Fig. 4 RA signaling inhibits and the ECS enhances osteoclast development. Zebrafish larvae were treated between 12 and 14 dpf with DEAB, RA, RIMO, OLE, and WIN and active osteoclasts were stained at 14 dpf with TRAP (A?F). DEAB or OLE treatment increased TRAP labeled osteoclasts (B,E), whereas RA or RIMO decreased stained cells (C,D). A medaka line with a cathepsin k promoter driving GFP was used to assess osteoclast development in neural arches at 21 dpf following 2 days of treatment (G?L). RA treatment decreased detectable osteoclasts (H,L). DEAB or WIN treatment increased osteoclast abundance (I,J,L). RIMO treatment showed no effect on osteoclasts (K,L). Length of fish, as a measure of developmental defects from treatments, was not different between treatment groups and controls (M). *<0.001, # = 0.153, + = 0.053. n = 8 for TRAP staining, n = 8?12 for neural arch assessments, n = 3?6 for length measurements.
Reprinted from Molecular and Cellular Endocrinology, 529, Fraher, D., Mann, R.J., Dubuisson, M.J., Ellis, M.K., Yu, T., Walder, K., Ward, A.C., Winkler, C., Gibert, Y., The endocannabinoid system and retinoic acid signaling combine to influence bone growth, 111267, Copyright (2021) with permission from Elsevier. Full text @ Mol. Cell. Endocrinol.