Figure 1. Endocannabinoids can be synthesized from exogenous ARA by RBL-2H3 cells.

RBL-2H3 cells were incubated with 1 nM [³H] ARA for 24 hours. Cells were washed and pre-treated with 100 μM AM404 for 10 min at 37 °C or KRH buffer without AM404. Cells were then treated either with buffer or 1 μM ionomycin for 10 min at 37 °C in order to stimulate AEA (A) and 2AG (B) synthesis and release, or ARA (C) release. The reaction buffer was collected, and the lipids were separated and analyzed as described in Materials and Methods. One-way ANOVA with Newman-Keul’s post-hoc test was performed for statistical analysis. * p<0.05, ionomycin vs. AM404+ionomycin. Data represent mean ± SEM from three separate experiments performed in duplicate. CPM values (means ± SEM) for [³H] AEA synthesis and release were: buffer = 87 ± 23; ionomycin = 1788 ± 736; and AM404+ionomycin = 243 ± 61. For [³H] 2-AG synthesis and release: buffer = 32 ± 6; ionomycin = 585 ± 95; and AM404+ionomycin = 138 ± 54. For [³H] ARA release: buffer = 49 ± 10; ionomycin = 166 ± 75; and AM404+ionomycin = 306 ± 143.