Experimental And Clinical Study Of Optic Nerve Protection Of Astragalus Membranaceus

Part One The experimental study of astragalus on optic neuroprotectionObjective:To observe the regulating effects of astragalus on nerve growth factor and its receptor in rat retinal tissue on the basis of creating a stable and reliable animal model on optic nerve injury, and to investigate the molecular mechanism of the protective effect of astragalus on optic nerve.Methods:Firstly, an animal model of optic nerve injury was built by using the transverse quantitative traction method. And then, using the method of fluorogold stereotaxic injection to label retrogradely retinal ganglion cells, to detect the survival rate of RGCs. Finally, to evaluate the feasibility of the animal model which was made by the method of transverse quantitative traction. After successful modeling, the rats were randomly divided into 3 groups as following:sham operation group, model group and astragalus treatment group. Sham operation group, no drug treatment; model group were given with normal saline by intraperitoneal injection, and treatment group were given with astragalus membranaceus injection for testing.14 days later, the changes of expression of nerve growth factor and its receptor related protein, genes in rat retinal tissue were detected with Western blot, real-time PCR, ELISA and EMSA experimental methods, and to compare the differences between groups.Results:(1) Model evaluation results:In the normal control group, the RGCs labeled by the fluorescent gold are round or oval, clear boundary, no obvious fluorescent dye leakage and partially visible cell processes. However, in the optic nerve traction groups, the number of RGCs decreased with time increasing and the cell distribution was not uniform; and a lot of fluorescent leakage and microglial cells were observed. Compared with the normal control group (right eye), there was no significant difference in the density of RGCs of sham operation group(left eye that only exposed the optic nerve) (P=0.283>0.05), showed that the nerve injury was not caused by optic nerve exposure. While, in the 1d,3 d,7d and 14d after traction of the optic nerve groups, the number of RGCs was reduced gradually and the density of RGCs of the left eye was significantly lower than that in the normal control group (P<0.01); And the survival rate of RGCs were decreased progressively(78.94%,60.07%, 38.32%,17.31%,P<0.01), showed the injury progress of RGCs. (2) Experimental results of molecular mechanism:After optic nerve injury, the expression level of NGF, TrkA and NFκB in the operative eyes of model group significantly reduced compared with the normal control eyes(P<0.05); Moreover, the protein expression of JNK, P-JNK and the mRNA levels of p75NTR were significantly higher than those of non operative eyes(P<0.05). After 14 days of treatment with astragalus membranaceus injection, the protein expression of NGF and its high affinity receptor TrkA were higher than that of model group(P<0.05); the gene expression of p75NTR that low affinity receptor of NGF and the protein expression of its intracellular pro-apoptotic signal JNK, P-JNK were decreased(P<0.05); And that, the protein expression of anti-apoptotic signal NFκB was significantly increased compare with the model group(P<0.05). The result suggested that astragalus membranaceus injection has the function of protecting optic nerve.Conclusions:(1)The transverse quantitative traction method can establish a model of easily quantifiable optic nerve injury, which occurred retinal ganglion cell death since the first day after damage, and with the passage of time, the degree of injury gradually worsened, the number of RGCs decreased gradually. Therefore, it can be used as a stable and reliable animal model for further study on the mechanism and treatment of optic nerve injury. (2) Astragalus membranaceus has the function of protecting optic nerve, its possible mechanism are as follows:① Astragalus could promote the expression of NGF in the retinal tissue of rats whose optic nerve injure, and increase the expression of NGF and its high affinity receptor TrkA, so as to stimulate the mechanism of nerve regeneration which was mediated by the combination of the nerve growth factor and TrkA receptor. ② Astragalus can reduce the mRNA expression of p75NTR that low affinity receptor of NGF, thus inhibiting the nerve cell apoptosis mechanism that was mediated by the binding of NGF and p75NTR. At the same time, through up increasing the protein expression of NF-κB, to promote nerve regeneration, enhance the ability of damage resistance of neuron, playing a role in optic neuroprotection.Part Two The clinical observation of astragalus on optic neuroprotectionObjective:To observe the clinical efficacy of Jiawei Shenxiao Huangqi Decoction in the treatment of nonarteritic anterior ischemic optic neuropathy (NAION), and objective to evaluate the effect of that on the visual function in NAION patients.Methods:35 cases (41 eyes) patients with NAION were observed by a randomized control study; Patients of control group were treated with routine comprehensive treatment, and the patients of observation group were given with Jiawei Shenxiao Huangqi Decoction to take orally on the basis of control group. After that, the best corrected visual acuity (BCVA), visual field and visual evoked potential of the two groups were recorded before and 1 month after treatment, to evaluate the clinical curative effect.Results:(1) Comprehensive curative effect:35 patients (41 eyes) were observed in this study. In the observation group, the numbers of remarkable effect, effect and inefficacy after treatment were 8,11 and 5 eyes respectively, the total effective rate was 79.16%, and in the control group,2 eyes have significant effect,8 eyes have effect,7 eyes have no effect, the total efficiency was 58.81%. (2) BCVA:the changes of BCVA in the two groups before and after treatment were statistically significant. The BCVA of the observation group was improved from 0.43±0.35 to 0.54±0.36 (P<0.01), and that of control group was improved from 0.44±0.35 to 0.52±0.37 (P<0.01). After drug treatment, the improved degree of BCVA in the observation group was more remarkable than the control group, but no significant difference between the two groups(P>0.05). (3) Visual field:①In the observation group, the MS of visual field was improved from 10.03±4.89 before treatment to 13.68±5.03 after treatment, and the difference was significant(P<0.01), in the control group, the MS was increased from 10.92±5.61 to 11.88±5.24, but the difference was not statistically significant(P=0.059>0.05).② The changes of MD in the observation groups before and after treatment were statistically significant(P<0.01),reduced from 16.85±5.48 to 13.13±5.67, however, in the control group, the MD of visual field was declined from 15.62±5.26 before treatment to 14.47±4.67 after treatment(P=0.114>0.05).③ Although compared with the control group, the changes of MS and MD were not significantly different in the observation group, the range of improvement of the MS and MD in the observation group was better than the control group, and the difference was statistically significant(P< 0.01,P<0.05). (4) Visual evoked potential:P100 peak latencies after treatment in the two groups were more improved than that before treatment(P<0.01),but there was no significant difference in P100 peak latencies between the two groups after treatment(P>0.05). The changes of N75-P100 amplitude before and after treatment in the two groups were statistically significant, and after treatment, the N75-P100 amplitude of observation group increased significantly more than the control group, with statistical difference (P<0.05).Conclusions:The comprehensive treatment of Jiawei Shenxiao Huangqi Decoction combined with conventional therapy could effectively improve the BCVA, MS of visual field in the AION patients, and reduce the MD of the visual field; In addition, this program can effectively increase the patient’s visual evoked potential N75-P100 amplitude intensity and relieve the delay of P100 latencies; Consequently, improving the quality of the visual function in patients.