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Increased alcohol consumption and heightened aggression have been linked to social isolation. Furthermore, animals treated with alcohol following social separation showed higher aggression together with lower serotonin transmission. Although reduced serotonin transmission in the brain may be related to alcohol-induced heightened aggression and fluoxetine has been used to reduce alcohol intake and aggression, it remains unclear whether there are specific brain regions where changes in serotonin transmission are critical for animal aggression following the alcohol treatment. In the present study, we isolated mice for 4-6weeks and injected them with alcohol, fluoxetine and alcohol with fluoxetine. We studied their aggression by using two types of behavioral paradigms: isolation-induced attack behavior towards a naïve mouse in a neutral cage, or shock-induced target biting aggression. We observed that alcohol administered at 500mg/kg significantly increased animal attack behaviors towards naïve mice 30min after injections. This dose of alcohol co-administered with a low dose of fluoxetine (2mg/kg) further increased the attack behaviors, but with higher doses of fluoxetine, the attack behaviors were decreased. Alcohol administered at a dose of 1,000mg/kg significantly decreased the shock-induced target biting rates 24h after injections. Interestingly, 24h after injections, we observed a significant increase in target biting rates when alcohol was co-administered with fluoxetine at a dose of 16mg/kg. We also observed the same heightened target biting rates when animals were injected with fluoxetine alone. This heightened biting attack engendered by the fluoxetine (alone or in combination with the alcohol) occurred at a time when brain serotonin activity was reduced by these drugs in the frontal cortex and hypothalamus. These observations, in concordance with previous findings reported by others, indicate that heightened biting attack behavior may be associated with reduced serotonergic activity in brain regions regulating aggression., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Autism is a heterogeneous, behaviorally defined developmental disorder with unknown etiology but thought to be the result of environmental insult acting upon the developing brain of a genetically susceptible individual. Approximately 30% of individuals with autism have normal development up to the age of about 30 months after which they experience behavioral regression and lose previously acquired motor, cognitive and social skills. Early post-natal toxicant administration to mice has been used to model autistic regression. To test the hypothesis that genetically altered mice might be more sensitive to toxicant exposure early in life, mice with a deletion of glutathione-S-transferaseM1 (GSTM1; a gene associated with increased risk of autism that codes for an enzyme involved in the management of toxicant-induced oxidative stress) and wild-type controls were exposed to valproic acid (VPA; a toxicant known to cause autism-like behavioral deficits that, in part, are mediated through oxidative stress) on post-natal day 14. VPA treatment caused significant increases in apoptosis in granule cells of the hippocampus and cerebellum. There was a genotype by treatment by sex interaction with wild-type females exhibiting significantly fewer apoptotic cells in these regions compared to all other groups. VPA treatment also resulted in long-lasting deficits in social behaviors and significant alterations in brain chemistry. VPA-treated GSTM1 knockout animals performed significantly fewer crawl-under behaviors compared to saline-treated knockout animals as well as wild-type controls receiving either treatment. Collectively, these studies indicate that VPA-treatment causes cerebellar and hippocampal apoptosis and that having the wild-type GSTM1 genotype may confer protection against VPA-induced neuronal death in female mice., (Copyright 2010 Elsevier B.V. All rights reserved.)

Treatment of p53(-/-) mice orally with caffeine, voluntary exercise or their combination for 2 weeks prior to a single irradiation with UVB (i) decreased the weight of the epididymal fat pads by 22, 40 and 56%, (ii) decreased the thickness of the dermal fat layer by 10, 26 and 42%, (iii) increased the number of apoptotic sunburn cells by 29, 100 and 489%, (iv) increased the number of caspase-3-positive cells by 33, 117 and 667% and (v) increased the number of mitotic cells with cyclin B1-positive staining by 40, 210 and 510%, respectively. Pearson's correlation coefficient indicated a statistically significant inverse relationship between the level of tissue fat and the number of mitotic cells with cyclin B1 in p53(-/-) mice but not in p53(+/+) littermates. Western blot analysis indicated that treatment of p53(-/-) mice with caffeine together with exercise increased the level of cyclin B1 significantly more than in p53(+/+) mice. p53(-/-) mice, but not p53(+/+) mice, treated with caffeine during exercise exhibited a dramatic decrease in the level of survivin. Our results suggest that voluntary exercise in combination with oral caffeine may exert a synergistic increase in UVB-induced apoptosis and that tissue fat may be a more important modulator of apoptosis and carcinogenesis in p53-deficient mice than in p53-normal mice. The stimulatory effects on apoptosis in p53(-/-) mice by the combination treatment might be associated with increased levels of cyclin B1 and decreased levels of survivin.

High-dose administration of amphetamine-like compounds is associated with acute behavioral toxicity (including stereotypic and self-injurious behavior and schizophrenic-like psychoses) as well as long-lasting damage to dopaminergic neurons. Several mechanisms are thought to be responsible for methamphetamine-induced neurotoxicity including the formation of reactive oxygen species, dopamine quinones, glutamatergic activity, apoptosis, etc. Recently, new factors regarding glial cell line-derived neurotorophic factor, tumor necrosis factor-alpha, and interferon-gamma have also been associated with methamphetamine-induced neurotoxicity. The objective of this review is to link the behavioral and neurotoxic responses of the amphetamines, emphasizing their common underlying mechanism of monoaminergic release together with inhibition of monoamine oxidase activity. The amphetamine-induced release of dopamine and inhibition of monoamine oxidase increases both cytosolic and synaptic levels of dopamine leading to the acute manifestation of stereotypic and self-injurious behavior. In turn, the enhanced extravesicular levels of dopamine lead to oxidative stress through the generation of reactive oxygen species and dopamine quinones, and cause the long-lasting neuronal damage. Thus, we propose that acute behavioral observation of subjects immediately following methamphetamine administration may provide insight into the long-lasting toxicity to dopaminergic neurons.

PAK6 is a member of the group B family of PAK serine/threonine kinases, and is highly expressed in the brain. The group B PAKs, including PAK4, PAK5, and PAK6, were first identified as effector proteins for the Rho GTPase Cdc42. They have important roles in filopodia formation, the extension of neurons, and cell survival. Pak4 knockout mice die in utero, and the embryos have several abnormalities, including a defect in the development of motor neurons. In contrast, Pak5 knockout mice do not have any noticeable abnormalities. So far nothing is known about the biological function of Pak6. To address this, we have deleted the Pak6 gene in mice. Since Pak6 and Pak5 are both expressed in the brain, we also generated Pak5/Pak6 double knockout mice. These mice were viable and fertile, but had several locomotor and behavioral deficits. Our results indicate that Pak5 and Pak6 together are not required for viability, but are required for a normal level of locomotion and activity as well as for learning and memory. This is consistent with a role for the group B PAKs in the nervous system.

It is believed that gene by environmental interactions contribute to the pathogenesis of autism spectrum disorders (ASD). We hypothesize that ASD are associated with early and repeated exposures to any of a number of toxicants or mixtures of toxicants. It is the cumulative effects of these repeated exposures acting upon genetically susceptible individuals that lead to the phenotypes of ASD. We report our initial observations of a considerable overlap of identified toxic landfills in the State of New Jersey and the residence of an ASD cohort, and a correlation between the identified toxic Superfund sites on each U.S. state and the total number of diagnosed cases of ASD in those states. The residence of 495 ASD patients in New Jersey by zip code and the toxic landfill sites were plotted on a map of Northern New Jersey. The area of highest ASD cases coincides with the highest density of toxic landfill sites while the area with lowest ASD cases has the lowest density of toxic landfill sites. Furthermore, the number of toxic Superfund sites and autism rate across 49 of the 50 states shows a statistically significant correlation (i.e. the number of identified superfund sites correlates with the rate of autism per 1000 residents in 49 of the states (p = 0.015; excluding the state of Oregon). These significant observations call for further organized studies to elucidate possible role(s) of environmental toxicants contributing to the pathogenesis of ASD.

In the present study, we investigated the effect of voluntary exercise on the formation and growth of the human pancreas Panc-1 and prostate PC-3 tumors in immunodeficient mice. Female severe combined immunodeficient (SCID) mice were injected subcutaneously with human pancreatic cancer Panc-1 cells, and male SCID mice were injected subcutaneously with human prostate cancer PC-3 cells. Voluntary running wheel exercise for 63 days, starting one week before the subcutaneous injection of Panc-1 or PC-3 tumor cells into SCID mice, suppressed the growth of Panc-1 and PC-3 tumors. The exercise regimen increased the food and fluid consumption in the female and male mice. Exercise also decreased the size of the parametrial fat pads in the female mice and the paradidymis fat pads in the male mice, but there was no effect on the body weight. Mechanistic studies showed that voluntary running wheel exercise inhibited proliferation as reflected by a decreased mitosis, and the exercise regimen also stimulated apoptosis as reflected by the increased caspase-3 (active form) expression in the Panc-1 and PC-3 tumors. Voluntary running wheel exercise decreased the ratio of the percent mitotic cells/apoptotic cells in Panc-1 and PC-3 tumors by 38 and 32%, respectively. The present study demonstrated an inhibitory effect of voluntary exercise on the growth of pancreas and prostate tumors in a SCID mouse xenograft model.

Various hypotheses have been proposed concerning the mechanisms responsible for methamphetamine (METH)-induced neurotoxicity including reactive oxygen species (ROS), dopamine quinones, glutamatergic activity, apoptosis, etc. Recently, new factors regarding glial cell line-derived neurotorophic factor, tumor necrosis factor-alpha, and alpha-synuclein contained in striatal interneural inclusions have also been associated with METH-induced neurotoxicity. In addition, METH-induced self-injurious behavior (SIB) has been proposed to be an acute or immediate behavioral marker predicting the long-lasting neurotoxicity induced by METH. Specifically, it has been proposed that the SIB response may accurately reflect the underlying mechanistic changes occurring in the neuron that eventually result in the long-lasting damage. Several studies have demonstrated that endogenous dopamine (DA) plays an important role in mediating METH-induced neuronal damage. DA release and redistribution from synaptic vesicles to cytoplasmic compartments is thought to involve METH-induced changes in both the vesicular monoamine transporter-2 and DA transporter function. In turn, the consequent elevation of cytosolic auto-oxidizable DA concentrations is thought generate ROS such as superoxide and hydroxyl radicals and cause the DA terminal injury. Finally, the inflammatory response of microglia and glutamatergic toxicity in astrocytes have been related to the METH-induced neurotoxicity. The objective of the present review will be to consolidate the new perspectives in an attempt to formulate a more cohesive explanation of the underlying mechanism responsible for METH-induced DA damage and its early biological markers.

Treatment of SKH-1 mice orally with caffeine (0.1 mg/ml in the drinking water), voluntary running wheel exercise, or a combination of caffeine and exercise for 2 weeks (i) decreased the weight of the parametrial fat pads by 35, 62, and 77%, respectively; (ii) decreased the thickness of the dermal fat layer by 38, 42, and 68%, respectively; (iii) stimulated the formation of UVB-induced apoptotic sunburn cells in the epidermis by 96, 120, and 376%, respectively; and (iv) stimulated the formation of UVB-induced caspase 3 (active form)-positive cells in the epidermis by 92, 120, and 389%, respectively (average of two experiments). Oral administration of caffeine (0.4 mg/ml in the drinking water) in combination with voluntary exercise was less effective than administration of the low dose of caffeine in combination with exercise in stimulating UVB-induced apoptosis. Although orally administrated caffeine (0.1 mg/ml in the drinking water) or voluntary exercise for 2 weeks caused only a small nonsignificant stimulation of UVB-induced increase in the percentage of phospho-p53 (Ser-15)-positive cells in the epidermis (27 or 18%, respectively), the combination of the two treatments enhanced the UVB-induced increase in phospho-p53 (Ser-15)-positive cells by 99%. The plasma concentration of caffeine in mice ingesting caffeine (0.1-0.4 mg/ml drinking water) is similar to that in the plasma of most coffee drinkers (one to four cups per day). Our studies indicate a greater than additive stimulatory effect of combined voluntary exercise and oral administration of a low dose of caffeine on UVB-induced apoptosis.

Perinatal exposure to methylmercury (MeHg) in rodents has been linked to changes in sensitivity to dopaminergic agents later in life. In an effort to determine the behavioral and neurochemical response to the indirect dopaminergic and serotonergic agonist amphetamine following neonatal exposure to MeHg, male BALB/c mice were administered MeHg during critical periods of neural development and challenged with amphetamine as adults. Mice were observed 15, 30 and 60 min after a single amphetamine injection (7.5 mg/kg i.p.) for presence of stereotypic and self-injurious behaviors, abnormal posture, and hyperthermia. Mice treated with 2 or 4 mg/kg MeHg on alternate days 3-15 of life demonstrated an increase in body temperature and the appearance of stereotypic and self-injurious behaviors not observed when amphetamine was administered to either vehicle-exposed mice or those treated with an equivalent total amount of MeHg administered on postnatal days 13 and 15. Neurochemical analysis of MeHg- and vehicle-exposed mice challenged with amphetamine or saline revealed alterations in dopaminergic and serotonergic activity which corresponded to the sensitized behavioral response to amphetamine. These observations demonstrate a critical window for MeHg exposure affecting the later appearance of amphetamine-induced self-injurious behavior and support the hypothesis that early exposure to environmental neurotoxicants may predispose individuals to engage in aberrant, intrusive behaviors later in life.

Earlier studies indicated that high dietary fat and obesity are associated with an increased risk of cancer at several organ sites in experimental animals and in humans. In a recent study we found that voluntary running wheel exercise decreased body fat and inhibited ultraviolet B light (UVB)-induced carcinogenesis in the epidermis of SKH-1 mice. In the present study we demonstrate that voluntary running wheel exercise stimulated UVB-induced apoptosis in the epidermis by a p53-independent mechanism, and voluntary exercise also stimulated apoptosis in UVB-induced tumors in tumor-bearing mice. Exercise had no effect in non-UVB-treated epidermis or in areas of the epidermis away from tumors in tumor-bearing mice. In addition, we found that removal of the parametrial fat pads (partial lipectomy) 2 weeks before UVB irradiation enhanced UVB-induced apoptosis. The results of our studies suggest that fat cells secrete substances that inhibit apoptosis in cells with DNA damage and possibly also in tumors. Our results help explain why exercise or various dietary regimens that decrease tissue fat inhibit carcinogenesis.

Earlier studies showed that oral administration of green tea or caffeine to SKH-1 mice inhibited ultraviolet B light (UVB)-induced skin carcinogenesis, decreased dermal fat thickness and increased locomotor activity. In the present study, the effects of voluntary running wheel exercise on thickness of dermal fat as well as on UVB-induced tumorigenesis in SKH-1 mice were studied in UVB-initiated high-risk and UVB-induced complete carcinogenesis models. In the high-risk model, animals were exposed to UVB (30 mJ/cm(2)) 3 times/week for 16 weeks. For 14 weeks subsequent to UVB exposure, half of the animals had access to running wheels in their cages whereas the other half did not. In the complete carcinogenesis model, animals were exposed to UVB (30 mJ/cm(2)) 2 times/week for 33 weeks. From the beginning, half of the animals had access to running wheels whereas the other half did not. At the conclusion of each study, body weights were not different between groups, although animals with running wheels consumed significantly more food and water than animals without running wheels. In addition, animals with running wheels had decreases in parametrial fat pad weight and thickness of the dermal fat layer. In both UVB-initiated high-risk and complete carcinogenesis models, voluntary running wheel exercise delayed the appearance of tumors, decreased the number of tumors per mouse and decreased tumor volume per mouse. Histopathology studies revealed that running wheel exercise decreased the number of non-malignant tumors (primarily keratoacanthomas) by 34% and total tumors per mouse by 32% in both models, and running wheel exercise decreased the formation of squamous cell carcinomas in the UVB-induced complete carcinogenesis model by 27%. In addition, the size of keratoacanthomas and squamous cell carcinomas were decreased substantially in both models. The effects described here indicate that voluntary running wheel exercise inhibits UVB-induced skin tumorigenesis and may also inhibit tumor growth.

Exercise exerts neuroprotective effects and facilitates neural recovery in animal models of Parkinson's disease. In the present studies, effects of exercise on amphetamine-induced dopaminergic toxicity were assessed in mice housed individually either with or without access to run wheels. Mice in run wheel cages ran approximately 20 000 revolutions/day (over 10 km/day). Some mice received amphetamine (18.5 mg/kg x 4 injections) whereas controls received saline. Amphetamine caused a 90% dopamine depletion in mice housed either with or without run wheels. A precipitous drop was seen in run wheel activity following amphetamine, lasting at least 7 days. A significant decrease in food intake, water intake and body weight also occurred. The opportunity to exercise did not facilitate behavioral or neurochemical recovery at 1, 2 or 3 days, or 2 weeks after injections. Therefore, shock stress, a component of some forced exercise studies, was evaluated to determine whether stress without exercise provided neuroprotection against amphetamine. Results indicate that shock stress exerted neuroprotective effects, reducing the amphetamine-induced dopamine depletion. It is concluded that voluntary running does not afford either behavioral or neuroprotection nor facilitate recovery from amphetamine-induced dopaminergic toxicity; rather, elevated glucocorticoid levels following shock stress were associated with a reduction in the dopamine depletion.

Autism symptoms, including impairments in language development, social interactions, and motor skills, have been difficult to model in rodents. Since children exposed in utero to sodium valproate (VPA) demonstrate behavioral and neuroanatomical abnormalities similar to those seen in autism, the neurodevelopmental effects of this antiepileptic agent were examined in mice following its pre- or postnatal administration. Exposed pups were evaluated in a battery of neurodevelopmental procedures designed to assess VPA-induced retardation (wherein a behavior fails to mature on schedule), regression (wherein a behavior does mature on time but then deteriorates), or intrusions (wherein normal behaviors are overshadowed by stereotypic or self-injurious behaviors). The resulting observations were interpreted in the context of this new strategy to model autism.

The effects of phencyclidine on an operant task were evaluated prior to and after neurotoxic lesions of the striatum in rats. Subjects were trained to respond on a fixed-interval 90-second schedule for water presentation. The degree to which phencyclidine disrupted responding was first evaluated (dose range 1.0-4.0 mg/kg). The subjects were then divided into three matched groups and received bilateral intraventricular injections of 6-hydroxydopamine (6-OHDA) (100 microg), kainic acid (0.25 microg), or vehicle delivered stereotaxically. 6-OHDA was used to destroy the presynaptic neurons of the nigro-striatal pathway and kainic acid was employed to destroy the postsynaptic neurons whose cell bodies are located in the striatum. Following recovery, the phencyclidine dose-response curve was repeated in the fixed-interval paradigm. It was observed that 6-OHDA-induced damage resulted in a rightward shift of the dose-response curve indicating tolerance to phencyclidine and caused a significant depletion of striatal dopamine and gamma-aminobutyric acid (GABA). Kainic acid-induced damage resulted in a leftward shift in the dose-response curve indicating sensitivity to the schedule-disruptive effects of phencyclidine and produced a significant GABA depletion. The vehicle-treated rats exhibited no shift in their sensitivity to phencyclidine. These observations indicate that the effects of phencyclidine are mediated, at least in part, by striatal dopaminergic neurons.

Background: The effects of caffeine on fatty liver induced by high-fat (low-carbohydrate) diets were examined in the presence or absence of alcohol consumption by rats., Material/methods: For periods ranging from two to twelve weeks, male Long-Evans rats were given alcohol-free or alcohol-containing liquid diets balanced for energy content, but varying in fat and carbohydrate. In addition, several of the groups were given 0.05% caffeine as a constituent of the liquid diet. At the end of the experiments, trunk blood was collected for blood glucose and plasma leptin, epididymal fat pads were weighed, and liver was taken for analysis of glycogen, glucose, and fat., Results: Ethanol-containing diets increased liver fat and depleted liver glycogen and glucose as compared to the corresponding ethanol-free diets, but these effects were less severe in rats given high-carbohydrate diets as compared to those maintained on the high-fat diet. The inclusion of 0.05% caffeine in the diet increased the motor activity of animals with access to a running wheel, yet had no protective effect against ethanol-induced depletion of liver glucose and induction of fatty liver. In fact, caffeine appears to exacerbate the effect of ethanol to deplete liver glycogen, decrease epididymal fat pad weight and lower serum leptin., Conclusions: Since liver glycogen stores can be depleted by treatments such as caffeine which do not exacerbate ethanol-related liver fat accumulation, the depletion of liver glycogen following chronic ethanol is not the single causal determinant of the resulting fatty liver. Other aspects of carbohydrate metabolism, including accumulations of endogenous regulatory intermediates or ethanol-derived compounds, might be more directly influenced by chronic alcohol ingestion.

The behavioral and neurochemical effects of high doses of amphetamine administered to BALB/c mice were examined in the presence and absence of co-administered haloperidol (a D2 antagonist), SCH 23390 (a D1 antagonist) and risperidone (a mixed 5-HT2/D2 antagonist). It was observed that mice displayed a dose-dependent increase in stereotypic behavior, oral dyskinesia, and self-injurious behavior (SIB) in response to amphetamine treatment. Furthermore, agents that blocked the SIB reversed the amphetamine-induced release of serotonin. This effect was unrelated to hyperthermia or non-specific sedation (as assessed by measurement of motor activity). These data are interpreted in the context of the underlying basis of murine SIB involving both dopaminergic and serotonergic activation and demonstrate the efficacy of risperidone in treating these behaviors.

Synucleins have attracted much attention because of their involvement in several neurodegenerative disorders. In a screening for genes differentially expressed after high-dose cocaine exposure, we found gamma-synuclein as a major upregulated candidate in the tegmentum. Overexpression of both alpha- and gamma-synuclein after drug treatment was confirmed by means of microarrays, yielding an increase in the hippocampus, the striatum and the tegmentum (2.65 x, 1.96 x and 3.5 x, respectively, for alpha-synuclein vs. 2.7 x, 1.96 x and 7.16 x for gamma-synuclein), but no change in the nucleus accumbens. Investigation of the distribution of mRNA (by in situ hybridization) and of the proteins (by immunocytochemistry) shows in both cases a clearly distinct pattern of expression for alpha- and gamma-synuclein. alpha-synuclein displays a very characteristic distribution, confined to specific nuclei, whereas gamma-synuclein is more widely expressed throughout the brain. mRNA of both alpha- and gamma-synucleins display a complementary pattern of expression all over the cortex. In contrast to gamma-synuclein, alpha-synuclein is neuronal, being only found in NeuN-expressing cells, and is expressed in the basal ganglia (faintly) and in the substantia nigra compacta where it is highly correlated with tyrosine hydroxylase. Immunocytochemistry shows that gamma-synuclein generally colocalizes with glial fibrillary acidic protein-expressing cells and is abundant in the red nucleus, the substantia nigra reticulata and the anterior commissure, while gamma-synuclein mRNA labels the matrix compartments of the caudate-putamen. The role of synucleins in relation to cocaine-induced plasticity or neurotoxicity is discussed.

Administration of green tea or caffeine was shown previously to inhibit ultraviolet B light-induced carcinogenesis in SKH-1 mice, and this effect was associated with a reduction in dermal fat. In the present study, oral administration of 0.6% green tea (6 mg tea solids/ml) or 0.04% caffeine (0.4 mg/ml; equivalent to the amount of caffeine in 0.6% green tea) as the sole source of drinking fluid to SKH-1 mice for 15 weeks increased total 24 hr locomotor activity by 47 and 24%, respectively (p<0.0001). Oral administration of 0.6% decaffeinated green tea (6 mg tea solids/ml) for 15 weeks increased locomotor activity by 9% (p<0.05). The small increase in locomotor activity observed in mice treated with decaffeinated green tea may have resulted from the small amounts of caffeine still remaining in decaffeinated green tea solutions (0.047 mg/ml). The stimulatory effects of orally administered green tea and caffeine on locomotor activity were paralleled by a 38 and 23% increase, respectively, in the dermal muscle layer thickness. In addition, treatment of the mice with 0.6% green tea or 0.04% caffeine for 15 weeks decreased the weight of the parametrial fat pad by 29 and 43%, respectively, and the thickness of the dermal fat layer was decreased by 51 and 47%, respectively. These results indicate that oral administration of green tea or caffeine to SKH-1 mice increases locomotor activity and muscle mass and decreases fat stores. The stimulatory effect of green tea and caffeine administration on locomotor activity described here may contribute to the effects of green tea and caffeine to decrease fat stores and to inhibit carcinogenesis induced by UVB in SKH-1 mice.

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.

Differential sensitivity to neurotoxic effects of methamphetamine on striatal dopaminergic neurones between C57BL/6 and BALB/c mice has been established. In the present studies, the interaction of methamphetamine-induced dopamine release, self-injurious behaviour, the neural immune response, and the long-term (3 day) dopamine depletion were examined in these strains after administration of 8 mg/kg methamphetamine. BALB/c mice showed increased hyperthermia compared to the C57BL/6 strain, as well as induction of interleukin-1beta. Additionally, homovanillic acid (HVA) levels, as well as HVA/DA turnover ratios were elevated in the striatum and frontal cortex of BALB/c mice, both compared to untreated mice and to the C57BL/6 strain after a single injection of methamphetamine. Pretreatment with acetaminophen eliminated the methamphetamine-induced hyperthermia in BALB/c mice and reduced body temperature in C57BL/6 mice. However, acetaminophen pretreatment did not affect any parameters of dopaminergic toxicity in the striatum or frontal cortex of the BALB/c strain following repeated methamphetamine injections. Furthermore, acetaminophen pretreatment did not alter the incidence of self-injurious behaviour in BALB/c mice. Therefore, hyperthermia and methamphetamine-induced toxicity appear to be independent phenomena while self-injurious behaviour may provide a better predictor of toxicity, which, in turn, may be related to dopamine release.

The effects of acute administration of nicotine on target biting (defensive) and resident-intruder (offensive) attack of male mice were assessed. In the target biting procedure confined mice received tail shock on a fixed time, 2-min schedule. Under baseline conditions, biting attack directed toward an inanimate target occurred at three distinct rates. A high target biting rate (13.5 +/- 3.8 bites/15 sec) followed shock delivery, an intermediate biting rate (9.6 +/- 4.1 bites/15 sec) occurred during the inter-shock interval, and a low biting rate (1.0 +/- 0.5 bites/15 sec) occurred during a tone stimulus which signalled the impending shock. Nicotine (administered IP, 15 min presession) reduced post-shock and inter-shock interval target biting in a dose-dependent manner (ED50 values estimated at 0.13 and 0.14 mg/kg, respectively) but exerted more variable effects on target biting during the tone. In the resident-intruder paradigm the same mice were exposed to an intruder introduced into its home cage for a 10-min test session. Under baseline conditions, residents directed 20 +/- 3.2 biting attacks toward the intruder during the session with an average latency of 89 +/- 40 sec to the first attack. Nicotine caused a dose-dependent decrease in this attack behavior (ED50 values estimated to be 0.48 and 0.49 mg/kg, respectively). These observations are interpreted to indicate that nicotine has an increased potency at reducing "defensive" aggression.

The effects of pretreatment with MPTP (1-methyl4-phenyl-1,2,3,6-tetrahydropyridine) on the acute and long-term effects of methamphetamine on striatal dopamine were evaluated in BALB/c mice. Four subcutaneous injections of a non-toxic dose of MPTP (8 mg/kg, at 2 hr intervals) were followed three days later by a toxic regimen of methamphetamine (four injections of 4 mg/kg, at 2 hr intervals) and mice were sacrificed immediately or three days later. Control mice received saline in place of the MPTP or methamphetamine and mice were observed for acute changes in body temperature, self-injurious behaviour, and striatal dopamine metabolites, or long-term changes in striatal dopamine levels, tyrosine hydroxylase immunoreactivity and glial fibrillary acidic protein. It was observed that pretreatment with MPTP protected mice against the acute increase in body temperature caused by the methamphetamine but, at the same time, delayed the occurrence of self-injurious behaviour following the repeated injections of methamphetamine. Likewise, pretreatment with MPTP attenuated the long-term depletion of striatal dopamine induced by the methamphetamine as well as the large increase in glial fibrillary acidic protein and the reduction in tyrosine hydroxylase immunoreactivity. The MPTP-treatment itself did not alter any of these neurotoxic markers. Finally, the acute decrease in 3,4-dihydroxyphenyacetic acid levels and increased ratio of 3-methoxytyramine/dopamine observed 60 min. after a single injection of methamphetamine (4 mg/kg) were also attenuated in MPTP-treated mice. These results are discussed in the context of the hypothesis that the low-dose treatment with MPTP may modify exchange diffusion across the striatal cell membrane thereby altering the acute and long-lasting effects of methamphetamine.

The effects of high fat and high carbohydrate diets on alcohol metabolism were studied on blood alcohol and liver fat concentration. In Experiment 1, rats consumed an alcohol-containing liquid diet. Blood was collected for ethanol, glucose and lactate analyses and livers were excised for lipid determination. Blood ethanol and liver fat were lower when rats consumed the high carbohydrate diet. Glucose concentrations were lower in rats fed the high fat diet compared with those fed the high carbohydrate diet when ethanol was consumed. In Experiment 2, rats consumed a high fat, ethanol-containing diet for 13 d. Half of the rats were switched to a high carbohydrate, ethanol-containing diet for an additional 11 d. The same analyses were carried out as for Experiment 1. Switching the high fat-fed rats to the high carbohydrate diet reversed the high blood ethanol and high liver fat values, even though the rats consumed significantly more alcohol with the high carbohydrate diet. In Experiment 3 the same high fat and high carbohydrate diets without ethanol were consumed for 2 wk, at which time ethanol was administered acutely, intraperitoneally, at 2 g/kg. Blood was analyzed for ethanol, glucose and lactate 30, 60 and 120 min after injection. Rats fed the high carbohydrate diet had lower blood ethanol but higher lactate at 120 min compared with those fed the high fat diet. The results suggest that the rate of ethanol elimination is slower in rats fed high fat than in those fed high carbohydrate diets, resulting in elevated blood ethanol and liver fat levels for the former.

Our laboratory has developed an integrative approach to study the molecular changes and behavioral effects of drug administration consisting of a combination of quantitative real-time reverse transcription polymerase chain reaction, RNA isolation and differential display, in situ hybridization, place preference conditioning and high-performance liquid chromatography. Although the techniques are not novel, this multi-systems approach allows for the examination of gene expression changes following the administration of drugs of abuse such as cocaine, and allows for an analysis of behavior and neurochemistry of gene knockout mice. As a result of this combination of techniques, we have been able to determine the expression, location and function of the CD81 protein. Specifically, CD81 was induced exclusively in the nucleus accumbens by cocaine treatment. Subsequent behavioral testing of CD81 knockout mice revealed these mice displayed altered sensitivity to cocaine.