Figure 2: Prevention of the morphine-induced tolerance by LASSBio-981 or amitriptyline. Morphine was infused (2.5 mg/kg/d, i.p.) through an osmotic mini-pump during 23 days. A) Latency in response to thermal stimulation in rats submitted to SNL. B) Withdrawal threshold in response to mechanical stimulation applied to the paw of rats submitted to SNL. (⌈) LASSBio-981 (10 mg/kg), (Δ) amitriptyline (10 mg/kg) or (♦) vehicle (DMSO) was administered daily by gavage during 16 days associated with the infusion of morphine. Data represent the mean ± SEM (n = 4). *P<0.05 versus day 0; #P<0.05 versus day 7.