Genome-wide DNA hydroxymethylation identifies potassium channels in the nucleus accumbens as discriminators of methamphetamine addiction and abstinence

Epigenetic consequences of exposure to psychostimulants are substantial but the relationship of these changes to compulsive drug taking and abstinence is not clear. Here, we used a paradigm that helped to segregate rats that reduce or stop their methamphetamine (METH) intake (nonaddicted) from those that continue to take the drug compulsively (addicted) in the presence of footshocks. We used that model to investigate potential alterations in global DNA hydroxymethylation in the nucleus accumbens (NAc) because neuroplastic changes in the NAc may participate in the development and maintenance of drug-taking behaviors. We found that METH-addicted rats did indeed show differential DNA hydroxymethylation in comparison with both control and nonaddicted rats. Nonaddicted rats also showed differences from control rats. Differential DNA hydroxymethylation observed in addicted rats occurred mostly at intergenic sites located on long and short interspersed elements. Interestingly, differentially hydroxymethylated regions in genes encoding voltage (Kv1.1, Kv1.2, Kvb1 and Kv2.2)- and calcium (Kcnma1, Kcnn1 and Kcnn2)-gated potassium channels observed in the NAc of nonaddicted rats were accompanied by increased mRNA levels of these potassium channels when compared with mRNA expression in METH-addicted rats. These observations indicate that changes in differentially hydroxymethylated regions and increased expression of specific potassium channels in the NAc may promote abstinence from drug-taking behaviors. Thus, activation of specific subclasses of voltage- and/or calcium-gated potassium channels may provide an important approach to the beneficial treatment for METH addiction.

Compulsive methamphetamine taking under punishment is associated with greater cue-induced drug seeking in rats

Methamphetamine (METH) addicts lose control over drug consumption despite suffering multiple adverse medicolegal consequences. To mimic the negative events associated with drug addiction in humans, we recently introduced a rat model of self-administration (SA) with response-contingent punishment on METH intake. These procedures allowed us to distinguish between two addiction-like phenotypes in rats, those that sustained METH taking despite negative consequences (shock-resistant, SR) and rats that significantly reduced their METH intake (shock-sensitive, SS). Here, we further developed our adverse consequence model and examined incubation of METH craving by measuring cue-induced drug seeking in SR and SS rats. Male Sprague-Dawley rats were trained to self-administer METH (0.1mg/kg/injection) or saline intravenously (i.v.) during twenty-two 9-h sessions that consisted of 3 separate 3-h sessions separated by 30min. Subsequently, rats were subjected to incremental footshocks during thirteen additional 9-h METH SA sessions performed in a fashion identical to the training phase. Cue-induced drug craving was then assessed at 2 and 21days after the footshock phase. All rats escalated their intake of METH, with both phenotypes showing similar drug taking patterns during SA training. In addition, rats that continued their METH intake despite negative consequences showed even greater cue-induced drug craving following withdrawal than the rats that reduced METH intake following negative consequences. Taken together, our adverse consequence-based model highlights the possibility of identifying rats by addiction-like phenotypes and subsequent vulnerability to relapse-like behaviors. The use of similar SA models should help in the development of better therapeutic approaches to treat different stages of METH addiction.

Methamphetamine addiction: involvement of CREB and neuroinflammatory signaling pathways

RATIONALE AND OBJECTIVES

Addiction to psychostimulant methamphetamine (METH) remains a major public health problem in the world. Animal models that use METH self-administration incorporate many features of human drug-taking behavior and are very helpful in elucidating mechanisms underlying METH addiction. These models are also helping to decipher the neurobiological substrates of associated neuropsychiatric complications. This review summarizes our work on the influence of METH self-administration on dopamine systems, transcription and immune responses in the brain.

METHODS

We used the rat model of METH self-administration with extended access (15 h/day for eight consecutive days) to investigate the effects of voluntary METH intake on the markers of dopamine system integrity and changes in gene expression observed in the brain at 2 h-1 month after cessation of drug exposure.

RESULTS

Extended access to METH self-administration caused changes in the rat brain that are consistent with clinical findings reported in neuroimaging and postmortem studies of human METH addicts. In addition, gene expression studies using striatal tissues from METH self-administering rats revealed increased expression of genes involved in cAMP response element binding protein (CREB) signaling pathway and in the activation of neuroinflammatory response in the brain.

CONCLUSION

These data show an association of METH exposure with activation of neuroplastic and neuroinflammatory cascades in the brain. The neuroplastic changes may be involved in promoting METH addiction. Neuroinflammatory processes in the striatum may underlie cognitive deficits, depression, and parkinsonism reported in METH addicts. Therapeutic approaches that include suppression of neuroinflammation may be beneficial to addicted patients.

Anti-NMDA receptor autoantibodies and associated neurobehavioral pathology in mice are dependent on age of first exposure to Toxoplasma gondii

BACKGROUND

Toxoplasma gondii is a pathogen implicated in psychiatric disorders. As elevated antibodies to T. gondii are also present in non-symptomatic individuals, we hypothesized that the age during first exposure to the pathogen may affect symptom manifestation. We tested this hypothesis by evaluating neurobehavioral abnormalities and the immune response in mice following adolescent or adult T. gondii infection.

METHODS

Mice were infected with T. gondii at postnatal day 33 (adolescent/juvenile) or 61 (adult). At 8weeks post-infection (wpi), pre-pulse inhibition of the acoustic startle (PPI) in mice administered MK-801 (0.1 and 0.3mg/kg) and amphetamine (5 and 10mg/kg) was assessed. Peripheral (anti-T. gondii, C1q-associated IgG and anti-GLUN2 antibodies) and central (C1q and Iba1) markers of the immune response were also evaluated. In addition, regional brain expression of N-methyl-d-aspartate receptor (NMDAR) subunits (GLUN1 and GLUN2A), glutamatergic (vGLUT1, PSD95) and GABAergic (GAD67) markers, and monoamines (DA, NE, 5-HT) and their metabolites were measured.

RESULTS

Juvenile and adult infected mice exhibited opposite effects of MK-801 on PPI, with decreased PPI in juveniles and increased PPI in adults. There was a significantly greater elevation of GLUN2 autoantibodies in juvenile-compared to adult-infected mice. In addition, age-dependent differences were found in regional expression of NMDAR subunits and markers of glutamatergic, GABAergic, and monoaminergic systems. Activated microglia and C1q elevations were found in both juvenile- and adult-T. gondii infected mice.

CONCLUSIONS

Our study demonstrates that the age at first exposure to T. gondii is an important factor in shaping distinct behavioral and neurobiological abnormalities. Elevation in GLUN2 autoantibodies or complement protein C1q may be a potential underlying mechanism. A better understanding of these age-related differences may lead to more efficient treatments of behavioral disorders associated with T. gondii infection.

An Acute Methamphetamine Injection Downregulates the Expression of Several Histone Deacetylases (HDACs) in the Mouse Nucleus Accumbens: Potential Regulatory Role of HDAC2 Expression

Methamphetamine (METH) administration alters gene expression in the nucleus accumbens (NAc). We recently demonstrated that an acute METH injection produced prolonged increases in the expression of immediate early genes in the NAc of HDAC2-deficient mice, suggesting that HDAC2 might be an important regulator of gene expression in the rodent brain. Here, we tested the possibility that HDAC2 deletion might also impact METH-induced changes in the expression of various HDAC classes in the NAc. Wild-type (WT) and HDAC2 knockout (KO) mice were given a METH (20 mg/kg) injection, and NAc tissue was collected at 1, 2, and 8 h post treatment. We found that METH decreased HDAC3, HDAC4, HDAC7, HDAC8, and HDAC11 mRNA expression but increased HDAC6 mRNA levels in the NAc of WT mice. In contrast, the METH injection increased HDAC3, HDAC4, HDAC7, HDAC8, and HDAC11 mRNA levels in HDAC2KO mice. These observations suggest that METH may induce large-scale transcriptional changes in the NAc by regulating the expression of several HDACs, in part, via HDAC2-dependent mechanisms since some of the HDACs showed differential responses between the two genotypes. Our findings further implicate HDACs as potential novel therapeutic targets for neurotoxic complications associated with the abuse of certain psychostimulants.

CAMKII-conditional deletion of histone deacetylase 2 potentiates acute methamphetamine-induced expression of immediate early genes in the mouse nucleus accumbens

Methamphetamine (METH) produces increases in the expression of immediate early genes (IEGs) and of histone deacetylase 2 (HDAC2) in the rat nucleus accumbens (NAc). Here, we tested whether HDAC2 deletion influenced the effects of METH on IEG expression in the NAc. Microarray analyses showed no baseline differences in IEG expression between wild-type (WT) and HDAC2 knockout (KO) mice. Quantitative-PCR analysis shows that an acute METH injection produced time-dependent increases in mRNA levels of several IEGs in both genotypes. Interestingly, HDAC2KO mice displayed greater METH-induced increases in Egr1 and Egr2 mRNA levels measured at one hour post-injection. The levels of Fosb, Fra2, Egr1, and Egr3 mRNAs stayed elevated in the HDAC2KO mice 2 hours after the METH injection whereas these mRNAs had normalized in the WT mice. In WT mice, METH caused increased HDAC2 recruitment to the promoters some IEGs at 2 hours post injection. METH-induced prolonged increases in Fosb, Fra2, Egr1, and Egr3 mRNA levels in HDAC2KO mice were associated with increased enrichment of phosphorylated CREB (pCREB) on the promoters of these genes. Based on our observations, we hypothesize that HDAC2 may regulate the expression of these genes, in part, by prolonging the actions of pCREB in the mouse NAc.

Methamphetamine downregulates striatal glutamate receptors via diverse epigenetic mechanisms

BACKGROUND

Chronic methamphetamine (METH) exposure causes neuroadaptations at glutamatergic synapses.

METHODS

To identify the METH-induced epigenetic underpinnings of these neuroadaptations, we injected increasing METH doses to rats for 2 weeks and measured striatal glutamate receptor expression. We then quantified the effects of METH exposure on histone acetylation. We also measured METH-induced changes in DNA methylation and DNA hydroxymethylation.

RESULTS

Chronic METH decreased transcript and protein expression of GluA1 and GluA2 alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) and GluN1 N-methyl-D-aspartate receptor subunits. These changes were associated with altered electrophysiological glutamatergic responses in striatal neurons. Chromatin immunoprecipitation-polymerase chain reaction revealed that METH decreased enrichment of acetylated histone H4 on GluA1, GluA2, and GluN1 promoters. Methamphetamine exposure also increased repressor element-1 silencing transcription factor (REST) corepressor 1, methylated CpG binding protein 2, and histone deacetylase 2 enrichment, but not of sirtuin 1 or sirtuin 2, onto GluA1 and GluA2 gene sequences. Moreover, METH caused interactions of REST corepressor 1 and methylated CpG binding protein 2 with histone deacetylase 2 and of REST with histone deacetylase 1. Surprisingly, methylated DNA immunoprecipitation and hydroxymethylated DNA immunoprecipitation-polymerase chain reaction revealed METH-induced decreased enrichment of 5-methylcytosine and 5-hydroxymethylcytosine at GluA1 and GluA2 promoter sequences. Importantly, the histone deacetylase inhibitor, valproic acid, blocked METH-induced decreased expression of AMPAR and N-methyl-D-aspartate receptor subunits. Finally, valproic acid also attenuated METH-induced decrease H4K16Ac recruitment on AMPAR gene sequences.

CONCLUSIONS

These observations suggest that histone H4 hypoacetylation may be the main determinant of METH-induced decreased striatal glutamate receptor expression.

Transcriptional and epigenetic substrates of methamphetamine addiction and withdrawal: evidence from a long-access self-administration model in the rat

Methamphetamine use disorder is a chronic neuropsychiatric disorder characterized by recurrent binge episodes, intervals of abstinence, and relapses to drug use. Humans addicted to methamphetamine experience various degrees of cognitive deficits and other neurological abnormalities that complicate their activities of daily living and their participation in treatment programs. Importantly, models of methamphetamine addiction in rodents have shown that animals will readily learn to give themselves methamphetamine. Rats also accelerate their intake over time. Microarray studies have also shown that methamphetamine taking is associated with major transcriptional changes in the striatum measured within a short or longer time after cessation of drug taking. After a 2-h withdrawal time, there was increased expression of genes that participate in transcription regulation. These included cyclic AMP response element binding (CREB), ETS domain-containing protein (ELK1), and members of the FOS family of transcription factors. Other genes of interest include brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor, type 2 (TrkB), and synaptophysin. Methamphetamine-induced transcription was found to be regulated via phosphorylated CREB-dependent events. After a 30-day withdrawal from methamphetamine self-administration, however, there was mostly decreased expression of transcription factors including junD. There was also downregulation of genes whose protein products are constituents of chromatin-remodeling complexes. Altogether, these genome-wide results show that methamphetamine abuse might be associated with altered regulation of a diversity of gene networks that impact cellular and synaptic functions. These transcriptional changes might serve as triggers for the neuropsychiatric presentations of humans who abuse this drug. Better understanding of the way that gene products interact to cause methamphetamine addiction will help to develop better pharmacological treatment of methamphetamine addicts.

CREB phosphorylation regulates striatal transcriptional responses in the self-administration model of methamphetamine addiction in the rat

Neuroplastic changes in the dorsal striatum participate in the transition from casual to habitual drug use and might play a critical role in the development of methamphetamine (METH) addiction. We examined the influence of METH self-administration on gene and protein expression that may form substrates for METH-induced neuronal plasticity in the dorsal striatum. Male Sprague-Dawley rats self-administered METH (0.1mg/kg/injection, i.v.) or received yoked saline infusions during eight 15-h sessions and were euthanized 2h, 24h, or 1month after cessation of METH exposure. Changes in gene and protein expression were assessed using microarray analysis, RT-PCR and Western blots. Chromatin immunoprecipitation (ChIP) followed by PCR was used to examine epigenetic regulation of METH-induced transcription. METH self-administration caused increases in mRNA expression of the transcription factors, c-fos and fosb, the neurotrophic factor, Bdnf, and the synaptic protein, synaptophysin (Syp) in the dorsal striatum. METH also caused changes in ΔFosB, BDNF and TrkB protein levels, with increases after 2 and 24h, but decreases after 1month of drug abstinence. Importantly, ChIP-PCR showed that METH self-administration caused enrichment of phosphorylated CREB (pCREB), but not of histone H3 trimethylated at lysine 4 (H3K4me3), on promoters of c-fos, fosb, Bdnf and Syp at 2h after cessation of drug intake. These findings show that METH-induced changes in gene expression are mediated, in part, by pCREB-dependent epigenetic phenomena. Thus, METH self-administration might trigger epigenetic changes that mediate alterations in expression of genes and proteins serving as substrates for addiction-related synaptic plasticity.

Modafinil abrogates methamphetamine-induced neuroinflammation and apoptotic effects in the mouse striatum

Methamphetamine is a drug of abuse that can cause neurotoxic damage in humans and animals. Modafinil, a wake-promoting compound approved for the treatment of sleeping disorders, is being prescribed off label for the treatment of methamphetamine dependence. The aim of the present study was to investigate if modafinil could counteract methamphetamine-induced neuroinflammatory processes, which occur in conjunction with degeneration of dopaminergic terminals in the mouse striatum. We evaluated the effect of a toxic methamphetamine binge in female C57BL/6 mice (4 × 5 mg/kg, i.p., 2 h apart) and modafinil co-administration (2 × 90 mg/kg, i.p., 1 h before the first and fourth methamphetamine injections) on glial cells (microglia and astroglia). We also evaluated the striatal expression of the pro-apoptotic BAX and anti-apoptotic Bcl-2 proteins, which are known to mediate methamphetamine-induced apoptotic effects. Modafinil by itself did not cause reactive gliosis and counteracted methamphetamine-induced microglial and astroglial activation. Modafinil also counteracted the decrease in tyrosine hydroxylase and dopamine transporter levels and prevented methamphetamine-induced increases in the pro-apoptotic BAX and decreases in the anti-apoptotic Bcl-2 protein expression. Our results indicate that modafinil can interfere with methamphetamine actions and provide protection against dopamine toxicity, cell death, and neuroinflammation in the mouse striatum.

Altered spatial learning, cortical plasticity and hippocampal anatomy in a neurodevelopmental model of schizophrenia-related endophenotypes

Adult rats exposed to the DNA-methylating agent methylazoxymethanol on embryonic day 17 show a pattern of neurobiological deficits that model some of the neuropathological and behavioral changes observed in schizophrenia. Although it is generally assumed that these changes reflect targeted disruption of embryonic neurogenesis, it is unknown whether these effects generalise to other antimitotic agents administered at different stages of development. In the present study, neurochemical, behavioral and electrophysiological techniques were used to determine whether exposure to the antimitotic agent Ara-C later in development recapitulates some of the changes observed in methylazoxymethanol (MAM)-treated animals and in patients with schizophrenia. Male rats exposed to Ara-C (30 mg/kg/day) at embryonic days 19.5 and 20.5 show reduced cell numbers and heterotopias in hippocampal CA1 and CA2/3 regions, respectively, as well as cell loss in the superficial layers of the pre- and infralimbic cortex. Birth date labeling with bromodeoxyuridine reveals that the cytoarchitectural changes in CA2/3 are a consequence rather that a direct result of disrupted cortical neurogenesis. Ara-C-treated rats possess elevated levels of cortical dopamine and DOPAC (3,4-didyhydroxypheylacetic acid) but no change in norepinephrine or serotonin. Ara-C-treated rats are impaired in their ability to learn the Morris water maze task and showed diminished synaptic plasticity in the hippocampocortical pathway. These data indicate that disruption of neurogenesis at embryonic days 19.5 and 20.5 constitutes a useful model for the comparative study of deficits observed in other gestational models and their relationship to cognitive changes observed in schizophrenia.

GluA3-deficiency in mice is associated with increased social and aggressive behavior and elevated dopamine in striatum

Glutamate signaling has been implicated in the regulation of social behavior. AMPA-glutamate receptors are assembled from four subunits (GluA1-4) of mainly GluA1/2 and GluA2/3 tetramers that form ion channels of distinct functional properties. Mice lacking GluA1 showed a reduced anxiety and male aggression. To understand the role of GluA3 in modulating social behavior, we investigated GluA3-deficient mice (Gria3-/Y) on C57BL/6J background. Compared to wild type (WT) littermates (n=14), Gria3-/Y mice (n=13) showed an increase in isolation-induced male aggression (p=0.011) in home cage resident-intruder test; an increase in sociability (p=0.01), and increase in male-male social interactions in neutral arena (p=0.005); an increase in peripheral activities in open field test (p=0.037) with normal anxiety levels in elevated plus maze and light-dark box; and minor deficits in motor and balance function in accelerating rotarod test (p=0.016) with normal grip strength. Gria3-/Y mice showed no significant deficit in spatial memory function in Morris-water maze and Y-maze tests, and normal levels of testosterone. Increased dopamine concentrations in stratum (p=0.034) and reduced serotonin turnover in olfactory bulb (p=0.002) were documented in Gria3-/Y mice. These results support a role of GluA3 in the modulation of social behavior through brain dopamine and/or serotonin signaling and different AMPA receptor subunits affect social behavior through distinct mechanisms.

Long-term protective effects of methamphetamine preconditioning against single-day methamphetamine toxic challenges

Methamphetamine (METH) use is associated with neurotoxic effects which include decreased levels of dopamine (DA), serotonin (5-HT) and their metabolites in the brain. We have shown that escalating METH dosing can protect against METH induced neurotoxicity in rats sacrificed within 24 hours after a toxic METH challenge. The purpose of the current study was to investigate if the protective effects of METH persisted for a long period of time. We also tested if a second challenge with a toxic dose of METH would cause further damage to monoaminergic terminals. Saline-pretreated rats showed significant METH-induced decreases in striatal DA and 5-HT levels in rats sacrificed 2 weeks after the challenge. Rats that received two METH challenges showed no further decreases in striatal DA or 5-HT levels in comparison to the single METH challenge. In contrast, METH-pretreated rats showed significant protection against METH-induced striatal DA and 5-HT depletion. In addition, the METH challenge causes substantial decreases in cortical 5-HT levels which were not further potentiated by a second drug challenge. METH preconditioning provided almost complete protection against METH -induced 5-HT depletion. These results are consistent with the idea that METH pretreatment renders the brain refractory to METH-induced degeneration of brain monoaminergic systems.

Chronic methamphetamine exposure suppresses the striatal expression of members of multiple families of immediate early genes (IEGs) in the rat: normalization by an acute methamphetamine injection

RATIONALE

Repeated injections of cocaine cause blunted responses to acute cocaine challenge-induced increases in the expression of immediate early genes (IEGs).

OBJECTIVES

The aim of this study was to test if chronic methamphetamine (METH) exposure might cause similar blunting of acute METH-induced increases in IEG expression.

RESULTS

Repeated saline or METH injections were given to rats over 14 days. After 1 day of withdrawal, they received a single injection of saline or METH (5 mg/kg). Acute injection of METH increased c-fos, fosB, fra2, junB, Egr1-3, Nr4a1 (Nur77), and Nr4a3 (Nor-1) mRNA levels in the striatum of saline-pretreated rats. Chronic METH treatment alone reduced the expression of AP1, Erg1-3, and Nr4a1 transcription factors below control levels. Acute METH challenge normalized these values in METH-pretreated rats. Unexpectedly, acute METH challenge to METH-pretreated animals caused further decreases in Nr4a2 (Nurr1) mRNA levels. In contrast, the METH challenge caused significant but blunted increases in Nr4a3 and Arc expression in METH-pretreated rats. There were also chronic METH-associated decreases in the expression of cAMP responsive element binding protein (CREB) which modulates IEG expression via activation of the cAMP/PKA/CREB signal transduction pathway. Chronic METH exposure also caused significant decreases in preprotachykinin, but not in prodynorphin, mRNA levels.

CONCLUSIONS

These results support the accumulated evidence that chronic administration of psychostimulants is associated with blunting of their acute stimulatory effects on IEG expression. The METH-induced renormalization of the expression of several IEGs in rats chronically exposed to METH hints to a potential molecular explanation for the recurrent self-administration of the drug by human addicts.

Chronic methamphetamine administration causes differential regulation of transcription factors in the rat midbrain

Methamphetamine (METH) is an addictive and neurotoxic psychostimulant widely abused in the USA and throughout the world. When administered in large doses, METH can cause depletion of striatal dopamine terminals, with preservation of midbrain dopaminergic neurons. Because alterations in the expression of transcription factors that regulate the development of dopaminergic neurons might be involved in protecting these neurons after toxic insults, we tested the possibility that their expression might be affected by toxic doses of METH in the adult brain. Male Sprague-Dawley rats pretreated with saline or increasing doses of METH were challenged with toxic doses of the drug and euthanized two weeks later. Animals that received toxic METH challenges showed decreases in dopamine levels and reductions in tyrosine hydroxylase protein concentration in the striatum. METH pretreatment protected against loss of striatal dopamine and tyrosine hydroxylase. In contrast, METH challenges caused decreases in dopamine transporters in both saline- and METH-pretreated animals. Interestingly, METH challenges elicited increases in dopamine transporter mRNA levels in the midbrain in the presence but not in the absence of METH pretreatment. Moreover, toxic METH doses caused decreases in the expression of the dopamine developmental factors, Shh, Lmx1b, and Nurr1, but not in the levels of Otx2 and Pitx3, in saline-pretreated rats. METH pretreatment followed by METH challenges also decreased Nurr1 but increased Otx2 and Pitx3 expression in the midbrain. These findings suggest that, in adult animals, toxic doses of METH can differentially influence the expression of transcription factors involved in the developmental regulation of dopamine neurons. The combined increases in Otx2 and Pitx3 expression after METH preconditioning might represent, in part, some of the mechanisms that served to protect against METH-induced striatal dopamine depletion observed after METH preconditioning.

Methamphetamine-induced dopamine-independent alterations in striatal gene expression in the 6-hydroxydopamine hemiparkinsonian rats

Unilateral injections of 6-hydroxydopamine into the medial forebrain bundle are used extensively as a model of Parkinson's disease. The present experiments sought to identify genes that were affected in the dopamine (DA)-denervated striatum after 6-hydroxydopamine-induced destruction of the nigrostriatal dopaminergic pathway in the rat. We also examined whether a single injection of methamphetamine (METH) (2.5 mg/kg) known to cause changes in gene expression in the normally DA-innervated striatum could still influence striatal gene expression in the absence of DA. Unilateral injections of 6-hydroxydopamine into the medial forebrain bundle resulted in METH-induced rotational behaviors ipsilateral to the lesioned side and total striatal DA depletion on the lesioned side. This injection also caused decrease in striatal serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels. DA depletion was associated with increases in 5-HIAA/5-HT ratios that were potentiated by the METH injection. Microarray analyses revealed changes (±1.7-fold, p<0.025) in the expression of 67 genes on the lesioned side in comparison to the intact side of the saline-treated hemiparkinsonian animals. These include follistatin, neuromedin U, and tachykinin 2 which were up-regulated. METH administration caused increases in the expression of c-fos, Egr1, and Nor-1 on the intact side. On the DA-depleted side, METH administration also increased the expression of 61 genes including Pdgf-d and Cox-2. There were METH-induced changes in 16 genes that were common in the DA-innervated and DA-depleted sides. These include c-fos and Nor-1 which show greater changes on the normal DA side. Thus, the present study documents, for the first time, that METH mediated DA-independent changes in the levels of transcripts of several genes in the DA-denervated striatum. Our results also implicate 5-HT as a potential player in these METH-induced alterations in gene expression because the METH injection also caused significant increases in 5-HIAA/5-HT ratios on the DA-depleted side.

Methamphetamine preconditioning causes differential changes in striatal transcriptional responses to large doses of the drug

Methamphetamine (METH) is a toxic drug of abuse, which can cause significant decreases in the levels of monoamines in various brain regions. However, animals treated with progressively increasing doses of METH over several weeks are protected against the toxic effects of the drug. In the present study, we tested the possibility that this pattern of METH injections might be associated with transcriptional changes in the rat striatum, an area of the brain which is known to be very sensitive to METH toxicity and which is protected by METH preconditioning. We found that the presence and absence of preconditioning followed by injection of large doses of METH caused differential expression in different sets of striatal genes. Quantitative PCR confirmed METH-induced changes in some genes of interest. These include small heat shock 27 kD proteins 1 and 2 (HspB1 and HspB2), brain derived neurotrophic factor (BDNF), and heme oxygenase-1 (Hmox-1). Our observations are consistent with previous studies which have reported that ischemic or pharmacological preconditioning can cause reprogramming of gene expression after lethal ischemic insults. These studies add to the growing literature on the effects of preconditioning on the brain transcriptome.

Methamphetamine self-administration is associated with persistent biochemical alterations in striatal and cortical dopaminergic terminals in the rat

Methamphetamine (meth) is an illicit psychostimulant that is abused throughout the world. Repeated passive injections of the drug given in a single day or over a few days cause significant and long-term depletion of dopamine and serotonin in the mammalian brain. Because meth self-administration may better mimic some aspects of human drug-taking behaviors, we examined to what extent this pattern of drug treatment might also result in damage to monoaminergic systems in the brain. Rats were allowed to intravenously self-administer meth (yoked control rats received vehicle) 15 hours per day for 8 days before being euthanized at either 24 hours or at 7 and 14 days after cessation of drug taking. Meth self-administration by the rats was associated with a progressive escalation of daily drug intake to 14 mg/kg per day. Animals that self-administered meth exhibited dose-dependent decreases in striatal dopamine levels during the period of observation. In addition, there were significant reductions in the levels of striatal dopamine transporter and tyrosine hydroxylase proteins. There were also significant decreases in the levels of dopamine, dopamine transporter, and tyrosine hydroxylase in the cortex. In contrast, meth self-administration caused only transient decreases in norepinephrine and serotonin levels in the two brain regions, with these values returning to normal at seven days after cessation of drug taking. Importantly, meth self-administration was associated with significant dose-dependent increases in glial fibrillary acidic protein in both striatum and cortex, with these changes being of greater magnitude in the striatum. These results suggest that meth self-administration by rats is associated with long-term biochemical changes that are reminiscent of those observed in post-mortem brain tissues of chronic meth abusers.

Methamphetamine preconditioning alters midbrain transcriptional responses to methamphetamine-induced injury in the rat striatum

Methamphetamine (METH) is an illicit drug which is neurotoxic to the mammalian brain. Numerous studies have revealed significant decreases in dopamine and serotonin levels in the brains of animals exposed to moderate-to-large METH doses given within short intervals of time. In contrast, repeated injections of small nontoxic doses of the drug followed by a challenge with toxic METH doses afford significant protection against monoamine depletion. The present study was undertaken to test the possibility that repeated injections of the drug might be accompanied by transcriptional changes involved in rendering the nigrostriatal dopaminergic system refractory to METH toxicity. Our results confirm that METH preconditioning can provide significant protection against METH-induced striatal dopamine depletion. In addition, the presence and absence of METH preconditioning were associated with substantial differences in the identity of the genes whose expression was affected by a toxic METH challenge. Quantitative PCR confirmed METH-induced changes in genes of interest and identified additional genes that were differentially impacted by the toxic METH challenge in the presence of METH preconditioning. These genes include small heat shock 27 kD 27 protein 2 (HspB2), thyrotropin-releasing hormone (TRH), brain derived neurotrophic factor (BDNF), c-fos, and some encoding antioxidant proteins including CuZn superoxide dismutase (CuZnSOD), glutathione peroxidase (GPx)-1, and heme oxygenase-1 (Hmox-1). These observations are consistent, in part, with the transcriptional alterations reported in models of lethal ischemic injuries which are preceded by ischemic or pharmacological preconditioning. Our findings suggest that multiple molecular pathways might work in tandem to protect the nigrostriatal dopaminergic pathway against the deleterious effects of the toxic psychostimulant. Further analysis of the molecular and cellular pathways regulated by these genes should help to provide some insight into the neuroadaptive potentials of the brain when repeatedly exposed to drugs of abuse.

Methamphetamine- and trauma-induced brain injuries: comparative cellular and molecular neurobiological substrates

The use of methamphetamine (METH) is a growing public health problem, because its abuse is associated with long-term biochemical and structural effects on the human brain. Neurodegeneration is often observed in humans, because of mechanical injuries (e.g., traumatic brain injury [TBI]) and ischemic damage (strokes). In this review, we discuss recent findings documenting the fact that the psychostimulant drug METH can cause neuronal damage in several brain regions. The accumulated evidence from our laboratories and those of other investigators indicates that acute administration of METH leads to activation of calpain and caspase proteolytic systems. These systems are also involved in causing neuronal damage secondary to traumatic and ischemic brain injuries. Protease activation is accompanied by proteolysis of endogenous neuronal structural proteins (alphaII-spectrin protein and microtubule-associated protein-tau), evidenced by the appearance of their breakdown products after these injuries. When taken together, these observations suggest that METH exposure, like TBI, can cause substantial damage to the brain by causing both apoptotic and necrotic cell death in the brains of METH addicts who use large doses of the drug during their lifetimes. Finally, because METH abuse is accompanied by functional and structural changes in the brain similar to those in TBI, METH addicts might experience greater benefit if their treatment involved greater emphasis on rehabilitation in conjunction with potential neuroprotective pharmacological agents such as calpain and caspase inhibitors similar to those used in TBI.

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.

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.

Methamphetamine preconditioning: differential protective effects on monoaminergic systems in the rat brain

Pretreatment with methamphetamine (METH) can attenuate toxicity due to acute METH challenges. The majority of previous reports have focused mainly on the effects of the drug on the striatal dopaminergic system. In the present study, we used a regimen that involves gradual increases in METH administration to rats in order to mimic progressively larger doses of the drug used by some human METH addicts. We found that this METH preconditioning was associated with complete protection against dopamine depletion caused by a METH challenge (5 mg/kg x 6 injections given 1 h apart) in the striatum and cortex. In contrast, there was no preconditioning-mediated protection against METH-induced serotonin depletion in the striatum and hippocampus, with some protection being observed in the cortex. There was also no protection against METH-induced norepinephrine (NE) depletion in the hippocampus. These results indicate that, in contrast to the present dogmas, there might be differences in the mechanisms involved in METH toxicity on monoaminergic systems in the rodent brain. Thus, chronic injections of METH might activate programs that protect against dopamine toxicity without influencing drug-induced pathological changes in serotoninergic systems. Further studies will need to evaluate the cellular and molecular bases for these differential responses.

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.

Amphetamine causes dopamine depletion and cell death in the mouse olfactory bulb

Amphetamine is a neurotoxic psychostimulant that causes dopamine depletion and neuronal death in the rodent striatum. In the present study, we sought to determine if toxic doses of the drug can also induce pathological changes in the mouse olfactory bulb. We found that injections of amphetamine (10 mg/kg x 4, given 2 h apart) caused significant decreases in dopamine levels in that structure. This dose of the drug also induced substantial increases in the number of terminal deoxynucleotidyl transferase-mediated deoxyribonucleotide triphosphate (dNTP) nick end labeling (TUNEL)-positive cells in the olfactory bulb indicative of elevated DNA fragmentation. These results show that the toxic effects of amphetamine involve the olfactory bulb in addition to the striatum. These observations need to be taken into consideration when discussing the clinical course of amphetamine addiction.

Interactions of HIV and methamphetamine: cellular and molecular mechanisms of toxicity potentiation

Methamphetamine (METH) is a highly addictive psychostimulant drug, whose abuse has reached epidemic proportions worldwide. METH use is disproportionally represented among populations at high risks for developing HIV infection or who are already infected with the virus. Psychostimulant abuse has been reported to exacerbate the cognitive deficits and neurodegenerative abnormalities observed in HIV-positive patients. Thus, the purpose of the present paper is to review the clinical and basic observations that METH potentiates the adverse effects of HIV infection. An additional purpose is to provide a synthesis of the cellular and molecular mechanisms that might be responsible for the increased toxicity observed in co-morbid patients. The reviewed data indicate that METH and HIV proteins, including gp120, gp41, Tat, Vpr and Nef, converge on various caspase-dependent death pathways to cause neuronal apoptosis. The role of reactive microgliosis in METH- and in HIV-induced toxicity is also discussed.

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.

Transcriptional responses to reinforcing effects of cocaine in the rat hippocampus and cortex

The psychostimulant effects of cocaine are thought to result from its ability to block dopamine (DA) uptake and increase DA levels in ventral striatum. In addition, cocaine causes biochemical changes in the brain areas involved in learning and memory, including hippocampus and cortex, whose role in drug reinforcement is now being actively investigated. Thus, we studied molecular events in the hippocampus and frontal cortex of rats treated with cocaine conditioned place preference (CPP) paradigm. After exposure to cocaine conditioning (cocaine paired), cocaine alone (cocaine non-paired) or saline rats were tested for place conditioning. Cocaine (10 mg/kg) caused increases in time spent in the drug-paired compartment. By using microarray analyses, we examined gene expression in the hippocampi and frontal cortices of cocaine-paired rats, cocaine non-paired and saline-treated controls. Our study revealed that 214 transcripts were differentially regulated in the hippocampi of cocaine-paired rats. These include genes that play roles in protein phosphorylation, RNA processing and protein synthesis, ubiquitin-dependent protein degradation and cytoskeleton organization. In contrast, 39 genes were differently expressed in the frontal cortex. Our data support the possibility that molecular changes in the hippocampus might participate in the formation and maintenance of memory patterns induced by cocaine in the brain. Differences in the transcriptional responses in the hippocampus and cortex suggest the primary importance of the hippocampus for recent memory processing associated with cocaine-induced CPP.

Neonatal dopamine depletion induces changes in morphogenesis and gene expression in the developing cortex

The mesocorticolimbic dopamine (DA) system is implicated in mental health disorders affecting attention, impulse inhibition and other cognitive functions. It has also been involved in the regulation of cortical morphogenesis. The present study uses focal injections of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle of BALB/c mice to examine morphological, behavioral and transcriptional responses to selective DA deficit in the fronto-parietal cortex. Mice that received injections of 6-OHDA on postnatal day 1 (PND1) showed reduction in DA levels in their cortices at PND7. Histological analysis at PND120 revealed increased fronto-cortical width, but decreased width of somatosensory parietal cortex. Open field object recognition suggested impaired response inhibition in adult mice after 6-OHDA treatment. Transcriptional analyses using 17K mouse microarrays showed that such lesions caused up-regulation of 100 genes in the cortex at PND7. Notably, among these genes are Sema3A which plays a repulsive role in axonal guidance, RhoD which inhibits dendritic growth and tubulin beta-5 microtubule subunit. In contrast, 127 genes were down-regulated, including CCT-epsilon and CCT-zeta that play roles in actin and tubulin folding. Thus, neonatal DA depletion affects transcripts involved in control of cytoskeletal formation and pathway finding, instrumental for normal differentiation and synaptogenesis. The observed gene expression changes are consistent with histological cortical and behavioral impairments in the adult mice treated with 6-OHDA on PND1. Our results point towards specific molecular targets that might be involved in disease process mediated by altered developmental DA regulation.

Amphetamine induces apoptosis of medium spiny striatal projection neurons via the mitochondria‐dependent pathway

Amphetamine (AMPH) is a psychostimulant whose chronic abuse may cause impairments in attention and memory in humans. These cognitive deficits might be related to neurotoxic effects of the drug. One such toxic effect is the well-described destruction of striatal dopaminergic terminals in mammals. In the present study, we investigated the possibility that AMPH might also cause neuronal apoptosis in the rodent striatum. Administration of a dose of the drug (10 mg/kg, 4 times, every 2 h) that is toxic to dopaminergic terminals resulted in the appearance of striatal cells that were positive for cleaved caspase-3 and for terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling (TUNEL), observations that are indicative of an ongoing apoptotic process. Dual immunofluorescence staining revealed that cleaved caspase-3-positive cells express calbindin and DARPP-32, but not somatostatin, parvalbumin, or cholinergic markers. In addition, AMPH also caused increased expression of p53 and Bax at both transcript and protein levels; in contrast, Bcl-2 levels were decreased after the AMPH injections. Moreover, Bax knockout mice showed resistance to AMPH-induced apoptotic cell death but not to AMPH-induced destruction of dopaminergic terminals. When taken together, these observations indicate that injections of doses of AMPH that are known to destroy striatal dopamine terminals can also cause apoptotic death of postsynaptic medium spiny projection neurons via mitochondria-dependent mechanisms.

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

The regional distribution of c-Jun expression and of the number of apoptotic cells was compared in various brain areas after methamphetamine administration to mice. Our results showed that there was methamphetamine-induced overexpression of c-Jun in the cortex and striatum but not in the cerebellar cortex. There was an almost totally similar regional appearance of methamphetamine-induced apoptotic cells in the mouse brain; no apoptosis was present in the cerebellum. Additionally, in the neocortical area, more positive signals for c-Jun immunoreactivity were observed in the piriform cortex, an area that also showed more positive terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) signals than the frontal and parietal cortices. These observations suggested that c-Jun might be involved in methamphetamine-induced apoptosis. This idea was confirmed by using heterozygous c-Jun knockout mice that showed much less apoptosis than wild-type controls. In addition, we found that the majority of TUNEL-positive cells were also positive for c-Jun-like immunoreactivity in both genotypes. Moreover, methamphetamine-induced caspase-3 activity and PARP cleavage were also reduced in c-Jun heterozygous knockout mice. In contrast, methamphetamine-induced hyperthermia was essentially identical in the two genotypes. When taken together, our data support the hypothesis that c-Jun is involved in methamphetamine-induced apoptosis.

Analysis of methamphetamine-induced changes in the expression of integrin family members in the cortex of wild-type and c-fos knockout mice

Methamphetamine (METH) is an illicit drug that is also neurotoxic. Recent studies suggest that in addition to dopamine terminal degeneration in the striatum, METH causes apoptosis in cortical neurons. Earlier, we showed that c-fos knockout mice are more susceptible to the toxic effects of the drug. In order to identify possible pathways related to these differences, we have used cDNA array that provided us with a comprehensive catalog of METH affected genes. In the present study, we report on the effects of METH on the integrin family members that were shown to be involved in intracellular signaling cascades effecting cell survival. We found that, in comparison to wild type animals, c-fos knockout mice have lower baseline levels of the integrins in the cortex. Moreover, METH caused time-dependent decreases in their transcripts in both strains of mice. Quantitative RT-PCR confirmed the changes obtained in cDNA array. These findings are discussed in view of the possible role of integrins in METH-induced toxic effects on the cortical neurons.

cDNA array analysis of gene expression profiles in the striata of wild-type and Cu/Zn superoxide dismutase transgenic mice treated with neurotoxic doses of amphetamine

Amphetamine (AMPH) is a drug of abuse that causes the degeneration of striatal dopamine terminals in mammals. Superoxide radicals seem to participate in AMPH-induced damage because its toxicity is attenuated in Cu/Zn superoxide dismutase transgenic (SOD-tg) mice. To provide a detailed analysis of molecular changes associated with AMPH toxicity, we used cDNA arrays consisting of 1176 genes to detect differential changes in gene expression in the striata of wild-type and SOD-tg mice treated with neurotoxic doses of the drug. We found 42 genes that showed >1.8-fold changes in at least two consecutive time points during the course of the study and were differentially affected by AMPH in the two genotypes. Specifically, more transcription factors and genes involved in responses to injury/inflammation were affected in wild-type mice after AMPH administration. Some of these stimulant-induced superoxide-dependent alterations in gene expression might affect neuronal functions and promote neuronal damage. Other changes might help to provide some degree of protection against AMPH toxicity. These results support the view that the use of global array analysis of gene expression will help to identify novel molecular mediators of AMPH-induced neurodegeneration.

Amphetamine-induced toxicity in dopamine terminals in CD-1 and C57BL/6J mice: complex roles for oxygen-based species and temperature regulation

In order to examine differential strain susceptibility to neurotoxic effects of amphetamine and to assess the potential role of superoxide radicals in amphetamine-induced dopaminergic damage, the drug was injected to mice with different levels of copper/zinc superoxide dismutase (Cu/Zn SOD) enzyme. Administration of amphetamine (10 mg/kg, i.p., given every 2 h, a total of four times) to wild-type CD-1 and C57BL/6J mice caused significant decreases in dopamine and 3,4-dihydroxyphenylacetic acid levels, in [(125)I]RTI-121-labeled dopamine transporters as well as a significant depletion in the concentration of dopamine transporter and vesicular monoamine transporter 2 proteins. The amphetamine-induced toxic effects were less prominent in CD-1 mice, which have much higher levels of Cu/Zn SOD activity (0.69 units/mg of protein) in their striata than C57BL/6J animals (0.007 units/mg of protein). Transgenic mice on CD-1 and C57BL/6J background, which had striatal levels of Cu/Zn SOD 2.57 and 1.67 units/mg of protein, respectively, showed significant protection against all the toxic effects of amphetamine. The attenuation of toxicity observed in transgenic mice was not caused by differences in amphetamine accumulation in wild-type and mutant animals. However, CD-1-SOD transgenic mice showed marked hypothermia to amphetamine whereas C57-SOD transgenic mice did not show a consistent thermic response to the drug. The data obtained demonstrate distinctions in the neurotoxic profile of amphetamine in CD-1 and C57BL/6J mice, which show some differences in Cu/Zn SOD activity and in their thermic responses to amphetamine administration. Thus, these observations provide evidence for possible complex interactions between thermoregulation and free radical load in the long-term neurotoxic effects of this illicit drug of abuse.

Effects of serotonin synthesis blockade on interleukin-1 beta action in the brain of rats

The ability of the brain serotonergic system to mediate the effects of interleukin-1beta (IL-1beta) was investigated. Intracerebroventricular administration of IL-1beta induced a significant pyrogenic reaction, depression in social behaviour, loss of body weight and reduced food intake in rats. Pre-treatment with p-chlorphenylalanine, an inhibitor of serotonin synthesis, blocked the IL-1beta-induced decrease in food intake and loss of body weight, but failed to alter the temperature increase and the decrease in communicative activity.

Analysis of amino acids in human serum by isocratic reversed-phase high-performance liquid chromatography with electrochemical detection

A simple, sensitive and reproducible isocratic high-performance liquid chromatography (HPLC) method has been developed for the determination of amino acids in human serum. The method involves precipitation of the serum proteins with methanol followed by pre-column derivatization of amino acids with o-phthalaldehyde-2-mercaptoethanol or o-phthalaldehyde-sodium sulfite. HPLC separation of the derivatives was performed using an ODS column with an isocratic mobile phase system and electrochemical detection (+0.75 V). The response was linear over the range 5-300 microM for all amino acids. The method allows quantitative determination of glutamic acid, asparagine, serine, glutamine, histidine, taurine, alanine, arginine, methionine, isoleucine, ornithine, leucine, phenylalanine, lysine and tryptophan at concentrations as low as 0.5-5.0 pmol (signal-to-noise ratio=2). Using this method, the levels of amino acids in serum from healthy donors and patients with ischemic stroke were determined.

Antipyretic effect of neuropeptide galanin in endotoxin-induced fever

Neuropeptide galanin produces a antipyretic effect in experimental pyrogenic reaction induced by intraperitoneal injection of lipopolysaccharide. Central intracerebroventricular injection of 100 ng galanin significantly attenuated, but did not completely abolish fever. Central galanin injection potentiated endotoxin-induced activation of the noradrenergic system and blocked activation of the serotoninergic system of the anterior hypothalamus.

Methamphetamine-induced neurotoxicity is attenuated in transgenic mice with a null mutation for interleukin-6

Increasing evidence implicates apoptosis as a major mechanism of cell death in methamphetamine (METH) neurotoxicity. The involvement of a neuroimmune component in apoptotic cell death after injury or chemical damage suggests that cytokines may play a role in METH effects. In the present study, we examined if the absence of IL-6 in knockout (IL-6-/-) mice could provide protection against METH-induced neurotoxicity. Administration of METH resulted in a significant reduction of [(125)I]RTI-121-labeled dopamine transporters in the caudate-putamen (CPu) and cortex as well as depletion of dopamine in the CPu and frontal cortex of wild-type mice. However, these METH-induced effects were significantly attenuated in IL-6-/- animals. METH also caused a decrease in serotonin levels in the CPu and hippocampus of wild-type mice, but no reduction was observed in IL-6-/- animals. Moreover, METH induced decreases in [(125)I]RTI-55-labeled serotonin transporters in the hippocampal CA3 region and in the substantia nigra-reticulata but increases in serotonin transporters in the CPu and cingulate cortex in wild-type animals, all of which were attenuated in IL-6-/- mice. Additionally, METH caused increased gliosis in the CPu and cortices of wild-type mice as measured by [(3)H]PK-11195 binding; this gliotic response was almost completely inhibited in IL-6-/- animals. There was also significant protection against METH-induced DNA fragmentation, measured by the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeled (TUNEL) cells in the cortices. The protective effects against METH toxicity observed in the IL-6-/- mice were not caused by differences in temperature elevation or in METH accumulation in wild-type and mutant animals. Therefore, these observations support the proposition that IL-6 may play an important role in the neurotoxicity of METH.

Intracerebroventricular administration of substance P increases dopamine content in the brain of 6-hydroxydopamine-lesioned rats

The interactions existing between substance P- and dopamine-positive neurons, notably in the basal ganglia, suggest that substance P may have therapeutic use in treatment of Parkinson's disease characterized by impaired dopaminergic transmission. The effects of intracerebroventricularly administered substance P were tested on the levels of dopamine and its metabolites in the striatum, nucleus accumbens and frontal cortex of 6-hydroxydopamine-lesioned rats. Intracerebroventricular injection of 6-hydroxydopamine decreased the levels of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the brain structures under investigation. Administration of substance P in low dose (0.35 nmol/kg) had no effect on the 6-hydroxydopamine-induced reduction of the dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid contents in the brain. However, treatment with substance P in higher dose (3.5 nmol/kg) increased the concentrations of dopamine and its metabolites in the striatum, nucleus accumbens and frontal cortex relative to saline-treated group. Additionally, 6-hydroxydopamine lesions significantly increased 3,4-dihydroxyphenylacetic acid/dopamine and homovanillic acid/dopamine ratios in the striatum and nucleus accumbens. Substance P (3.5 nmol/kg) partially reversed lesion-induced increases in 3,4-dihydroxyphenylacetic acid/dopamine and homovanillic acid/dopamine ratios in the striatum, but did not alter these ratios in nucleus accumbens. To test whether substance P fragmentation is responsible for this phenomenon, substance P(5-11), which is one of the main substance P fragments in rat CNS, was administered in equimolar dose. Substance P(5-11) was found to have no effect on the content of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the striatum and nucleus accumbens. In the frontal cortex, substance P(5-11) produced decreases in dopamine levels and increases in homovanillic acid/dopamine ratio. The results of this study suggest that substance P helps to restore dopamine deficit in the brain in an animal model of Parkinson's disease, with the positive effects being more prominent on the nigrostriatal than on the mesocorticolimbic dopaminergic system, but substance P(5-11) is not responsible for this effect.

[A quantitative analysis of amino acids in blood serum by isocratic reverse-phase HPLC]

A method for chromatographic analysis of human serum amino acids is proposed. Orthophthalic aldehyde in combination with 2-mercaptoethanol or sodium sulfite as a reagent for amino acid transfer into derivatives permits the identification of 15 amino acids within the framework of a single chromatographic system with an isocratic elution regimen. Glutamic acid, asparagine, serine, glutamine, histidine, taurine, alanine, arginine, methionine, isoleucin, ornithine, leucin, phenylalanine, lysin, and triptophane were measured in the sera of healthy donors and patients with ischemic stroke.

Neuraminidase activity of NAG vibrios and of some representatives of the intestinal group of bacteria

It was studied 203 strains of NAG vibrios and 71 strains of different enterobacteria for the ability to produce neuraminidase. The most frequent neuraminidase producers were found among the strains isolated from humans (99 strain of 131). There was no correlation between neuraminidase production and other properties of the vibrios. The examined strains of the family Enterobacteriaceae did not produce the enzyme.

[Typing of vibrions by specific O-sera]

Vibrios which were not agglutinated with cholera O-serum in various areas of the USSR from persons suffering from intestinal diseases, carriers, from the water and hydrobionts (550 in all) were typed serologically. Forty three specific O-sera were used ofr serological typing. A determination was made of the serological type in 93% of the strains of vibrios isolated from humans. The given sera were also capable of typing 87% of vibrio strains belonging to the I group Heiberg, isolated from water and hydrobionts, 56% of the strains of the II group and individual strains of the III group, whereas cultures belonging to the IV-VIII groups were not agglutinated by these sera. Circulation of 33 serological types of vibrios not agglutinable by cholera O-serum was revealed in the Soviet Union.