The Study Of The Protection And Mechanism Of Ciliary Neurotrophic Factor And Compound Light Granules On Traumatic Optic Neuropathies

Traumatic optic neuropathy (TON) is the injury-induced damage of the optic nervefunction that results in sudden loss of vision and can occur after direct or indirect injury.Ophthalmologically, TONs result in changes of virtually all optic nerve functions includingvisual acuity, visual fields, pupillary reflexes and funduscopically detectable morphologicalchanges. Retrograde degeneration of the RGCs is the final common outcome underlyingTON.The axon injury initiates ganglion cell disease and death. The failure of the optic nerveto regenerate after injury remains a major clinical and scientific problem. TON will directlydamage the retinal ganglion cells, lead to the degeneration and apoptosis, and ultimatelycause the loss of visual function.Improving the survival ratio of RGCs,maintaining orbuilding the structures,accelerating transportation of axonal plasm,and improving themicroenvironment for optic nerve fiber to survive or regenerate, saving the visual function ofpatients is a major issue in the contemporary nerve biomedical field.The optic nerve is composed of retinal ganglion cells (RGCs), axons and glia. Damagecan occur to any part of the optic nerve, causing partial or complete loss of visual function.Therefore, the protection of optic nerves is one of the main focuses of research in the field ofmodern visual science. Increasing attention has been paid to the diagnosis and treatment ofoptic nerve injury, and the protection of optic nerves. This study aimed to verify the effectsof ciliary neurotrophic factor (CNTF) and/or compound light granules in the treatment ofoptic nerve injury in experimental rabbit models by morphological,ultrastructure,F-VEP andbiomechanical analyses, in a broader attempt to provide biomechanical basis for clinicalpractice.1. Establishment and evaluation of TON models of rabbitsEstablishing animal models of optic nerve injury is fundamental for nerve injuryresearch. Stable and reproducible animal model of mild, medium and severe optic nervecrush was established by using the mosquito clamp.This method was very simpleand convenient. In mild injury group, changes of morphology were slight, and visual functionwas fine. In medium injury group, pathological changes of optic nerve were obvious, and theinjury deteriorated gradually within4w observing time, however, part visual functionremained. With the lapse of time, pathological changes deteriorated quickly.In severe injurygroup, changes of morphology were irreversible sooner after injury, and the visual functionlost completely.The medium optic nerve crush model can be used to observe the therapyeffect of different treatment methods of TON.2. The effects of CNTF and compound light granules on the pathological changes ofinjured optic nerve in rabbits.The rabbits were randomly divided into Group A(normal control)，B(injury group)，C(CNTF group)，D(compound light granules group) and E(CNTF and compound lightgranules group) following traumatic optic nerve injury.The morphological changes in thelongitudinal profiles of the optic nerve were observed by hematoxylin-eosin staining andoptical microscopy. In normal control group, optic nerve fibers were arranged in a regularand parallel manner, the staining was uniform, axons and other contents were clearly seenand the glia were of similar sizes. In the injury group, optic nerve fibers were thin, tortuous,irregularly arrange, and the nuclei were not uniform. At3d after injury, nucleus pyknosis ofRGC was seen in injury group, then RGC loss were seen within2w, and the thickness ofretina become thin. With the lapse of time, these changes deteriorated quickly.In the CNTFgroup, optic nerve fibers were disordered, and the optic nerve appeared healthier and thedegree of injury was lighter than the model group.In the compound light granule group, aportion of optic nerve fibers were in a disordered arrangement, there was no thinning of theoptic nerve and glial nuclei were not uniform. These pathological changes of CNTF andcompound light granules group were more obvious in injury group at each point. In theCNTF+compound light granule group, optic nerve fibers were disordered, glial nuclei weresignificantly increased and were mostly in an ordered arrangement (a small amount were stillirregular), there was no thinning of the optic nerve and the degree of optic nerve injury waslighter than the CNTF and compound light granule groups. Compound light granules andciliary neurotrophic factor can prevent retinal tissue edema and alleviate optic nerve injury at the histological level, and the combined treatment is more effective than either treatmentalone.3. The effects of CNTF and compound light granules on the ultrastructure of traumaticoptic neuropathy in rabbits at different times.Axon injury disrupts the connections of RGCs to their target, resulting in a loss oftarget-derived neurotrophic support. The molecular responses at the site of axon injuryinvolve an interruption of axonal transport. Retinal ganglion cell (RGC) axons coursethrough the optic nerve and carry all the visual information to the brain, but after injury, theyfail to regrow through the optic nerve and RGC cell bodies typically die, leading topermanent loss of vision. Retrograde degeneration of the RGCs is the final common outcomeunderlying TON.The axon injury initiates ganglion cell disease and death.In injury control group,Lamellar separation of myelin can be seen.The numberof axons reduced, and parts of them collapse.The numbers of microfilaments andmicrotubules were both reduced significantly.The mitochondrions were swelled, crest gapwidened,or totally collapsed and disappeared. With the lapse of time, these changesdeteriorated quickly.Compound light granules and ciliary neurotrophic factor can acceleratetransportation of axonal plasm and protect the microstructures of optic nerve,which isvaluable for restorating the transportation of axonal plasm. Compound light granules andciliary neurotrophic factor can alleviate optic nerve injury at the ultrastrucure level, and thecombined treatment is more effective than either treatment alone.4. The effects of CNTF and compound light granules on the Flash visual evobepotentials of traumatic optic neuropathy in rabbits at different times.The bright flash VEP uses full-field illumination and elicits a mass response from theanterior visual pathway. Thus, responses from abnormal regions of the field are summedwith those from normal regions.In normal group, the latency of P1wave was32.19±1.88ms，and the amplitude of P1wave was21.24±1.78μv. F-VEP of the healthy rabbits revealed typical PNP contours, whilethe waves in the injureded groups were low and flat.The latency period of P1waves waslengthened and the amplitude reduced. The delay of P1wave latency was found in injury group at3days、1week、2weeks and4weeks after injury compared with normal group,CNTF,compound light granule and CNTF+compound light granule groups and the amplitude waslower than normal group(P<0.05).5. The effects of CNTF and compound light granules on the biomechanical changes ofinjured optic nerve in rabbits.Under normal physiological conditions imposed by posture and movement, nerves areexposed to various mechanical stresses. Optic nerves extremity need toaccommodate a vastarray of mechanical stresses associated with the diverse repertoire of human movementrelated to function and participation in daily activities. The structural elements of optic nervemust support the ultimate function of conduction of electrical impulses through myriadpositions, postures, and movements that often stress the nerves over multiple limb segmentsand joints simultaneously. At a point, the amount of applied load starts to permanentlydeform particular elements of the nerve.Tensile test showed that the maximum tensile load, stress and strain, and the elasticlimit load, stress and strain of the optic nerve in the normal control group were significantlyhigher than those in the model, CNTF, compound light granule and CNTF+compound lightgranule groups (P <0.05). Compared with model group, the above indexes were increased inthe CNTF, compound light granule and CNTF+compound light granule groups, with themost significant difference in the CNTF+compound light granule group (P<0.05). Wecould see that the normal optic nerve had the strongest tensile bearing capacity, followed bythe injured optic nerve in the CNTF+compound light granule group, the injured optic nervein the compound light granule group, and the injured optic nerve in the CNTF group. Theinjured optic nerve in the model group without any treatment had the weakest tensile bearingcapacity. These experimental findings indicate that compound light granules and ciliaryneurotrophic factor can alleviate optic nerve injury at the biochemical level, and thecombined treatment is more effective than either treatment alone.This experiment study the effects of ciliary neurotrophic factor (CNTF) and/orcompound light granules in the treatment of optic nerve injury in experimental rabbit modelsby morphological、ultrastructure、F-VEP and biomechanical analyses. The present study found that CNTF and compound light granules play an important role in neural activity.CNTF and compound light granules can promote the survival of a variety of retinal ganglioncells and nerve fibers，and is important for nervous system development, differentiation andrestoration after clamp injury. CNTF and compound light granule promote RGCs survivaland growth in vitro, significantly delay RGCs death after optic nerve crush injury, andimprove survival rate. In summary,these studies detecte the relevant factors using animalmodel to prove that CNTF and compound light granules can increase the activity of RGCsand promote the growth of processes,and protect the injured RGCs with anti-apoptoticpathways and increase the amount of growth associated protein to promote the regenerationof processes. Provide a better experimental basis and theoretical basis for more in-depthstudy of traumatic optic neuropathy, also provide a new direction and possibilities for itstreatment.