Diabetic retinopathy: Role of inflammation and potential therapies for anti-inflammation

Figure 1 The best-known cannabinoids from marijuana. (-)-Δ⁹-tetrahydrocannabinol (THC), but not cannabinol or (-)-cannabidiol (CBD), is known to exert psychotropic effects.

Figure 2 The hypothetical mechanism of anti-inflammation effect CBD in diabetic retinopathy. Diabetes causes release of adenosine and pro-inflammatory cytokines via superoxide formation and MAPK activation, leading to DR. Adenosine-initiated anti-inflammation via A_2AAR-Gs-cAMP signaling is terminated rapidly due to adenosine reuptake by equilibrative nucleoside transporter (ENT) and subsequent metabolism. CBD blocks superoxide formation and inhibits adenosine reuptake via inhibiting ENT1, thereby activating A_2AAR-Gs-cAMP signaling.