Protein Expression In Cortex Research Articles

Effects of short-term exposure to lithium on antiapoptotic Bcl-xL protein expression in cortex and hippocampus of rats after acute stress

The antiapoptotic protein Bcl-xL is involved in development of neurobiological resilience to stress; hence, the possibility of use of psychotropic drugs to increase its expression in brain in response to stress is of considerable interest. Lithium is a neurotropic drug widely used in psychiatry. In work, we studied effects of lithium administration (for 2 or 7 days) on the expression of Bcl-xL mRNA and protein in the hippocampi and cortices of rats subjected to stress that induced depression-like behavior in the animals. In contrast to the brain-derived neurotrophic factor (BDNF), whose expression decreased in the hippocampus in response to acute stress, stress increased the level of Bcl-xL mRNA in the hippocampus, but decreased it in the frontal cortex. Treatment of stressed animals with lithium for 2 or 7 days increased Bcl-xL protein levels 1.5-fold in the hippocampus, but it decreased them in the cortex. Therefore, Bcl-xL expression in the brain can be modulated by both stress and psychotropic drugs, and the effects of these factors are brain region-specific: both stress exposure and lithium administration activated Bcl-xL expression in the hippocampus and suppressed it in the frontal cortex. The activation of Bcl-xL expression in the hippocampus by lithium, demonstrated for the first time in this study, suggests an important role of this protein in the therapeutic effects of lithium in the treatment of stress-induced psychoemotional disorders.

Augmentation of angiotensinogen expression in the proximal tubule by intracellular angiotensin II via AT1a/MAPK/NF-кB signaling pathways.

Long-term angiotensin II (ANG II) infusion significantly increases ANG II levels in the kidney through two major mechanisms: AT1 receptor-mediated augmentation of angiotensinogen (AGT) expression and uptake of circulating ANG II by the proximal tubules. However, it is not known whether intracellular ANG II stimulates AGT expression in the proximal tubule. In the present study, we overexpressed an intracellular cyan fluorescent ANG II fusion protein (Ad-sglt2-ECFP/ANG II) selectively in the proximal tubule of rats and mice using the sodium and glucose cotransporter 2 (sglt2) promoter. AGT mRNA and protein expression in the renal cortex and 24-h urinary AGT excretion were determined 4 wk following overexpression of ECFP/ANG II in the proximal tubule. Systolic blood pressure was significantly increased with a small antinatriuretic effect in rats and mice with proximal tubule-selective expression of ECFP/ANG II (P < 0.01). AGT mRNA and protein expression in the cortex were increased by >1.5-fold and 61 ± 16% (P < 0.05), whereas urinary AGT excretion was increased from 48.7 ± 5.7 (n = 13) to 102 ± 13.5 (n = 13) ng/24 h (P < 0.05). However, plasma AGT, renin activity, and ANG II levels remained unaltered by ECFP/ANG II. The increased AGT mRNA and protein expressions in the cortex by ECFP/ANG II were blocked in AT1a-knockout (KO) mice. Studies in cultured mouse proximal tubule cells demonstrated involvement of AT1a receptor/MAP kinases/NF-кB signaling pathways. These results indicate that intracellular ANG II stimulates AGT expression in the proximal tubules, leading to increased AGT formation and secretion into the tubular fluid, which contributes to ANG II-dependent hypertension.

Age-related alteration in cerebral blood flow and energy failure is correlated with cognitive impairment in the senescence-accelerated prone mouse strain 8 (SAMP8)

Cerebrovascular dysfunction is an early pathogenic event in Alzheimer's disease (AD) and plays a key role in the disease process. Cerebral hypoperfusion, brain glucose hypometabolism and disrupted blood-brain barrier (BBB) integrity contributed to the onset and progression of AD. However, the relationships between the age-related cognitive impairment and cerebral blood flow (CBF), energy metabolism and BBB have not been clearly explained. In this study, we investigated the cognitive function, CBF, BBB damage and expression level of glucose transporter (GLUT) 1 and 3 of senescence-accelerated mouse prone 8 (SAMP8), and the correlations between each of them were analyzed. When compared with SAMR1 (senescence-accelerated mouse resistant 1), the cognitive abilities of SAMP8 were damaged apparently even at 4 months of age, showing up a slower and more capricious acquisition in Morris water maze tasks. In both SAMP8 and SAMR1, reduced CBF and increased BBB leakage were observed with increasing age, but an earlier and more severe impairment was detected in SAMP8. In addition, alterations of GLUT1 and GLUT3 protein expression in cortex and hippocampus were more prominent in SAMP8. Correlation analysis demonstrated that the increased escape latency was correlated negatively with CBF and expression of glucose transporters; and positively with BBB permeability in the hippocampus. These results suggested that CBF, BBB integrity, the expression of GLUT1 and GLUT3 were significantly affected by age and strain, which were also closely associated with cognitive ability. The alteration in CBF and energy failure induced by aging and vascular insults resulted in cognitive decline in SAMP8.

Hyperammonemia induced oxidative stress in cirrhotic rats without promoting differential protein expression in the brain cortex: A 2D-DIGE analysis

Oxidative stress induced by a high ammonia concentration could modify protein expression in the brain. This study was undertaken in order to investigate the impact of hyperammonemia, caused by thioacetmide (TAA) in rats, on brain cortex protein expression using 2D-DIGE, and analyzing its role in the pathogenesis of HE. Hyperammonemia was induced with TAA. Ammonia and active oxidants were measured by L-glutamate dehydrogenase and dichlorodihydrofluorescein diacetate methods, respectively. Lipid peroxidation and protein oxidation biomarkers were also studied. Differential protein expression in the cortex of TAA- and control-rats was studied by 2D-DIGE. Image analysis was performed using the DeCyder? Software. Ammonia concentration in plasma and brain tissue was higher in TAA-rats compared to control-rats, 3.12 and 2.43 fold higher, respectively. Active oxidants production in TAA-rats was increased by 2.7 fold compared to control-rats. Measurements of MDA, HNE and carbonyl groups, biomarkers of lipid peroxidation and protein oxidation respectively, were found to be statistically significantly increased in TAA-rats compared to control-rats (3.16-, 2.44- and 1.95-fold, respectively), reflecting the presence of oxidative stress in the brain of TAA-rats. 2D-DIGE analysis of brain cortex protein allowed the detection of 2896 spots, however, image analysis showed no statistically significant differential protein expression between the proteins expressed in TAA- and control-rats. No statistical significant differential protein expression in the cortex of TAA-rats was observed, although oxidative stress biomarkers for lipid and proteins were higher in the brain of TAA-rats than in control-rats. These results support the idea that oxidative post-translational modifications are implicated in HE physiopathology.

Changes in intracellular protein expression in cortex, thalamus and hippocampus in a genetic rat model of absence epilepsy

Epilepsy is a chronic disorder characterized by repeated seizures resulting from abnormal activation of neurons in the brain. Although mutations in genes related to Na +, K +, Ca 2+ channels have been defined, few studies show intracellular protein changes. We have used proteomics to investigate the expression of soluble proteins in a genetic rat model of absence epilepsy “Genetic Absence Epilepsy Rats from Strasbourg (GAERS)”. The advantage of this technique is its high throughput quantitative and qualitative detection of all proteins with their post-translational modifications at a given time. The parietal cortex and thalamus, which are the regions responsible for the generation of absence seizures, and the hippocampus, which is not involved in this activity, were dissected from GAERS and from non-epileptic control rat brains. Proteins from each tissue sample were isolated and separated by two-dimensional gel electrophoresis. Spots that showed significantly different levels of expression between controls and GAERS were identified by nano LC–ESI-MS/MS. Identified proteins were: ATP synthase subunit delta and the 14-3-3 zeta isoform in parietal cortex; myelin basic protein and macrophage migration inhibitory factor in thalamus; and macrophage migration inhibitory factor and 0-beta 2 globulin in hippocampus. All protein expressions were up-regulated in GAERS except 0-beta globulin. These soluble proteins are related to energy generation, signal transduction, inflammatory processes and membrane conductance. These results indicate that not only membrane proteins but also cytoplasmic proteins may take place in the pathophysiology and can be therapeutic targets in absence epilepsy.

Proteomic Analysis of Hypoxia/Ischemia-Induced Alteration of Cortical Development and Dopamine Neurotransmission in Neonatal Rat

Perinatal hypoxia/ischemia (HI) is a common cause of neurological deficits in children. Our goal was to elucidate the underlying mechanisms that contribute to the neurological sequelae of HI-induced brain injury. HI was induced by permanent ligation of the left carotid artery followed by 90 min of hypoxia (7.8% O2) in female P7 rats. A two-dimensional differential proteome analysis was used to assess changes in protein expression in cortex 2 h after HI. In total, 17 proteins reflecting a 2-fold or higher perturbation of expression after HI as compared to sham-treated pups were identified by mass spectrometry. Of the altered proteins, 14-3-3epsilon and TUC-2, both playing an important role in the development of the central nervous system, decrease after HI, consistent with an early disturbance of cortical development. Also affected, DARPP-32 and alpha-synuclein, two proteins important for dopamine neurotransmission, increased more than 2-fold 2 h after HI injury. The differential expression of these proteins was validated by individual Western blot assays. The expression of several metabolic enzymes and translational factors was also perturbed early after HI brain injury. These findings provide initial insights into the mechanisms underlying neurodegenerative events after HI and may allow for the rational design of therapeutic strategies that enhance neuronal adaptation and compensation after HI.

Serine racemase protein expression in cortex and hippocampus in schizophrenia

Evidence of glutamatergic dysfunction in schizophrenia associated with the N-methyl-D-aspartate receptor has historically demonstrated changes primarily attributable to neurons. We propose an astrocytic component to N-methyl-D-aspartate receptor dysfunction in this illness. We studied the expression of serine racemase, an astrocytic enzyme which synthesizes the N-methyl-D-aspartate receptor coagonist D-serine, using Western blot analysis in postmortem hippocampus and cortex in schizophrenia and a comparison group. We found increased expression in the hippocampus in schizophrenia. This is the first study to demonstrate alterations in schizophrenia of an astrocytic enzyme responsible for synthesizing a neuromodulator, and further evidence that astrocytes may play a direct role in N-methyl-D-aspartate receptor dysfunction in schizophrenia.