Nociplastic pain Tourniquet-induced chronic post-ischemic pain (CPIP)

Background information: Chronic post-ischemic pain (CPIP) induced by a 3h- tourniquet placement in the rat ankle joint is a well-characterized preclinical model of complex regional pain syndrome (CRPS), manifested by acute hindpaw inflammation and long-lasting referred pain (hypersensitivity to acute application of noxious (hyperalgesia) and non-noxious (allodynia) stimuli to the hind paw).

Animals: Wistar rats.

Efficacy test: The efficacy of drugs (systemic or topical administration) can be evaluated after acute administration during the period of stable allodynia (approximately between days 7 and 14 after tourniquet placement) (acute analgesic effect), or after repeated treatment in a preventive protocol (preventive or disease-modifying effect). Efficacy evaluation of drug combinations is also possible, including isobolographic analysis of the interaction.

Assessments: Mechanical allodynia is evaluated by measuring hind paw withdrawal threshold (g) in response to mechanical (von Frey test) stimulation.

Positive control: Pregabalin (acute analgesic efficacy)

Criteria for significance: ANOVA followed by Tukey’s test is applied for comparison between the vehicle and treatment groups. Significant activity is considered at the P<0.05 level.

Turnaround time: xx Days.