Figure 3

Reactive p27^L-/L- Müller glia maintain neuronal metabolic support. (A) Schematic of neuron-glia metabolic interaction via the glutamate-glutamine cycle. (B-E) Differential metabolite content of cells in p27^L-/L- retina visualized and quantified using computational molecular phenotyping (CMP). Plasticized tissue was serially sectioned at 200 nm, probed with specific anti-hapten IgGs, and visualized with silver-intensification of 1.4 nm gold granules coupled to species-specific secondary IgGs. Each metabolic map was captured as a high-resolution, monochrome image. (F-G) Metabolic mapping of tamoxifen control and experimental retina at the peak of GFAP expression (6 weeks after tamoxifen injections). Red-green-blue channels represents taurine-glutamate-glutamine mapping highlighted with GLUL as an alpha-channel. RGB images with alpha channels were prepared with Adobe Photoshop CS3. The yellow background is the distinctive taurine-glutamine signature of Müller glia. The pink and red compartments in the photoreceptor outer segments (OS) and inner segments (IS) contain distinct taurine-glutamate-glutamine mixtures. While various blue-to-azure cells in the interneuron layer (INL) and ganglion cell layer (GCL) are neurons with distinctive glutamate-glutamine mixtures. (H) Metabolite pixel value in Müller glia was extracted using the GLUL signal. Data are expressed as the mean ± SD. There was no statistically significant difference between tamoxifen control animals (n = 3) and experimental p27^L-/L- animals (n = 3). Asterisks, arrows and arrowheads indicate blood vessels, endfeet and somas, respectively. Additional abbreviations: CRALBP, cellular retinaldehyde-binding protein; GSH, glutathione.