Materials
AT-403 (2-(1-(1-((1s,4s)-4-isopropylcyclohexyl)piperidin-4-yl)-2-oxoindolin-3-yl)Nmethylacetamide) was synthesized by Dr NT Zaveri at Astraea Therapeutics (Mountain View, CA, USA) (Arcuri et al. , 2018). CCG-203920 (4-(2-(methoxyethyl-)-2-ethyl-1,2,4-thiadiazolidine-3,5-dione) was synthesized by the Medicinal Chemistry Core at Michigan State University (East Lansing, MI, USA). L-Dopa and benserazide were purchased from Sigma-Aldrich (Milan, Italy). 6-OHDA hydrobromide and N/OFQ were purchased from Tocris Bioscience (Bristol, UK). U1079 antibody was a generous gift of Dr S Mumby (University of Texas Southwestern, Dallas, TX, USA). AT-403 was dissolved in 2% CH3COOH 1M and 4% DMSO water, L-DOPA, benserazide and CCG-203920 were dissolved in saline, 6-OHDA was dissolved in saline with 0.02% ascorbic acid. N/OFQ and SKF-38393 were dissolved in water. LANCE Ultra cAMP assay was purchased from Perkin Elmer (Waltham, MA). All plasmids were purchased from cDNA Resource center (Bloomsburg, PA, USA).