ObjectiveTo observe the expression of glutamate (Glu) andγ-aminobutyric acid (GABA) in the retina of diabetic rats which were intervened later by insulin intensive therapy, and to investigate the mechanism of metabolic memory of hyperglycemia which induced the retina neuropathy in diabetic rats. Methods60 Brown Norway rats were randomly divided into normal control (NC) group, diabetes mellitus (DM) group (6 weeks at DM1, 12 weeks at DM2) and metabolic memory (MM) group, 15 rats in each group. Diabetes was induced by intraperitoneal injection of streptozocin. After 6 weeks, MM group was treated with insulin intensive therapy for 6 weeks. DM1 group was sacrificed at the end of 6 weeks and other groups were sacrificed at the end of 12 weeks. High performance liquid chromatography was used to detect the amount of Glu and GABA in the rat retina. Real-time polymerase chain reaction was applied to quantify the mRNA expressions of Glutamate decarboxylase (GAD). TdT mediated dUTP nick ending labelling was used to detect cell apoptosis. ResultsThe concentration of Glu (t=6.963), GABA (t=4.385) and the ratio of Glu/GABA (t=4.163) in MM group were significantly higher than DM1 group, but the concentration of Glu (t=3.411) and GABA (t=3.709) were significantly lower than DM2 group (P < 0.05). And there was no significant difference in the ratio of Glu/GABA between MM and DM2 groups (t=1.199, P > 0.05). The level of expressions of GAD mRNA in MM group was significantly lower than DM1 group (t=3.496, P < 0.05), but higher than DM2 group (t=8.613, P < 0.05). The number of nerve cells apoptosis in MM group was significantly higher than DM1 group (t=2.584, P < 0.05), but lower than DM2 group (t=3.531, P < 0.05). ConclusionsIntensive therapy later by insulin can partially reduce the content of Glu and GABA and the rate of nerve cells apoptosis, which cannot return to normal levels, and has no effect on the rise in the ratio of Glu/GABA caused by the hyperglycemia. The disorders of Glu and GABA may participate in the metabolic memory of hyperglycemia.
Objective:To observe the effect of beta;estradiol on gluta mate concentration in rabbitsprime; retinae injured by ischemic reperfusion. Methods:Twenty r abbits ware randomly divided into two groups, the control group and the treatmen t group, with 10 rabbits in each group. Before examined by binocular flash elect roretinography (FERG), retinal ischemic reperfusion (RIR) model was induced in t h e right eyes of all the rabbits by increasing intraocular pressure to 120 mm Hg for 60 minutes; the left eyes were as the control eyes. The rabbits were hypoder mically injected with beta;estradiol (0.1 mg/kg) in treatment group and with phys i ological saline in the control group 2 hours before ischemia. The results of FER G of the right eyes in both of the 2 groups 0, 4, 8, and 24 hours after reperfus ion were record respectively and were compared with the results of FERG before r eperfusion. The retina tissue was collected after the last time of FERG. The con c entration of glutamate was detected by Hitachi L8800 amino acid analyzer. Results:In the right eyes in both of the 2 groups, the result of F ERG showed a beeli ne just after reperfusion. There was no significant difference of awave amplit u de between the 2 groups (t=1.357, 0.798, 0.835; Pgt;0.05); the b wave amplitudes i n experimental group were much higher than those in the control group (t=4.447, 2.188, 3.106; Plt;0.01). The concentration of glutamate in retina was (0.265plusmn;0.014) g/L in the right eyes and (0.207plusmn;0.013) g/L in the left eyes in the control group, and (0.231plusmn;0.007) g/L in the right eyes and (0.203plusmn;0 .014) g/L in the le ft eyes in the treatment group; the difference between the 2 groups was signific ant (F=50.807, P=0.000). There was statistical difference between righ t and left eyes both in the 2 groups and the significant difference of the right eyes betw een the two groups was also found (P=0.000); there was no statistical diffe rence of the left eyes between the 2 groups (P＝0.505). Conclusion:beta;-estradiol may prevent the increase of the concentration of glutamate in retina induced by RIR to protect retinal tissue.
Repeated transcranial magnetic stimulation (rTMS) is one of the commonly used brain stimulation techniques. In order to investigate the effects of rTMS on the excitability of different types of neurons, this study is conducted to investigate the effects of rTMS on the cognitive function of mice and the excitability of hippocampal glutaminergic neurons and gamma-aminobutyric neurons from the perspective of electrophysiology. In this study, mice were randomly divided into glutaminergic control group, glutaminergic magnetic stimulation group, gamma-aminobutyric acid energy control group, and gamma-aminobutyric acid magnetic stimulation group. The four groups of mice were injected with adeno-associated virus to label two types of neurons and were implanted optical fiber. The stimulation groups received 14 days of stimulation and the control groups received 14 days of pseudo-stimulation. The fluorescence intensity of calcium ions in mice was recorded by optical fiber system. Behavioral experiments were conducted to explore the changes of cognitive function in mice. The patch-clamp system was used to detect the changes of neuronal action potential characteristics. The results showed that rTMS significantly improved the cognitive function of mice, increased the amplitude of calcium fluorescence of glutamergic neurons and gamma-aminobutyric neurons in the hippocampus, and enhanced the action potential related indexes of glutamergic neurons and gamma-aminobutyric neurons. The results suggest that rTMS can improve the cognitive ability of mice by enhancing the excitability of hippocampal glutaminergic neurons and gamma-aminobutyric neurons.
ObjectiveTo analyze the protective mechanism of spinal cord ischemia-reperfusion injury mediated by N-methyl-D-aspartate (NMDA) receptor.MethodsA total of 42 SD rats were randomly assigned to 4 groups: a non-blocking group (n=6), a saline group (n=12), a NMDA receptor blocker K-1024 (25 mg/kg) group (n=12) and a voltage-gated Ca2+ channel blocker nimodipine (0.5 mg/kg) group (n=12). The medications were injected intraperitoneally 30 min before ischemia. The neural function was evaluated. The neuronal histologic change of spinal cord lumbar region, the release of neurotransmitter amino acids and expression of spinal cord neuronal nitric oxide synthase (nNOS) were compared.ResultsAt 8 h after reperfusion, the behavioral score of the K-1024 group was 2.00±0.00 points, which was statistically different from those of the saline group (5.83±0.41 points) and the nimodipine group (5.00±1.00 points, P<0.05). Compared with the saline group and nimodipine group, K-1024 group had more normal motor neurons (P<0.05). There was no significant difference in glutamic acid concentration in each group at 10 min after ischemia (P=0.731). The nNOS protein expression in the K-1024 group was significantly down-regulated compared with the saline group (P<0.01). After 8 h of reperfusion, the expression of nNOS protein in the K-1024 group was significantly up-regulated compared with the saline group (P<0.05).ConclusionK-1024 plays a protective role in spinal cord ischemia by inhibiting NMDA receptor and down-regulating nNOS protein expression; during the reperfusion, K-1024 has a satisfactory protective effect on spinal cord function, structure and biological activity of nerve cells.
Objective To evaluate the inhibiting effect of adenosine on rat retinal ganglion cells (RGC) death induced by P2X7 and N-methyl-D-aspartate (NMDA) receptor. Methods (1) Long-Evan neonatal rats were back labeled with aminostilbamidine to identify RGC. The viability of RGC affected by P2X7 excitomotor BzATP (50 mu;mol/L), glutamate receptor excitomotor NMDA (100 mu;mol/L) and adenosine (300 mu;mol/L) was detected. (2) RGC from the retinae of unlabeled neonatal rats were cultured in vitro. After labeled with Fura-2 methyl acetate, an intracellular calcium indicator, the effect of BzATP, NMDA and adenosine on intracellular Ca2+ level was detected byCa2+ imaging system. Results Both BzATP (50 mu;mol/L) and NMDA(100 mu;mol/L) could kill about 30% of the RGC. Cell death was prevented by adenosine (300 mu;mol/L) with the cell viability increased from (68.9plusmn;2.3)% and (69.9plusmn;3.2)% to (91.2plusmn;3.5)% (P＜0.001) and (102.1plusmn;3.9)% (P＜0.001), respectively. BzATP (50 mu;mol/L) led to a large, sustained increase of intracellular Ca2+ concentration to (1183plusmn;109) nmol/L. After the adenosine intervened, Ca2+ concentration increased slightly to (314plusmn;64) nmol/L (P＜0.001). Conclusion Adenosine may prevent RGC death and increase of intracellular Ca2+ concentration from P2X7and NMDA receptor stimulation. (Chin J Ocul Fundus Dis, 2007, 23: 133-136)
Objective To investigate the expression of induced heat shock protein (HSP) 70 in ratprime;s retinal neurons (RNs) and Muuml;ller cells, and evaluate the protective effect of HSP 70 on RNs injured with glucose deprivation and glutamate. Methods Ratprime;s RNs and Muuml;ller cells cultured in vitro were treated with heat shock (42℃ for 1 hour), and duration of the expression of HSP70 was detected by immunocytochemical techniques. Viability of the cells was measured by methyl thiazolyl tetrazolium (MTT) chromatometry after incitant toxic injury with glucose deprivation (0.56 mmol/L glucose for 6 hours) and glutamate (100 mu;mol/L for 6 hours). Simultaneously, the expression was interdicted by HSP70. Results Hypereffective expression of HSP70 was found in cultured RNs and Muuml;ller cells after heat shock. The viability of RNs pretreated by heat shock after injured with glucose deprivation and glutamate significantly increased which could be interdicted by HSP70 antibody. Conclusion Hypereffective expression of HSP 70 may be induced by heat shock, which enhances the ability of tolerance of RNs to the incitant toxic injury by glucose deprivation and exitotoxicity. (Chin J Ocul Fundus Dis, 2005,21:110-113)
Transcranial magnetic stimulation (TMS) as a noninvasive neuromodulation technique can improve the impairment of learning and memory caused by diseases, and the regulation of learning and memory depends on synaptic plasticity. TMS can affect plasticity of brain synaptic. This paper reviews the effects of TMS on synaptic plasticity from two aspects of structural and functional plasticity, and further reveals the mechanism of TMS from synaptic vesicles, neurotransmitters, synaptic associated proteins, brain derived neurotrophic factor and related pathways. Finally, it is found that TMS could affect neuronal morphology, glutamate receptor and neurotransmitter, and regulate the expression of synaptic associated proteins through the expression of brain derived neurotrophic factor, thus affecting the learning and memory function. This paper reviews the effects of TMS on learning, memory and plasticity of brain synaptic, which provides a reference for the study of the mechanism of TMS.
Objective To investigate the glutamate toxicity on inner stratum retinal neurons(ISRN) and the neurotoxicity quantity-efficacy relation. Method Retinal explants obtained from 30 neonatal mices were implanted into two pieces of 24-well culture plates (48 wells). The 48 wells were divided into three groups: control group, glutamate exposure 24 h group, and glutamate exposure with further lasting 6 h group. The retinal explants were sectioned, and then stained with HE after 24 h in vitro. The cells in retinal ganglion cells (RGCs) layer and inner nuclear layer (INL) were analyzed by light microscope at 1 000times; magnification , and the number of normal morphological cells was counted under three 1 000times; magnificat ion fields. Results Some cells in ISRN (include RGCs and INL c ells) showed pykno tic nuclei and necrosis after 24 h in control culture. Glutamate exposure 24 h group:at the 2 mmol and 4 mmol concentrations of glutamate, the situation of the normal morphological cells in ISRN had no difference from that of the control group (Pgt;0.05). At the concentration of glutamate more than or equal to 6 mmol, the number of normal morphological cells in ISRN was significantly less than that of the control group (Plt;0.05), and with the increase of glutamate concentration, the number of normal morphological cells was reduced. Glutamate exposure with fur ther lasting 6 h group: at the concentration of glutamate equal to 6 mmol, the n umber of normal morphological cells in INL was significantly less than that of the control group (Plt;0.05), while the number of normal morphological cells in RGCs layer had no difference between two groups (Pgt;0.05). At the concentration of glutamate more than or equal to 8 mmol, the number of normal morphological cels in RGC s layer and INL was significantly less than that of the control group (Plt;0.05 ). Conclusion Glutamate has the neurotoxicity for ISRN in vitro, and the effect is dose-dependant. (Chin J Ocul Fundus Dis, 2001,17:311-314)