DRD1 and attention deficit-hyperactivity disorder: In addition, a significant DRD1/DRD2 imbalance was found in the brain tissue of SHRs, and the cAMP/PKA signaling pathway was in a downregulated state; tomoxetine (a non-neuroleptic stimulant for ADHD) or Jingning granules (an herbal prescription) rescued the DRD1/DRD2 imbalance by activating the cAMP/PKA signaling pathway, thereby improving behavioral and cognitive function in SHRs (Ding et al., 2022).