Figure 2.

Effect of the selective CB₁ receptor agonist ACEA (50 μg) and the selective CB₂ receptor agonist JWH-015 (50 μg) on λ-carrageenin (CAR)-induced mast cell activation. In panel (a) is shown a representative histological analysis of mast cells present in granulomatous tissue. Mast cells were evaluated in paraffin sections stained with 0.05% (w v⁻¹) toluidine blue and counterstained with 0.1% (w v⁻¹) nuclear fast red (magnification × 100). The square panel is an enlargement showing the differences between not degranulated (deep blue) and degranulated (light blue) mast cells. In panel (b) is shown the total number of mast cells; in panel (c) the percentage of mast cell degranulation (the ratio between not degranulated and degranulated mast cells) is shown; in panel (d) is shown the percentage of the β−hexosaminidase release, as a specific marker of mast cell degranulation. Ketotifen (KET; 50 μg) was used as a positive control. Results are expressed as mean±s.e.m. of three separate experiments. ^*P<0.05, ^**P<0.01, ^***P<0.001 vs saline; °°°P<0.001 vs λ-carrageenin alone.