Our observation of a decrease in levels of GAPDH together with those of α- and γ-enolases suggests the operation in the retina of a feed-back negative regulatory mechanism of glycolysis in response to blockade of mitochondrial complex I. Other glycolytic enzymes downregulated in the pathological retina are aldolase C at the onset of AMD [61] and triose phosphate isomerase in alloxan-treated, DR model rats [67], while underexpressed Krebs cycle enzymes include pyruvate dehydrogenase in the midbrain of Park2 KO mice [14] and rotenone-treated rats [75]. The gene discussed is GAPDH; the disease is age-related macular degeneration.