GPR6 is an orphan receptor which has been associated with Parkinson's disease. CBD acts as inverse agonist of GPR6, suggesting therapeutic potential to treat Parkinson's disease.
GPR3 and GPR6 have been previously linked to Alzheimer's and Parkinson's diseases. These receptors share about 35% of amino acid sequence with CB1 and CB2. CBD acts as an inverse agonist for these receptors as it has been shown in a β-arrestin2 recruitment assay (Laun & Song, 2017).
Laun, A. S., & Song, Z.-H. (2017). GPR3 and GPR6, novel molecular targets for cannabidiol. Biochemical and Biophysical Research Communications, 490(1), 17-21. https://doi.org/10.1016/j.bbrc.2017.05.165