PR002032 (Project)

Description:CNS injuries of the anuran amphibian, Xenopus laevis, are uniquely befitted for studying the molecular compositions of neuronal regeneration of retinal ganglion cells (RGC) due to a functional recovery of optic axons disparate to adult mammalian analogues. RGCs and their optic nerve axons undergo irreversible neurodegeneration in glaucoma and associated optic neuropathies, resulting in blindness in mammals. Conversely, Xenopus demonstrates RGC lifetime-spanning regenerative capabilities after optic nerve crush, inciting opportunities to compare de novo regeneration and develop efficient pharmaceutical approaches for vision restoration. Studies revealing metabolome alterations during optic nerve regeneration are sparse and could serve as a solid foundation for these underlying molecular changes. We profile the metabolite changes in the optic tissues of a transgenic line of 1 year old Xenopus laevis Tg(islet2b:gfp) frogs that either had a monocular surgery of either a left optic crush injury (crush) or sham surgery (sham). The matching controls of uninjured right optic nerves were also collected (control). Tg(islet2b:gfp) frogs were allowed to recover for 12 and 27 days post optic nerve crush. Following euthanasia, the tissues were collected for metabolomic analysis. Samples were pooled for each category (crush, sham, and control) at n =3 to obtain sufficient metabolite concentrations for analysis. Metabolites were extracted using a Precellys Homogenizer and a serial extraction method: (1) 1:1 Methanol/Water and (2) 8:1:1 Acetonitrile/Methanol/Acetone. Metabolites were analyzed by untargeted liquid chromatography-mass spectrometry (LC MS-MS) profiling using a Q-Exactive Orbitrap instrument coupled with Vanquish Horizon Binary UHPLC LC-MS system. Metabolites were identified and quantified using Compound Discoverer 3.3 and isotopic internal metabolites standards.