FIGURE 11.

Chronic cannabinoid receptor agonists induce receptor sensitization. Naive Jurkat cells expressing CB2 (A) and IL-4-stimulated Jurkat cells expressing CB1 and CB2 (B) were preincubated for 8 h with cannabinoid receptor agonists (MAEA, 500 nm; JWH015, 250 nm), antagonists (AM281, 500 nm; AM630, 500 nm), or vehicle at 37 °C. Then cells were washed three times for 5 min with phosphate-buffered saline (0 °C) and then incubated for another 15 min in a 37 °C water bath with cannabinoid receptor agonists, antagonists, or vehicle, as indicated. Then cells were lysed, and cAMP was determined. All of the samples are compared with controls (100%) that were identically preincubated for 8 h, washed, and incubated for 15 min with vehicle. The asterisks define samples that are significantly different from these controls. Secondary comparisons are indicated by brackets. The data represent the means ± S.E. of at least three individual experiments performed in duplicate. *, p < 0.05; **, p < 0.01; ***, p < 0.001.