ABSTRACT
Glutamate excitotoxicity mediated by metabotropic glutamate receptor 1 (mGluR1) overexpression or overactivation plays an important role in the development of Parkinson's disease (PD). Although clinical trials support the therapeutic potential of certain mGluR negative allosteric modulators (NAMs), there are still some limitations of precise modulation of mGluR using NAMs. Thus, the identification of small molecules or endogenous genes that facilitate mGluR1 modulation might be potentially beneficial for PD treatment. We determined the role of interacting partner cystic fibrosis transmembrane conductance regulator-associated ligand (CAL) in overactivated mGluR1-mediated cell apoptosis and signaling pathway in vitro and in vivo. HEK293 cells were used as an experimental tool to directly examine the interaction between CAL and mGluR1. We found that agonist of mGluR1 significantly enhanced the interaction between CAL and mGluR1 (P< 0. 05). Furthermore, CAL suppressed overactivated mGluR1-induced cell apoptosis and the activation of mGluR1 downstream signaling pathways. CAL overexpression relieved rotenone-induced neuron death (P< 0. 001) by inhibiting the activation of mGluR1-mediated signaling pathways in rotenone-induced rat model of PD. This study may reveal a new mechanism of mGluR1 activity regulation, and hopefully provide a novel molecular mechanism for the nervous system related diseases.
ABSTRACT
Objective To explore the effect of blood-brain barrier disruption on expression of AQP-4,through comparing the cell morphology and the expression of aquaporin-4(AQP-4)of cultured astrocytes in medium with and without fetal bovine serum(FBS). Methods Cerebral cortical astrocytes from female Wistar rats were cultured in serum free medium,DMEM supplement-ed with 10% FBS,and serum free medium supplemented with 10% FBS.Phase contrast microscope was used to detect the cell morphology and cell size. Immunofluorescence staining and reverse real-time quantitative poly-merase chain reaction(RT-qPCR)were used to examine the expression of glial fibrillary acidic protein(GFAP), AQP-4 and metabotropic glutamate receptor 5(mGluR5). Results Astrocytes in serum free medium showed extensive process bearing morphology,small body and nucleus,and high refractivity.In contrast,in two kinds of 10% FBS-containing medium,astrocytes were flat with large body and nucleus,weak refractivity,as well as short process.Analysis of immunofluorescence staining and RT-qPCR revealed a down-regulation of GFAP and AQP-4 protein and mRNA expression in two kinds of 10% FBS-con-taining medium, compared with that in serum free medium (P<0.001), however, there was no difference in mGluR5 protein and mRNA expression(P>0.05). Conclusion FBS changed astrocyte morphology and down-regulated the expression of GFAP and AQP-4.
ABSTRACT
Objective To study the role of glutamate receptor subtypes in nucleus tractus solitarius(NTS)in cardiac-somatic motor reflex (CMR)induced by intrapericardial administration of capsaicin,and to clarify the modulation mechanism of NTS to cardiac nociceptoion.Methods 60 SD rats were randomly divided into ibotenic (IBO)group, glutamate group, MK-801 group, MCGP group, MK-801 + MCPG group and DNQX group. The NTS microinjected with 130 mmol·L-1 IBO 100 nL,100,200,500 mmol·L-1 L-glutamate 100 nL,NMDA receptor antagonist 40 and 60 mmol · L-1 MK-801 100 nL, metabotropic glutamate receptors antagonist 25 and 50 mmol·L-1 MCPG 100 nL,25 mmol· L-1 MCPG 50 nL plus 40 mmol· L-1 MK-801 50 nL,non-NMDA receptor antagonist 20 and 50 mmol·L-1 DNQX 100 nL,respectively.The changes of CMR of the rats in various groups were observed.Results Compared with control group,the CMR of the rats in IBO group was decreased (P0.05).Conclusion NTS play an facilictory role in cardiac nociception,and the NMDA receptors and mGluRs receptors mediate this facilitory modulation.
ABSTRACT
BACKGROUND: Metabotropic glutamate receptors (mGluRs) participate in the induction of synaptic plasticity phenomena, such as long-term potentiation and long-term depression that are thought to be at the origin of learning and memory. They are also likely to play a role in modulating glutamate-induced neurotoxicity. It will become apparent that mGluRs are excellent targets for the development of drugs that modulate excitatory synaptic transmission. But there were several controversies about the exact role of group 1 mGluRs subtype 5 (mGluR5). This study was designed for evaluation of the neuroprotective role of mGluR5. METHODS: Fifty male Sprague-Dawley rats were divided into three groups, control, MK-801 and lamotrigine. The hippocampus and basal ganglia were removed at 6 hours and 3 days after the one hour transient middle cerebral artery occlusion. The gene expression of mRNA of the brain samples were evaluated by using reverse transcriptase polymerase chain reaction technique. RESULTS: The gene expression of mGluR5 mRNA in hippocampus was increased by 101.96 +/- 18.45% at 6 hours after ischemia and decreased by 50.70 +/- 15.73% at 3 days after ischemia (p<0.01). MK-801 and lamotrigine attenuated the ischemia-induced increases of gene expression of mGluR5 mRNA. In MK-801 group, the expression in basal ganglia was increased by only 0.23 +/- 5.41% at 6 hours after ischemia and decreased by 9.82 +/- 4.35% at 3 days after ischemia. In MK-801 group, the expression in hippocampus was decreased by 3.45 +/- 8.24% and 9.35 5.69% at 6 hours and 3 days after ischemia. In lamotrigine group, the expressions in hippocampus and basal ganglia were decreased by 26.66 +/- 9.85% and 9.45 +/- 5.22% at 6 hours after ischemia. CONCLUSIONS: From these results, the role of mGluR5 was defined as a mediator for neuronal damage after transient focal cerebral ischemia in hippocampus and basal ganglia.