MC5R and diabetic retinopathy: Furthermore, in mice with STZ-induced diabetic retinopathy, intravitreal injection of the MC5R peptidomimetic agonist PG-901 attenuated, while MC5R antagonist PG20N augmented, retinal release of various inflammatory cytokines, such as IL-1α, IL-1β, IL-6, MIP-1α, MIP-2α, and MIP-3α (Rossi et al., 2016).