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Objective To investigate the expression of Nogo-A in the retinal ganglion cells (RGCs) and their axons of mouse embryos and its time course changes. Methods Sections of retinofugal pathway of C57 mouse embryos at different developmental stages were immunostained with Nogo-A specific antibody and observed by a confocal microscopy. The identity of Nogo-A positive cells was partially revealed by double-staining together with Tuj-1. Results At the early stage of E12, Nogo-A was densely expressed in some radially-orientated cells in retina. The immunopositive signals appeared in the cytoplasm, on the cell membrane and axons. The double-labeling together with Tuj-1, a neuronal marker, showed that nearly all the RGCs and their axons expressed Nogo-A protein. At the later stage of E13, the number of Nogo-A positive neurons in retina decreased dramatically. And those Nogo-A positive RGCs were specifically located in the ventricular part and the ciliary margin zone of the retina. At this stage, only a very few axons maintained their Nogo-A expression in the fiber layer of the retina, while most lost their Nogo-A distribution. When most RGCs had fully differentiated at E15, there was no detectable Nogo-A immunopositive staining in the retina and only a few retinal fibers were Nogo-A immunopositive. The similar expression patterns of Nogo-A was found in a few axons along the optic disc, optic stalk, optic chiasm and optic tract. Worthy of note, the retinal axons with Nogo-A distribution in the optic tract were exclusively found in the superficial area, where the newly-arrived axons were traveling through during development. Conclusion The expression pattern and its time course change suggested that Nogo-A was an important protein expressed by the newly differentiated RGC neurons and their projecting axons, whilst the mature RGCs down-regulated their expression. Nogo-A in the new born RGCs might play some cell-intrinsic roles such as decreasing axon branching in vivo.
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BACKGROUND: The environmental change of regeneration of peripheral nerve fiber can accelerate the regeneration of nerve fiber and the recovery of nerve function. Physiotherapy can improve the local microcirculation of the injured area, and promote and stimulate the recovery course of trauma. Therefore, whether choosing different physiotherapies and controlling irradiation dose can speed up the regeneration of nerve fiber?OBJECTIVE: To observe the effects of different physiotherapies in promoting the regeneration of injured nerve fiber.DESIGN:Randomized grouping and controlled animal experiment.SETTING: Laboratory of Anthropotomy and Histo-Embryology Department,Peking University Health Science Center.MATERIALS: The experiment was conducted in the Laboratory of Anthropotomy and Histo-Embryology Department, Peking University Health Science Center, from September 2001 to September 2002. Fifteen adult male SD rats, weighting 185-220 g, were selected.INTERVENTIONS: The model of sciatic nerve injury was established and randomly assigned to 3 groups. Bio-spectrum group and infrared group with 5rats in each received the corresponding physical irradiation. Injury control group was given no irradiation. The slices of sciatic nerve at the operation side of the animals in the three groups were collected on day 14 after operation. The degeneration rate of the injured nerve fiber was observed under the optical microscope to make indirect assessment of the protective effect of physiotherapy after the nerve was injured.MAIN OUTCOME MEASURES: The degeneration rate of nerve fibers at the breakpoint and at 4 points near the spinal cord ( 1,2,3,4 mm) and away from the spinal cord( 1,2,3,4 mm).difference in the degeneration rate of nerve fibers at the breakpoint away from the spinal cord in bio-spectrum group and infrared group as compared with the degeneration rate of nerve fibers in bio-spectrum group(68% ) and infrared group(89% ) was obviously reduced and that in control group was the the spinal cord in the 3 groups showed decreasing trend: the closer to the spinal cord, the fewer the degenerative nerve fibers. The number of degenerative nerve fibers was the smallest in bio-spectrum group, second smallest in infrared group, and the largest in control group.CONCLUSION: The assisting physiotherapy can decrease the number of regenerative nerve fibers, thus promoting and accelerating their recovery. Irradiation with bio-spectrum equipment is more effective.
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Objective To study the distribution of Nogo-A in the retina and the changes after the optic nerve(ON) injury in hamsters. Methods In this experiment,ON was crushed at 2?mm behind of the eyeball.After 3?d,5?d and 7?d post-axotomy,the Nogo antiserum immunoreactive staining on section of the retina was performed. Results Nogo was expressed at every layer of the retina with the strongest expression on 3?d post-axotomy.The numbers of Nogo-A positive RGCs decrease as the survived time increased.Conclusion Nogo-A in the retina is not unique secretion from the neuroglia.The change in the distribution and level of expressed of Nogo-A in the retina is correlated with time advancement after injured of ON.
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Objective To observe the expression of the small heat shock protein (HSP27) in the optic chiasma (OC), optic tract (OT), dorsal lateral geniculate body(LG) and superior colliculus (SC) of the adult golden hamster after intraorbital transection of the left optic nerve (ON). Methods The experimental animals were left to survive for l, 2, 3, 4, 5, 6, 8 weeks following ON transection. The animals were perfused with formol-saline and brains were excised, sectioned and stained with the immunohistochemistry. The sections were observed under the light microscope, the optical density (A) was measured and the data were analysed statistically. Results Immunohistochemical results indicated that the HSP27-expressions were not different between the right and left side of the OC, OT, LG and SC in normal or sham-operation controls. However, following transection of the left ON, HSP27 immunohistochemical stainings in the right site of OC, OT,LG and SC were increased, comparing with the left side. The maximum difference of HSP27 immunostaining between the right and left side appeared in the lst week following left ON axotomy. The sharply decrease of the A difference occurred at the 2nd week after axotomy with insignificant changes in the subsequent several weeks. And the significant A difference was observed in most time except 6th week. Most of HSP27-positive cells had morphological appearances similar to astrocytes with smaller cell body and numerous processes. Conclusion After the transection of monolateral ON, HSP27 expressions in the contralateral optic pathway of brain increased and persisted up to 8 weeks. This result suggested that the increase of HSP27 expression had something to do with the injury of the optic pathway, but the mechanism and biological significance of the increase in HSP27 expression level required to be studied further.;
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Objective To study methylprednisolone's effect of up-regulation of Hsp27 on provocation and enhancement of self-protection and self-repair to injured central nerves,and if the injured nerves can get protection in early period,and therefore benefit injured central nerves'survival and regeneration. Methods Optic nerve axotomy was used in the experiment.The animals survived for 4,7,14,21,28 days respectively after surgery with and without MP treatment.The retinas were taken out and cut,then the number and morphological changes of RGCs with Nissl staining and the expression of Hsp27(optic density) in ganglion cell layers with immunohistochemical staining were observed respectively.The data were analysed with SAS soft ware. Results The quantity of the surviving retina ganglion cells increased in the group with high-dose intravenous methylprednisolone treatment at 7th and 14th days(P