BACKGROUND: Atherosclerosis is a common chronic disease characterized by the formation of atheromatous plaques and endothelial dysfunction. Endothelial-to-mesenchymal transition (EndMT) has been identified as a crucial driver of atherosclerosis, with TGF-β serving as a pivotal mediator of EndMT. Isoforskolin (ISOF), derived from the plant Coleus forskohlii, is an effective activator of adenylyl cyclase (AC). AC can catalyze the production of cyclic adenosine monophosphate (cAMP), mediating various biological functions. Several phosphodiesterase (PDE) inhibitors that degrade cAMP have been clinically utilized in the treatment of atherosclerosis. However, the evidence regarding the efficacy and mechanisms of AC agonists in the treatment of atherosclerosis remains inadequate. PURPOSE: In this study, our primary objective was to examine the therapeutic impact of ISOF on atherosclerosis and elucidate its potential mechanisms. METHODS: Male ApoE RESULTS: ISOF effectively inhibited atherosclerotic plaque progression and improved aortic vasodilatory function in ApoE CONCLUSION: The study showed that ISOF effectively combats atherosclerosis by inhibiting EndMT through the regulation of the AC5-dependent cAMP/PKA/TGF-β axis. This finding suggests a potential promising therapeutic strategy for treating atherosclerosis.