Impact of Elevated Brain IL-6 in Transgenic Mice on the Behavioral and Neurochemical Consequences of Chronic Alcohol Exposure.

Alcohol consumption activates the neuroimmune system of the brain, a system in which brain astrocytes and microglia play dominant roles. These glial cells normally produce low levels of neuroimmune factors, which are important signaling factors and regulators of brain function. Alcohol activation of the neuroimmune system is known to dysregulate the production of neuroimmune factors, such as the cytokine IL-6, thereby changing the neuroimmune status of the brain, which could impact the actions of alcohol. The consequences of neuroimmune-alcohol interactions are not fully known. In the current studies we investigated this issue in transgenic (TG) mice with altered neuroimmune status relative to IL-6. The TG mice express elevated levels of astrocyte-produced IL-6, a condition known to occur with alcohol exposure. Standard behavioral tests of alcohol drinking and negative affect/emotionality were carried out in homozygous and heterozygous TG mice and control mice to assess the impact of neuroimmune status on the actions of chronic intermittent alcohol (ethanol) (CIE) exposure on these behaviors. The expressions of signal transduction and synaptic proteins were also assessed by Western blot to identify the impact of alcohol-neuroimmune interactions on brain neurochemistry. The results from these studies show that neuroimmune status with respect to IL-6 significantly impacts the effects of alcohol on multiple levels.

Neuroimmune interactions with binge alcohol drinking in the cerebellum of IL-6 transgenic mice.

The neuroimmune system of the brain, which is comprised primarily of astrocytes and microglia, regulates a variety of homeostatic mechanisms that underlie normal brain function. Numerous conditions, including alcohol consumption, can disrupt this regulatory process by altering brain levels of neuroimmune factors. Alcohol and neuroimmune factors, such as proinflammatory cytokines IL-6 and TNF-alpha, act at similar targets in the brain, including excitatory and inhibitory synaptic transmission. Thus, alcohol-induced production of IL-6 and/or TNF-alpha could be important contributing factors to the effects of alcohol on the brain. Recent studies indicate that IL-6 plays a role in alcohol drinking and the effects of alcohol on the brain activity following the cessation of alcohol consumption (post-alcohol period), however information on these topics is limited. Here we used homozygous and heterozygous female and male transgenic mice with increased astrocyte expression of IL-6 to examined further the interactions between alcohol and IL-6 with respect to voluntary alcohol drinking, brain activity during the post-alcohol period, IL-6 signal transduction, and expression of synaptic proteins. Wildtype littermates (WT) served as controls. The transgenic mice model brain neuroimmune status with respect to IL-6 in subjects with a history of persistent alcohol use. Results showed a genotype dependent reduction in voluntary alcohol consumption in the Drinking in the Dark protocol and in frequency-dependent relationships between brain activity in EEG recordings during the post-alcohol period and alcohol consumption. IL-6, TNF-alpha, IL-6 signal transduction partners pSTAT3 and c/EBP beta, and synaptic proteins were shown to play a role in these genotypic effects.

Alcohol alters IL-6 Signal Transduction in the CNS of Transgenic Mice with Increased Astrocyte Expression of IL-6.

Neuroimmune factors, including the cytokine interleukin-6 (IL-6), are important chemical regulators of central nervous system (CNS) function under both physiological and pathological conditions. Elevated expression of IL-6 occurs in the CNS in a variety of disorders associated with altered CNS function, including excessive alcohol use. Alcohol-induced production of IL-6 has been reported for several CNS regions including the cerebellum. Cerebellar actions of alcohol occur through a variety of mechanisms, but alcohol-induced changes in signal transduction, transcription, and translation are known to play important roles. IL-6 is an activator of signal transduction that regulates gene expression. Thus, alcohol-induced IL-6 production could contribute to cerebellar effects of alcohol by altering gene expression, especially under conditions of chronic alcohol abuse, where IL-6 levels could be habitually elevated. To gain an understanding of the effects of alcohol on IL-6 signal transduction, we studied activation/expression of IL-6 signal transduction partners STAT3 (Signal Transducer and Activator of Transcription), CCAAT-enhancer binding protein (C/EBP) beta, and p42/p44 mitogen-activated protein kinase (MAPK) at the protein level. Cerebella of transgenic mice that express elevated levels of astrocyte produced IL-6 in the CNS were studied. Results show that the both IL-6 and chronic intermittent alcohol exposure/withdrawal affect IL-6 signal transduction partners and that the actions of IL-6 and alcohol interact to alter activation/expression of IL-6 signal transduction partners. The alcohol/IL-6 interactions may contribute to cerebellar actions of alcohol, whereas the effects of IL-6 alone may have relevance to cerebellar changes occurring in CNS disorders associated with elevated levels of IL-6.

Altered brain activity during withdrawal from chronic alcohol is associated with changes in IL-6 signal transduction and GABAergic mechanisms in transgenic mice with increased astrocyte expression of IL-6.

Interleukin-6 (IL-6) is an important neuroimmune factor that is increased in the brain by alcohol exposure/withdrawal and is thought to play a role in the actions of alcohol on the brain. To gain insight into IL-6/alcohol/withdrawal interactions and how these interactions affect the brain, we are studying the effects of chronic binge alcohol exposure on transgenic mice that express elevated levels of IL-6 in the brain due to increased astrocyte expression (IL-6 tg) and their non-transgenic (non-tg) littermate controls. IL-6/alcohol/withdrawal interactions were identified by genotypic differences in spontaneous brain activity in electroencephalogram (EEG) recordings from the mice, and by Western blot analysis of protein activation or expression in hippocampus obtained from the mice after the final alcohol withdrawal period. Results from EEG studies showed frequency dependent genotypic differences in brain activity during withdrawal. For EEG frequencies that were affected by alcohol exposure/withdrawal in both genotypes, the nature of the effect was similar, but differed across withdrawal cycles. Differences between IL-6 tg and non-tg mice were also observed in Western blot studies of the activated form of STAT3 (phosphoSTAT3), a signal transduction partner of IL-6, and subunits of GABAA receptors (GABAAR). Regression analysis revealed that pSTAT3 played a more prominent role during withdrawal in the IL-6 tg mice than in the non-tg mice, and that the role of GABAAR alpha-5 and GABAAR alpha-1 in brain activity varied across genotype and withdrawal. Taken together, our results suggest that IL-6 can significantly impact mechanisms involved in alcohol withdrawal.

Intravenous cocaine self-administration in a panel of inbred mouse strains differing in acute locomotor sensitivity to cocaine.

RATIONALE: Initial sensitivity to drugs of abuse often predicts subsequent use and abuse, but this relationship is not always observed in human studies. Moreover, studies examining the relationship between initial locomotor sensitivity and the rewarding and reinforcing effects of drugs in animal models have also been equivocal. Understanding the relationship between initial drug effects and propensity to continue use, potentially resulting in the development of a substance use disorder, may help to identify key targets for prevention and treatment. OBJECTIVES: We examined intravenous cocaine self-administration in a set of mouse strains that were previously identified to be at the phenotypic extremes for cocaine-induced locomotor activation to determine if initial locomotor sensitivity predicted acquisition, extinction, dose response, or progressive ratio (PR) breakpoint. METHODS: We selected eight inbred mouse strains based on locomotor sensitivity to 20 mg/kg cocaine. These strains, designated as low and high responders, were tested in an intravenous self-administration paradigm that included acquisition of 0.5 mg/(kg*inf) under a FR1 schedule, extinction, re-acquisition, dose response to 0.125, 0.25, 0.5, 1, and 2 mg/(kg*inf), and progressive ratio. RESULTS: We observed overall differences in self-administration behavior between high and low responders. Low responders self-administered less cocaine and had lower breakpoints under the PR schedule. However, we also observed strain differences within each group. Self-administration in the low responder, LG/J, more closely resembled the behavior of the high-responding group, and the high responder, P/J, had self-administration behavior that more closely resembled the low-responding group. CONCLUSIONS: We conclude that acute cocaine-induced locomotor activation does predict self-administration behavior, but in a strain-specific manner. These data support the idea that genetic background influences the relationship among addiction-related behaviors.

Effects of Withdrawal from Chronic Intermittent Ethanol Exposure on Sleep Characteristics of Female and Male Mice.

BACKGROUND: Sleep disruptions are an important consequence of alcohol use disorders. There is a dearth of preclinical studies examining sex differences in sleep patterns associated with ethanol (EtOH) dependence despite documented sex differences in alcohol-related behaviors and withdrawal symptoms. The purpose of this study was to investigate the effects of chronic intermittent EtOH on sleep characteristics in female and male mice. METHODS: Female and male C57BL6/J mice had access to EtOH/water 2-bottle choice (2BC) 2 h/d for 3 weeks followed by exposure to EtOH vapor (vapor-2BC) or air for 5 cycles of 4 days. An additional group never experienced EtOH (naïve). Mice were implanted with electroencephalographic (EEG) electrodes, and vigilance states were recorded across 24 hours on the fourth day of withdrawal. The amounts of wakefulness, slow-wave sleep (SWS), and rapid eye movement sleep were calculated, and spectral analysis was performed by fast Fourier transformation. RESULTS: Overall, vapor-2BC mice showed a decrease in the amount of SWS 4 days into withdrawal as well as a decrease in the power density of slow waves, indicating disruptions in both the amount and quality of sleep in EtOH-dependent mice. This was associated with a decrease in duration and an increase in number of SWS episodes in males and an increase in latency to sleep in females. CONCLUSIONS: Our results revealed overall deficits in sleep regulation in EtOH-dependent mice of both sexes. Female mice appeared to be more affected with regard to the triggering of sleep, while male mice appeared more sensitive to disruptions in the maintenance of sleep.

Pharmacological Targeting the REV-ERBs in Sleep/Wake Regulation.

The circadian clock maintains appropriate timing for a wide range of behaviors and physiological processes. Circadian behaviors such as sleep and wakefulness are intrinsically dependent on the precise oscillation of the endogenous molecular machinery that regulates the circadian clock. The identical core clock machinery regulates myriad endocrine and metabolic functions providing a link between sleep and metabolic health. The REV-ERBs (REV-ERBα and REV-ERBß) are nuclear receptors that are key regulators of the molecular clock and have been successfully targeted using small molecule ligands. Recent studies in mice suggest that REV-ERB-specific synthetic agonists modulate metabolic activity as well as alter sleep architecture, inducing wakefulness during the light period. Therefore, these small molecules represent unique tools to extensively study REV-ERB regulation of sleep and wakefulness. In these studies, our aim was to further investigate the therapeutic potential of targeting the REV-ERBs for regulation of sleep by characterizing efficacy, and optimal dosing time of the REV-ERB agonist SR9009 using electroencephalographic (EEG) recordings. Applying different experimental paradigms in mice, our studies establish that SR9009 does not lose efficacy when administered more than once a day, nor does tolerance develop when administered once a day over a three-day dosing regimen. Moreover, through use of a time response paradigm, we determined that although there is an optimal time for administration of SR9009 in terms of maximal efficacy, there is a 12-hour window in which SR9009 elicited a response. Our studies indicate that the REV-ERBs are potential therapeutic targets for treating sleep problems as those encountered as a consequence of shift work or jet lag.

Transgenic mice with increased astrocyte expression of IL-6 show altered effects of acute ethanol on synaptic function.

A growing body of evidence has revealed that resident cells of the central nervous system (CNS), and particularly the glial cells, comprise a neuroimmune system that serves a number of functions in the normal CNS and during adverse conditions. Cells of the neuroimmune system regulate CNS functions through the production of signaling factors, referred to as neuroimmune factors. Recent studies show that ethanol can activate cells of the neuroimmune system, resulting in the elevated production of neuroimmune factors, including the cytokine interleukin-6 (IL-6). Here we analyzed the consequences of this CNS action of ethanol using transgenic mice that express elevated levels of IL-6 through increased astrocyte expression (IL-6-tg) to model the increased IL-6 expression that occurs with ethanol use. Results show that increased IL-6 expression induces neuroadaptive changes that alter the effects of ethanol. In hippocampal slices from non-transgenic (non-tg) littermate control mice, synaptically evoked dendritic field excitatory postsynaptic potential (fEPSP) and somatic population spike (PS) at the Schaffer collateral to CA1 pyramidal neuron synapse were reduced by acute ethanol (20 or 60 mM). In contrast, acute ethanol enhanced the fEPSP and PS in hippocampal slices from IL-6 tg mice. Long-term synaptic plasticity of the fEPSP (i.e., LTP) showed the expected dose-dependent reduction by acute ethanol in non-tg hippocampal slices, whereas LTP in the IL-6 tg hippocampal slices was resistant to this depressive effect of acute ethanol. Consistent with altered effects of acute ethanol on synaptic function in the IL-6 tg mice, EEG recordings showed a higher level of CNS activity in the IL-6 tg mice than in the non-tg mice during the period of withdrawal from an acute high dose of ethanol. These results suggest a potential role for neuroadaptive effects of ethanol-induced astrocyte production of IL-6 as a mediator or modulator of the actions of ethanol on the CNS, including persistent changes in CNS function that contribute to cognitive dysfunction and the development of alcohol dependence.

Pharmacological targeting of the mammalian clock regulates sleep architecture and emotional behaviour.

Synthetic drug-like molecules that directly modulate the activity of key clock proteins offer the potential to directly modulate the endogenous circadian rhythm and treat diseases associated with clock dysfunction. Here we demonstrate that synthetic ligands targeting a key component of the mammalian clock, the nuclear receptors REV-ERBα and ß, regulate sleep architecture and emotional behaviour in mice. REV-ERB agonists induce wakefulness and reduce REM and slow-wave sleep. Interestingly, REV-ERB agonists also reduce anxiety-like behaviour. These data are consistent with increased anxiety-like behaviour of REV-ERBß-null mice, in which REV-ERB agonists have no effect. These results indicate that pharmacological targeting of REV-ERB may lead to the development of novel therapeutics to treat sleep disorders and anxiety.

Astrocytes contribute to gamma oscillations and recognition memory.

Glial cells are an integral part of functional communication in the brain. Here we show that astrocytes contribute to the fast dynamics of neural circuits that underlie normal cognitive behaviors. In particular, we found that the selective expression of tetanus neurotoxin (TeNT) in astrocytes significantly reduced the duration of carbachol-induced gamma oscillations in hippocampal slices. These data prompted us to develop a novel transgenic mouse model, specifically with inducible tetanus toxin expression in astrocytes. In this in vivo model, we found evidence of a marked decrease in electroencephalographic (EEG) power in the gamma frequency range in awake-behaving mice, whereas neuronal synaptic activity remained intact. The reduction in cortical gamma oscillations was accompanied by impaired behavioral performance in the novel object recognition test, whereas other forms of memory, including working memory and fear conditioning, remained unchanged. These results support a key role for gamma oscillations in recognition memory. Both EEG alterations and behavioral deficits in novel object recognition were reversed by suppression of tetanus toxin expression. These data reveal an unexpected role for astrocytes as essential contributors to information processing and cognitive behavior.

Effects of lurasidone in behavioral models of depression. Role of the 5-HT7 receptor subtype.

Major depression is a common psychiatric disorder associated with high symptomatic and functional burdens. Pharmacological treatment is often effective, but there remain substantial unmet needs in the form of non-responders, delayed onset of clinical effect, and side effects. Recent studies have positioned the serotonin 5-HT7 receptor as a new target for the treatment of depression. Preclinical studies have shown that antagonists induce an antidepressant-like response, a phenotype that can also be observed in mice lacking the receptor. Lurasidone is a new atypical antipsychotic agent with very high affinity for the 5-HT7 receptor. Patients in clinical trials have reported improved scores in depression ratings. We have tested lurasidone in both acute and chronic mouse models of depression. In the tail suspension and forced swim tests lurasidone decreased immobility, an antidepressant-like response. The effect required functional 5-HT7 receptors as it was absent in mice lacking the receptor. In the repeated open-space swim test lurasidone was able to reverse the despair induced by repeated swims in a manner similar to the commonly used antidepressant citalopram. The results provide evidence that lurasidone can act as a 5-HT7 receptor antagonist and provide a possible explanation for the antidepressant effect data currently emerging from lurasidone clinical trials. Additionally, the results give further support for targeting the 5-HT7 receptor in the treatment of depression. It will be of interest to clinically evaluate lurasidone as an antidepressant either as monotherapy or as an adjunctive therapy to available drugs.

Characterization of Highper, an ENU-induced mouse mutant with abnormal psychostimulant and stress responses.

RATIONALE: Chemical mutagenesis in the mouse is a forward genetics approach that introduces random mutations into the genome, thereby providing an opportunity to annotate gene function and characterize phenotypes that have not been previously linked to a given gene. OBJECTIVES: We report on the behavioral characterization of Highper, an N-ethyl-N-nitrosourea (ENU)-induced mutant mouse line. METHODS: Highper and B6 control mice were assessed for locomotor activity in the open field and home cage environments. Basal and acute restraint stress-induced corticosterone levels were measured. Mice were tested for locomotor response to cocaine (5, 20, 30, and 45 mg/kg), methylphenidate (30 mg/kg), and ethanol (0.75, 1.25, and 1.75 g/kg). The rewarding and reinforcing effects of cocaine were assessed using conditioned place preference and self-administration paradigms. RESULTS: Highper mice are hyperactive during behavioral tests but show normal home cage locomotor behavior. Highper mice also exhibit a twofold increase in locomotor response to cocaine, methylphenidate, and ethanol and prolonged activation of the hypothalamic-pituitary-adrenal axis in response to acute stress. Highper mice are more sensitive to the rewarding and reinforcing effects of cocaine, although place preference in Highper mice appears to be significantly influenced by the environment in which the drug is administered. CONCLUSIONS: Altogether, our findings indicate that Highper mice may provide important insights into the genetic, molecular, and biological mechanisms underlying stress and the drug reward pathway.

Basic sleep mechanisms: an integrative review.

Regulation of the sleep-waking cycle is complex and involves diverse brain circuits and molecules. On one hand, an interplay among many neuroanatomical and neurochemical systems including acetylcholine, dopamine, noradrenaline, serotonin, histamine, and hypocretin has been shown to control the waking state. On the other hand the sleep-onset is governed by the activity of sleep-promoting neurons placed in the anterior hypothalamus that utilize GABA to inhibit wake-promoting regions. Moreover, brainstem regions inhibited during wakefulness (W) and slow wave sleeps (SWS) become active during rapid eye movement (REM) sleep. Further complexity has been introduced by the recognition of sleep-promoting molecules that accumulate in the brain in prolonged W as well as the physiological role of gene expression during sleep. The sleep-wake cycle is currently undergoing intense research with many new findings leading to new paradigms concerning sleep regulation, brain organization and sleep function. This review provides a broader understanding of our present knowledge in the field of sleep research.

Strain-specific viral distribution and neuropathology of feline immunodeficiency virus.

Feline immunodeficiency virus (FIV) is a naturally occurring lentivirus of domestic cats, and is the causative agent of feline AIDS. Similar to human immunodeficiency virus (HIV), the pathogenesis of FIV involves infection of lymphocytes and macrophages, and results in chronic progressive immune system collapse and death. Neuropathologic correlates of FIV infection have not yet been elucidated, and may be relevant to understanding HIV-associated neurologic disease (neuroAIDS). As in HIV, FIV strains have been shown to express differential tendencies towards development of clinical neuroAIDS. To interrogate viral genetic determinants that might contribute to neuropathogenicity, cats were exposed to two well-characterized FIV strains with divergent clinical phenotypes and a chimeric strain as follows: FIV(PPR) (PPR, relatively apathogenic but associated with neurologic manifestations), FIV(C36) (C36, immunopathogenic but without associated neurologic disease), and Pcenv (a chimeric virus consisting of a PPR backbone with substituted C36 env region). A sham inoculum control group was also included. Peripheral nerve conduction velocity, CNS imaging studies, viral loads and hematologic analysis were performed over a 12 month period. At termination of the study (350 days post-inoculation), brain sections were obtained from four anatomic locations known to be involved in human and primate lentiviral neuroAIDS. Histological and immunohistochemical evaluation with seven markers of inflammation revealed that Pcenv infection resulted in mild inflammation of the CNS, microglial activation, neuronal degeneration and apoptosis, while C36 and PPR strains induced minimal neuropathologic changes. Conduction velocity aberrations were noted peripherally in all three groups at 63 weeks post-infection. Pcenv viral load in this study was intermediate to the parental strains (C36 demonstrating the highest viral load and PPR the lowest). These results collectively suggest that (i) 3' C36 genomic elements contribute to viral replication characteristics, and (ii) 5' PPR genomic elements contribute to CNS manifestations. This study illustrates the potential for FIV to provide valuable information about neuroAIDS pathogenesis related to genotype and viral kinetics, as well as to identify strains useful to evaluation of therapeutic intervention.

Biochemical modulation of the sleep-wake cycle: endogenous sleep-inducing factors.

Regulation of the sleep-wake cycle involves diverse brain circuits and molecules. Further complexity has been introduced by the recognition of sleep-promoting factors that accumulate in the brain naturally or during prolonged waking. The variety of sleep-inducing molecules includes peptides, cytokines, and lipids. With regard to the lipids, current evidence indicates the existence of endogenous lipids, called endocannabinoids, that mimic the pharmacological actions of the psychoactive ingredient of marijuana and that are likely to be essential factors in sleep promotion. This Mini-Review presents current knowledge concerning the role of endogenous compounds with sleep-promoting properties.

Chronic alcohol consumption impairs visuo-spatial associative memory in periadolescent rhesus monkeys.

UNLABELLED: Alcohol abuse in the adult is often preceded by high alcohol consumption during adolescence. Profound changes in brain structure and function occur during this developmental period, therefore alcohol may impact essential cognitive skill development during the formal educational years. The objective of this study was to determine if chronic oral alcohol intake slows acquisition and performance of cognitive tasks in male adolescent rhesus monkeys. Treatment groups (Alcohol, N=4; Control, N=3) were evaluated on bimanual dexterity and tests of visuo-spatial memory and learning adapted from the Cambridge Neuropsychological Test Automated Battery. Animals were trained daily in 30 min sessions and had subsequent access to alcohol/Tang® solutions (Alcohol group) or Tang® only (Control group) Monday through Friday for 11 months. Recordings of brainstem auditory evoked potentials (BSAEP) were conducted periodically before and during the chronic drinking. RESULTS: Chronic alcohol drinking (ave of 1.78 g/kg alcohol per session) impaired behavioral performance assessed ∼22 h after the prior drinking session. The Alcohol group required more trials than the Control group to reach criterion on the visuo-spatial memory task and showed increased sensitivity to trial difficulty and retention interval. Alcohol animals also had slowed initial acquisition of the bimanual task. The latency of P4 and P5 BSAEP peaks were also delayed in the Alcohol group. Chronic alcohol consumption impaired the acquisition and performance of a spatial memory task and disrupted brainstem auditory processing, thus these results show that repeated alcohol exposure in adolescence interferes with a range of brain functions including complex visuo-spatial mnemonic processing.

Methamphetamine and lentivirus interactions: reciprocal enhancement of central nervous system disease.

Use of methamphetamine is increasingly a significant factor for the spread of human immunodeficiency virus type 1, for in certain populations, there is a convergence of methamphetamine abuse with human immunodeficiency virus type 1 infection. Methamphetamine and human immunodeficiency virus type 1 are both individually neuropathogenic, and the neuropathology caused by these two agents occurs in overlapping brain regions. However, the biological interaction of methamphetamine with lentiviruses remains unknown. Here, we investigate the effects of simultaneous exposure of these two agents on disease progression using the feline immunodeficiency virus model. The study models the bingeing methamphetamine user with sequential and repeated episodes of use, which were interrupted by periods of abstinence. Methamphetamine exposure significantly accelerated and enhanced the severity of the feline immunodeficiency virus model-induced central nervous system functional pathology, as measured in delays in brainstem auditory evoked potentials. Reciprocally, feline immunodeficiency virus enhanced the severity of the methamphetamine-induced effects on brain monoamine neurotransmitter and dopamine transporter levels. The results of this study indicate that a dual potentiation occurred. That is, methamphetamine enhanced feline immunodeficiency virus model-induced central nervous system disease and feline immunodeficiency virus model enhanced the toxic effects of methamphetamine, heralding a significant concern for those individuals that are exposed to both agents.

Neuropeptide S reinstates cocaine-seeking behavior and increases locomotor activity through corticotropin-releasing factor receptor 1 in mice.

Neuropeptide S (NPS) is a recently discovered neuropeptide that increases arousal and wakefulness while decreasing anxiety-like behavior. Here, we used a self-administration paradigm to demonstrate that intracerebroventricular infusion of NPS reinstates extinguished cocaine-seeking behavior in a dose-dependent manner in mice. The highest dose of NPS (0.45 nM) increased active lever pressing in the absence of cocaine to levels that were equivalent to those observed during self-administration. In addition, we examined the role of the corticotropin-releasing factor receptor 1 (CRF(1)) in this behavior as well as locomotor stimulation and anxiolysis. CRF(1) knock-out mice did not respond to either the locomotor stimulant or cocaine reinstatement effects of NPS, but still responded to its anxiolytic effect. The CRF(1) antagonist antalarmin also blocked the increase in active lever responding in the reinstatement model and the locomotor activating properties of NPS without affecting its anxiolytic actions. Our results suggest that NPS receptors may be an important target for drug abuse research and treatment and that CRF(1) mediates the cocaine-seeking and locomotor stimulant effects of NPS, but not its effects on anxiety-like behavior.

Effects of simian immunodeficiency virus on the circadian rhythms of body temperature and gross locomotor activity.

In monkeys infected with simian immunodeficiency virus (SIV), changes in body temperature and locomotor activity occur after the acute retroviral syndrome stage of the disease. However, alterations to the circadian rhythm of these factors in SIV-infected monkeys have not been reported. To determine whether the circadian rhythm of body temperature and locomotor activity are disrupted during SIV infection, we analyzed the temperature and activity patterns of SIV-infected monkeys through different stages of the disease, progressing to SIV encephalitis by using the cosinor model for circadian oscillation. We found that SIV infection resulted in significant impairments of the amplitude and mean of the circadian rhythm of body temperature and activity and in the acrophase of the circadian rhythm for temperature. These alterations were not related to changes observed in the acute febrile response induced after viral inoculation. In animals killed once marked circadian anomalies were evident, microglia infiltration and macrophage accumulation in the hypothalamus were observed. Together, these results clearly demonstrate that SIV infection compromises aspects of circadian regulation in monkeys, with important implications for physiological functions, including cognition, in HIV-infected individuals.

Cortistatin promotes and negatively correlates with slow-wave sleep.

Sleep need is characterized by the level of slow-wave activity (SWA) and increases with time spent awake. The molecular nature of this sleep homeostatic process is practically unknown. Here, we show that intracerebroventricular administration of the neuropeptide, cortistatin (CST-14), enhances EEG synchronization by selectively promoting deep slow-wave sleep (SWS) during both the light and dark period in rats. CST-14 also increases the level of slow-wave activity (SWA) within deep SWS during the first two hours following CST-14 administration. Steady-state levels of preprocortistatin mRNA oscillate during the light:dark cycle and are four-fold higher upon total 24-h sleep deprivation, returning progressively to normal levels after eight hours of sleep recovery. Preprocortistatin mRNA is expressed upon sleep deprivation in a particular subset of cortical interneurons that colocalize with c-fos. In contrast, the number of CST-positive cells coexpressing pERK1/2 decreases under sleep deprivation. The capacity of CST-14 to increase SWA, together with preprocortistatin's inverse correlation with time spent in SWS, suggests a potential role in sleep homeostatic processes.