Background information: Chronic neuropathic pain induced in rats by transection of the common peroneal and tibial branches of the sciatic nerve has become one of the standard models for mechanistic studies of peripheral neuropathy and for the screening of novel analgesic compounds. Neuropathy is manifested by robust and long-lasting referred pain (hypersensitivity to acute application of noxious (hyperalgesia) and non-noxious (allodynia) stimuli) in the skin territory of the spared, intact sural nerve.

Animals: Wistar rats.

Efficacy test: The efficacy of systemic administered drugs can be evaluated after acute administration during the period of stable allodynia (approximately between days 14 and 28 after nerve damage) (acute analgesic effect), or after repeated treatment in a preventive or curative protocol (disease-modifying effect, analgesia potentiation or tolerance). 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. Additional readouts can also be evaluated (i.e., cold allodynia) (not validated).

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.