistent cardiovascular and behavioral nociceptive responses to subcutaneous formalin require peripheral nerve input

摘要: Hindpaw injection of formalin produces acute (Phase 1) and persistent 2) nociceptive behaviors. This model has provided critical evidence supporting a contribution central sensitization (hyperexcitability spinal neurons) to the expression pain. Here, we evaluated ongoing peripheral nerve inputs Phase 2 pain responses. In addition behavior (flinching), measured formalin-evoked increases in arterial pressure heart rate; these cardiovascular responses were also biphasic nature. The response correlated highly with behavior, was dependent on concentration (0.625-5.0%), indicating that it largely driven by noxious input. Lightly anesthetized (0.7% halothane) rats exhibited robust blood absence did not reflect somatomotor-cardiovascular coupling. Animals obtained from Charles River slightly larger flinching rate compared those Bantin Kingman, suggesting cardiovascular-related can vary source animal. We next activity pressor, tachycardia, flinch After 1 subsided, but before began, locally ipsilateral or contralateral (control) hindpaw hydrophilic lidocaine derivative, QX-314 (2%). Intraplantar blocked tachycardia behavioral only when injected into paw received (2.5% 10.0%). conclude afferent fibers during is required for evoked formalin.