“The endogenous cannabinoid system plays important roles in the retina of mice and monkeys via their classic CB1 and CB2 receptors.
We have previously reported that the G protein-coupled receptor 55 (GPR55), a putative cannabinoid receptor, is exclusively expressed in rod photoreceptors in the monkey retina, suggesting its possible role in scotopic vision.
These results support the hypothesis that GPR55 plays an instrumental role in mediating scotopic vision.”