ABSTRACT
OBJECTIVE: To observe the effect of maltolate aluminum on synaptic plasticity in the hippocampus of rats and to explore the regulatory effect and mechanism of metabotropic glutamate receptor 1(mGluR1). METHODS: Specific pathogen free healthy adult male SD rats were randomly divided into control group, aluminum group, aluminum agonist group and aluminum antagonist group, 8 rats in each group. The rats in the control group received no treatment; the rats in aluminum group were injected with 5 μL 10 mmol/L maltolate aluminum solution into the lateral ventricle; the rats in aluminum agonists and aluminum antagonist group were injected with 3 μL 10 mmol/L maltolate aluminum solution plus 2 μL 0.1 μmol/L mGluR1 agonist or 2 μL 0.2 μmol/L mGluR1 antagonists into the lateral ventricle, respectively.Maltolate aluminum solution was injected every 2 days and continued for 10 days. After maltolate aluminum exposure, the amplitudes of long-term potentiation(LTP) in hippocampal CA1 region of rats were measured, and the relative expression levels of mRNA and protein of mGluR1, N-methyl-D-aspartate receptor(NMDAR1) and protein kinase C(PKC) in hippocampus tissue of rats were detected by real-time fluorescence quantitative polymerase chain reaction and Western blotting. RESULTS: The amplitude of LTP in hippocampal CA1 region in aluminum group and aluminum agonist group was lower than that in the control group and the aluminum antagonist group(P<0.05). Compared with the control group, the relative expression of mGluR1 mRNA and protein in the aluminum group increased, the relative expression of PKC and NMDAR1 mRNA and protein in the aluminum group decreased(P<0.05). Compared with the aluminum group, the relative expression of mGluR1 mRNA and protein in the aluminum agonist group increased, while the NMDAR1 mRNA decreased(P<0.05); the relative expression of mGluR1 mRNA and protein in the aluminum antagonist group decreased, while the NMDAR1 mRNA and protein increased(P<0.05). Compared with the aluminum agonist group, the relative expression of mGluR1 mRNA and protein decreased, while the NMDAR1 mRNA and protein increased in the aluminum antagonist group(P<0.05). The relative expression level of PKC mRNA and protein in aluminum agonist group and aluminum antagonist group was not statistically significant(P>0.05), and there was no statistical significance in these two groups compared with control group and aluminum group(P>0.05). CONCLUSION: Maltolate aluminum exposure can inhibit synaptic plasticity by inhibiting LTP in hippocampus of rats, and the mechanism may be related to the regulation of NMDAR1 expression by mGluR1.
ABSTRACT
Objective To investigate the protective effect and its mechanism of metabotropic glutamate receptor 1 ( mGluR1) negative allosteric modulator JNJ16259685 on neuron after subarachnoid hemorrhage (SAH) in rats. Methods Ninety SPF-grade SD male rats were selected. They were randomly divided into 3 groups:sham operation group (n=18),SAH+placebo group (n=36),and SAH+JNJ16259685(JNJ) group (n=36). A SAH model was induced by intravascular puncture. SAH +placebo group received intraperitoneal injection of aseptic water containing 5% dimethyl sulfoxide (DMSO) at 2,24 and 48 h after operation. The SAH+JNJ group was intraperitoneally injected with 1 mg/kg JNJ16259685 ( dissolved in sterile water in 5% DMSO). Garcia scoring criteria were used to assess neurological deficits at 72 h after SAH. Dry and wet weight method was used to detect brain edema. Evans Blue method was used to assess blood-brain barrier permeability. A calcium assay kit was used to detect the mitochondrial calcium ion concentration. Immunofluorescence staining was used to observe neuronal apoptosis. GraphPad 7. 0 software was used to conduct one-way analysis of variance in all indicators among the 3 groups. Results Compared with the sham operation group,the Garcia score (11. 0 ± 0. 4) decreased in the SAH+placebo group. The water content in left and right hemispheres was 80. 5 ± 0. 1% and 80. 3 ± 0. 2% respectively,the Evans blue dye extravasation (2. 8 ± 0. 2),basal cortical mitochondrial calcium ion concentration (2. 5 ± 0. 3),and neuronal apoptosis in basal cortex and hippocampus CA1 region (the number of active caspase-3/NeuN positive cells was 300 ±30/mm2and 20 ± 2/mm respectively) increased (all P<0. 05);and the Garcia score (13. 0 ± 0. 5) was significantly higher in the SAH+JNJ group than in the SAH+placebo group. Water content in left and right hemispheres was 79. 8 ± 0. 2% and 79. 3 ± 0. 1% respectively,Evans blue dye extravasation (1. 8 ±0. 2),basal cortex mitochondrial calcium ion concentration (1. 7 ± 0. 1),basal cortex and the number of neuronal apoptosis in hippocampal CA1 region (the number of active caspase-3/NeuN positive cells were 180 ± 10/mm2,12 ±2/mm) reduced compared with the SAH+placebo group (all P<0. 05). Conclusion After SAH,JNJ16259685 relieves cerebral edema and reduces blood-brain barrier permeability,inhibits the increase of cortical mitochondrial calcium ion concentration,and reduces neuronal apoptosis,thereby exerting neuroprotective effects.