Differential response of apoptosis-regulatory Bcl-2 and Bax proteins to an inflammatory challenge in the cerebral cortex and hippocampus of aging mice

Neuroprotective and anti-amnesic effects of Laurus Nobilis essential oil against scopolamine-induced memory deficits in mice brain

ETHNOPHARMACOLOGICAL RELEVANCE

Laurus nobilis L. (Lauraceae family) has been widely used in traditional Tunisian medicine for the treatment of different health problems such as rheumatism and some neurological disorders.

AIM

In this study, the essential oil obtained from Laurus nobilis L. species from Tunisia (LEO) was studied for its chemical composition and anti-amnesic activities on memory impairment caused by scopolamine injection in mice. The major compounds of LEO oil, 1,8-cineole and, α-terpinyl acetate were docked with AChE (Acetylcholinesterase), using Autodock Vina and Discovery Studio visualizer software.

MATERIALS AND METHODS

The Morris water maze (MWM) tests and the Y maze were used to assess the anti-amnesic effects of LEO in mice with scopolamine-induced memory impairments. In brain tissues, the levels of biomarkers, enzyme activity, and protein expression related to the cholinergic system were measured.

RESULTS

Chronic administration of scopolamine led to a significant decline in cognitive performance in both the Morris Water Maze (MWM) and Y maze tests, accompanied by pronounced oxidative damage and a significant increase in acetylcholinesterase activity compared to the other groups. However, compared to the scopolamine group, treatment with LEO (100 mg/kg) significantly enhanced cognitive function and ameliorated the oxidative damage (p < 0.05 versus scopolamine) CONCLUSION: This study demonstrates the beneficial effect of LEO on scopolamine-induced dementia in mice, potentially achieved through the modulation of cholinergic activity and antioxidant properties. The docking analysis of the major compounds, 1,8-cineole and α-terpinyl acetate, further substantiates their potential as memory enhancers.

Inflammation as common link to progressive neurological diseases

Life expectancy has increased immensely over the past decades, bringing new challenges to the health systems as advanced age increases the predisposition for many diseases. One of those is the burden of neurologic disorders. While many hypotheses have been placed to explain aging mechanisms, it has been widely accepted that the increasing pro-inflammatory status with advanced age or "inflammaging" is a main determinant of biological aging. Furthermore, inflammaging is at the cornerstone of many age-related diseases and its involvement in neurologic disorders is an exciting hypothesis. Indeed, aging and neurologic disorders development in the elderly seem to share some basic pathways that fundamentally converge on inflammation. Peripheral inflammation significantly influences brain function and contributes to the development of neurological disorders, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Understanding the role of inflammation in the pathogenesis of progressive neurological diseases is of crucial importance for developing effective treatments and interventions that can slow down or prevent disease progression, therefore, decreasing its social and economic burden.

Early Brain Injury and Neuroprotective Treatment after Aneurysmal Subarachnoid Hemorrhage: A Literature Review

Early brain injury (EBI) subsequent to subarachnoid hemorrhage (SAH) is strongly associated with delayed cerebral ischemia and poor patient prognosis. Based on investigations into the molecular mechanisms underlying EBI, neurovascular dysfunction resulting from SAH can be attributed to a range of pathological processes, such as microvascular alterations in brain tissue, ionic imbalances, blood-brain barrier disruption, immune-inflammatory responses, oxidative stress, and activation of cell death pathways. Research progress presents a variety of promising therapeutic approaches for the preservation of neurological function following SAH, including calcium channel antagonists, endothelin-1 receptor blockers, antiplatelet agents, anti-inflammatory agents, and anti-oxidative stress agents. EBI can be mitigated following SAH through neuroprotective measures. To enhance our comprehension of the relevant molecular pathways involved in brain injury, including brain ischemia-hypoxic injury, neuroimmune inflammation activation, and the activation of various cell-signaling pathways, following SAH, it is essential to investigate the evolution of these multifaceted pathophysiological processes. Facilitating neural repair following a brain injury is critical for improving patient survival rates and quality of life.

The Potential Neuroprotective Effect of Cyperus esculentus L. Extract in Scopolamine-Induced Cognitive Impairment in Rats: Extensive Biological and Metabolomics Approaches

The aim of the present study is to investigate the phytochemical composition of tiger nut (TN) (Cyperus esculentus L.) and its neuroprotective potential in scopolamine (Scop)-induced cognitive impairment in rats. The UHPLC-ESI-QTOF-MS analysis enabled the putative annotation of 88 metabolites, such as saccharides, amino acids, organic acids, fatty acids, phenolic compounds and flavonoids. Treatment with TN extract restored Scop-induced learning and memory impairments. In parallel, TN extract succeeded in lowering amyloid beta, β-secretase protein expression and acetylcholine esterase (AChE) activity in the hippocampus of rats. TN extract decreased malondialdehyde levels, restored antioxidant levels and reduced proinflammatory cytokines as well as the Bax/Bcl2 ratio. Histopathological analysis demonstrated marked neuroprotection in TN-treated groups. In conclusion, the present study reveals that TN extract attenuates Scop-induced memory impairments by diminishing amyloid beta aggregates, as well as its anti-inflammatory, antioxidant, anti-apoptotic and anti-AChE activities.

Analysis of the Effects of Ninjin’yoeito on Physical Frailty in Mice

Physical frailty is an aging-related clinical syndrome involving decreases in body weight, mobility, activity, and walking speed that occurs in individuals with sarcopenia and is accelerated by increased oxidative stress. Ninjin’yoeito, a traditional Japanese Kampo medicine, is used for treating conditions, including anemia and physical weakness. Here, we investigated whether ninjin’yoeito could improve physical frailty by controlling oxidative stress in the senescence-accelerated mouse prone 8 (SAMP8) model. First, SAMP8 mice were divided into two groups, ninjin’yoeito treated and untreated, with the former consuming a diet containing 3% ninjin’yoeito from 3 months of age. At 7 months of age, body weight, motor function, locomotor activity, and mean walking speed were measured. Subsequently, mice were euthanized and measured for muscle weight, 8-hydroxy-2′-deoxyguanosine levels in muscle and brain, and cleaved caspase-3 expression in brain. The results showed reductions in weight, locomotor function, locomotion, and average walking speed in the untreated group, which were significantly improved by ninjin’yoeito. Furthermore, 8-hydroxy-2′-deoxyguanosine levels were reduced in muscle and brain from ninjin’yoeito-treated mice, compared with the levels in untreated mice; cleaved caspase-3 expression was similarly reduced in brain from the treated mice, indicating reduced apoptosis. Our findings suggest that ninjin’yoeito inhibits sarcopenia-based physical frailty through its antioxidant effects.

Neuroprotective Effect of Bcl-2 on Lipopolysaccharide-Induced Neuroinflammation in Cortical Neural Stem Cells

Neuroinflammation is involved in the pathogenesis of neurodegenerative diseases due to increased levels of pro-inflammatory cytokines in the central nervous system (CNS). Chronic neuroinflammation induced by neurotoxic molecules accelerates neuronal damage. B-cell lymphoma 2 (Bcl-2) is generally accepted to be an important anti-apoptotic factor. However, the role of Bcl-2 in neuroprotection against neuroinflammation remains to be determined. The purpose of this study was to investigate the neuroprotective effect of Bcl-2 on lipopolysaccharide (LPS)-induced neuroinflammation in cortical neural stem cells (NSCs). LPS decreased mRNA and protein levels of Tuj-1, a neuron marker, and also suppressed neurite outgrowth, indicating that LPS results in inhibition of neuronal differentiation of NSCs. Furthermore, LPS treatment inhibited Bcl-2 expression during neuronal differentiation; inhibition of neuronal differentiation by LPS was rescued by Bcl-2 overexpression. LPS-induced pro-inflammatory cytokines, including interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α), were decreased by Bcl-2 overexpression. Conversely, Bcl-2 siRNA increased the LPS-induced levels of IL-6 and TNF-α, and decreased neuronal differentiation of NSCs, raising the possibility that Bcl-2 mediates neuronal differentiation by inhibiting the LPS-induced inflammatory response in NSC. These results suggest that Bcl-2 has a neuroprotective effect by inhibiting the LPS-induced inflammatory response in NSCs.

Spermine protects aluminium chloride and iron-induced neurotoxicity in rat model of Alzheimer's disease via attenuation of tau phosphorylation, Amyloid-β (1-42) and NF-κB pathway

Alzheimer's disease (AD) is the most prevalent type of dementia, characterized by a gradual decline in cognitive and memory functions of the aged peoples. Long-term exposure to heavy metals (aluminium and iron) cause neurotoxicity by amyloid plaques accumulation, tau phosphorylation, increased oxidative stress, neuroinflammation, and cholinergic neurons degeneration, contributes to the development of AD-like symptoms. The present research work is designed to investigate the neuroprotective effect of spermine in aluminium chloride (AlCl₃), and iron (Fe) induced AD-like symptoms in rats. Rats were administered of AlCl₃ (100 mg/kg p.o.) alone and in combination with iron (120 μg/g, p.o.) for 28 days. Spermine (5 and 10 mg/kg) through intraperitoneal (i.p.) route was given for 14 days. The recognition and spatial memory impairment were tasted using Morris water maze (MWM), actophotometer, and Novel Object Recognition test (NORT). All the rats were sacrificed on day 29, brains were isolated, and tissue homogenate was used for neuroinflammatory, biochemical, neurotransmitters, metals concentration, and nuclear factor-kappa B (NF-κB) analysis. In the present study, AlCl₃ and iron administration elevated oxidative stress, cytokines release, dysbalanced neurotransmitters concentration, and biochemical changes. Rats treated with spermine dose-dependently improved the recognition and spatial memory, attenuated proinflammatory cytokine release, and restored neurotransmitters concentration and antioxidant enzymes. Spermine also mitigated the increased beta-amyloid (Aβ42), with downregulation of tau phosphorylation. Furthermore, spermine augmented the hippocampal levels of B cell leukaemia/lymphoma-2 (Bcl-2), diminished nuclear factor-kappa B (NF-κB) and caspase-3 (casp-3) expression. Moreover, spermine exhibited the neuroprotective effect through anti-inflammatory, antioxidant, neurotransmitters restoration, anti-apoptotic Aβ42 concentration.

SIRT2 and FOXO3a expressions in the cerebral cortex and hippocampus of young and aged male rats: antioxidant and anti-apoptotic effects of melatonin

Melatonin has antioxidant, anti-apoptotic and anti-aging effects in the brain. Sirtuin2 (SIRT2) accumulates in the central nervous system with aging, and its inhibition appears to be protective in aging and aging-related neurodegenerative diseases. Forkhead Box-class O3a (FOXO3a) transcription factor is one of the main targets of SIRT2, and SIRT2-mediated FOXO3a deacetylation is closely related to aging, oxidative stress, and apoptosis. This study aimed to investigate the effects of melatonin on SIRT2 and FOXO3a expressions in the cerebral cortex and hippocampus of aged rats. Young (3 months, n = 18) and aged (22 months, n = 18) male Wistar rats were divided into control (4% DMSO-PBS, sc, for 21 days), melatonin (10 mg/kg, sc, for 21 days) and salermide (1 mM; 25 μl/100 g bw, ip, for 21 days) groups. SIRT2, FOXO3a, Bcl-2, Bax and Bim expressions in the cerebral cortex and hippocampus were demonstrated by Western blotting. SIRT2 and FOXO3a protein levels were also measured by a sandwich ELISA method. Oxidative stress index (OSI) was calculated by measuring total oxidant status (TOS) and total antioxidant status (TAS). Aging increased SIRT2, FOXO3a, Bim (only in the cerebral cortex), Bax (only in the hippocampus), TOS, and OSI, while decreasing Bcl-2, Bcl-2/Bax and TAS in both brain regions. Melatonin decreased SIRT2, FOXO3a, oxidative stress parameters and pro-apoptotic proteins, while increasing TAS, Bcl-2 and Bcl-2/Bax, more specifically in the hippocampus of the aged brain. Our results indicate that inhibition of SIRT2 and FOXO3a expressions appears to be involved in the protective effects of melatonin in the hippocampus of aged rats.

Apigenin Ameliorates Scopolamine-Induced Cognitive Dysfunction and Neuronal Damage in Mice

We investigated the protective effect and mechanisms of apigenin against cognitive impairments in a scopolamine-injected mouse model. Our results showed that intraperitoneal (i.p.) injection of scopolamine leads to learning and memory dysfunction, whereas the administration of apigenin (synthetic compound, 100 and 200 mg/kg/day) improved cognitive ability, which was confirmed by behavioral tests such as the T-maze test, novel objective recognition test, and Morris water maze test in mice. In addition, scopolamine-induced lipid peroxidation in the brain was attenuated by administration of apigenin. To further evaluate the protective mechanisms of apigenin on cognitive and memory function, Western blot analysis was carried out. Administration of apigenin decreased the B-cell lymphoma 2-associated X/B-cell lymphoma 2 (Bax/Bcl-2) ratio and suppressed caspase-3 and poly ADP ribose polymerase cleavage. Furthermore, apigenin down-regulated the β-site amyloid precursor protein-cleaving enzyme, along with presenilin 1 (PS1) and PS2 protein levels. Apigenin-administered mice showed lower protein levels of a receptor for advanced glycation end-products, whereas insulin-degrading enzyme, brain-derived neurotrophic factor (BDNF), and tropomyosin receptor kinase B (TrkB) expression were promoted by treatment with apigenin. Therefore, this study demonstrated that apigenin is an active substance that can improve cognitive and memory functions by regulating apoptosis, amyloidogenesis, and BDNF/TrkB signaling pathways.

miR-34a/Bcl-2 signaling pathway contributes to age-related hearing loss by modulating hair cell apoptosis

MicroRNAs, such as miR-34, have been reported to influence age-related diseases. In this study, we explored the role of the miR-34a/Bcl-2 signaling pathway in age-related hearing loss (AHL). Using an AHL mouse model (C57BL/6), we found that the expression of miR-34a in the cochlea increased with age, whereas expression of Bcl-2 decreased. Increasing the amount of a miR-34a mimetic in a mouse auditory cell line (HEI-OC1) inhibited Bcl-2, leading to enhanced apoptosis; in contrast, miR-34a inhibition produced the opposite effect. Our results support a link between age-related cochlear hair cell apoptosis and miR-34a/Bcl-2 signaling. The latter may thus serve as a potential target for AHL therapy.

Role of F3/contactin expression profile in synaptic plasticity and memory in aged mice

We have recently shown that overexpression of the F3/contactin adhesive glycoprotein (also known as Contactin-1) promotes neurogenesis in adult hippocampus, which correlates with improved synaptic plasticity and memory. Because F3/contactin levels physiologically decrease with age, here, we aim at investigating whether its overexpression might counteract the cognitive decline in aged animals. For this we use 20- to 24-month-old TAG/F3 transgenic mice in which F3/contactin overexpression is driven by regulatory sequences from the gene encoding the transient axonal glycoprotein TAG-1 throughout development. We show that aged TAG/F3 mice display improved hippocampal long-term potentiation and memory compared with wild-type littermates. The same mice undergo a decrease of neuronal apoptosis at the hippocampal level, which correlated to a decrease of active caspase-3; by contrast, procaspase-3 and Bax as well as the anti-apoptotic and plasticity-related pathway BDNF/CREB/Bcl-2 were rather increased. Interestingly, amyloid-precursor protein processing was shifted toward sAPPα generation, with a decrease of sAPPβ and amyloid-beta levels. Our data confirm that F3/contactin plays a role in hippocampal synaptic plasticity and memory also in aged mice, suggesting that it acts on molecular pathways related to apoptosis and amyloid-beta production.

Beclin 1 interactome controls the crosstalk between apoptosis, autophagy and inflammasome activation: impact on the aging process

Autophagy and apoptosis are crucial cellular housekeeping and tissue survival mechanisms. There is emerging evidence of important crosstalk between apoptosis and autophagy which can be linked to inflammasome activation. Beclin 1 is a platform protein which assembles an interactome consisting of diverse proteins which control the initiation of autophagocytosis and distinct phases in endocytosis. Recent studies have demonstrated that the anti-apoptotic Bcl-2 family members can interact with Beclin 1 and inhibit autophagy. Consequently, impaired autophagy can trigger inflammasome activation. Interestingly, the hallmarks of the ageing process include a decline in autophagy, increased resistance to apoptosis and a low-grade inflammatory phenotype. Age-related stresses, e.g. genotoxic, metabolic and environmental insults, enhance the expression of NF-κB-driven anti-apoptotic Bcl-2 proteins which repress the Beclin 1-dependent autophagy. Suppression of autophagocytosis provokes inflammation including NF-κB activation which further potentiates anti-apoptotic defence. In a context-dependent manner, this feedback defence mechanism can enhance the aging process or provoke tumorigenesis or cellular senescence. We will review the role of Beclin 1 interactome in the crosstalk between apoptosis, autophagy and inflammasomes emphasizing that disturbances in Beclin 1-dependent autophagy can have a crucial impact on the aging process.

T Cell Recruitment in the Brain during Normal Aging

Aging-related changes in the peripheral immune response are well documented, but less is known about changes of the immune response in the central nervous system. Reactivity of microglia, effectors of the brain innate immunity, is known to increase in the aged brain, but little attention has been hitherto devoted to T cell recruitment. Data in rodents point to a gradual enhancement of T cell homing to the brain in the steady state since the middle age. Experimental findings also point to enhanced transmigration of lymphocytes as part of an amplified response of the aging brain to acute exogenous inflammatory insults. Thus, available data support the capacity of the aged brain to mount a robust immune response, in contrast with peripheral immunity decline, and indicate that such central response involves recruitment of lymphocytes. These findings open many questions, including blood-brain barrier molecular regulation and infiltrated T cell subtypes during normal aging. The crosstalk between T cells, glia, and neurons also remains to be clarified in the aged brain parenchyma. This intercellular dialogue and related signaling could be relevant for both protection of the aged brain and its vulnerability to neurological disease.

Context-Dependent Regulation of Autophagy by IKK-NF-κB Signaling: Impact on the Aging Process

The NF-κB signaling system and the autophagic degradation pathway are crucial cellular survival mechanisms, both being well conserved during evolution. Emerging studies have indicated that the IKK/NF-κB signaling axis regulates autophagy in a context-dependent manner. IKK complex and NF-κB can enhance the expression of Beclin 1 and other autophagy-related proteins and stimulate autophagy whereas as a feedback response, autophagy can degrade IKK components. Moreover, NF-κB signaling activates the expression of autophagy inhibitors (e.g., A20 and Bcl-2/xL) and represses the activators of autophagy (BNIP3, JNK1, and ROS). Several studies have indicated that NF-κB signaling is enhanced both during aging and cellular senescence, inducing a proinflammatory phenotype. The aging process is also associated with a decline in autophagic degradation. It seems that the activity of Beclin 1 initiation complex could be impaired with aging, since the expression of Beclin 1 decreases as does the activity of type III PI3K. On the other hand, the expression of inhibitory Bcl-2/xL proteins increases with aging. We will review the recent literature on the control mechanisms of autophagy through IKK/NF-κB signaling and emphasize that NF-κB signaling could be a potent repressor of autophagy with ageing.

Protective Effect of Coriolus versicolor Cultivated in Citrus Extract Against Nitric Oxide-Induced Apoptosis in Human Neuroblastoma SK-N-MC Cells

Nitric oxide (NO) is a reactive free radical and a messenger molecule in many physiological functions. However, excessive NO is believed to be a mediator of neurotoxicity. The medicinal plant Coriolus versicolor is known to possess anti-tumor and immune-potentiating activities. In this study, we investigated whether Coriolus versicolor possesses a protective effect against NO donor sodium nitroprusside (SNP)-induced apoptosis in the human neuroblastoma cell line SK-N-MC. We utilized 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, 4,6-diamidino-2-phenylindole (DAPI) staining, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, DNA fragmentation assay, reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis, and caspase-3 enzyme activity assay in SK-N-MC cells. MTT assay showed that SNP treatment significantly reduces the viability of cells, and the viabilities of cells pre-treated with the aqueous extract of Coriolus versicolor cultivated in citrus extract (CVE_citrus) was increased. However, aqueous extract of Coriolus versicolor cultivated in synthetic medium (CVE_synthetic) showed no protective effect and aqueous citrus extract (CE) had a little protective effect. The cell treated with SNP exhibited several apoptotic features, while those pre-treated for 1 h with CVE_citrus prior to SNP expose showed reduced apoptotic features. The cells pre-treated for 1 h with CVE_citrus prior to SNP expose inhibited p53 and Bax expressions and caspase-3 enzyme activity up-regulated by SNP. We showed that CVE_citrus exerts a protective effect against SNP-induced apoptosis in SK-N-MC cells. Our study suggests that CVE_citrus has therapeutic value in the treatment of a variety of NO-induced brain diseases.

Treadmill exercise prevents aging-induced failure of memory through an increase in neurogenesis and suppression of apoptosis in rat hippocampus

Aging leads to functional changes in the hippocampus, and consequently induces cognitive deficits, such as failure of memory. Neurogenesis in the hippocampal dentate gyrus continues throughout life, but steadily declines from early adulthood. Apoptosis occurs under various pathologic and physiologic conditions, and excessive apoptotic cell death can cause a number of functional disorders in humans. Apoptosis in the hippocampus also disturbs cognitive functions. In this study, we examined the effect of treadmill exercise on memory in relation to neurogensis and apoptosis in the hippocampal dentate gyrus of old-aged rats. The present results showed that loss of memory by aging was associated with a decrease in neurogenesis and an increase in apoptosis in the hippocampal dentate gyrus. Treadmill exercise improved short-term and spatial memories by enhancing neurogenesis and suppressing apoptosis in the hippocampal dentate gyrus of old-aged rats. In the present study, we showed that treadmill exercise is a very useful strategy for preventing failure of memory in the elderly.

Regulation of cytokine signaling and T-cell recruitment in the aging mouse brain in response to central inflammatory challenge

Aging is often accompanied by increased levels of inflammatory molecules in the organism, but age-related changes in the brain response to inflammatory challenges still require clarification. We here investigated in mice whether cytokine signaling and T-cell neuroinvasion undergo age-related changes. We first analyzed the expression of molecules involved in T-cell infiltration and cytokine signaling regulation in the septum and hippocampus of 2-3 months and 20- to 24-month-old mice at 4h after intracerebroventricular injections of tumor necrosis factor (TNF)-alpha or interferon-gammaversus saline injections. Transcripts of the chemokine CXCL9, intercellular adhesion molecule (ICAM)-1 and suppressor of cytokine signaling molecules (SOCS) 1 and 3 were increased in both age groups after cytokine injection; microglia-derived matrix metalloproteinase (MMP) 12 mRNA was induced in old mice also after control saline injections. Age-related changes in ICAM-1 protein expression and T-cell infiltration were then analyzed in mice of 3-4, 8-9 and 15-16 months at 48h after TNF-alpha injections. ICAM-1 immunoreactivity, and Western blotting in striatum, septum, hippocampus and hypothalamus showed progressive age-related enhancement of TNF-alpha-elicited ICAM-1 upregulation. Double immunofluorescence revealed ICAM-1 expression in microglia and astrocytic processes. CD3(+), CD4(+) and CD8(+) T-cells exhibited progressive age-related increases in brain parenchyma and choroid plexus after cytokine exposure. The findings indicate that the brain responses to inflammatory challenges are not only preserved with advancing age, but also include gradual amplification of ICAM-1 expression and T-cell recruitment. The data highlight molecular and cellular correlates of age-related increase of brain sensitivity to inflammatory stimuli, which could be involved in altered brain vulnerability during aging.

Role of p38 MAPK and pro-inflammatory cytokines expression in glutamate-induced neuronal death of neonatal rats

Pro-inflammatory cytokines TNF-alpha, IL-1beta and IL-6 rises significantly during neuronal damage and activate the signaling p38 MAPK pathway, which is involved in the apoptotic (AP) neuronal death. Systemic administration of glutamate as monosodium salt (MSG) to newborn animals induces neuronal death, however whether neurons die by AP or necrosis through MAPK p38 pathway activation it is unknown. In this study, TNF-alpha, IL-1beta and IL-6 expression levels, AP neuronal death and cellular type that produces TNF-alpha was also identified in the cerebral cortex (CC) and striatum (St) of rats at 8, 10, and 14 days of age after neonatal exposure to MSG. TNF-alpha production and AP neuronal death was significantly increased in the CC at PD8-10, and in the St in all ages studied by excitotoxicity effect induced with MSG. This effect was completely inhibited by SB203580 (p38 inhibitor) in both regions studied. TNF-alpha, IL-1beta and IL-6 RNAm increased after MSG administration, whereas SB203580 did not modify their expression. These data indicates that neuronal death induced by excitotoxicity appears to be mediated through p38 signaling pathway activated by TNF-alpha and their inhibition may have an important neuroprotective role as part of anti-inflammatory therapeutic strategy.