| Objectives: To investigate the effects of electroacupuncture (EA) withdifferent acupoints and frequencies on the survival of axotomized retinal ganglioncells (RGCs) after optic nerve transection (ONT) in adult rats and to exploreneuroprotection mechanisms of EA to injured RGCs.Research1: Fifty-four operated animals were randomly divided into9groups after ONT: Control2,7and14d groups, and EA groups with differentcombinations of acupoints, frequencies and survival times (Sham-acupoint4/20Hz EA7d, Baihui4/20Hz EA7d, Jingming2Hz EA7d, Jingming4/20Hz EA2,7and14d groups),(n=6). These animals were killed at the appropriatesurvival time points. The numbers of surviving RGCs retrogradely-labeled withFluoroGold in the right retinas were counted and the RGC densities (cells/mm2)were calculated accordingly. Values shown are Mean±SEM. Results:(1) Themean density of surviving RGCs in Jingming4/20Hz EA7d group (1600±72)was significantly higher (P<0.01) than those in Control (1104±41), Shamacupoint (1222±68) and Baihui (1168±56)7d groups, but no significantdifference was found among the last3groups;(2) The mean RGC densities inJingming2Hz and4/20Hz EA7d groups were similar to each other, but weresignificantly higher (P<0.01) than that in Control7d group;(3) Significantlyhigher RGC density could only be detected in Jingming4/20Hz EA7d group (P＜0.01) when the RGC densities in Jingming4/20Hz EA2,7,14d groups were compared to Control groups at the corresponding time points, respectively.Research2: Another60were randomly divided into10groups: Normalgroup, Sham-operated2,7and14d groups, another36operated animals weredistributed to Control2,7and14d groups and EA (with the selected Jingmingacupoint and4/20Hz frequency)2,7and14d groups,(n=6). Aqueous humorsamples were aspirated from the anterior and posterior aqueous chambers atspecified time points after the animals were euthanized. The amounts ofglutamate (μmol/L) were determined using high-performance liquidchromatography. Results: All intraocular glutamate levels in EA (47.62±4.29,54.72±1.98,52.27±1.16, respectively) and Control groups (59.74±4.62,88.17±1.94,56.56±1.15, respectively) were significantly higher than those inNormal and Sham-operated2,7and14d groups (43.54±0.53,43.71±0.66,43.21±0.94,43.04±0.44, respectively). The intraocular levels of glutamate in EA2and7d groups were significantly lower than those in Control2and7d groupsrespectively, but no significant difference could be detected between EA andControl14d groups.Research3: Another54operated animals were distributed to Control2,7and14day groups and EA (with the selected Jingming acupoint and4/20Hzfrequency)2,7and14d groups (n=9). Expressions of sodium-dependentglutamate-aspartate transporter (GLAST) and glutamine synthetase (GS), whichare respectively vital for the removal and metabolization of glutamate in theretinas, were assessed by Western-blot and immunohistochemical staining.Results: The expression of GLAST in EA7d group was significantly higher thanthat in Control7d group, but no significant differences were found between EAand Control2,14d groups respectively. The expression of GS in retinasremained stable in all groups. Conclusion:4/20Hz EA treatments in Jingming acupoints can delay thedeath of axotomized RGCs by decreasing intraocular glutamate level at7d afterONT in adult rat. And up-regulated expression of GLAST at this time maycontribute to the decreased intraocular glutamate level and glutamate-inducedexcitotoxicity by taking up more glutamate. |
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