Fig. 11. Assessment of peripheral opioids distribution in early (A ) and later (B ) phases of neuropathic pain in C57BL/6C and nonobese diabetic-severe combined immune deficiency (NOD-SCID) mice. The opioid receptor antagonist (subcutaneous 5 μg naloxone methiodide) exacerbated thermal hyperalgesia at the later phases, after partial sciatic nerve ligation (PSNL) in wild-type C57BL/6C mice but not in NOD-SCID mice. Results are expressed as mean ± SD. For each data set, n = 8. *P < 0.05 for naloxone versus vehicle; paired t tests.