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Dopaminergic role in stimulant-induced wakefulness.

The role of dopamine in sleep regulation and in mediating the effects of wake-promoting therapeutics is controversial. In this study, polygraphic recordings and caudate microdialysate dopamine measurements in narcoleptic dogs revealed that the wake-promoting antinarcoleptic compounds modafinil and amphetamine increase extracellular dopamine in a hypocretin receptor 2-independent manner. In mice, deletion of the dopamine transporter (DAT) gene reduced non-rapid eye movement sleep time and increased wakefulness consolidation independently from locomotor effects. DAT knock-out mice were also unresponsive to the normally robust wake-promoting action of modafinil, methamphetamine, and the selective DAT blocker GBR12909 but were hypersensitive to the wake-promoting effects of caffeine. Thus, dopamine transporters play an important role in sleep regulation and are necessary for the specific wake-promoting action of amphetamines and modafinil.

Amphetamine↗

Bias in magnitude estimation following left hemisphere injury.

There is a growing interest both in identifying the neural mechanisms of magnitude estimation and in identifying forms of bias that can explain aspects of behavioral syndromes like unilateral neglect. Magnitude estimation is associated with activation of temporo-parietal cortex in both cerebral hemispheres of normal subjects; however, it is unclear if and how left hemisphere lesions bias magnitude estimation because the infrequency of neglect and the presence of aphasia in these subjects confound examination. In contrast, we examined magnitude estimation using 12 different types of sensory stimuli that spanned five sensory domains in two patients with very different clinical presentations following unilateral left hemisphere stroke. One patient had neglect sub-acutely without aphasia. The other had aphasia chronically after a temporo-parietal lesion but not neglect. The neglect patient was re-examined 48 h after being treated with modafinil (Provigil) for decreased arousal. Both patients demonstrated bias in magnitude estimation relative to normal subjects (n=83). Alertness improved in the neglect patient after taking modafinil. His neglect also resolved and his magnitude estimates more closely resembled those of normal subjects. This is the first evidence, to our knowledge, that left hemisphere injury can bias magnitude estimation in a manner similar but not identical to that associated with right hemisphere injury.

Adult↗

Sleep latency on the maintenance of wakefulness test (MWT) for 530 patients with narcolepsy while free of psychoactive drugs.

OBJECTIVES: To compare maintenance of wakefulness test (MWT) data gathered at baseline in the course of two, multicenter studies on the therapeutic efficacy of modafinil with published MWT norms. METHODS: The MWT is a procedure that uses electrophysiological measures to determine the ability to remain awake while sitting in a quiet, darkened room. The test consists of 4 20 min trials conducted 4 times at 2 h intervals commencing 2 h after awakening from a night of sleep. MWT data were gathered at baseline in the course of two, multicenter studies on the therapeutic efficacy of modafinil. Subjects were 17-68 year old men (n = 239) and women (n = 291) diagnosed with narcolepsy according to the International Classification of Sleep Disorders (ICSD). All patients were free of psychoactive medication for a minimum of 14 days. RESULTS: Mean MWT sleep latency was 6.0 +/- 4.8 min. However, the mean for the first MWT trial was 7.0 min which was longer that the means for the following 3 trials (5.8, 5.6 and 5.7 min, respectively). The 4 distributions of the individual MWT trials were similar and adequately summarized by the distribution of the average MWT sleep latency. As a group, patients with narcolepsy were less able to remain awake than normals; only 8 of 530 (1.5%) patients were able to remain awake on 4 20 min MWT trials compared with 35 of 64 (54.7%) normals in another study. However, using a mean MWT sleep latency of 12 min (the 5th percentile for normals) as the lowest cut-point for normalcy, 15% of patients with narcolepsy appeared to have an unimpaired ability to remain awake. CONCLUSIONS: The diagnosis of narcolepsy did not always predict inability to remain awake on the MWT. Age, gender and the duration of illness did not predict ability to remain awake. Patients with severe cataplexy and other ancillary symptoms were least able to remain awake on MWT trials. Patients who used tobacco and caffeine moderately had the lowest MWT sleep latencies relative to patients with heavy and light use.

Adolescent↗

Changes in EEG spectral power in the prefrontal cortex of conscious rats elicited by drugs interacting with dopaminergic and noradrenergic transmission.

1. The electroencephalographic (EEG) effects of drugs interacting with dopaminergic and noradrenergic systems were studied in conscious rats. Power spectra (0 - 30 Hz) were recorded from electrodes implanted bilaterally in the prefrontal cortex. Drug effects on EEG power were calculated as the spectral power following drug administration divided by the spectral power after vehicle administration. 2. Dopaminergic agonists at low doses, (apomorphine 0. 01 mg kg-1 s.c., quinpirole 0.01 mg kg-1 i.p.) and dopaminergic antagonists (haloperidol 1 mg kg-1 i.p., raclopride 2.5 mg kg-1 s.c. ), which decrease dopaminergic transmission, induced an increase of EEG power. Conversely, dopaminergic agonists at higher doses (apomorphine 0.5 mg kg-1 s.c., quinpirole 0.5 mg kg-1 i.p.) which increase activation of postsynaptic D2 and D3 receptors, induced a decrease of EEG power. 3. The alpha1-adrenoceptor antagonists (phenoxybenzamine 0.64 mg kg-1 s.c., prazosin 0.32 mg kg-1 s.c.) and the alpha2-adrenoceptor agonists (UK 14304 0.05 mg kg-1 s.c., clonidine 0.025 mg kg-1 i.p.), which decrease noradrenergic transmission, induced an increase of EEG power. Conversely, the alpha1-adrenoceptor agonist, cirazoline (0.05 mg kg-1 s.c.), the adrenergic agent modafinil (250, 350 mg kg-1 i.p.) and alpha2-adrenoceptor antagonists (RX 821002 0.01 mg kg-1 s.c., yohimbine 0.5 mg kg-1 i.p.), which increase noradrenergic transmission, induced a decrease of EEG power. The effects of prazosin (0.64 mg kg-1 s.c.) were dose-dependently antagonized by co-administration with modafinil and cirazoline, but not by apomorphine. 4. In conclusion, pharmacological modulation of dopaminergic and noradrenergic transmission may result in consistent EEG changes: decreased dopaminergic or noradrenergic activity induces an increase of EEG spectral power; while increased dopaminergic or noradrenergic activity decreases EEG spectral power.

Adrenergic Agents↗

Paradoxical sleep deprivation increases the content of glutamate and glutamine in rat cerebral cortex.

We investigated the influence of the sleep/waking cycle, the effects of paradoxical sleep deprivation (PSD) and of the vigilance-promoting drug modafinil on the amino acid contents of rat brain cortex. No significant nycthemeral variations in amino acid levels could be detected. PSD (12-24 hours), using the water tank method, significantly increased the levels of glutamate and glutamine. The increase was still observed after the sleep rebound period. gamma-Aminobutyric acid (GABA) levels did not change significantly during the instrumental sleep deprivation but increased during the rebound period. Control experiments indicate that the increase in glutamate and glutamine levels is due to PSD rather than to the stress associated with the experimental procedure. The increase in glutamate content cannot arise only from transamination reactions, because the levels of other amino acids (such as aspartate) did not decrease. Modafinil treatment did not significantly modify the brain cortex content of any of the amino acids tested.

Animals↗

The preoptic hypothalamus and basal forebrain play opposing roles in the descending modulation of sleep and wakefulness in infant rats.

Recent findings in infant rats suggest that the preoptic area (POA) and/or basal forebrain (BF) contribute to developmental changes in sleep and wake organization between postnatal day 2 (P2) and P9. To examine the contributions of these forebrain areas to sleep and wakefulness, separate lesions of the POA or BF, or combined lesions (POA + BF), were performed at P9, and precollicular transections were performed at P2. In addition, modafinil, a drug of unknown mechanism of action the effects of which on sleep and wakefulness have been hypothesized to result from inhibition of POA activity, was administered at P2 and P9. Finally, extracellular neuronal activity was recorded from the POA and BF. POA lesions decreased sleep bout durations and increased wake bout durations. BF lesions inhibited sleep bout durations to a lesser extent, while leaving wake bout durations unaffected. POA + BF lesions produced a combination of these effects, resulting in short bouts of sleep and wakefulness similar to those of transected P8 rats. Even at P2, transections decreased sleep bout durations. The finding, however, that the sleep-inhibiting and wake-promoting effects of modafinil were more potent at P9 than at P2 suggests increasing sleep-wake modulation by the POA between these two ages. Finally, neuronal recordings confirmed the presence of state-dependent neurons within the infant POA and BF. We propose that the POA, in addition to promoting sleep, inhibits wakefulness via direct and indirect inhibitory connections with wake-promoting neurons in the BF, and that this inhibitory influence increases across early development.

Animals↗

Management of fatigue in patients with multiple sclerosis.

As long as no causal treatment is available for multiple sclerosis (MS), and as long as only some patients with MS respond to immunomodulators, symptomatic treatment is of paramount importance. Fatigue is the most common symptom of MS and is associated with a reduced quality of life. It is described as the worst symptom of their disease by 50-60% of patients. The first step in managing MS-related fatigue is identifying and eliminating any secondary causes. Primary fatigue syndrome can be alleviated with drug treatment in many cases. Modafinil has been shown to be effective in some studies, and amantadine is an alternative for patients who do not respond to or cannot tolerate modafinil. The nonpharmacological management of fatigue in MS includes inpatient rehabilitation and aerobic endurance exercise. This article describes the pathophysiology, diagnosis and treatment of MS-related fatigue--the most common symptom of MS.

Amantadine↗

Shift work sleep disorder: burden of illness and approaches to management.

More than 6 million Americans work night shifts on a regular or rotating basis. The negative consequences of shift work have been established, and recent evidence suggests that patients with shift work sleep disorder (SWSD) are at increased risk of these consequences and co-morbidities. SWSD is a relatively common but under-recognised, and hence undertreated, condition with potentially serious medical, social, economic and quality-of-life consequences. In addition to increased risk of gastrointestinal and cardiovascular disease, patients with SWSD experience clinically significant excessive sleepiness or insomnia associated with work during normal sleep times, which has important safety implications. A number of studies have evaluated countermeasures or interventions in shift workers; proposed treatments include chronobiotic interventions, such as light exposure, melatonin, hypnotic agents, caffeine and CNS stimulants (amphetamine), and the wake-promoting agents modafinil and armodafinil. However, most studies evaluating pharmacological therapies and nonpharmacological interventions simulate night-shift work under conditions that may not accurately reflect real-world activities. Pharmacological and nonpharmacological countermeasures evaluated mostly in simulated laboratory conditions have been shown to improve alertness or sleep in shift workers but have not yet been evaluated in patients with SWSD. To date, three randomised, double-blind clinical studies have evaluated pharmacological therapies in patients with SWSD. These studies showed that modafinil and armodafinil significantly improve the ability to sustain wakefulness during waking activities (e.g. working, driving), overall clinical condition, and sustained attention or memory in patients with SWSD. In conclusion, SWSD is a common condition that remains under-recognised and undertreated. Further research is needed to evaluate different treatment approaches for this condition, to clarify the substantial health and economic consequences of SWSD, and to determine the potential for interventions or treatments to reduce the negative consequences of this condition.

Benzhydryl Compounds↗

Alertness-enhancing drugs as a countermeasure to fatigue in irregular work hours.

Irregular work/rest patterns frequently cause disturbed sleep and excessive sleepiness and accidents. This review is focused on four pharmacological countermeasures-the "new" drugs modafinil and pemoline, the traditional caffeine, and, as a reference, amphetamine. It is concluded that there is still too little data available to decide whether systematic use of alertness-enhancing drugs is feasible in occupational settings. D-Amphetamine is ruled out because of its abuse potential and mood effects. Modafinil and pemoline have not been tested in field situations, whereas caffeine certainly is used to improve alertness during work, but the use is spontaneous/ad hoc, and there is still a lack of data on its systematic application. Particularly, the optimal amount and pattern of administration need elucidation.

Amphetamine↗

Histamine H3 receptor antagonists: from target identification to drug leads.

The successful cloning and functional expression of the histamine H(3) receptor in the late 1990 s has greatly facilitated our efforts to identify small molecule, non-imidazole based compounds to permit the evaluation of H(3) antagonists in models of CNS disorders. High-throughput screening identified several series of lead compounds, including a series of imidazopyridines, which led to JNJ-6379490, a compound with high affinity for the human H(3) receptor. Analysis of structural features common to several series of non-imidazole H(3) receptor ligands resulted in a pharmacophore model. This model led to the design of JNJ-5207852, a diamine-based H(3) antagonist with good in vitro and in vivo efficacy but with an undesirable long half-life. However, further modifications of the template provided an understanding of the effect of structural modifications on pharmacokinetic properties, ultimately affording several additional series of compounds including JNJ-10181457, a compound with an improved pharmacokinetic profile. These compounds allowed in vivo pharmacological evaluation to show that H(3) antagonists promote wakefulness, but unlike modafinil and classical psychostimultants, they do not increase locomotor activity or produce any alteration of the EEG power spectral activity in rats. H(3) antagonists also increase extracellular acetylcholine and norepinephrine but not dopamine in rat frontal cortex and show efficacy in various models of learning-memory deficit. In addition, cFos immunoreactivity studies show H(3) antagonists activate neuronal cells in restricted rat brain regions in contrast to widespread activation after modafinil or amphetamine treatment. Therefore, H(3) antagonists are promising clinical candidates for the treatment of excessive day time sleepiness and/or cognitive disorders.

Animals↗

Sleep and brain lesions: a critical review of the literature and additional new cases.

We present a comprehensive review of sleep studies performed in patients with brain lesions complemented by 16 additional personal selected cases and by discussion of the corresponding animal data. The reader is cautioned about the risk of establishing an erroneous correlation between abnormal sleep and a given disorder due to the important inter and intra variability of sleep parameters among individuals. Salient points are stressed: the high frequency of post-stroke sleep breathing disorders is becoming increasingly recognised and may, in the near future, change the way this condition is managed. Meso-diencephalic bilateral infarcts induce a variable degree of damage to both waking and non-REM sleep networks producing and abnormal waking and sometimes a stage 1 hypersomnia reduced by modafinil or bromocriptine, which can be considered as a syndrome of cathecholaminergic deficiency. Central pontine lesions induce REM and non-REM sleep insomnia with bilateral lateral gaze paralysis. Bulbar stroke leads to frequent sleep breathing disorders. Polysomnography can help define the extent of involvement of various degenerative diseases. Fragmented sleep in Parkinson's disease may be preceded by REM sleep behavioural disorders. Multiple system atrophies are characterised by important sleep disorganization. Sleep waking disorganization and a specific ocular REM pattern are often seen in supra-nuclear ophtalmoplegia. In Alzheimer patients, sleep perturbations parallel the mental deterioration and are possibly related to cholinergic deficiency. Fronto-temporal dementia may be associated with an important decrease in REM sleep. Few narcoleptic syndromes are reported to be associated with a tumour of the third ventricle or a multiple sclerosis or to follow a brain trauma; all these cases raise the question whether this is a simple coincidence, a revelation of a latent narcolepsy or, as in non-DR16/DQ5 patients, a genuine symptomatic narcolepsy. Trypanosomiasis and the abnormal prion protein precociously after sleep patterns. Polysomnography is a precious tool for evaluating brain function provided it is realised under optimal conditions in stable patients and interpreted with caution. Several unpublished cases are presented: one case of pseudohypersomnia due to a bilateral thalamic infarct and corrected by modafinil, four probable late-onset autosomal recessive cerebellar ataxias without sleep pattern anomalies, six cases of fronto-temporal dementia with strong reduction in total sleep time and REMS percentage on the first polysomnographic night, one case of periodic hypersomnia associated with a Rathke's cleft cyst and four cases of suspected symptomatic narcolepsy with a DR16-DQ5 haplotype, three of which were post-traumatic without MRI anomalies, and one associated with multiple sclerosis exhibiting pontine hyper signals on MRI.

Animals↗

The SK-N-MC cell line expresses an orexin binding site different from recombinant orexin 1-type receptor.

Orexin A and B (also known as hypocretins), two recently discovered neuropeptides, play an important role in food intake, sleep/wake cycle and neuroendocrine functions. Orexins are endogenous ligands of two G-protein-coupled receptors, termed OX1 and OX2. This work presents the first short orexin A and B analogues, orexin A 23-33 and orexin B 18-28, with high affinity (119 +/- 49 and 49 +/- 23 nm) for OX1 receptors expressed on SK-N-MC cells and indicates the importance of the C-terminal part of the orexin peptides for this ligand-receptor interaction. However, these C-terminal fragments of orexin did not displace the 125I-labelled orexin B from the recombinant orexin 1 receptor stably expressed in Chinese hamster ovary cells. To examine the role of the shortened orexin A 23-33 in feeding, its effects in mimicking or antagonizing the effects of orexin A were studied in rats after administration via the lateral hypothalamus. In contrast with orexin A, which potently induced feeding up to 4 h after administration, orexin A 23-33 neither induced feeding nor inhibited orexin A-induced feeding. Modafinil (Vigil), which was shown earlier to activate orexin neurons, displayed binding neither to the orexin receptor expressed on SK-N-MC cells nor to the recombinant orexin 1 receptor, which indicates that modafinil displays its antinarcoleptic action via another yet unknown mechanism. PCR and subsequent sequencing revealed expression of the full-length orexin 1 receptor mRNA in SK-N-MC and NT-2 cells. Interestingly, sequencing of several cDNA clones derived from RNA of both SK-N-MC and NT-2 cells differed from the published nucleotide sequence at position 1375. Amino acid prediction of this A -->G change results in an isoleucine --> valine substitution at the protein level, which may provide evidence for an editing process.

Amino Acid Sequence↗

Pharmacotherapy and other treatments for cocaine abuse and dependence.

PURPOSE OF REVIEW: This review examines progress being made in the treatment of cocaine abuse and dependence, with a particular focus on pharmacotherapies. Medications with apparently very different mechanisms of action have been reported to reduce cocaine use in controlled clinical trials in outpatient settings. This review will summarize the latest findings in this area. RECENT FINDINGS: Of all the medications tested to date, disulfiram has demonstrated the most consistent effect to reduce cocaine use. Several medications have been reported to reduce cocaine use in double-blind, placebo-controlled clinical trials, namely baclofen, modafinil, tiagabine, and topiramate. All pharmacotherapy trials in cocaine-dependent patients include a behavioral therapy that is common to all participants. Consequently, these pharmacotherapy trials can be considered to evaluate whether the medication is adding to the effect of the behavioral therapy. SUMMARY: Confirmatory clinical studies are necessary to replicate the initial efficacy findings for baclofen, modafinil, tiagabine, and topiramate. More research is needed in both cocaine and cocaine-alcohol dependent populations. Once confirmatory studies have been carried out, testing of rational medication combinations with different behavioral therapies is an obvious next step to increase the ability to manage cocaine dependence.

Journal Article↗

Benefits and risks of pharmacotherapy for narcolepsy.

Narcolepsy is a life-long central nervous system (CNS) syndrome characterised by excessive sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations and disturbed night-time sleep. Unsuccessfully treated narcolepsy confers increased risks on patients and on society due to the patient's increased chance of becoming involved in vehicle crashes and workplace mishaps. The syndrome may be diagnosed by a clinical history positive for cataplexy and excessive daytime sleepiness and negative for other more common sleep disorders such as sleep apnoea and sleep deprivation. Night-time polysomnography and multiple sleep latency testing are helpful in differentiating narcolepsy from other sleep problems. Recent data from canine, murine, and human forms of narcolepsy indicate that genetically or developmentally mediated deficits in the hypocretin neurotransmitter system may cause some, but not all, forms of narcolepsy. Pharmacotherapy for narcolepsy is required to control symptoms and involves the use of CNS stimulants or modafinil to control sleepiness and antidepressant medications or sodium oxybate to control cataplexy. Modafinil and sodium oxybate have been developed and approved specifically for the indication of narcolepsy based on large, double-blind, placebo-controlled, parallel group efficacy and safety studies. The efficacy of drugs in the treatment of narcolepsy is variable from patient to patient and usually associated with adverse effects that can limit patient compliance and, therefore, symptom control. Nevertheless, the benefits of pharmacotherapy are judged to outweigh the risks to the patient. The favourable benefit-risk ratio of pharmacotherapy is greater if one considers the reduced risk to society of vehicle crashes and workplace mishaps that might be precipitated by attentional lapses or sleep attacks in the untreated or under-treated patient with narcolepsy.

Animals↗

Increased dopaminergic transmission mediates the wake-promoting effects of CNS stimulants.

Amphetamine-like stimulants are commonly used to treat sleepiness in narcolepsy. These compounds have little effect on rapid eye movement (REM) sleep-related symptoms such as cataplexy, and antidepressants (monoamine uptake inhibitors) are usually required to treat these symptoms. Although amphetamine-like stimulants and antidepressants enhance monoaminergic transmission, these compounds are non-selective for each monoamine, and the exact mechanisms mediating how these compounds induce wakefulness and modulate REM sleep are not known. In order to evaluate the relative importance of dopaminergic and noradrenergic transmission in the mediation of these effects, five dopamine (DA) uptake inhibitors (mazindol, GBR-12909, bupropion, nomifensine and amineptine), two norepinephrine (NE) uptake inhibitors (nisoxetine and desipramine), d-amphetamine, and modafinil, a non-amphetamine stimulant, were tested in control and narcoleptic canines. All stimulants and dopaminergic uptake inhibitors were found to dose-dependently increase wakefulness in control and narcoleptic animals. The in vivo potencies of DA uptake inhibitors and modafinil on wake significantly correlated with their in vitro affinities to the DA and not the NE transporter. DA uptake inhibitors also moderately reduced REM sleep, but this effect was most likely secondary to slow wave sleep (SWS) suppression, since selective DA uptake inhibitors reduced both REM sleep and SWS proportionally. In contrast, selective NE uptake inhibitors had little effect on wakefulness, but potently reduced REM sleep. These results suggest that presynaptic activation of DA transmission is critical for the pharmacological control of wakefulness, while that of the NE system is critical for REM sleep regulation. Our results also suggest that presynaptic activation of DA transmission is a key pharmacological property mediating the wake-promoting effects of currently available CNS stimulants.

Animals↗

[Wake disorders. I. Primary wake disorders].

Primary wake disorders encompass various conditions of excessive daytime sleepiness and/or increased nighttime sleep, of unknown origin beginning most often in adolescence and of chronic or recurrent natural history. The best known of these conditions is narcolepsy associating two major clinical features, irresistible episodes of sleep, sleep onset REM periods and an almost constant association with HLA DR2-DQ1. The prevalence of the condition is close to the one of multiple sclerosis but positive diagnosis requires most often over 10 years to be made. The treatment of excessive daytime sleepiness has recently benefited from a new non-amphetamine awakening compound, modafinil, active in 60 to 70 p. 100 of the cases. The treatment of cataplexy still relies on antidepressants, tricyclics or selective serotonin reuptake blockers. Major advances in pathophysiology and pathogeny have been obtained through a natural model of the disease, canine narcolepsy. Pharmacological studies point to the importance of alpha-1 b adrenergic mechanisms in cataplexy, while dopaminergic systems seem more involved in excessive daytime sleepiness. As concerns genetics, the HLA DQB1*0602 gene predisposes to narcolepsy. In the canine model it is mirrored by an autosomal recessive gene showing a strong homology with the human immunoglobulin gene mu-switch. Familial studies have shown that besides typical phenotypes, attenuated forms of the condition characterized by isolated recurrent daytime naps and/or lapses into sleep do exist. In addition one or several other genes may be involved. Narcolepsy is multifactorial, including one or several genes as well as environmental factors. Idiopathic hypersomnia is noted for very long night sleep, difficulty waking up and more or less constant excessive daytime sleepiness. In contrast with narcolepsy sleep in not refreshing. There is no polysomnographic or immunogenetic special feature. Idiopathic hypersomnia is 10 times less frequent than narcolepsy. It is often overdiagnosed due to insufficient knowledge of other causes of excessive daytime sleepiness such as the upper airway resistance syndrome. Modafinil is also of great value in the treatment of idiopathic hypersomnia. In the absence of an animal model, pathophysiology and pathogeny are still poorly understood. Even rarer is the Kleine-Levin syndrome which is easily distinguishable through its recurrent character and its tendency to progressively disappear. It mainly occurs in early adolescent males. Its main features are episodes of sleep of a week duration recurring at a several months' interval along with disturbances of alimentary and sexual behavior. There is no satisfactory treatment of hypersomniac episodes. On the other hand a prophylactic treatment with carbamazepine or lithium may be active. Pathophysiology remains unsettled in spite of some evidence of a hypothalamic functional disturbance.

Animals↗

Management of methamphetamine abuse and dependence.

Preliminary implications for evidence-based treatments and future practice may be drawn from new research findings that inspire a fresh view of methamphetamine dependence and associated medical consequences. Current user populations include increasingly impacted subgroups (ie, youths, women, men who have sex with men, and rural residents); complex consequences of methamphetamine abuse among these subgroups require additional efforts involving contextual understanding of characteristics and needs to develop effective treatments. The neurobiological data on cellular activity of methamphetamine taken with findings from neuroimaging studies indicate potential targets for pharmacologic interventions. In early trials, several candidate medications--bupropion, modafinil, and, to a lesser extent, baclofen--have shown promise in treating aspects of methamphetamine dependence, including aiding memory function necessary to more effectively participate in and benefit from behavioral therapies. Clinicians and researchers must interact to efficiently address the problems of methamphetamine dependence, a major drug problem in the United States and the world.

Baclofen↗

Altered sleep latency and arousal regulation in mice lacking norepinephrine.

Latency to sleep and the amount of sensory stimulation required to awaken an animal are measures of arousal threshold, which are ultimately modulated by an arousal regulation system involving many brain areas. Among these brain areas and network connections are wake-promoting nuclei of the brainstem and their corresponding neurotransmitters, including norepinephrine (NE). In this study, we used mice that are unable to produce NE to study its role in regulating sleep latency after a variety of interventions, and to study arousal from sleep after sleep deprivation (SD). Sleep latency was measured after gentle awakening or after injections of saline, caffeine or modafinil. Sleep latency was also measured before and after partial restoration of NE pharmacologically. Arousal threshold was measured by recording the number of decibels of white noise required to wake each mouse from NREM sleep after 0, 3 and 3 + 3 h SD (3 h SD followed by < 2 min sleep, followed by an additional 3 h SD). Results showed that when mice were awakened without being touched, there were no differences in sleep latency between the genotypes. However, after an injection of saline, the control mice increased their sleep latency, whereas the NE-deficient mice did not. There were no group differences in sleep latency after treatment with either stimulant. The sleep latency difference between the genotypes was ameliorated by partial restoration of NE. The arousal threshold experiments revealed that significantly more noise was required to wake the NE-deficient mice after 3 and 3 + 3 h of SD. These findings show that mice lacking NE fall asleep more rapidly only after a mild stressor, such as an intraperitoneal injection. NE-deficient mice are also more difficult to wake up using audio stimulation after SD. The results presented here suggest that NE promotes wakefulness during transitions between sleep and wake under conditions involving mild stress and SD, but not under baseline circumstances.

Amphetamine↗