It seems that COX-2 and its major products, i.e. prostaglandins (PGs), have an important role in neurotransmitter release and PD-associated rigidity as reported in previous works (4, 5, 17, 22), suggesting that COX-2 causes increased levels of acetylcholine in brain via the production of PGE2 and increases in expression of cholinergic markers, such as choline acetyl transferase and vesicular acetylcholine transporter protein. This evidence concerns the gene SLC18A3 and Parkinson disease.