Figure 1.

The impact of cGMP signaling on RGC function and the retinal neurovascular unit.

(A) Dysfunctional cGMP signaling in mice leads to increased RGC degeneration with age. (B) Mice that have disrupted cGMP signaling exhibit aberrant astrocyte morphology, with areas of dense matting of astrocytic networks around retinal blood vessels. Furthermore, retinal blood vessels appear dilated compared to wild-type animals. (C) In healthy wild-type mice, astrocytes express a moderate amount of Cx43 that only slightly decreases with age. In mice with dysfunctional cGMP signaling, astrocytes express less Cx43, with increased loss with age. In the presence of dysfunctional cGMP, astrocytes express higher levels of GFAP, a marker correlated with increased astrocyte reactivity. cGMP: Cyclic guanosine monophosphate; Cx43: connexin-43 protein; GFAP: glial fibrillary acidic protein; RGC: retinal ganglion cells.