Mice with partial deficiency of c-Jun show attenuation of methamphetamine-induced neuronal apoptosis

Prenatal Methamphetamine Hydrochloride Exposure Leads to Signal Transduction Alteration and Cell Death in the Prefrontal Cortex and Amygdala of Male and Female Rats' Offspring

In the last decade, there has been a great increase in methamphetamine hydrochloride (METH) abuse by pregnant women that exposes fetus and human offspring to a wide variety of developmental impairments that may be the underlying causes of future psychosocial issues. Herein, we investigated whether prenatal METH exposure with different doses (2 and 5 mg/kg) could influence neuronal cell death and antioxidant level in the different brain regions of adult male and female offspring. Adult male and female Wistar rats prenatally exposed to METH (2 or 5 mg/kg) and/or saline was used in this study. At week 12, adult rats' offspring were decapitated to collect different brain region tissues including amygdala (AMY) and prefrontal cortices (PFC). Western blot analysis was performed to evaluate the apoptosis- and autophagy-related markers, and enzymatic assay was used to measure the level of catalase and also reduced glutathione (GSH). Our results showed that METH exposure during pregnancy increased the level of apoptosis (BAX/Bcl-2 and Caspase-3) and autophagy (Beclin-1 and LC3II/LC3I) in the PFC and AMY areas of both male and female offspring's brain. Also, we found an elevation in the GSH content of all both mentioned brain areas and catalase activity of PFC in the offspring's brain. These changes were more significant in female offspring. Being prenatally exposed to METH increased cell death at least partly via apoptosis and autophagy in AMY and PFC of male and female offspring's brain, while the antioxidant system tried to protect cells in these regions.

Molecular mechanisms of programmed cell death in methamphetamine-induced neuronal damage

Methamphetamine, commonly referred to as METH, is a highly addictive psychostimulant and one of the most commonly misused drugs on the planet. Using METH continuously can increase your risk for drug addiction, along with other health complications like attention deficit disorder, memory loss, and cognitive decline. Neurotoxicity caused by METH is thought to play a significant role in the onset of these neurological complications. The molecular mechanisms responsible for METH-caused neuronal damage are discussed in this review. According to our analysis, METH is closely associated with programmed cell death (PCD) in the process that causes neuronal impairment, such as apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. In reviewing this article, some insights are gained into how METH addiction is accompanied by cell death and may help to identify potential therapeutic targets for the neurological impairment caused by METH abuse.

Glial cell diversity and methamphetamine-induced neuroinflammation in human cerebral organoids

Methamphetamine (METH) is a potent stimulant that induces a euphoric state but also causes cognitive impairment, neurotoxicity and neurodevelopmental deficits. Yet, the molecular mechanisms by which METH causes neurodevelopmental defects have remained elusive. Here we utilized human cerebral organoids and single-cell RNA sequencing (scRNA-seq) to study the effects of prenatal METH exposure on fetal brain development. We analyzed 20,758 cells from eight untreated and six METH-treated cerebral organoids and found that the organoids developed from embryonic stem cells contained a diverse array of glial and neuronal cell types. We further identified transcriptionally distinct populations of astrocytes and oligodendrocytes within cerebral organoids. Treatment of organoids with METH-induced marked changes in transcription in multiple cell types, including astrocytes and neural progenitor cells. METH also elicited novel astrocyte-specific gene expression networks regulating responses to cytokines, and inflammasome. Moreover, upregulation of immediate early genes, complement factors, apoptosis, and immune response genes suggests a neuroinflammatory program induced by METH regulating neural stem cell proliferation, differentiation, and cell death. Finally, we observed marked METH-induced changes in neuroinflammatory and cytokine gene expression at the RNA and protein levels. Our data suggest that human cerebral organoids represent a model system to study drug-induced neuroinflammation at single-cell resolution.

Methamphetamine-Induced Neuronal Damage: Neurotoxicity and Neuroinflammation

Methamphetamine (METH) is a highly addictive psychostimulant and one of the most widely abused drugs worldwide. The continuous use of METH eventually leads to drug addiction and causes serious health complications, including attention deficit, memory loss and cognitive decline. These neurological complications are strongly associated with METH-induced neurotoxicity and neuroinflammation, which leads to neuronal cell death. The current review investigates the molecular mechanisms underlying METH-mediated neuronal damages. Our analysis demonstrates that the process of neuronal impairment by METH is closely related to oxidative stress, transcription factor activation, DNA damage, excitatory toxicity and various apoptosis pathways. Thus, we reach the conclusion here that METH-induced neuronal damages are attributed to the neurotoxic and neuroinflammatory effect of the drug. This review provides an insight into the mechanisms of METH addiction and contributes to the discovery of therapeutic targets on neurological impairment by METH abuse.

Methamphetamine induces neuronal death: Evidence from rodent studies

Animal studies have consistently observed neuronal death following methamphetamine (MA) administration, however, these have not been systematically reviewed. This systematic review aims to present the evidence for MA-induced neuronal death in animals (rodents) and identify the regions affected. Locating the brain regions in which neuronal death occurs in animal studies will provide valuable insight into the linkage between MA consumption and the structural alterations observed in the human brain. The data were collected from three databases: Scopus, Ovid, and the Web of Science. Thirty-seven studies met the inclusion criteria and were divided into two sub-groups, i.e. acute and repeated administration. Twenty-six (of 27) acute and ten (of 11) repeated administration studies observed neuronal death. A meta-analysis was not possible due to different variables between studies, i.e. species, treatment regimens, withdrawal periods, methods of quantification, and regions studied. Acute MA treatment induced neuronal death in the frontal cortex, striatum, and substantia nigra, but not in the hippocampus, whereas repeated MA administration led to neuronal loss in the hippocampus, frontal cortex, and striatum. In addition, when animals self-administered the drug, neuronal death was observed at much lower doses than the doses administered by experimenters. There is some overlap in the regions where neuronal death occurred in animals and the identified regions from human studies. For instance, gray matter deficits have been observed in the prefrontal cortex and hippocampus of MA users. The findings presented in this review implicate that not only does MA induce neuronal death in animals, but it also damages the same regions affected in human users. Despite the inter-species differences, animal studies have contributed significantly to addiction research, and are still of great assistance for future research with a more relevant model of compulsive drug use in humans.

Effects of lithium and valproate on ERK/JNK signaling pathway in an animal model of mania induced by amphetamine

Bipolar disorder (BD) is a severe and chronic psychiatric disorder, characterized by recurrent mood episodes of depression and mania. Some studies have indicated that there are ERK and JNK pathways alterations in the brain from bipolar patients. The animal model of mania induced by dextroamphetamine (d-AMPH) has been considered an excellent model to study intracellular alterations related to BD. The present study aimed to evaluate the effects of lithium (Li) and valproate (VPA) on the behavioral and ERK1/2/JNK1/2 signaling pathway in an animal model of mania induced by d-AMPH. Wistar rats were first given d-AMPH or saline (Sal) for 14 days, and then, between the 8th and 14th days, the rats were treated with Li, VPA, or Sal. The open-field test was used to evaluate the locomotion and exploration behaviors of rats. The levels of phosphorylated ERK1/2 and JNK1/2 were assessed in the hippocampus and frontal cortex of the rats. Li and VPA reversed the increased of locomotion and exploration induced by d-AMPH. The treatment with VPA or AMPH per se decreased the levels of pERK1 in the hippocampus. The treatment with VPA in the animals submitted to the administration of d-AMPH decreased the levels of ERK1, JNK-1, and JNK-2 phosphorylated in the hippocampus of the animals. The treatment with Li decreased the JNK-1 phosphorylated in the hippocampus of the animals submitted to the animal model of mania induced by d-AMPH. Although the association of VPA plus amphetamine alters some proteins involved in the JNK pathway in the hippocampus, these alterations were very random and seemed that were not related to the d-AMPH-induced manic-like behavior. These results suggest that the manic-like effects induced by d-AMPH and the antimanic effects of mood stabilizers, Li and VPA, are not related to the alteration on ERK1/2 and JNK1/2 pathways.

The Effect of Chronic Methamphetamine Exposure on the Hippocampal and Olfactory Bulb Neuroproteomes of Rats

Nowadays, drug abuse and addiction are serious public health problems in the USA. Methamphetamine (METH) is one of the most abused drugs and is known to cause brain damage after repeated exposure. In this paper, we conducted a neuroproteomic study to evaluate METH-induced brain protein dynamics, following a two-week chronic regimen of an escalating dose of METH exposure. Proteins were extracted from rat brain hippocampal and olfactory bulb tissues and subjected to liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Both shotgun and targeted proteomic analysis were performed. Protein quantification was initially based on comparing the spectral counts between METH exposed animals and their control counterparts. Quantitative differences were further confirmed through multiple reaction monitoring (MRM) LC-MS/MS experiments. According to the quantitative results, the expression of 18 proteins (11 in the hippocampus and 7 in the olfactory bulb) underwent a significant alteration as a result of exposing rats to METH. 13 of these proteins were up-regulated after METH exposure while 5 were down-regulated. The altered proteins belonging to different structural and functional families were involved in processes such as cell death, inflammation, oxidation, and apoptosis.

The JNK inhibitor, SP600125, potentiates the glial response and cell death induced by methamphetamine in the mouse striatum

This study investigates the effect of the selective Jun NH2-terminal kinase 1/2 (JNK1/2) inhibitor, (SP600125) on the striatal dopamine nerve terminal loss and on the increased interleukin-15 (IL-15) expression and glial response induced by methamphetamine (METH). Mice were given repeated low doses of METH (4 mg/kg, i.p., three times separated by 3 h) and killed 24 h or 7 d after the last dose. SP600125 (30 mg/kg, i.p) was administered 30 min before the last METH injection. Results indicate that METH produced dopaminergic axonal neurotoxicity reflected as a marked decrease in the striatal density of tyrosine hydroxylase-immunoreactive (TH-ir) fibres and dopamine transporter-immunoreactivity (DAT-ir) 24 h after dosing. These effects were not modified by SP600125. This compound also failed to prevent the long-term loss of dopamine levels and DAT observed 7 d following METH injection. Nevertheless, SP600125 potentiated METH-induced striatal cell loss reflected by an increase in Fluoro-Jade immunostaining, cleaved capase-3 immunoreactivity and the number of terminal deoxyncleotidyl transferase-mediated dUTP nick end labelling (TUNEL) positive cells. In line with a deleterious effect of JNK1/2 inhibition, SP600125 increased the astroglial and microglial response induced by METH and interfered with drug-induced IL-15 expression. Together these data indicate that, not only does SP600125 fail to protect against the dopaminergic damage induced by METH but also, in fact, it potentiates the glial response and the non-dopaminergic striatal cell loss caused by the drug.

The neuropeptide Y Y1 receptor knockdown modulates activator protein 1-involved feeding behavior in amphetamine-treated rats

BACKGROUND

Hypothalamic neuropeptide Y (NPY) and two immediate early genes, c-fos and c-jun, have been found to be involved in regulating the appetite-suppressing effect of amphetamine (AMPH). The present study investigated whether cerebral catecholamine (CA) might regulate NPY and POMC expression and whether NPY Y1 receptor (Y1R) participated in activator protein-1 (AP-1)-mediated feeding.

METHODS

Rats were given AMPH daily for 4 days. Changes in the expression of NPY, Y1R, c-Fos, c-Jun, and AP-1 were assessed and compared.

RESULTS

Decreased CA could modulate NPY and melanocortin receptor 4 (MC4R) expressions. NPY and food intake decreased the most on Day 2, but Y1R, c-Fos, and c-Jun increased by approximately 350%, 280%, and 300%, respectively, on Day 2. Similarly, AP-1/DNA binding activity was increased by about 180% on Day 2. The expression patterns in Y1R, c-Fos, c-Jun, and AP-1/DNA binding were opposite to those in NPY during AMPH treatment. Y1R knockdown was found to modulate the opposite regulation between NPY and AP-1, revealing an involvement of Y1R in regulating NPY/AP-1-mediated feeding.

CONCLUSIONS

These results point to a molecular mechanism of CA/NPY/Y1R/AP-1 signaling in the control of AMPH-mediated anorexia and may advance the medical research of anorectic and anti-obesity drugs.

Protective effect of geranylgeranylacetone against methamphetamine-induced neurotoxicity in rat pheochromocytoma cells

BACKGROUND

Methamphetamine is a central nervous system stimulant and is one of the agents most commonly abused by illicit drug users which could induce neuron apoptosis when it is used repeatedly and overdosed. Our previous study demonstrated that geranylgeranylacetone (GGA) was an inducer of thioredoxin-1 (Trx-1) and heat shock protein 70 (Hsp70), which played a cytoprotective role against neurotoxicity.

METHODS

Using the MTT assay, we detected the effect of GGA on cell viability by methamphetamine in rat pheochromocytoma (PC12) cells. Tyrosine hydroxylase, Trx-1, Hsp70, procaspase-9, procaspase-12 and procaspase-3 expression were examined by Western blot analysis. We also detected enzymatic activities of caspase-3 and caspase-9.

RESULTS

We found that GGA protected PC12 cells from apoptosis caused by methamphetamine. Furthermore, GGA reversed the decreases in Trx-1 and Hsp70 by methamphetamine, and prevented the methamphetamine-induced decreases in procaspase-9 and procaspase-3. On the other hand, GGA prevented the methamphetamine-induced increases in the enzymatic activity of caspase-9 and caspase-3. Procaspase-12 was not changed by any treatment.

CONCLUSIONS

These results indicate that GGA protects PC12 cells from methamphetamine-induced toxicity by increasing Trx-1 and Hsp70 and by preventing mitochondria pathway-mediated apoptosis. In summary, GGA may be used as a therapy for neurotoxicity induced by methamphetamine.

Methamphetamine-induced neurotoxicity linked to ubiquitin-proteasome system dysfunction and autophagy-related changes that can be modulated by protein kinase C delta in dopaminergic neuronal cells

A compromised protein degradation machinery has been implicated in methamphetamine (MA)-induced neurodegeneration. However, the signaling mechanisms that induce autophagy and ubiquitin-proteasome system (UPS) dysfunction are not well understood. The present study investigates the contributions of protein kinase C delta (PKCδ)-mediated signaling events in MA-induced autophagy, UPS dysfunction, and cell death. Using an in vitro mesencephalic dopaminergic cell culture model, we demonstrate that MA-induced early induction of autophagy is associated with reduction in proteasomal function and concomitant dissipation of mitochondrial membrane potential (MMP), followed by significantly increased PKCδ activation, caspase-3 activation, accumulation of ubiquitin-positive aggregates and microtubule-associated light chain-3 (LC3-II) levels. Interestingly, siRNA-mediated knockdown of PKCδ or overexpression of cleavage-resistant mutant of PKCδ dramatically reduced MA-induced autophagy, proteasomal function, and associated accumulation of ubiquitinated protein aggregates, which closely paralleled cell survival. Importantly, when autophagy was inhibited either pharmacologically (3-MA) or genetically (siRNA-mediated silencing of LC3), the dopaminergic cells became sensitized to MA-induced apoptosis through caspase-3 activation. Conversely, overexpression of LC3 partially protected against MA-induced apoptotic cell death, suggesting a neuroprotective role for autophagy in MA-induced neurotoxicity. Notably, rat striatal tissue isolated from MA-treated rats also exhibited elevated LC3-II, ubiquitinated protein levels, and PKCδ cleavage. Taken together, our data demonstrate that MA-induced autophagy serves as an adaptive strategy for inhibiting mitochondria-mediated apoptotic cell death and degradation of aggregated proteins. Our results also suggest that the sustained activation of PKCδ leads to UPS dysfunction, resulting in the activation of caspase-3-mediated apoptotic cell death in the nigrostriatal dopaminergic system.

Environmental enrichment does not reduce the rewarding and neurotoxic effects of methamphetamine

Abuse of amphetamine analogues, such as methamphetamine (METH), represents an important health problem because of their powerful addictive and neurotoxic effects. Abuse of METH induces dopamine neuron terminals loss and cell death in the striatum similar to what is found in other neurodegenerative processes. Exposing mice and rats to enriched environments (EE) has been shown to produce significant protective effects against drug-induced reward as well as against neurodegenerative processes. Here, we investigated whether exposure to EE could reduce the METH-induced reward and neurotoxicity. For this, we reared mice for 2 months during early stages of life in standard environments or EE and then, at adulthood, we tested the ability of METH to induce conditioned place preference and neurotoxicity. We found that, contrary to what we found with other drugs such as cocaine and heroin, EE was unable to reduce the rewarding effects of METH. In addition, contrary to what we found with other toxins such as MPTP, EE did not diminish the striatal neurotoxicity induced by METH (4 x 10 mg/kg) as measured by dopamine content, tyrosine hydroxylase protein levels and apoptosis. Our results demonstrate that the rewarding and neurotoxic effects of METH are not reduced by EE and highlight the great risks associated with the increased popularity of this drug amongst the young population.

Methamphetamine treatment causes delayed decrease in novelty-induced locomotor activity in mice

Methamphetamine (METH) is a psychostimulant that causes damage to dopamine (DA) axons and to non-monoaminergic neurons in the brain. The aim of the present study was to investigate short- and long-term effects of neurotoxic METH treatment on novelty-induced locomotor activity in mice. Male BALB/c mice, 12-14 weeks old, were injected with saline or METH (i.p., 7.5 mg/kg x 4 times, every 2 h). Behavior and neurotoxic effects were assessed at 10 days, 3 and 5 months following drug treatment. METH administration caused marked decreases in DA levels in the mouse striatum and cortex at 10 days post-drug. However, METH did not induce any changes in novelty-induced locomotor activity. At 3 and 5 months after treatment METH-exposed mice showed significant recovery of DA levels in the striatum and cortex. In contrast, these animals demonstrated significant decreases in locomotor activity at 5 months in comparison to aged-matched control mice. Further assessment of METH toxicity using TUNEL staining showed that the drug induced increased cell death in the striatum and cortex at 3 days after administration. Taken together, these data suggest that delayed deficits in novelty-induced locomotor activity observed in METH-exposed animals are not due to neurodegeneration of DA terminals but to combined effects of METH and age-dependent dysfunction of non-DA intrinsic striatal and/or corticostriatal neurons.

Reduction in the protein level of c-Jun and phosphorylation of Ser73-c-Jun in rat frontal cortex after repeated MK-801 treatment

Repeated administration of NMDA antagonists can induce behavioral alterations that mimic symptoms of psychosis, as seen in schizophrenia. JNK, one of the MAPKs, and c-Jun, its downstream target molecule, play important roles in regulating apoptosis in neural cells, and have been suggested as being associated with the pathophysiology of psychosis and the mechanism of action of some antipsychotics. We investigated changes in the JNK-c-Jun pathway and other Jun family proteins in the rat frontal cortex after single and repeated administration of MK-801 to examine acute and chronic responses. Neither the protein level nor the phosphorylation of JNK changed after single or repeated doses of MK-801. However, after repeated treatments, but not a single treatment, with MK-801, a down-regulation occurred in the protein level and of Ser73 phosphorylation of c-Jun in the rat frontal cortex. Other members of the Jun family, JunB and JunD, were unchanged. Repeated exposure to MK-801 down-regulated the phosphorylation and protein level of c-Jun in the rat frontal cortex, which may be related to the long-term effects of chronic treatment with MK-801.

Mitochondrial fragmentation is involved in methamphetamine-induced cell death in rat hippocampal neural progenitor cells

Methamphetamine (METH) induces neurodegeneration through damage and apoptosis of dopaminergic nerve terminals and striatal cells, presumably via cross-talk between the endoplasmic reticulum and mitochondria-dependent death cascades. However, the effects of METH on neural progenitor cells (NPC), an important reservoir for replacing neurons and glia during development and injury, remain elusive. Using a rat hippocampal NPC (rhNPC) culture, we characterized the METH-induced mitochondrial fragmentation, apoptosis, and its related signaling mechanism through immunocytochemistry, flow cytometry, and Western blotting. We observed that METH induced rhNPC mitochondrial fragmentation, apoptosis, and inhibited cell proliferation. The mitochondrial fission protein dynamin-related protein 1 (Drp1) and reactive oxygen species (ROS), but not calcium (Ca2+) influx, were involved in the regulation of METH-induced mitochondrial fragmentation. Furthermore, our results indicated that dysregulation of ROS contributed to the oligomerization and translocation of Drp1, resulting in mitochondrial fragmentation in rhNPC. Taken together, our data demonstrate that METH-mediated ROS generation results in the dysregulation of Drp1, which leads to mitochondrial fragmentation and subsequent apoptosis in rhNPC. This provides a potential mechanism for METH-related neurodegenerative disorders, and also provides insight into therapeutic strategies for the neurodegenerative effects of METH.

Methamphetamine toxicity and messengers of death

Methamphetamine (METH) is an illicit psychostimulant that is widely abused in the world. Several lines of evidence suggest that chronic METH abuse leads to neurodegenerative changes in the human brain. These include damage to dopamine and serotonin axons, loss of gray matter accompanied by hypertrophy of the white matter and microgliosis in different brain areas. In the present review, we summarize data on the animal models of METH neurotoxicity which include degeneration of monoaminergic terminals and neuronal apoptosis. In addition, we discuss molecular and cellular bases of METH-induced neuropathologies. The accumulated evidence indicates that multiple events, including oxidative stress, excitotoxicity, hyperthermia, neuroinflammatory responses, mitochondrial dysfunction, and endoplasmic reticulum stress converge to mediate METH-induced terminal degeneration and neuronal apoptosis. When taken together, these findings suggest that pharmacological strategies geared towards the prevention and treatment of the deleterious effects of this drug will need to attack the various pathways that form the substrates of METH toxicity.

Molecular bases of methamphetamine-induced neurodegeneration

Methamphetamine (METH) is a highly addictive psychostimulant drug, whose abuse has reached epidemic proportions worldwide. The addiction to METH is a major public concern because its chronic abuse is associated with serious health complications including deficits in attention, memory, and executive functions in humans. These neuropsychiatric complications might, in part, be related to drug-induced neurotoxic effects, which include damage to dopaminergic and serotonergic terminals, neuronal apoptosis, as well as activated astroglial and microglial cells in the brain. Thus, the purpose of the present paper is to review cellular and molecular mechanisms that might be responsible for METH neurotoxicity. These include oxidative stress, activation of transcription factors, DNA damage, excitotoxicity, blood-brain barrier breakdown, microglial activation, and various apoptotic pathways. Several approaches that allow protection against METH-induced neurotoxic effects are also discussed. Better understanding of the cellular and molecular mechanisms involved in METH toxicity should help to generate modern therapeutic approaches to prevent or attenuate the long-term consequences of psychostimulant use disorders in humans.

Methamphetamine causes microglial activation in the brains of human abusers

Methamphetamine is a popular addictive drug whose use is associated with multiple neuropsychiatric adverse events and toxic to the dopaminergic and serotonergic systems of the brain. Methamphetamine-induced neuropathology is associated with increased expression of microglial cells that are thought to participate in either pro-toxic or protective mechanisms in the brain. Although reactive microgliosis has been observed in animal models of methamphetamine neurotoxicity, no study has reported on the status of microglial activation in human methamphetamine abusers. The present study reports on 12 abstinent methamphetamine abusers and 12 age-, gender-, and education-matched control subjects who underwent positron emission tomography using a radiotracer for activated microglia, [(11)C](R)-(1-[2-chlorophenyl]-N-methyl-N-[1-methylpropyl]-3-isoquinoline carboxamide) ([(11)C](R)-PK11195). Compartment analysis was used to estimate quantitative levels of binding potentials of [(11)C](R)-PK11195 in brain regions with dopaminergic and/or serotonergic innervation. The mean levels of [(11)C](R)-PK11195 binding were higher in methamphetamine abusers than those in control subjects in all brain regions (>250% higher; p < 0.01 for all). In addition, the binding levels in the midbrain, striatum, thalamus, and orbitofrontal and insular cortices (p < 0.05) correlated inversely with the duration of methamphetamine abstinence. These results suggest that chronic self-administration of methamphetamine can cause reactive microgliosis in the brains of human methamphetamine abusers, a level of activation that appears to subside over longer periods of abstinence.

Differential effects of the ascorbyl and tocopheryl derivative on the methamphetamine-induced toxic behavior and toxicity

A previous study showed that high doses of methamphetamine induce self-injurious behavior (SIB) in rodents. Furthermore, the combination of methamphetamine and morphine increased lethality in mice. We recently surmised that the rise in SIB and mortality induced by methamphetamine and/or morphine may be related to oxidative stress. The present study was designed to determine whether an antioxidant could inhibit SIB or mortality directly induced by methamphetamine and/or morphine. The SIB induced by 20mg/kg of methamphetamine was abolished by the administration of Na L-ascorbyl-2-phosphate (APS: 300 mg/kg), but not Na DL-alpha-tocopheryl phosphate (TPNa: 200mg/kg). In contrast, APS (300 mg/kg) and TPNa (200mg/kg) each significantly attenuated the lethality induced by methamphetamine and morphine. The present study showed that the signal intensity of superoxide adduct was increased by 20mg/kg of methamphetamine in the heart and lungs, and methamphetamine plus morphine tended to increase superoxide adduct in all of the tissues measured by ESR spin trap methods. Adduct signal induced in brain by methamphetamine administration increased in significance, but in mouse administrated methamphetamine plus morphine. There are differential effects of administration of methamphetamine and coadministration of methamphetamine plus morphine on adduct signal. These results suggest that APS and TPNa are effective for reducing methamphetamine-induced toxicity and/or toxicological behavior. While APS and TPNa each affected methamphetamine- and/or morphine-induced toxicology and/or toxicological behavior, indicating that both drugs have antioxidative effects, their effects differed.

Methamphetamine induces ectopic expression of tyrosine hydroxylase and increases noradrenaline levels within the cerebellar cortex

Methamphetamine produces locomotor activation and typical stereotyped motor patterns, which are commonly related with increased catecholamine activity within the basal ganglia, including the dorsal and ventral striatum. Since the cerebellum is critical for movement control, and for learning of motor patterns, we hypothesized that cerebellar catecholamines might be a target of methamphetamine. To test this experimental hypothesis we injected methamphetamine into C57 Black mice at the doses of 5 mg/kg two or three times, 2 h apart. This dosing regimen is known to be toxic for striatal dopamine terminals. However, we found that in the cerebellum, methamphetamine increased the expression of the primary transcript of the tyrosine hydroxylase (TH) gene, followed by an increased expression of the TH protein. Increased TH was localized within Purkinje cells, where methamphetamine increased the number of TH-immunogold particles, and produced a change in the distribution of the enzyme by increasing the cytoplasmic percentage. Increased TH expression was accompanied by a slight increase in noradrenaline content. This effect was highly site-specific for the cortex of posterior vermal lobules, while only slight effects were detectable in the hemispheres. The present data indicate that the cerebellum does represent a target of methamphetamine, which produces specific and fine alterations of the catecholamine system involving synthesis, amount, and compartmentalization of TH as well as increased noradrenaline levels. This may be relevant for motor alterations induced by methamphetamine. In line with this, inherited cerebellar movement disorders in various animal species including humans are associated with increased TH immunoreactivity within intrinsic neurons of the same lobules of the cerebellar cortex.

Calpain and caspase proteolytic markers co-localize with rat cortical neurons after exposure to methamphetamine and MDMA

Abuse of the club drugs Methamphetamine (Meth) and Ecstasy (MDMA) is an international problem. The seriousness of this problem is the result of what appears to be programmed cell death (PCD) occurring within the brain following their use. This follow up study focused on determining which cell types, neurons and/or glial cells, were affected in the brains of drug-injected rats. Two proteolytic enzyme families involved in PCD, calpains and caspases, were previously shown to be activated and to degrade the brain cytoskeletal associated protein alphaII-spectrin. Using methods employed and confirmed in traumatic brain injury (TBI) studies, rat brain tissues were examined, 24 and 48 h after Meth and MDMA exposure, for the activation of calpain-1 and caspase-3, and their subsequent alphaII-spectrin cleavage breakdown products (SBDPs), SBDP145, and SBDP120, respectively. Based upon our previous studies we know that activated calpain-1 and caspase-3 were up-regulated after drug use as were the levels of their cleaved SBDPs, SBDP145, and SBDP120, respectively, which is indicative of PCD. Here we show that activated calpain-1 and caspase-3 increases could be localized to neurons in the cortex where the products of their cleaved targets were found to be concentrated, particularly, to the axonal regions. These findings support the hypothesis that calpains and caspases mediate PCD in cortical neurons following club drug abuse and, more importantly, appear to contribute to the neuropathology suffered by abusers.

Neurotoxicity of substituted amphetamines: Molecular and cellular mechanisms

The amphetamines, including amphetamine (AMPH), methamphetamine (METH) and 3,4-methylenedioxymethamphetamine (MDMA), are among abused drugs in the US and throughout the world. Their abuse is associated with severe neurologic and psychiatric adverse events including the development of psychotic states. These neuropsychiatric complications might, in part, be related to drug-induced neurotoxic effects, which include damage to dopaminergic and serotonergic terminals, neuronal apoptosis, as well as activated astroglial and microglial cells in the brain. The purpose of the present review is to summarize the toxic effects of AMPH, METH and MDMA. The paper also presents some of the factors that are thought to underlie this toxicity. These include oxidative stress, hyperthermia, excitotoxicity and various apoptotic pathways. Better understanding of the cellular and molecular mechanisms involved in their toxicity should help to generate modern therapeutic approaches to prevent or attenuate the long-term consequences of amphetamine use disorders in humans.

Methamphetamine administration causes death of dopaminergic neurons in the mouse olfactory bulb

BACKGROUND

Methamphetamine (METH) is an addictive drug that can cause neurological and psychiatric disorders. In the rodent brain, toxic doses of METH cause damage of dopaminergic terminals and apoptosis of nondopaminergic neurons. The olfactory bulb (OB) is a brain region that is rich with dopaminergic neurons and terminals.

METHODS

Rats were given a single injection of METH (40 mg/kg) and sacrificed at various time points afterward. The toxic effects of this injection on the OB were assessed by measuring monoamine levels, tyrosine hydroxylase (TH) immunocytochemistry, terminal deoxynucleotidyl transferase-mediated deoxyribonucleotide triphosphate (dNTP) nick end labeling (TUNEL) histochemistry, and caspase-3 immunochemistry.

RESULTS

Methamphetamine administration caused marked decreases in dopamine (DA) levels and TH-like immunostaining in the mouse OB. The drug also caused increases in TUNEL-labeled OB neurons, some of which were also positive for TH expression. Moreover, there was METH-induced expression of activated caspase-3 in TH-positive cells. Finally, the METH injection was associated with increased expression of the proapoptotic proteins, Bax and Bid, but with decreased expression of the antideath protein, Bcl2.

CONCLUSIONS

These observations show, for the first time, that METH can cause loss of OB DA terminals and death of DA neurons, in part, via mechanisms that are akin to an apoptotic process.

Methamphetamine downregulates peroxiredoxins in rat pheochromocytoma cells

Methamphetamine (METH) is an abusive psychostimulant that induces neuronal cell death/degeneration in experimental animals and humans. METH-induced apoptosis in rat pheochromocytoma cells was utilized to study the neurotoxic mechanism. During METH intoxication, we found that peroxiredoxins and thioredoxins/thioredoxin reductases (peroxiredoxin reducing systems) which are known to prevent oxidative stress and apoptosis were differentially downregulated and upregulated, respectively. We also found not only the free radicals but also the oxidative forms of peroxiredoxin and thioredoxin were increased, indicating the dysfunction of these enzymes. Thus, METH-induced differential regulation and oxidation of peroxiredoxins and thioredoxin may be an important mechanism for apoptosis.

Ecstasy Toxicity

Ecstasy use is a growing problem in the United States. Techniques to demonstrate and characterize the toxicity associated with its use have been limited and employed infrequently. In this study, we compare the deleterious effects of ecstasy use in rats with that of methamphetamine and traumatic brain injury. Specifically, we investigate the degradation of structural proteins alphaII-spectrin and tau by the pro-necrotic calpain and pro-apoptotic caspase systems. Ecstasy-induced neurotoxicity is shown after 24 hours, although to a much lesser extent than that of methamphetamine or traumatic brain injury. Neurotoxicity is still evident after 72 hours. Furthermore, apoptosis of the liver is seen 72 hours after ecstasy use. Use of protease inhibitors may be useful in preventing ecstasy-induced toxicity.

Multiple high doses of methamphetamine increase the number of preproneuropeptide Y mRNA-expressing neurons in the striatum of rat via a dopamine D1 receptor-dependent mechanism

Neuropeptide Y (NPY) is a neuropeptide that may be involved with emotional regulation and drug addiction and may act as a neuroprotective agent during toxic insults, such as is associated with multiple, high doses of methamphetamine (METH). The purpose of the present study was to elucidate the nature of METH-induced changes in the NPY system by examining the effect of multiple, high doses of METH on preproNPY (ppNPY) mRNA expression in the striatum and the role that dopamine (DA) D1 and D2 receptors might play in these changes. Rats were administered five injections of 10 mg/kg METH at 6-h intervals, along with the D1 receptor antagonist 7-chloro-8-hydoxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benazepine hydrochloride (SCH22390) or the D2 receptor antagonist eticlopride, and they were sacrificed 3 h after the last dose of METH. The number of neurons expressing ppNPY mRNA in striatum was examined using in situ hybridization histochemistry. An acute dose of METH as well as multiple, high doses of METH increased the number of neurons expressing ppNPY mRNA in all regions of striatum examined. There was no change in the number of prosomatostatin (pSOM) mRNA-containing neurons. The increase in the number of ppNPY mRNA-expressing neurons was abolished by pretreatment with SCH22390. Eticlopride alone increased the number of ppNPY mRNA-expressing neurons in striatum, and METH treatment did not further increase the number. These findings suggest that exposure to multiple, high doses of METH increases the number of neurons expressing detectable levels of ppNPY mRNA and that this phenomenon is dependent on DA D1-receptor activation.

Neuropeptide Y protects against methamphetamine-induced neuronal apoptosis in the mouse striatum

Methamphetamine (METH) is an illicit drug that causes neuronal apoptosis in the mouse striatum, in a manner similar to the neuronal loss observed in neurodegenerative diseases. In the present study, injections of METH to mice were found to cause the death of enkephalin-positive projection neurons but not the death of neuropeptide Y (NPY)/nitric oxide synthase-positive striatal interneurons. In addition, these METH injections were associated with increased expression of neuropeptide Y mRNA and changes in the expression of the NPY receptors Y1 and Y2. Administration of NPY in the cerebral ventricles blocked METH-induced apoptosis, an effect that was mediated mainly by stimulation of NPY Y2 receptors and, to a lesser extent, of NPY Y1 receptors. Finally, we also found that neuropeptide Y knock-out mice were more sensitive than wild-type mice to METH-induced neuronal apoptosis of both enkephalin- and nitric oxide synthase-containing neurons, suggesting that NPY plays a general neuroprotective role within the striatum. Together, our results demonstrate that neuropeptide Y belongs to the class of factors that maintain neuronal integrity during cellular stresses. Given the similarity between the cell death patterns induced by METH and by disorders such as Huntington's disease, our results suggest that NPY analogs might be useful therapeutic agents against some neurodegenerative processes.

Progressive degeneration of human mesencephalic neuron-derived cells triggered by dopamine-dependent oxidative stress is dependent on the mixed-lineage kinase pathway

Models of Parkinson's disease (PD) based on selective neuronal death have been used to study pathogenic mechanisms underlying nigral cell death and in some instances to develop symptomatic therapies. For validation of putative neuroprotectants, a model is desirable in which the events leading to neurodegeneration replicate those occurring in the disease. We developed a human in vitro model of PD based on the assumption that dysregulated cytoplasmic dopamine levels trigger cell loss in this disorder. Differentiated human mesencephalic neuron-derived cells were exposed to methamphetamine (METH) to promote cytoplasmic dopamine accumulation. In the presence of elevated iron concentrations, as observed in PD, increased cytosolic dopamine led to oxidative stress, c-Jun N-terminal kinase (JNK) pathway activation, neurite degeneration, and eventually apoptosis. We examined the role of the mixed-lineage kinases (MLKs) in this complex degenerative cascade by using the potent inhibitor 3,9-bis[(ethylthio)methyl]-K-252a (CEP1347). Inhibition of MLKs not only prevented FeCl2+/METH-induced JNK activation and apoptosis but also early events such as neurite degeneration and oxidative stress. This broad neuroprotective action of CEP1347 was associated with increased expression of an oxidative stress-response modulator, activating transcription factor 4. As a functional consequence, transcription of the cystine/glutamate and glycine transporters, cellular cystine uptake and intracellular levels of the redox buffer glutathione were augmented. In conclusion, this new human model of parkinsonian neurodegeneration has the potential to yield new insights into neurorestorative therapeutics and suggests that enhancement of cytoprotective mechanisms, in addition to blockade of apoptosis, may be essential for disease modulation.

Methamphetamine-induced neuronal apoptosis involves the activation of multiple death pathways. Review

The abuse of the illicit drug methamphetamine (METH) is a major concern because it can cause terminal degeneration and neuronal cell death in the brain. METH-induced cell death occurs via processes that resemble apoptosis. In the present review, we discuss the role of various apoptotic events in the causation of METH-induced neuronal apoptosis in vitro and in vivo. Studies using comprehensive approaches to gene expression profiling have allowed for the identification of several genes that are up-regulated or down-regulated after an apoptosis-inducing dose of the drug. Further experiments have also documented the fact that the drug can cause demise of striatal enkephalinergic neurons by cross-talks between mitochondria-, endoplasmic reticulum- and receptor-mediated apoptotic events. These neuropathological observations have also been reported in models of drug-induced neuroplastic alterations used to mimic drug addiction (Nestler, 2001).

Concurrent calpain and caspase-3 mediated proteolysis of alpha II-spectrin and tau in rat brain after methamphetamine exposure: a similar profile to traumatic brain injury

Neurotoxicity in rat cortex and hippocampus following acute methamphetamine administration was characterized and compared to changes following traumatic brain injury. Doses of 10, 20, and 40 mg/kg of methamphetamine produced significant increases in calpain- and caspase-cleaved alpha II-spectrin and tau protein fragments, suggesting cell injury or death. Changes in proteolytic products were significantly increased over vehicle controls. Use of fragment specific biomarkers detected prominent calpain-mediated protein fragments in the cortex and hippocampus while caspase-mediated protein fragments were also detected in the hippocampus. Remarkably, proteolytic product increases at the 40 mg/kg dose after 24 h were as high as those observed in experimental traumatic brain injury. Use of calpain and caspase proteolytic inhibitors may be useful in preventing methamphetamine-induced neurotoxicity.

Activations of c-fos/c-jun signaling are involved in the modulation of hypothalamic superoxide dismutase (SOD) and neuropeptide Y (NPY) gene expression in amphetamine-mediated appetite suppression

Amphetamine (AMPH) is known as an anorectic agent. The mechanism underlying the anorectic action of AMPH has been attributed to its inhibitory action on hypothalamic neuropeptide Y (NPY), an appetite stimulant in the brain. This study was aimed to examine the molecular mechanisms behind the anorectic effect of AMPH. Results showed that AMPH treatment decreased food intake, which was correlated with changes of NPY mRNA level, but increased c-fos, c-jun and superoxide dismutase (SOD) mRNA levels in hypothalamus. To determine if c-fos or c-jun was involved in the anorectic response of AMPH, infusions of antisense oligonucleotide into the brain were performed at 1 h before daily AMPH treatment in freely moving rats, and the results showed that c-fos or c-jun knockdown could block this anorectic response and restore NPY mRNA level. Moreover, c-fos or c-jun knockdown could partially block SOD mRNA level that might involve in the modulation of NPY gene expression. It was suggested that c-fos/c-jun signaling might involve in the central regulation of AMPH-mediated feeding suppression via the modulation of NPY gene expression.

Calcineurin/NFAT-induced up-regulation of the Fas ligand/Fas death pathway is involved in methamphetamine-induced neuronal apoptosis

Methamphetamine [METH ("speed")] is an abused psychostimulant that can cause psychotic, cognitive, and psychomotor impairment in humans. These signs and symptoms are thought to be related to dysfunctions in basal ganglionic structures of the brain. To identify possible molecular bases for these clinical manifestations, we first used cDNA microarray technology to measure METH-induced transcriptional responses in the striatum of rats treated with an apoptosis-inducing dose of the drug. METH injection resulted in increased expression of members of the Jun, Egr, and Nur77 subfamilies of transcription factors (TFs), changes that were confirmed by quantitative PCR. Because pathways linked to these factors are involved in the up-regulation of Fas ligand (FasL), FasL mRNA was quantified and found to be increased. Immunohistochemical studies also revealed METH-induced increased FasL protein expression in striatal GABAergic neurons that express enkephalin. Moreover, there were METH-mediated increases in calcineurin, as well as shuttling of nuclear factor of activated T cells (NFAT)c3 and NFATc4 from the cytosol to the nucleus of METH-treated rats, mechanisms also known to be involved in FasL regulation. Furthermore, METH induced cleavage of caspase-3 in FasL- and Fas-containing neurons. Finally, the METH-induced changes in the FasL-Fas death pathway were attenuated by pretreatment with the dopamine D1 receptor antagonist, SCH23390, which also caused attenuation of METH-induced apoptosis. These observations indicate that METH causes some of its neurodegenerative effects, in part, via stimulation of the Fas-mediated cell death pathway consequent to FasL up-regulation mediated by activation of multiple TFs.

Neurotoxic regimens of methamphetamine induce persistent expression of phospho-c-Jun in somatosensory cortex and substantia nigra

Repeated systemic administration of moderate doses of methamphetamine (mAMPH) can result in neuronal damage. In addition to the prominent damage of forebrain dopamine and serotonin terminals, mAMPH also injures certain non-monoaminergic neuronal somata in the cerebral cortex. In previous studies, we have localized the damaged neurons to the "whisker barrels" in primary somatosensory cortex, reported the time course of their appearance, and found that sensory inputs from the mystacial vibrissae appear to play a crucial role in the mechanism of their injury by mAMPH. One common feature of these studies is that they used a single marker for neuronal injury, the fluorochrome dye Fluoro-Jade, which stains neurons injured by disparate mechanisms. Here we compare mAMPH-induced damage to somatosensory cortical neurons as assessed by Fluoro-Jade and immunohistochemical staining for phospho-c-Jun. A neurotoxic regimen of mAMPH induced phospho-c-Jun-positive neurons in both cortical whisker barrels and the substantia nigra. Neurons in the barrel cortex can be sufficiently damaged by mAMPH that they become Fluoro-Jade-positive within 2 hr after the final mAMPH injection. By contrast, phospho-c-Jun immunoreactivity does not appear until 12-24 hr after mAMPH. As reported in an earlier study, unilateral removal of vibrissae prior to mAMPH treatment affords partial protection from injury in the hemisphere contralateral to the vibrissotomy. The vibrissotomized animals show similar decreases in Fluoro-Jade staining and phospho-c-Jun immunoreactivity in the protected hemisphere. Since phospho-c-Jun indicates activation of Jun N-terminal kinase pathways, which have been implicated in apoptosis, we conclude that phospho-c-Jun provides a useful new marker for mAMPH-induced damage to cortical neurons.

Effect of environmental hyperthermia on gastrin, somatostatin and motilin in rat ulcerated antral mucosa

AIM: To study the effect of environmental hyperthermia on gastrin, somatostatin and motilin in rat ulcerated antral mucosa.

METHODS: Forty-two Wistar rats were equally divided into six groups, according to the room temperature (high and normal) and the treatment (acetic acid, normal saline and no treatment). Levels of gastrin, somatostatin and motilin in rat ulcerated antral mucosa were measured with a radioimmunoassay method.

RESULTS: The average temperature and humidity were 32.5 °C and 66.7% for the high temperature group, and 21.1 °C and 49.3% for the normal temperature group, respectively. Gastric ulcer model was successfully induced in rat injected with 0.05 mL acetic acid into the antrum. In rats with gastric ulcers, the levels of gastrin and motilin increased, whereas the somatostatin level declined in antral mucosa, compared with those in rats treated with normal saline and the controls. However, the change extent in the levels of gastrin, motilin and somatostatin in antral mucosa was less in the high temperature group than in the normal temperature group.

CONCLUSION: The levels of gastrin, somatostatin and motilin in rat ulcerated antral mucosal tissue remain relatively stable in a high temperature environment, which may relate to the equilibration of the dynamic system.

Methamphetamine induces neuronal apoptosis via cross-talks between endoplasmic reticulum and mitochondria-dependent death cascades

Methamphetamine (METH) is an illicit drug that causes neurodegenerative effects in humans. In rodents, METH induces apoptosis of striatal glutamic acid decarboxylase (GAD) -containing neurons. This paper provides evidence that METH-induced cell death occurs consequent to interactions of ER stress and mitochondrial death pathways. Specifically, injections of METH are followed by an almost immediate activation of proteases calpain and caspase-12, events consistent with drug-induced ER stress. Involvement of ER stress was further supported by observations of increases in the expression of GRP78/BiP and CHOP. Participation of the mitochondrial pathway was demonstrated by the transition of AIF, smac/DIABLO, and cytochrome c from mitochondrial into cytoplasmic fractions. These changes occur before the apoptosome-associated pro-caspase-9 cleavage. Effector caspases-3 and -6, but not -7, were cleaved with the initial time of caspase-3 activation occurring before caspase 9 cleavage; this suggests possible earlier cleavage of caspase-3 by caspase-12. These events preceded proteolysis of the caspase substrates DFF-45, lamin A, and PARP in nuclear fractions. These findings indicate that METH causes neuronal apoptosis in part via cross-talks between ER- and mitochondria-generated processes, which cause activation of both caspase-dependent and -independent pathways.

Identification of differentially regulated transcripts in mouse striatum following methamphetamine treatment - an oligonucleotide microarray approach

Methamphetamine is an addictive drug of abuse that can produce neurotoxic effects in dopamine nerve endings of the striatum. The purpose of this study was to identify new genes that may play a role in the highly complex cascade of events associated with methamphetamine intoxication. Using Affymetrix oligonucleotide arrays, 12 488 genes were simultaneously interrogated and there were 152 whose expression levels were changed following methamphetamine treatment. The genes are grouped into broad functional categories with inflammatory/immune response elements, receptor/signal transduction components and ion channel/transport proteins among the most populated. Many genes within these categories can be linked to ion regulation and apoptosis, both of which have been implicated in methamphetamine toxicity, and numerous factors associated with microglial activation emerged with significant changes in expression. For example, brain-derived neurotrophic factor (BDNF), chemokine (C-C) receptor 6 (CCr6) and numerous chemokine transcripts were increased or decreased in expression more than 2.8-fold. These results point to activated microglia as a potential source of the reactive oxygen/nitrogen species and cytokines that have been previously associated with methamphetamine toxicity and other neurotoxic conditions.

Speed kills: cellular and molecular bases of methamphetamine‐induced nerve terminal degeneration and neuronal apoptosis

Methamphetamine (METH) is a drug of abuse that has long been known to damage monoaminergic systems in the mammalian brain. Recent reports have provided conclusive evidence that METH can cause neuropathological changes in the rodent brain via apoptotic mechanisms akin to those reported in various models of neuronal death. The purpose of this review is to provide an interim account for a role of oxygen-based radicals and the participation of transcription factors and the involvement of cell death genes in METH-induced neurodegeneration. We discuss data suggesting the participation of endoplasmic reticulum and mitochondria-mediated activation of caspase-dependent and -independent cascades in the manifestation of METH-induced apoptosis. Studies that use more comprehensive approaches to gene expression profiling should allow us to draw more instructive molecular portraits of the complex plastic and degenerative effects of this drug.

Current research on methamphetamine-induced neurotoxicity: animal models of monoamine disruption

Methamphetamine (METH)-induced neurotoxicity is characterized by a long-lasting depletion of striatal dopamine (DA) and serotonin as well as damage to striatal dopaminergic and serotonergic nerve terminals. Several hypotheses regarding the mechanism underlying METH-induced neurotoxicity have been proposed. In particular, it is thought that endogenous DA in the striatum may play an important role in mediating METH-induced neuronal damage. This hypothesis is based on the observation of free radical formation and oxidative stress produced by auto-oxidation of DA consequent to its displacement from synaptic vesicles to cytoplasm. In addition, METH-induced neurotoxicity may be linked to the glutamate and nitric oxide systems within the striatum. Moreover, using knockout mice lacking the DA transporter, the vesicular monoamine transporter 2, c-fos, or nitric oxide synthetase, it was determined that these factors may be connected in some way to METH-induced neurotoxicity. Finally a role for apoptosis in METH-induced neurotoxicity has also been established including evidence of protection of bcl-2, expression of p53 protein, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), activity of caspase-3. The neuronal damage induced by METH may reflect neurological disorders such as autism and Parkinson's disease.

Ischemia-reperfusion-related repair deficit after oxidative stress: implications of faulty transcripts in neuronal sensitivity after brain injury

Diseases of the heart are the No. 1 killer in industrialized countries. Brain injury can develop as a result of cerebral ischemia-reperfusion due to stroke (brain attack) and other cardiovascular diseases. Learning about the disease is the best way to reduce disability and death. We present here whether gene repair activities are associated with neuronal death in an ischemia-reperfusion model that simulates stroke in male Long-Evans rats. This experimental stroke model is known to induce necrosis in the ischemic cortex. Cerebral ischemia causes overactivation of membrane receptors and accumulation of extracellur glutamate and intracellular calcium, which activates neuronal nitric oxide synthase, causing damage to lipids, proteins, and nucleic acids, and reduces energy sources with consequent functional deterioration, leading to cell death. Restoration processes normally repair genes with few errors. However, ischemia elevates oxidative DNA lesions despite these repair mechanisms. These episodes concurrently occur with the induction of immediate-early genes that critically activate other late genes in the signal transduction pathway. Damage, repair, and transcription of the c-FOS gene are presented here as examples, because Fos peptide, one of the components of activator protein 1, activates nerve growth factor and repair mechanisms. The results of our studies show that treatments with 7-nitroindazole, a specific inhibitor of nitric oxide synthase known to attenuate nitric oxide, oxidative DNA lesions, and necrosis, increase intact c-fos mRNA levels after stroke. This suggests that the accuracy of gene expression could be accounted for the recovery of cellular function after cerebral injury.