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OBJECTIVE: To observe the effect of catgut embedment at "Baihui" (GV 20), "Dazhui" (GV 14), etc. on learning-memory ability, expression of hippocampal protein kinase C interacting protein 1 (PICK 1) and glutamate receptor 2 (GluR 2) proteins and level of calcium ions, so as to explore its mechanism underlying improvement of vascular cognitive impairment. METHODS: A total of 56 male SD rats were randomly divided into sham operation, model, catgut embedment and medication groups (n=14 in each). The chronic ischemic cognitive impairment model was established by permanent occlusion of bilate-ral common carotid arteries. The catgut embedment was applied to GV 20, GV 14, "Shenshu" (BL 23) and "Xuanzhong" (GB 39), once a week, for 4 weeks. Rats of the medication group received intraperitoneal injection of monosialate tetrahexose ganglioside sodium (GM-1, 0.33 mg/kg), once daily for 4 weeks. The rats' learning-memory ability was detected by Morris water maze tasks, pathological changes of hippocampal Nissl's bodies were tested by Nissl staining. The expression levels of PICK 1 and GluR 2 proteins in the hippocampus were detected by Western bolt (WB), and the concentration of calcium ions in the hippocampus tissue was measured by Bicinchoninic acid (BCA) assay. RESULTS: After modeling, the mean escape latencies of place navigation test were significantly increased while the crossing times of target platform quadrant of space probing test notably decreased in the model, catgut embedment and medication groups compared with their own individual pre-modeling (P0.05). CONCLUSION: Catgut implantation at GV 20 etc. can effectively improve the learning-memory ability in rats with chronic ischemic cognitive impairment, which may be related to its effects in down-regulating the expression of PICK 1 and calcium ion concentration and up-regulating the expression of AMPA receptor subunit GluR 2 protein in the hippocampus.
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OBJECTIVE: To study the potential effects of subacute 1-bromopropane( 1-BP) inhalation on the expression of synapse specific biomarkers synaptophysin( SYP),glutamate receptor 2( GluR2) and N-methyl-D-aspartate receptor 2B( NR2B) in the hippocampus of male rats. METHODS: Forty-eight specific pathogen free adult male Wistar rats were randomly divided into control group,low-,medium-,and high-dose groups according to body weight. Each group consisted of 12 rats. By dynamic inhalation intoxication method,the control group was exposed to fresh air,the dose groups were given 1 250,2 500 and 5 000 mg / m3 of 1-BP respectively,6 hours per day,5 days per week for continuous 4 weeks. After the exposure,the rats were executed and the whole brains were separated into cerebrum( included hippocampus),brainstem and cerebellum. Real time quantitative polymerase chain reaction and Western blot were used for detection of SYP,GluR2 and NR2 B mRNA and protein expression in hippocampus. RESULTS: Slow response and muscle strength descended in hind limbs were found in high-dose group in the 3rd week. Body weights of rats in high-dose group were lower than those of control group from the 1st to the 4th week( P < 0. 01). Weights of whole brain,cerebrum and brainstem in high-dose group were lower than those of control group( P < 0. 05). Rats in high-does group were found neuron necrosis in hippocampus cornu ammonis 3 and dentate gyrus region. No significant difference was found in SYP,GluR2 and NR2 B mRNA relative expression in all groups( P > 0. 05). No significant difference was found in SYP protein relative expression in different groups( P > 0. 05). The GluR2 protein relative expression in high-dose group was lower than that of control group( P < 0. 05). The NR2 B protein relative expression was higher than that of control group( P < 0. 05). CONCLUSION: The GluR2 and NR2 B protein expression in hippocampus can be potential biomarkers for 1-BP central neurotoxicity,but its physiological meaning needs further elucidation.
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Metabotropie glutamate receptor (mGluR) 2/3 plays an important role on the nociceptive transmission from periphery to spinal cord.The previous studies demonstrated that mGluR2 can contribute to mechanical hypersensitivity and thermal hypersensitivity in rat.Therefore,in the present study,by using the immunofluorescenee histochemical technique,we try to explore that whether mGluR2 is colocalized with acid-sensing ion channel 3 (ASIC3),a muhi-modulator of mechanosensation,or transient receptor potential/vanilloid receptor subtype-1 (TRPV1),which responses for thermosensation in dorsal root ganglion (DRG).Morphological observations showed that mGluR2-immunoreactivity was mainly distributed in cellular plasma of neurons in DRG.The counting number results indicated that 35.84% of DRG neurons were mGluR2-immunoreactive (ir).On the other hand,82.61% of mGluR2-ir cells were the small-diameter neurons (diameter:＜30 μm),5.79% of which were the medium-diameter neurons (diameter:30-50μm) and 11.59% of which was the large-diameter neurons (diameter:＞50 tun).Furthermore,42.45% and 79.78% of mGiuR2-ir cells was individually co-localized with ASIC3-or TRPVI-ir in small-diameter neurons in the double-labeled immunofluorescence sections.The present results suggest that mGhiR2 mainly exists in small neurons of the DRG,which are regarded as nociceptors consisting of AS-and C-fibers.While mGluR2 is highly co-localized with ASIC3 and TRPV1,implying their potential relationship in DRG may be involved in mechanical hypersensitivity and thermal hypersensitivity.
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Objective To investigate the effects of electromagnetic irradiation on activation of protein kinase C(PKC)and phosphorylation of glutamate receptor 2(GluR2)in rat cerebellum.Methods Sixty male Wistar rats were divided randomly into a control group and an electromagnetic exposure group(including 5 subgroups ob- served at different time points after the irradiation,eg.0 hour,3 hours,12 hours,24 hours and 72 hours after irradi- ation),with 10 rats in each group.All the rats in the exposure group were exposed to 90 mW/cm2 electromagnetic ir- radiation for 20 minutes,their rectal temperature was detected immediately after irradiation and the specific absorption rate(SAR)value was calculated,activation of PKC was detected with improved TaKai method,the level of cerebellar GluR2 expression and phosphorylation(ser880)was detected by using Western blot.Results Immediately(0 hour)after exposure,the rectal temperature of rats increased 2.99℃,SAR value was 8.66 W/kg.When compared to the control group,it was found that there was no significant difference between the exposure group and the control group with regard to all the parameters at 3,12,24 and 72 hours after exposure,except that the cerebellar PKC acti- vation and GluR2(ser 880)phosphorylation decreased significantly immediately after irradiation.Conclusion The electromagnetic irradiation has injurious effects on cerebellar signal pathway of for motor learning.
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Objective To know the mechanism of the adverse effect of formaldehyde on cortex neurons. Methods In the present study, incubation of postnatal Wistar rat cortex neurons in culture with formaldehyde at 1.0, 2.0, 4.0, 8.0 mg/L (medium) was carried out to have knowledge of the effect of formaldehyde on the expressions of GluR2 and GABAR. For keeping the given concentration of formaldehyde, formaldehyde was added to the medium every hour for 4 consecutive hours. Results Immunocytochemistry showed a significant down-regulation of GluR2 and up-regulation of GABAR after 4 consecutive hours of formaldehyde treatment compared with the control (P