Rat Cerebral Cortex Research Articles

Changes in Expression of Monocarboxylate Transporters in the Rat Cerebral Cortex after Exercise-induced Fatigue Under Simulated High-altitude Hypoxia and its Significance

Changes in Expression of Monocarboxylate Transporters in the Rat Cerebral Cortex after Exercise-induced Fatigue Under Simulated High-altitude Hypoxia and its Significance

Caffeic acid phenethyl ester ameliorates imidacloprid-induced acute toxicity in the rat cerebral cortex

This study aimed to investigate the role of caffeic acid phenethyl ester (CAPE), a compound found in propolis, on imidacloprid (IMI), a nicotinic acetylcholine receptor agonist that causes cerebral toxicity. 60 adult rats were randomly divided into five groups: control, IMI (100 mg/kg), and IMI+CAPE (1, 5, 10 mg/kg). Cerebral cortex tissue was examined histopathologically, biochemically, spectrophotometrically and immunohistochemically. The results showed that IMI caused toxicity in the cerebral cortex. However, CAPE (5 and 10 mg/kg) attenuated the deteriorated histopathological score and normalized the apoptotic markers (Bax and Caspase-3). Additionally, CAPE dose-dependently normalized the levels of TNF-α, dopamin, GFAP and NGF, and at the highest dose (10 mg/kg) also normalized the balance of oxidative parameters (MDA, SOD, CAT, and GSH). In conclusion, the antioxidant, anti-inflammatory, and anti-apoptotic effects of CAPE may be a promising treatment for acute IMI-induced cerebral cortex toxicity.

Knockdown of sortilin improves the neurological injury and regional cerebral blood flow in rats after subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a severe subtype of stroke. Sortilin protein is elevated in cerebrospinal fluid (CSF) of SAH patients. This study explored the mechanism of sortilin in SAH. SAH model was established by occipital cisternal blood injection. Neurological evaluation was performed on SAH rats using the Gracia scoring system and beam-balance tests. Regional cerebral blood flow (rCBF) and intracranial pressure (ICP) changes were measured using a laser Doppler blood flow monitor and an intraparenchymal Camino ICP probe. The correlation between rCBF changes and neurological deficit was analyzed using the Spearman method. Sortilin protein level in rat cerebral cortex and CSF was detected by Western blot. The Garcia score and beam-balance score of rats at 1, 12, 24, 48, and 72 h after SAH were lowered. Blood clots were observed on the ventral surface of the brain in SAH rats, around Willis ring, and ventral surface of brain stem, but no blood clots were found in the control group. At 1, 12, 24, 48, and 72 h after SAH in rats, the severity of SAH was aggravated, rCBF was decreased, and ICP was increased. The changes of rCBF in rat cerebral cortex at 1 and 72 h after SAH were correlated with the Garcia score. Sortilin was highly expressed in the cerebral cortex and CSF of SAH rats. Knockdown of sortilin improved the neurological injury and rCBF in rats. Sortilin was highly expressed in the cerebral cortex and CSF of SAH rats. Sortilin silencing improved neurological injury and CBF in rats.

Pharmacological characterization of novel synthetic opioids: Isotonitazene, metonitazene, and piperidylthiambutene as potent μ-opioid receptor agonists

Recent trends of opioid abuse and related fatalities have highlighted the critical role of Novel Synthetic Opioids (NSOs). We studied the μ-opioid-like properties of isotonitazene (ITZ), metonitazene (MTZ), and piperidylthiambutene (PTB) using different approaches. In vitro studies showed that ITZ and MTZ displayed a higher potency in both rat membrane homogenates (EC50:0.99 and 19.1 nM, respectively) and CHO-MOR (EC50:0.71 and 10.0 nM, respectively) than [D-Ala2, NMe-Phe4, Gly-ol5]-enkephalin (DAMGO), with no difference in maximal efficacy (Emax) between DAMGO and NSOs. ITZ also has higher affinity (Ki:0.06 and 0.05 nM) at the MOR than DAMGO in both systems, whilst MTZ has higher affinity in CHO-MOR (Ki=0.23 nM) and similar affinity in rat cerebral cortex (Ki = 0.22 nM). PTB showed lower affinity and potency than DAMGO. In vivo, ITZ displayed higher analgesic potency than fentanyl and morphine (ED50:0.00156, 0.00578, 2.35 mg/kg iv, respectively); ITZ (0.01 mg/kg iv) and MTZ (0.03 mg/kg iv) reduced behavioral activity and increased dialysate dopamine (DA) in the NAc shell (max. about 200% and 170% over basal value, respectively. Notably, ITZ elicited an increase in DA comparable to that of higher dose of morphine (1 mg/kg iv), but higher than the same dose of fentanyl (0.01 mg/kg iv). In silico, induced fit docking (IFD) and metadynamic simulations (MTD) showed that binding modes and structural changes at the receptor, ligand stability, and the overall energy score of NSOs were consistent with the results of the biological assays.

Exploring the molecular mechanisms underlie the endoplasmic reticulum stress-mediated methylmercury-induced neuronal developmental damage

Methylmercury (MeHg) is a ubiquitous environmental pollutant, which can cross the placenta and blood brain barrier, thus affecting fetal growth and development. Although previous studies have demonstrated that MeHg induces endoplasmic reticulum (ER) stress in rat cerebral cortex and primary neurons, the role of ER stress in MeHg-induced neurodevelopmental toxicity remains unclear. Here, we used ICR pregnant mice and hippocampal neurons cells (HT22 cells) to investigate the molecular mechanism by which MeHg exposure during pregnancy affects neurodevelopment. We found that prenatal MeHg exposure caused developmental delay in offspring, accompanied with ER stress, cell apoptosis, cell cycle arrest and abnormal DNA methylation. Then, we used ER stress specific inhibitor 4-PBA and CHOP siRNA to investigate the role of ER stress on HT22 cells damage caused by MeHg. The results showed that 4-PBA pretreatment restored MeHg-induced axonal shortening and alleviated apoptosis, cell cycle arrest and DNA methylation. At the same time, the activation of CHOP/c-Jun/GADD45A signaling pathway was inhibited, and the interaction between CHOP and c-Jun was weakened. In addition, CHOP siRNA reduced the expression of c-Jun and GADD45A, and relieved DNA methylation levels to some extent. In summary, our study suggested that ER stress induced by MeHg mediated cell apoptosis and cell cycle arrest, and may affect DNA methylation through activation of CHOP/c-Jun/GADD45A signaling pathway, thus leading to neuronal damage.

Ultrastructure of rat cerebral cortex cells in normal and experimental dioxin poisoning

Purpose the study of the ultrastructure of the cerebral cortex of rats in normal and experimental poisoning with dioxin.
 Materials and methods. We studied the ultrastructure of the cells of the pyramidal layer of the cerebral cortex of rats of the control and experimental groups that were chronic poisoned with small doses of dioxin (2,3,7,8-tetrachlorodibenzo-para-dioxin or TCDD). Morphometric analysis was carried out to determine the length of synaptic clefts, the number of synapses per unit area, the thickness of the myelin layer of the processes and the number of wrappers of myelin sheaths.
 Results. The pathology of neurons has been observed both at the optical and ultrastructural levels. It is characterized by a decrease in nuclei, cell death, thinning of myelin sheaths and demyelination. The dose of poisoning correlates with the degree of destruction of neurons: with an increase in the dose of dioxin, changes become more significant. The number of synaptic contacts decreases but there is a significant increase in their average length.
 Conclusions. The processes of demyelination, impaired cellular respiration and destruction of synaptic contacts indicate the ability of dioxin to indirectly cause accelerated aging of neurons and their death (apoptosis).

Development of l-Dopa-containing diketopiperazines as blood-brain barrier shuttle

In our overall goal to develop anti-Parkinson drugs, we designed novel diketopiperazines (DKP1-6) aiming to both reach the blood-brain barrier and counteract the oxidative stress related to Parkinson's Disease (PD).The anti-Parkinson properties of DKP 1–6 were evaluated using neurotoxin-treated PC12 cells, as in vitro model of PD, while their cytotoxicity and genotoxicity potentials were investigated in newborn rat cerebral cortex (RCC) and primary human whole blood (PHWB) cell cultures. The response against free radicals was evaluated by the total antioxidant capacity (TAC) assay. Comet assay was used to detect DNA damage while the content of 8-hydroxyl-2′-deoxyguanosine (8-OH-dG) was determined as a marker of oxidative DNA damage. PAMPA-BBB and Caco-2 assays were employed to evaluate the capability of DKP1-6 to cross the membranes. Stability studies were conducted in simulated gastric and intestinal fluids and human plasma.Results showed that DKP5-6 attenuate the MPP + -induced cell death on a nanomolar scale, but a remarkable effect was observed for DKP6 on Nrf2 activation that leads to the expression of genes involved in oxidative stress response thus increasing glutathione biosynthesis and ROS buffering. DKP5-6 resulted in no toxicity for RCC neurons and PHWB cells exposed to 10–500 nM concentrations during 24 h as determined by MTT and LDH assays and TAC levels were not altered in both cultured cell types. No significant difference in the induction of DNA damage was observed for DKP5-6. Both DKPs resulted stable in simulated gastric fluids (t1/2 > 22h). In simulated intestinal fluids, DKP5 underwent immediate hydrolysis while DKP6 showed a half-life higher than 3 h. In human plasma, DKP6 resulted quite stable. DKP6 displayed both high BBB and Caco-2 permeability confirming that the DKP scaffold represents a useful tool to improve the crossing of drugs through the biological membranes.

Sodium Para-aminosalicylic Acid Inhibits Lead-Induced Neuroinflammation in Brain Cortex of Rats by Modulating SIRT1/HMGB1/NF-κB Pathway.

Lead (Pb) is considered to be a major environmental pollutant and occupational health hazard worldwide which may lead to neuroinflammation. However, an effective treatment for Pb-induced neuroinflammation remains elusive. The aim of this study was to investigate the mechanisms of Pb-induced neuroinflammation, and the therapeutic effect of sodium para-aminosalicylic acid (PAS-Na, a non-steroidal anti-inflammatory drug) in rat cerebral cortex. The results indicated that Pb exposure induced pathological damage in cerebral cortex, accompanied by increased levels of inflammatory factors tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β). Moreover, Pb decreased the expression of silencing information regulator 2 related enzyme 1 (SIRT1) and brain-derived neurotrophic factor (BDNF), and increased the levels of high mobile group box 1 (HMGB1) expression and p65 nuclear factor-κB (NF-κB) phosphorylation. PAS-Na treatment ameliorated Pb-induced histopathological changes in rat cerebral cortex. Moreover, PAS-Na reduced the Pb-induced increase of TNF-α and IL-1β levels concomitant with a significant increase in SIRT1 and BDNF levels, and a decrease in HMGB1 and the phosphorylation of p65 NF-κB expression. Thus, PAS-Na may exert anti-inflammatory effects by mediating the SIRT1/HMGB1/NF-κB pathway and BDNF expression. In conclusion, in this novel study PAS-Na was shown to possess an anti-inflammatory effect on cortical neuroinflammation, establishing its efficacy as a potential treatment for Pb exposures.

Changes in sex differences in neuroanatomical structure and cognitive behavior across the life span.

Sex differences occur in the structure and function of the rat cerebral cortex and hippocampus, which can change from the juvenile period through old age. Although the evidence is incomplete, it appears that in at least some portions of the cortex these differences develop due to the rise of ovarian hormones at puberty and are potentially not dependent on the perinatal rise in testosterone, which is essential for sexual differentiation of the hypothalamus and sexual behavior. During aging of female rats, the presence of continued ovarian hormone secretion after cessation of the estrous cycle also influences sex differences in neuroanatomical structure and cognitive behavior, resulting in nullification or reversal of sex differences seen in younger adults. Sex differences can be altered by experience in a stimulating environment during the juvenile/adolescent period, and sex differences in performance even can be affected by the parameters of a task. Thus, broad generalizations about differences such as "spatial ability" are to be avoided. It is clear that to understand how the brain produces behavior, sex and hormones have to be taken into account.

Analysis of Melatonin-Modulating Effects Against Tartrazine-Induced Neurotoxicity in Male Rats: Biochemical, Pathological and Immunohistochemical Markers

Tartrazine (E-102) is one of the most widely used artificial food azo-colors that can be metabolized to highly sensitizing aromatic amines such as sulphanilic acid. These metabolites are oxidized to N-hydroxy derivatives that cause neurotoxicity. Melatonin is a neurohormone. That possesses a free-radical scavenging effect. The present work was mainly designed to evaluate the possible ameliorative role of melatonin against tartrazine induced neurotoxicity in cerebral cortex and cerebellum of male rats. Adult male rats were administered orally with tartrazine (7.5 mg/kg) with or without melatonin (10 mg/kg) daily for four weeks. The data revealed that tartrazine induced redox disruptions as measured by significant (p < 0.05) increased malondialdehyde (MDA) level and inhibition of (GSH) concentration and catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant enzyme activities. Besides, brain acetyl cholin (Ach) and gamma-aminobutyric acid (GABA) were elevated while, dopamine (DA) was depleted in trtrazine -treated rats. Moreover, tartrazine caused a significant (p < 0.05) increase in the brain interleukin-6 (IL-6), interleukin-1β (IL-1 β) and tumor necrosis factor-α (TNFα). At the tissue level, tartrazine caused severe histopathological changes in the cerebellum and cerebral cortex of rats. The immunohistochemical results elucidated strong positive expression for Caspase-3 and GFAP and weak immune reaction for BcL2 and synaptophysin in tatrazine- treated rats. The administration of melatonin to tartrazine -administered rats remarkably alleviated all the aforementioned tartrzine-induced effects. It could be concluded that, melatonin has a potent ameliorative effect against tartrazine induced neurotoxicity via the attenuation of oxidative/antioxidative responses.

1DE-MS Profiling for Proteoform-Correlated Proteomic Analysis, by Combining SDS-PAGE, Whole-Gel Slicing, Quantitative LC-MS/MS, and Reconstruction of Gel Distributions of Several Thousands of Proteins.

SDS-PAGE has often been used in proteomic analysis, but generally for sample prefractionation although the technique separates proteins by molecular masses (Mws) and the information would contribute to proteoform-level analysis. Here, we report a method that combines SDS-PAGE, whole-gel slicing, and quantitative LC-MS/MS for establishing gel distributions of several thousand proteins in a proteome. A previously obtained data set on rat cerebral cortex with cerebral ischemia-reperfusion injury1 was analyzed, and the gel distributions of 5906 proteins were reconstructed. These distributions, referred to as 1DE-MS profiles, revealed that about 30% of the proteins had more than one proteoform detected in the gels. The profiles were categorized into six types by distribution (narrow, dispersed, or broad) and relative deviations between the abundance-peak apparent Mws and calculated Mws. Only 56% of the proteins showed narrow distributions and matched Mws, while the others had rather complex profiles. Bioinformatic analysis on example profiles showed the resolved proteoforms involved alternative splicing, proteolytic processing, glycosylation and ubiquitination, fragmentation, and probably transmembrane structures. Profile-based differential analysis revealed that many of the disease-caused changes were proteoform dependent. This work provided a proteome-scale view of protein distributions in SDS-PAGE gels, and the method would be useful to obtain proteoform-correlated information for in-depth proteomics.

Effect of electroacupuncture of Governor Vessel on expression of GAD67 and GABA-T in cerebral cortex of rats with post-stroke limb spasticity

To observe the effect of electroacupuncture (EA) of Governor Vessel (GV) on the expressions of glutamate decarboxylase 67 (GAD67) and γ-aminobutyric acid transaminase (GABA-T) in the cerebral cortex of rats with post-stroke limb spasticity, so as to explore its mechanism underlying improvement of limb spasticity. Twenty four male SD rats were randomly and equally divided into control, sham operation, model, and EA groups. The cerebral ischemia model was established by occlusion of the middle cerebral artery (MCAO). EA (100 Hz, 1-3 mA) was applied to "Dazhui"(GV14), "Jizhong"(GV6) and "Houhui"( anteromedial of transverse process of the sixth lumbar vertebra) for 30 min, once daily for 7 consecutive days. The neurologic deficit score (0-5 points) was evaluated according to Zea Longa's method, and the muscular tension severity (0-5 points) was assessed according to the modified Ashworth muscle tone rating scale, and the tension signals of the quadriceps ferroris of the affected limb were recorded using tonotransducer and BL-420F electrophysiological recorder. The expression levels of GAD67 and GABA-T proteins and mRNAs in the cerebral cortex were detected by immunohistochemistry, fluorescence quantitative real-time PCR and Western blot, separately. After modeling, the neurological deficit score, muscle tone score, and the expression levels of GABA-T mRNA and protein in cerebral cortex were significantly increased (P<0.01, P<0.05), tension signal value and the expression levels of GAD67 mRNA and protein in cerebral cortex were significantly decreased (P<0.01) in the model group relevant to the control and sham operation groups. Following the intervention, the neurological deficit score, muscle tone score, and expression levels of GABA-T mRNA and protein in cerebral cortex were significantly decreased (P<0.01), tension signal value and the expression levels of GAD67 mRNA and protein in cerebral cortex were significantly increased (P<0.01, P<0.05) in the EA group in contrast to the model group. EA stimulation of Governor Vessel can ameliorate the limb spasticity symptom in MCAO rats, which may be associated with its functions in increasing the expressions of GAD67 protein and mRNA and inhibiting the expressions of GABA-T protein and mRNA, thereby playing the inhibitory role of GABA.

γ-Glutamylcysteine Exerts Neuroprotection Effects against Cerebral Ischemia/Reperfusion Injury through Inhibiting Lipid Peroxidation and Ferroptosis.

Ferroptosis is a non-apoptotic form of cell death driven by iron-dependent lipid peroxidation. Recent evidence indicates that inhibiting ferroptosis could alleviate cerebral ischemia/reperfusion (CIR) injury. γ-glutamylcysteine (γ-GC), an intermediate of glutathione (GSH) synthesis, can upregulate GSH in brains. GSH is the co-factor of glutathione peroxidase 4 (GPX4), which is the negative regulator of ferroptosis. In this study, we explored the effect of γ-GC on CIR-induced neuronal ferroptosis and brain injury. We found that γ-GC significantly reduced the volume of cerebral infarction, decreased the loss of neurons and alleviated neurological dysfunction induced by CIR in rats. Further observation showed that γ-GC inhibited the CIR-caused rupture of the neuronal mitochondrial outer membrane and the disappearance of cristae, and decreased Fe2+ deposition and lipid peroxidation in rat cerebral cortices. Meanwhile, γ-GC altered the expression of some ferroptosis-related proteins in rat brains. Mechanistically, γ-GC increased the expression of GSH synthetase (GSS) for GSH synthesis via protein kinase C (PKC)ε-mediated activation of nuclear factor erythroid 2-related factor (Nrf2). Our findings suggest that γ-GC not only serves as a raw material but also increases the GSS expression for GSH synthesis against CIR-induced lipid peroxidation and ferroptosis. Our study strongly suggests that γ-GC has potential for treating CIR injury.

Astrocytes profiling in acute hepatic encephalopathy: Possible enrolling of glial fibrillary acidic protein, tumor necrosis factor-alpha, inwardly rectifying potassium channel (Kir 4.1) and aquaporin-4 in rat cerebral cortex.

Hepatic encephalopathy (HE) is a neurological disarray manifested as a sequel to chronic and acute liver failure (ALF). A potentially fatal consequence of ALF is brain edema with concomitant astrocyte enlargement. This study aims to outline the role of astrocytes in acute HE and shed light on the most critical mechanisms driving this role. Rats were allocated into two groups. Group 1, the control group, received the vehicle. Group 2, the TAA group, received TAA (300 mg/kg) for 3 days. Serum AST, ALT, and ammonia were determined. Liver and cerebral cortical sections were processed for hematoxylin and eosin staining. Additionally, mRNA expression and immunohistochemical staining of cortical GFAP, TNFα, Kir4.1, and AQP4 were performed. Cortical sections from the TAA group demonstrated neuropil vacuolation and astrocytes enlargement with focal gliosis. GFAP, TNFα, and AQP4 revealed increased mRNA expression, positive immunoreactivity, and a positive correlation to brain water content. In contrast, Kir 4.1 showed decreased mRNA expression and immunoreactivity and a negative correlation to brain water content. In conclusion, our findings revealed altered levels of TNFα, Kir 4.1, GFAP, and AQP4 in HE-associated brain edema. A more significant dysregulation of Kir 4.1 and TNFα was observed compared to AQP4 and GFAP.

The Effect of Isosaponarin Derived from Wasabi Leaves on Glutamate Release in Rat Synaptosomes and Its Underlying Mechanism

Excessive glutamate release is known to be involved in the pathogenesis of neurological diseases, and suppression of glutamate release from nerve terminals is considered to be a treatment strategy. In this study, we investigated whether isosaponarin, a flavone glycoside isolated from wasabi leaves, could affect glutamate release in rat cerebral cortex nerve terminals (synaptosomes). The release of glutamate was evoked by the K+ channel blocker 4-aminopyridine (4-AP) and measured by an online enzyme-coupled fluorimetric assay. Isosaponarin produced a concentration-dependent inhibition of 4-AP-evoked glutamate release with a half-maximum inhibition of release value of 22 μM. The inhibition caused by isosaponarin was prevented by eliminating extracellular Ca2+ or by using bafilomycin A1, an inhibitor of synaptic vesicle exocytosis. Isosaponarin decreased intrasynaptosomal rises in Ca2+ levels that were induced by 4-AP, without affecting the synaptosomal membrane potential. The isosaponarin-induced inhibition of glutamate release was significantly prevented in synaptosomes that were pretreated with a combination of the calcium channel blockers ω-conotoxin GVIA (N-type) and ω-agatoxin IVA (P/Q-types). The protein kinase C (PKC) pan-inhibitor GF109203X and the Ca2+-dependent PKC inhibitor Go6976 abolished the inhibition of glutamate release by isosaponarin, while the Ca2+-independent PKC inhibitor rottlerin did not show any effect. The results from immunoblotting assays also showed that isosaponarin lowered PKC, PKCα, synaptosomal-associated protein of 25 kDa (SNAP-25), and myristoylated alanine-rich C-kinase substrate (MARCKS) phosphorylation induced by 4-AP. In addition, FM1-43-labeled synaptic vesicles in synaptosomes showed that treatment with isosaponarin resulted in an attenuation of the 4-AP-induced decrease in fluorescence intensity that is consistent with glutamate release. Transmission electron microscopy of synaptosomes also provided evidence that isosaponarin altered the number of synaptic vesicles. These results indicate that isosaponarin suppresses the Ca2+-dependent PKC/SNAP-25 and MARCKS pathways in synaptosomes, causing a decrease in the number of available synaptic vesicles, which inhibits vesicular glutamate release from synaptosomes.

The nNOS and NeuN expression aspects in the cerebral cortex of rats with different cognitive abilities in cerebral hypoperfusion with short-term physical exercise

Introduction. Physical activity is often used in rehabilitation to restore cognitive function after cerebral blood flow impairment and typological features like baseline cognitive ability may alter their effectiveness.The aim was to evaluate the expression of nNOS and NeuN in the large hemisphere cortex in the cerebral hypoperfusion occurrence in rats having different scores in the Morris maze.Materials and methods. Cerebral hypoperfusion was simulated by bilateral ligation of the common carotid arteries. Before surgery, Wistar rats were divided into equal subgroups with high (HCA) and low levels of cognitive ability (LCA) according to the results of Morris maze testing. Animals were removed from the experiment at 8, 21, 35, 60, and 90 days after surgery, a total of 184 rats, 24 formed the control group and 80 formed the cerebral hypoperfusion subgroup with 80 animals undergoing short-term swimming daily starting on day 7 of the experiment.Results. We revealed the earlier changes in HCA animals (8th day of the experiment) induced by cerebral hypoperfusion accompanied by a more intense nNOS-positive neurons density reduction to 47 % of control values, the length of their processes, and an increase in pericarion area. In LCA the decrease of density was only 75 % of control values and pericarion area does not differ from control values. At later periods on the 60 and 90 days of the experiment LCA demonstrates the preservation of the neurons density and greater length of their processes (67 % of the control subgroup values).Conclusion. HCA is a risk factor for damage of nNOS-positive neurons in cerebral hypoperfusion. Physical exercise more effectively decreases nNOS expression in animals with HCA, which may be one of the sanogenetic mechanisms of this factor.

PANoptosis: new insights in regulated cell death in ischemia/reperfusion models.

PANoptosis: new insights in regulated cell death in ischemia/reperfusion models.

Lappaconitine inhibits glutamate release from rat cerebrocortical nerve terminals by suppressing Ca2+ influx and protein kinase A cascade

The inhibition of the excessive release of glutamate in the brain has emerged as a promising new option for developing therapeutic strategies for neurodegenerative disorders. This study investigated the effect and mechanism of lappaconitine, a diterpenoid alkaloid found in species of Aconitum, on glutamate release in rat cerebral cortex nerve terminals (synaptosomes). Here, we report that in the rat cortical synaptosomal preparation, lappaconitine reduced the K+ channel blocker 4-aminopyridine (4-AP)-evoked Ca2+-dependent release of glutamate. The inhibitory effect of lappaconitine on the evoked glutamate release was blocked by the vesicular transporter inhibitor bafilomycin A1 and calcium-chelating agent ethylene glycol tetraacetic acid (EGTA), but was unaffected by exposure to the glutamate transporter inhibitor dl-threo-beta-benzyloxyaspartate (dl-TBOA). The depolarization-induced elevation of cytosolic calcium concentration ([Ca2+]c) was inhibited by lappaconitine, while the 4-AP-mediated depolarization of the synaptosomal membrane potential was not affected. The inhibition of glutamate release by lappaconitine was markedly decreased in synaptosomes pretreated with the Cav2.3 (R-type) channel blocker SNX-482 or the protein kinase A inhibitor H89. Nevertheless, the lappaconitine-mediated inhibition of glutamate release was not abolished by the intracellular Ca2+-release inhibitors dantrolene and CGP37157. Lappaconitine also significantly decreased the 4-AP-induced phosphorylation of PKA and SNAP-25, a presynaptic substrate for PKA. Our data suggest that lappaconitine reduces Ca2+ influx through R-type Ca2+ channels, subsequently reducing the protein kinase A cascade to inhibit the evoked glutamate release from rat cerebral cortex nerve terminals.

Flavonoids from Stems and Leaves of Scutellaria baicalensis Georgi Regulate the Brain Tau Hyperphosphorylation at Multiple Sites Induced by Composited Aβ in Rats.

Neurofibrillary Tangles (NFTs), formed by hyperphosphorylation of Tau protein in Alzheimer's Disease (AD), arethe main pathomechanisms of neuronal degeneration, which indicate a sign of brain disorder. NFTs are positively correlated with the degree of cognitive impairment in AD. The objective of this study isto investigate the effect of flavonoids from the stems and leaves of Scutellaria baicalensis Georgi (SSF) on the hyperphosphorylated expression levels at multiple sites of Tau protein induced by β-amyloid protein 25-35 (Aβ25-35) in combination with aluminum trichloride (AlCl3) and recombinant human transforming growth factor-β1(RHTGF-β1) (composited Aβ) in rats. The AD rat models were established by intracerebroventricular injection of Aβ25-35 and AlCl3 combined with RHTGF-β1. On day 45, after the operation, the Morris water maze test was conducted to screen the memory impairment of AD models. The successful model rats were randomly divided into the model group and the three-dose drug group. The drug group rats were orally administered SSF daily for 38 days. Western blotting was performed to detect the protein expression of P-Tau (Thr 181), P-Tau (Thr 217), P-Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-- Tau (Ser 396), and P-Tau (Ser 404) in the hippocampus and cerebral cortex of rats. Compared with the sham group, the expression of P-Tau (Thr 181), P-Tau (Thr 217), P-- Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-Tau (Ser 396), and P-Tau (Ser 404)was significantly increased in the hippocampus and cerebral cortex of the model group (P < 0.01). However, the three doses of SSF, i.e., 35, 70, and 140 mg/kg, regulated the expression of phosphorylated Tau proteinto varying degrees in the hippocampus and cerebral cortex of AD model rats (P < 0.01). SSF could significantly reduce the protein expression levels of P-Tau (Thr 181), PTau (Thr 217), P-Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-Tau (Ser 396), and P-Tau (Ser 404), induced by the intracerebroventricular injection of composited Aβ, in rats' brain. These results indicated that the neuro-protection and the improvement in the impaired memory of rats by SSF were due to the inhibition of hyperphosphorylation of Tau protein at multiple sites in rats' brain.

Study on the difference of curative effect of conventional mercury displacement treatment on mercury in brain and kidney

Objective: To explore the expulsion effect of sodium dimercaptopropanesulfonate (DMPS) on mercury in different organs of mercury poisoning and the therapeutic effect of glutathione (GSH) combined with antioxidant therapy on mercury poisoning. Methods: In February 2019, 50 SPF male SD rats were randomly divided into 5 groups, 10 rats in each group: A (saline negative control group) , B (HgCL2 positive control group) , treatment group (C: intramuscular injection of DMPS 15 mg/kg treatment, D: intramuscular injection of DMPS30 mg/kg treatment, E: intramuscular injection of DMPS 15 mg/kg and intraperitoneal injection of GSH200 mg/kg treatment) . Rats in group B, C, D and E were subcutaneously injected with mercury chloride solution (1 mg/kg) to establish a rat model of subacute mercury poisoning kidney injury. Rats in group A were subcutaneously injected with normal saline. After the establishment of the model, rats in the treatment group were injected with DMPS and GSH. Rats in group A and group B were injected with normal saline. At 21 d (treatment 7 d) and 28 d (treatment 14 d) after exposure, urine and blood samples of 5 rats in each group were collected. Blood biochemistry, urine mercury, urine microalbumin and mercury content in renal cortex, cerebral cortex and cerebellum were detected. Results: After exposure to mercury, the contents of mercury in renal cortex, cerebrum and cerebellum of rats in group B, C, D and E increased, and urine microalbumin increased. Pathology showed renal tubular injury and renal interstitial inflammation. Compared with group B, urinary mercury and renal cortex mercury in group C, D and E decreased rapidly after DMPS treatment, and there was no significant decrease in mercury levels in cerebellum and cerebral cortex of rats, accompanied by transient increase in urinary albumin after DMPS treatment (P<0.05) ; the renal interstitial inflammation in group E was improved after GSH treatment. There was a positive correlation between urinary mercury and the contents of mercury in renal cortex, cerebral cortex and cerebellum (r=0.61, 0.47, 0.48, P<0.05) . Conclusion: DMPS mercury expulsion treatment can significantly reduce the level of metal mercury in the kidney, and there is no significant change in the level of metal mercury in the cortex and cerebellum.