DRD2 and cocaine dependence: Within the cocaine addiction pathway, the highest positive fold change occurred in Control weaned females for 9 of the 12 genes: adenylate cyclase 5 (ADCY5), cyclin-dependent kinase 5 regulatory subunit 1 (CDK5R1), dopamine receptor D1 (DRD1), dopamine receptor D2 (DRD2), glutamate ionotropic receptor NMDA-type subunit 2C (GRIN2C), glutamate metabotropic receptor 3 (GRM3), protein kinase CAMP-activated catalytic subunit β (PRKACB), PPP1R1B, and RGS9.