Increased expression of AGS3 in rat brain cortex after traumatic brain injury

Receptor‐independent activators of G protein signaling (AGS) offer alternative modes of signal processing for the G protein signaling system that has broad mechanistic and functional significance. Previous studies have demonstrated that AGS3, which belongs to the AGS family, is involved in a number of different cellular activities. However, the distribution and function of AGS3 in the central nervous system (CNS) remain unclear. To investigate whether AGS3 is involved in CNS injury and repair, we used an acute traumatic brain injury (TBI) model in adult rats. Western blot analysis and immunohistochemistry showed a significant upregulation of AGS3 in ipsilateral peritrauma cortex. Double immunofluorescence staining showed that AGS3 was coexpressed with NeuN but rarely with glial fibrillary acidic protein. In addition, we detected that active caspase‐3 had colocalization with NeuN and AGS3, suggesting that AGS3 might be involved in the neuron apoptosis after TBI. To investigate the potential function of AGS3 further, a neuronal cell line, PC12, was employed to establish a cell apoptosis model. Western blot analysis indicated that AGS3 shared a similar dynamic variation in animal experiments, and phosphorylated cyclic AMP response element‐binding protein (CREB) increased in parallel. Additionally, knocking down AGS3 with siRNA partially attenuated the protein level of phosphorylated CREB in PC12 stimulated by H₂O₂, while reinforcing active caspase‐3 expression, demonstrating a probable antiapoptotic role through CREB played by AGS3 in neuronal apoptosis. We hypothesize that AGS3 might play an important antiapoptotic role through enhancing phosphorylation of CREB. © 2013 Wiley Periodicals, Inc.     

Differential expression of brain-derived neurotrophic factor and neurotrophin 3 mRNA in lingual papillae and taste buds indicates roles in gustatory and somatosensory innervation

Although many studies have demonstrated the dependency of taste bud function and/or survival on intact innervation, relatively few have dealt with the development of taste bud innervation. Using in situ hybridization histochemistry, we show that brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3) mRNA are expressed in a specific pattern in the taste buds, tongue papillae, and lingual epithelium during development and that expression persists into adulthood. BDNF mRNA is expressed in a fraction of the taste cells of the developing and adult taste buds in rats, showing different labeling intensities among the labeled cells. NT3 mRNA seems to be located in areas other than those where BDNF mRNA is expressed, mainly in the superior epithelial surfaces of circumvallate papillae, the outer surface epithelium of foliate papilae, the superior surface and the lateral epithelium of the fungiform papillae, and the epithelium of the filiform papillae. NT3 mRNA labeling is also observed among muscle and connective tissue of the tongue. The morphological appearance, expression of NT3 mRNA, and ramification of nerve fibers in defined epithelial structures in the posterior wall of the anterior filiform papillae suggest the existence of a mechanosensory apparatus in these papillae. Nerve growth factor and neurotrophin 4 probes did not give rise to selective labeling in tongue, although their presence cannot be totally excluded. Based on present and prior studies, we suggest that BDNF is needed during initiation and for maintenance of gustatory innervation of taste buds and gustatory papillae and that NT3 is mainly needed for somatosensory innervation of the tongue. © 1996 Wiley-Liss, Inc.     

Brain-derived neurotrophic factor and neurotrophin-4 increase neurotrophin-3 expression in the rat hippocampus

Hippocampal levels of mRNA encoding nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are rapidly induced by enhanced neuronal activity following seizures and glutamate or muscarinic receptor activation. However, the levels of neurotrophin-3 (NT-3) mRNA acutely decrease after limbic seizures suggesting that a different mode of regulation may exist for these neurotrophins. Here we show that BDNF and neurotrophin-4 (NT-4), but not NT-3 itself, up-regulate NT-3 mRNA in cultured hippocampal neurons. In the rat hippocampus, the muscarinic receptor agonist, pilocarpine increased BDNF mRNA levels rapidly and those of NT-3 with a delay of several hours. Injection of BDNF into neonatal rats elevated NT-3 mRNA in the hippocampus which demonstrates that BDNF is able to enhance NT-3 expression in vivo. The regulation of NT-3 by BDNF and NT-4 enlargens the neurotrophic spectrum of these neurotrophins to include neuron populations responsive primarily to NT-3.     

Correlation of brain-derived neurotrophic factor to cognitive impairment following traumatic brain injury in rats**☆

BACKGROUND： In vitro and in vivo studies have confirmed that brain-derived neurotrophic factor （BDNF） can promote survival and differentiation of cholinergic, dopaminergic and motor neurons, and axonal regeneration. BDNF has neuroprotective effects on the nervous system. OBJECTIVE： To explore changes in BDNF expression and cognitive function in rats after brain injury. DESIGN, TIME AND SETTING： The neuropathology experiment was performed at the Second Research Room, Department of Neurosurgery, Fujian Medical University （China） from July 2007 to July 2008. MATERIALS： A total of 72 healthy, male, Sprague Dawley, rats were selected for this study. METHODS： Rat models of mild and moderate traumatic brain injury were created by percussion, according to Feeney＇s method （n = 24, each group）. A bone window was made in rats from the sham operation group （n = 24）, but no attack was conducted. MAIN OUTCOME MEASURES： At days 1, 2, 4 and 7 following injury, BDNF expression in the rat frontal lobe cortex, hippocampus and basal forebrain was examined by immunohistochemistry （streptavidin-biotin-peroxidase complex method）. Changes in rat cognitive function were assessed by the walking test, balance-beam test and memory function detection. RESULTS： Cognitive impairment was aggravated at day 2, and recovered to normal at days 3 and 7 in rats from the mild and moderate traumatic brain injury groups. BDNF expression in the rat frontal lobe cortex, hippocampus and basal forebrain was increased at 1 day, decreased at day 2, and then gradually increased in the mild and moderate traumatic brain injury groups. BDNF expression was greater in rats from the moderate traumatic brain injury group than in the sham operation and mild traumatic brain injury groups （P 〈 0.05）. CONCLUSION： BDNF expression in the rat frontal lobe cortex, hippocampus and basal forebrain is correlated to cognitive impairment after traumatic brain injury. BDNF has a protective effect on cognitive function in rats following i     

Correlation of brain-derived neurotrophic factor to cognitive impairment following traumatic brain injury in rats

BACKGROUND: In vitro and in vivo studies have confirmed that brain-derived neurotrophic factor (BDNF) can promote survival and differentiation of cholinergic, dopaminergic and motor neurons, and axonal regeneration. BDNF has neuroprotective effects on the nervous system. OBJECTIVE: To explore changes in BDNF expression and cognitive function in rats after brain injury DESIGN, TIME AND SETTING: The neuropathology experiment was performed at the Second Research Room, Department of Neurosurgery, Fujian Medical University (China) from July 2007 to July 2008. MATERIALS: A total of 72 healthy, male, Sprague Dawley, rats were selected for this study. METHODS: Rat models of mild and moderate traumatic brain injury were created by percussion, according to Feeney's method (n = 24, each group). A bone window was made in rats from the sham operation group (n = 24), but no attack was conducted. MAIN OUTCOME MEASURES: At days 1,2, 4 and 7 following injury, BDNF expression in the rat frontal lobe cortex, hippocampus and basal forebrain was examined by immunohistochemistry (streptavidin-biotin-peroxidase complex method). Changes in rat cognitive function were assessed by the walking test, balance-beam test and memory function detection. RESULTS: Cognitive impairment was aggravated at day 2, and recovered to normal at days 3 and 7 in rats from the mild and moderate traumatic brain injury groups. BDNF expression in the rat frontal lobe cortex, hippocampus and basal forebrain was increased at 1 day, decreased at day 2, and then gradually increased in the mild and moderate traumatic brain injury groups. BDNF expression was greater in rats from the moderate traumatic brain injury group than in the sham operation and mild traumatic brain injury groups (P < 0.05). CONCLUSION: BDNF expression in the rat frontal lobe cortex, hippocampus and basal forebrain is correlated to cognitive impairment after traumatic brain injury. BDNF has a protective effect on cognitive function in rats following injury     

The brain-derived neurotrophic factor receptor TrkB is critical for the acquisition but not expression of conditioned incentive value

Stimuli paired with reward acquire incentive properties that are important for many aspects of motivated behavior, such as feeding and drug-seeking. Here we used a novel chemical–genetic strategy to determine the role of the brain-derived neurotrophic factor (BDNF) receptor TrkB, known to be critical to many aspects of neural development and plasticity, during acquisition and expression of positive incentive value by a cue paired with food. We assessed that cue's learned incentive value in a conditioned reinforcement task, in which its ability to reinforce instrumental responding later, in the absence of food itself, was examined. In TrkB ^F616A knock-in mice, TrkB kinase activity was suppressed by administering the TrkB inhibitor 1NMPP1 during the period of initial cue incentive learning only (i.e. Pavlovian training), during nose-poke conditioned reinforcement testing only, during both phases, or during neither phase. All mice acquired cue–food associations as indexed by approach responses. However, TrkB ^F616A mice that received 1NMPP1 during initial cue incentive learning failed to show conditioned reinforcement of nose-poking, regardless of their treatment in testing, whereas administration of 1NMMP1 only during the testing phase had no effect. The effects of 1NMPP1 administration were due to inhibition of TrkB^F616A, because the performance of wild-type mice was unaffected by administration of the compound during either phase. These data indicate that BDNF or NT4 signaling through TrkB receptors is required for the acquisition of positive incentive value, but is not needed for the expression of previously acquired incentive value in the reinforcement of instrumental behavior.     

Age-dependent time course of cerebral brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3 in APP23 transgenic mice

Neurotrophins, including brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and neurotrophin-3 (NT-3), have repeatedly been shown to be involved in the pathophysiology of Alzheimer's disease (AD). Recent studies have claimed that these neurotrophic factors are important tools for therapeutic intervention in neurodegenerative diseases. So far, little is known about the age- and disease-modulated time course of cerebral neurotrophins. Therefore, we have studied protein concentrations of BDNF, NGF, and NT-3 in different brain areas and sciatic nerve, a neurotrophin-transporting peripheral nerve, in a well-characterized AD model of amyloid precursor protein-overexpressing rodents (APP23 mice) at the ages of 5.0, 10.5, and 20.0 months. In APP23 mice, there was a significant increase of BDNF and NGF in the frontal and occipital cortices (for BDNF also in the striatum) of old 20.0-month-old mice (with respect to median values up to 8.2-fold), which was highly correlated with amyloid concentrations of these brain areas. Median values of NGF and NT-3 showed up to a 6.0-fold age-dependent increase in the septum that was not detectable in APP23 mice. Hippocampus, olfactory bulb, and cerebellum (except NT-3) did not show substantial age- or genotype-related regulation of neurotrophins. In the sciatic nerve, BDNF and NGF levels are increased in5-month-old APP23 mice and decrease with age to control levels. In conclusion, APP23 mice show a genotype-dependent increase of cortical BDNF and NGF that is highly correlated with amyloid concentrations and may reflect an amyloid-related glia-derived neurotrophin secretion or an altered axonal transport of these neurotrophic factors.     

In situ expression of brain-derived neurotrophic factor or neurotrophin-3 promotes sprouting of cortical serotonergic axons following a neurotoxic lesion

Neurotrophins promote sprouting and elongation of central nervous system (CNS) axons following injury. Consequently, it has been suggested that neurotrophins could be used to repair the CNS by inducing axonal sprouting from nearby intact axons, thereby compensating for the loss of recently injured axons. We tested whether long-term overexpression of neurotrophins in the rat cortex would induce sprouting of cortical serotonergic axons following a neurotoxic injury. After a single subcutaneous injection of para-chloroamphetamine (PCA; 9 mg/ml) that lesions the majority of serotonergic axons in the rat cortex, we injected adenoviral vectors containing cDNAs for brain-derived neurotrophic factor (Adv.BDNF), neurotrophin-3 (Adv.NT-3), or nerve growth factor (Adv.NGF) into the rat frontal cortex. Nine days later, we measured significant increases in the concentration of the respective neurotrophins surrounding the vector injection sites, as measured by ELISA. Immunohistochemical localization of serotonin revealed a fourfold increase in the density of serotonergic fibers surrounding the injection sites of Adv.BDNF and Adv.NT-3, corresponding to a 50% increase in cortical serotonin concentration, compared with a control vector containing the cDNA for enhanced green fluorescent protein (Adv.EGFP). In contrast, there was no difference in serotonergic fiber density or cortical serotonin concentration surrounding the injection of Adv.NGF compared with Adv.EGFP. These data demonstrate that localized overexpression of BDNF or NT-3, but not NGF, is sufficient to promote sprouting of serotonergic axons in the cortex following an experimental neurotoxic injury.     

Differential effects of brain-derived neurotrophic factor and neurotrophin-3 on hindlimb function in paraplegic rats

We compared the effect of viral administration of brain-derived neurotrophic factor (BDNF) or neurotrophin 3 (NT-3) on locomotor recovery in adult rats with complete thoracic (T10) spinal cord transection injuries, in order to determine the effect of chronic neurotrophin expression on spinal plasticity. At the time of injury, BDNF, NT-3 or green fluorescent protein (GFP) (control) was delivered to the lesion via adeno-associated virus (AAV) constructs. AAV-BDNF was significantly more effective than AAV-NT-3 in eliciting locomotion. In fact, AAV-BDNF-treated rats displayed plantar, weight-supported hindlimb stepping on a stationary platform, that is, without the assistance of a moving treadmill and without step training. Rats receiving AAV-NT-3 or AAV-GFP were incapable of hindlimb stepping during this task, despite provision of balance support. AAV-NT-3 treatment did promote the recovery of treadmill-assisted stepping, but this required continuous perineal stimulation. In addition, AAV-BDNF-treated rats were sensitized to noxious heat, whereas AAV-NT-3-treated and AAV-GFP-treated rats were not. Notably, AAV-BDNF-treated rats also developed hindlimb spasticity, detracting from its potential clinical applicability via the current viral delivery method. Intracellular recording from triceps surae motoneurons revealed that AAV-BDNF significantly reduced motoneuron rheobase, suggesting that AAV-BDNF promoted the recovery of over-ground stepping by enhancing neuronal excitability. Elevated nuclear c-Fos expression in interneurons located in the L2 intermediate zone after AAV-BDNF treatment indicated increased activation of interneurons in the vicinity of the locomotor central pattern generator. AAV-NT-3 treatment reduced motoneuron excitability, with little change in c-Fos expression. These results support the potential for BDNF delivery at the lesion site to reorganize locomotor circuits.     

大鼠局灶性脑缺血再灌注后BDNF mRNA及其蛋白的表达变化

目的 观察大鼠脑缺血再灌注后缺血半暗带皮质脑源性神经营养因子(BDNF)mRNA和蛋白的表达变化.方法 采用线栓法制作局灶性脑缺血大鼠(MCAO)模型,用原位杂交法和免疫组化法观察脑缺血后3、6、12h及1、3、7d共6个时间点BDNF mRNA及其蛋白的表达变化.结果 缺血半暗带BDNF mRNA及其蛋白的表达均于缺血再灌注后3h开始明显上升,6h表达继续增强,12h达高峰,3d后表达开始减弱(P＜0.05或0.01),7d后降至基础水平.结论 脑缺血再灌注后缺血半暗带BDNFmRNA及蛋白表达均明显增加,提示其可能参与了脑缺血后神经保护.     

Expression of brain-derived neurotrophic factor mRNA in rat hippocampus after treatment with antipsychotic drugs

Typical and atypical antipsychotic drugs, though both effective, act on different neurotransmitter receptors and are dissimilar in some clinical effects and side effects. The typical antipsychotic drug haloperidol has been shown to cause a decrease in the expression of brain-derived neurotrophic factor (BDNF), which plays an important role in neuronal cell survival, differentiation, and neuronal connectivity. However, it is still unknown whether atypical antipsychotic drugs similarly regulate BDNF expression. We examined the effects of chronic (28 days) administration of typical and atypical antipsychotic drugs on BDNF mRNA expression in the rat hippocampus using in situ hybridization. Quantitative analysis revealed that the typical antipsychotic drug haloperidol (1 mg/kg) down-regulated BDNF mRNA expression in both CA1 (P < 0.05) and dentate gyrus (P < 0.01) regions compared with vehicle control. In contrast, the atypical antipsychotic agents clozapine (10 mg/kg) and olanzapine (2.7 mg/kg) up-regulated BDNF mRNA expression in CA1, CA3, and dentate gyrus regions of the rat hippocampus compared with their respective controls (P < 0.01). These findings demonstrate that the typical and atypical antipsychotic drugs differentially regulate BDNF mRNA expression in rat hippocampus.     

Neuronal injury and brain-derived neurotrophic factor expression in a rat model of amygdala kindling seizures Differences in brain regions and kindling courses

BACKGROUND:Studies have demonstrated that brain-derived neurotrophic factor (BDNF) has a dual effect on epilepsy. However, the relationship between epilepsy-induced brain injury and BDNF remains poorly understood.OBJECTIVE:According to ultrastructural and molecular parameters, to detect the degree of neuronal injury and BDNF expression changes at different brain regions and different kindling times to determine the effects of BDNF on epilepsy-induced brain injury.DESIGN, TIME AND SETTING:A randomized, controlled, animal experiment based on neuropathology and molecular biology was performed at the Department of Physiology and Department of Pathology, Basic Medical College of Jilin University in 2003.MATERIALS:UltraSensitiveTM SP kit for immunohistochemistry (Fuzhou Maxim Biotechnology, China), BDNF antibody (concentrated type, Wuhan Boster Biological Technology, China), JEM-1000SX transmission electron microscopy (JEOL, Japan), and BH-2 light microscope (Olympus, Japan) were used in the present study.METHODS:Wistar rats were randomly assigned to control (n = 6), sham-surgery (n = 6), and model (n = 60) groups. The control group rats were not treated; an electrode was embedded into the amygdala in rats from the sham-surgery and model groups; an amygdala kindling epilepsy model was established in the model group.MAIN OUTCOME MEASURES:Pathological changes in the temporal lobe and hippocampus were observed by light and electron microscopy at 1, 3, 7, 14, and 21 days following kindling, and BDNF expression in the various brain regions was determined by immunohistochemistry.RESULTS:In the model group, temporal lobe cortical and hippocampal neurons were swollen and the nuclei were laterally deviated. There were also some apoptotic neurons 3 days after kindling. The nucleoli disappeared and the nuclei appeared broken or lysed, as well as slight microglia hyperplasia, at 7 days. Electron microscopic observation displayed chromatin aggregation in the nuclei and slight mitochondrion swelling 3 days after kindling. Injury changes were aggravated at 7 days, characterized by broken cytoplasmic membrane and pyknosis. With the development of seizure, the number of BDNF-positive neurons in the hippocampus and temporal lobe increased and peaked at 7 days. Moreover, hippocampal and cortical temporal lobe injury continued. Following termination of electrical stimulation after 7 days of kindling, BDNF expression decreased, but continued to be expressed, up to 21 days of kindling. In addition, the number of temporal and hippocampal BDNF-positive neurons was greater than the control group.CONCLUSION:Brain injury and BDNF expression peaked at 7 days after kindling, and hippocampal changes were significant.     

Serum levels of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in depressed patients with schizophrenia

Aim: Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are neurotrophins—proteins that induce the survival, development, and function of neurons. Their role in the development of schizophrenia and mood disorders is widely studied. This study was aimed to determine whether depression affects levels of BDNF and NT-3 in patients with schizophrenia. Methods: Data for 53 Caucasian adult hospitalized patients with chronic paranoid schizophrenia was compared with 27 healthy subjects. Clinical symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) and positive, negative and general sub-scores, the Calgary Depression Scale for Schizophrenia (CDSS), the Hamilton Depression Rating Scale (HDRS), and the Clinical Global Impressions scale (CGI). Patients were defined as depressed (SHZ-DEP) with scores CDSS?>?6 and HDRS?>?7, otherwise they were included into the non-depressed group (SHZ-nonDEP). Results: In total, 17 patients (32.1%) with schizophrenia met criteria for depression. SHZ-DEP patients had higher scores in HDRS, CDSS, PANSS total, PANSS negative, PANSS general and CGI (p?p?=?0.045. NT-3 levels were higher in SHZ-DEP compared to SHZ-nonDEP: 133.31?±?222.19 versus 56.04?±?201.28 pg/mL, p?=?0.033. Conclusion: There were no differences in neurotrophin levels between patients with schizophrenia and controls. We found lower BDNF and higher NT-3 serum levels in depressed patients with schizophrenia.     

Differences in neurotrophic factor gene expression profiles between neonate and adult rat spinal cord after injury

The capacity of the central nervous system for axonal growth decreases as the age of the animal at the time of injury increases. Changes in the expression of neurotrophic factors within embryonic and early postnatal spinal cord suggest that a lack of trophic support contributes to this restrictive growth environment. We examined neurotrophic factor gene profiles by ribonuclease protection assay in normal neonate and normal adult spinal cord and in neonate and adult spinal cord after injury. Our results show that in the normal developing spinal cord between postnatal days 3 (P3) and P10, compared to the normal adult spinal cord, there are higher levels of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), and glial-derived neurotrophic factor (GDNF) mRNA expression and a lower level of ciliary neurotrophic factor (CNTF) mRNA expression. Between P10 and P17, there is a significant decrease in the expression of NGF, BDNF, NT-3, and GDNF mRNA and a contrasting steady and significant increase in the level of CNTF mRNA expression. These findings show that there is a critical shift in neurotrophic factor expression in normal developing spinal cord between P10 and P17. In neonate spinal cord after injury, there is a significantly higher level of BDNF mRNA expression and a significantly lower level of CNTF mRNA expression compared to those observed in the adult spinal cord after injury. These findings suggest that high levels of BDNF mRNA expression and low levels of CNTF mRNA expression play important roles in axonal regrowth in early postnatal spinal cord after injury.     

Treatment with ginseng total saponins reduces the secondary brain injury in rat after cortical impact

The present study was designed to investigate the neuroprotective effect of ginseng total saponins (GTSs) and its underlying mechanisms in a rat model of traumatic brain injury (TBI). Rats were injected with GTSs (20 mg/kg, i.p.) or vehicle for 14 days after TBI. Neurological functions were determined using beam balance and prehensile traction tests at 1-14 days after trauma. Brain samples were extracted at 1 day after trauma for determination of water content, Nissl staining, enzyme-linked immunosorbent assay, immunohistochemistry, terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick end labeling, and measurement of oxidative stress variables and inflammatory cytokines. Moreover, the dose response of the neuroprotective effect and time window of the efficacy of GTSs were also determined. We found that treatment of GTSs 1) improved the neurological function with an effective dosage of 5-80 mg/kg and an efficacy time window of 3-6 hr after TBI; 2) reduced brain water content and neuronal loss in the hippocampal CA3 area; 3) increased the activity of superoxide dismutase and decreased the activity of nitric oxide synthase and the amount of malondialdehyde and nitric oxide; 4) down-regulated interleukin-1β, interleukin-6, and tumor necrosis factor-α and upregulated interleukin-10 in the cortical area surrounding the injured core; and 5) inhibited the apoptotic cell death and expression of caspase-3 and bax and raised the expression of bcl-2. These findings suggest that administration of GTSs after TBI could reduce the secondary injury through inhibiting oxidative and nitrative stress, attenuating inflammatory response, and reducing apoptotic cell death.     

Early expression of glutamate transporter proteins in ramified microglia after controlled cortical impact injury in the rat

Traumatic brain injury is followed by increased extracellular glutamate concentration. Uptake of glutamate is mainly mediated by the glial glutamate transporters GLAST and GLT-1. Extent and distribution of GLAST and GLT-1 were studied in a rat model of controlled cortical impact injury (CCII). Western Blot analysis revealed lowest levels of GLAST and GLT-1 with a decrease by 40%-54% and 42%-49% between 24 and 72 h posttrauma. By 8 h after CCII, CSF glutamate levels were increased (10.5 microM vs. 2.56 microM in controls; P < 0.001), reaching maximum values by 48 h. A significant increase in de novo GLAST and GLT-1 expressing ramified microglia was observed within 4 h, reached a stable level by 48 h, and remained high up to 72 h after CCII. Furthermore, ramified microglia de novo expressed the neuronal glutamate transporter EAAC1 after CCII. Following CCII, GLAST/GLT-1 and GFAP coexpressing astrocytes were immediately reduced, reaching minimum levels within 8 h. This reduction of expression could be either due to protein downregulation or loss of astrocytes. At 72 h, a marked population of GLAST- and GLT-1-positive reactive astrocytes appeared. These results support the hypothesis that reduced astrocytic GLAST and GLT-1 protein levels following CCII contribute to evolving secondary injury. Microglia are capable of de novo expressing glutamate transporter proteins, indicating that the expression of glial and neuronal glutamate transporters is not restricted to a specific glial or neuronal lineage. Ramified microglia may play an important compensatory role in the early regulation of extracellular glutamate after CCII.     

Effects of electroconvulsive seizures and antidepressant drugs on brain-derived neurotrophic factor protein in rat brain.

BACKGROUND: The antidepressant-like effects of brain-derived neurotrophic factor (BDNF) infusions in brain, and the upregulation of BDNF mRNA and its receptor in rats exposed to electroconvulsive seizure (ECS) and antidepressants, suggested a role for increased BDNF protein. METHODS: We measured BDNF protein levels with a two-site enzyme-linked immunosorbent assay (ELISA) in six brain regions of adult male rats that received daily ECS or daily injections of antidepressant drugs. RESULTS: The BDNF ELISA method was validated by the 50% loss of BDNF protein in the brains of +/- BDNF knockout mice, the 60%-100% recovery of spiked recombinant BDNF, and by the amounts and regional variations of BDNF measured in the six brain regions. Ten consecutive daily exposures to ECS increased BDNF protein in the parietal cortex (219%), entorhinal cortex (153%), hippocampus (132%), frontal cortex (94%), neostriatum (67%), and septum (29%). BDNF increased gradually in the hippocampus and frontal cortex, with a peak response by the fourth day of ECS. Increases peaked at 15 hours after the last ECS and lasted at least 3 days thereafter. Two weeks of daily injections with the monoamine (MAO)-A and -B inhibitor tranylcypromine (8-10 mg/kg, IP) increased BDNF by 15% in the frontal cortex, and 3 weeks treatment increased it by 18% in the frontal cortex and by 29% in the neostriatum. Tranylcypromine, fluoxetine, and desmethylimipramine did not elevate BDNF in the hippocampus. CONCLUSIONS: Elevations in BDNF protein in brain are consistent with the greater treatment efficacy of ECS and MAO inhibitors in drug-resistant major depressive disorder and may be predictive for the antidepressant action of the more highly efficacious interventions.