Figure 1.

Experimental design for animal model, behavioral studies, and biochemical and molecular analysis. In the first experiment, we evaluated pain threshold following cafeteria diet and during abstinence period. Rats were fed with chow only (CO) or fed 24 h with both chow and extended access to cafeteria diet (EA) for 40 days. On day 41, EA group was fed with only chow until day 68. Pain behavioral tests and Western blot analysis were performed on days 40, 54, and 68. In the second experiment, the CO and EA groups were treated with a selective FAAH inhibitor, PF-3845 (10 mg/kg, IP) from days 41 to 68. Pain behavioral tests were performed on days 54 and 68. Moreover, in the third experiment, at day 54, CB-1 and mu-opioid receptor antagonists were administrated 1 h before performing hot plate test.