Changes in metabolic proteins in ex vivo rat retina during glutamate-induced neural progenitor cell induction

Mechanism of Propofol-Lidocaine Hydrochloride Nano-Emulsion on Retinal Ganglion Cytopathic Effect in Diabetic Rats

The study drew attention to the influence mechanism of propofol and lidocaine hydrochloride nanoemulsion (NE) in the retinal ganglion cell pathology in diabetic rats. Specifically, the propofollidocaine hydrochloride NE was prepared using the emulsification method. The microscope and laser particle size analyser were used to observe the morphology and particle size of NE, respectively. Also, the viscosity of the NE and the recovery rate of the main ingredient were explored. 45 adult male Wistar rats were randomly divided into control group (PBS control), model group (diabetes model), and test group (diabetes model+propofol-lidocaine hydrochloride NE), with 15 rats in each group. The three groups were compared for the blood glucose, body weight, TNF-α and IL-1β mRNA levels in retinal tissue, and the number and apoptosis rate of ganglion cells. It was found that the average particle size of the NE was 89.76 nm, the maximum absorption wavelength was 280.0 nm, and the viscosity was 106.49 N/m/s. The average recovery rate of propofol in NE was 99.91%, and that of lidocaine hydrochloride was 99.80%. At 12th week after modeling, the blood glucose of the test group was lower versus the model group (P < 0.05); the blood glucose and body weight of rats in the control group were lower than those in the other two groups (P < 0.001). The test group exhibited lower mRNA levels of TNF-α and IL-1β and apoptosis index of retinal ganglion cells versus the model group (P < 0.05). The model group showed a lower number of retinal ganglion cells versus the other two groups (P < 0.05). It was inferred that propofol-lidocaine hydrochloride NE of a small particle size and good syringeability can notably reduce blood glucose, TNF-α and IL-1β mRNA levels, and retinal ganglion cell apoptosis index, and at the same time increase the number of retinal ganglion cells.

Altered Energy Metabolism During Early Optic Nerve Crush Injury: Implications of Warburg-Like Aerobic Glycolysis in Facilitating Retinal Ganglion Cell Survival

Neurons, especially axons, are metabolically demanding and energetically vulnerable during injury. However, the exact energy budget alterations that occur early after axon injury and the effects of these changes on neuronal survival remain unknown. Using a classic mouse model of optic nerve-crush injury, we found that traumatized optic nerves and retinas harbor the potential to mobilize two primary energetic machineries, glycolysis and oxidative phosphorylation, to satisfy the robustly increased adenosine triphosphate (ATP) demand. Further exploration of metabolic activation showed that mitochondrial oxidative phosphorylation was amplified over other pathways, which may lead to decreased retinal ganglion cell (RGC) survival despite its supplement to ATP production. Gene set enrichment analysis of a microarray (GSE32309) identified significant activation of oxidative phosphorylation in injured retinas from wild-type mice compared to those from mice with deletion of phosphatase and tensin homolog (PTEN), while PTEN-/- mice had more robust RGC survival. Therefore, we speculated that the oxidation-favoring metabolic pattern after optic nerve-crush injury could be adverse for RGC survival. After redirecting metabolic flux toward glycolysis (magnifying the Warburg effect) using the drug meclizine, we successfully increased RGC survival. Thus, we provide novel insights into a potential bioenergetics-based strategy for neuroprotection.

Up-regulation of the pentose phosphate pathway and HIF-1α expression during neural progenitor cell induction following glutamate treatment in rat ex vivo retina

The metabolic state influences the regulation of neural stem/progenitor cells. The pentose phosphate pathway (PPP), an alternative metabolic pathway that operates parallel to glycolysis, not only provides key intermediates for biosynthetic reactions but also controls the fate of neural stem/progenitor cells. We have previously shown that glutamate application leads to the induction of neural progenitor cells in mature ex vivo rat retina. In this study, we investigated whether regulation of the PPP might be changed following glutamate treatment of the retina. Immunoblot analysis revealed that the amount of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the PPP as well as that of 6-phosphogluconate dehydrogenase (6PGD), another enzyme in this pathway, increased in the glutamate-treated retina. Consistent with the fact that both these enzymes generate reduced nicotinamide adenine dinucleotide phosphate (NADPH), the amount of NAPDH in the treated retina was significantly higher compared with that in the untreated retina. We also found that both DNA synthesis as well as the expression of fatty acid synthase (FASN) increased significantly in the glutamate-treated retina. Furthermore, hypoxia-inducible factor 1-α (HIF-1α), a positive transcriptional regulator of PPP enzymes, was up-regulated at both messenger RNA (mRNA) and protein levels. Finally, we found the interaction of HIF-1α with the M2 isozyme of pyruvate kinase (PKM2), with this interaction having been shown to contribute to a positive feedback loop in the control of glycolysis. Our results thus show that specific metabolic change in the PPP occurs in the process of neural progenitor cell induction in the mature rat retina.

A novel mutation of PANK4 causes autosomal dominant congenital posterior cataract

Though many mutations have been identified to be associated with the occurrence of congenital cataract, pathogenic loci in some affected families are still unknown. Clinical data and genomic DNA were collected from a four-generation Chinese family. Candidate mutations were independently verified for cosegregation in the whole pedigree. Linkage analysis showed that the disease-causing mutation was located between 1p36.21 and 1p36.33. Analysis of the whole-exome sequencing data combined with linkage analysis identified a novel pathogenic variant (g.2451906C>T) at intron 4 of Pantothenate kinase 4 (PANK4 protein, PANK4 gene) in 1p36.32|606162. This variant showed complete cosegregation with the phenotype in the pedigree. The mutation was not detected in 106 normal controls nor in 40 sporadic congenital cataract patients. The mutation was demonstrated to significantly reduce the expression of the PANK4 protein level in the blood of cataract patients than that in normal individuals by ELISA. Pank4^-/- mice showed a cataract phenotype with increased numbers of apoptotic lens epithelial cells, fiber cell aggregation, and significant mRNA variation of crystallin family members. Thus, the association of a new entity of an autosomal dominant cataract with mutations in PANK4, which influences cell proliferation, apoptosis of lens epithelial cells, crystallin abnormalities, and fiber cell derangement, subsequently induces cataract.