Limonene, a natural cyclic terpene, is an agonistic ligand for adenosine A2A receptors

► Limonene exhibits selective affinity to A2A receptors. ► Limonene increases cytosolic cAMP concentration and induced activation of protein kinase A. ► Limonene induces phosphorylation of cAMP-response element-binding protein. ► Limonene increases cytosolic calcium concentration.