FIGURE 2.

Enduring potentiation of CCI active (dark) phase voluntary wheel running by 5 days of systemic morphine co-administered with systemic P2X7 or TLR4 inhibitors; no such change in the absence of morphine. In unilateral CCI rats, systemic co-administration of 5 days of morphine with either (+)-NLX (non-opioid TLR4 antagonist) or A438079 (P2X7 antagonist) (vertical gray bar) resulted in enhanced active phase running distance (a) and maximum running speed (b), relative to CCI rats treated with morphine plus saline (vehicle). This potentiation of voluntary wheel running continued through the 5-week observation after all drug dosing ceased. No such potentiation of running behavior was observed in response to identical A438079 or (+)-NLX dosing (vertical gray bar) in the absence of co-administered morphine (c, d). n = 5–6 per group