Fig. 3. Peripherally acting opioid receptor antagonists blocked systemic loperamide-induced reduction in allodynia.
(A) Systemic pretreatment with methyl-naltrexone (5mg/kg, i.p., n = 10) and naloxone hydrochloride (10 mg/kg, i.p., n = 6) each significantly attenuated the anti-allodynic effect of loperamide (1.5 mg/kg, s.c.) on day 7 post-SNL, compared with saline pretreatment (n = 7). (B) PWT on the contralateral side did not change significantly after drug treatment. Data are expressed as medians. *P < 0.05 versus pre-drug baseline; #P < 0.05, ##P < 0.01 versus the saline-pretreated group.