Armodafinil promotes wakefulness and activates Fos in rat brain

Insomnia-related rodent models in drug discovery

Despite the widespread prevalence and important medical impact of insomnia, effective agents with few side effects are lacking in clinics. This is most likely due to relatively poor understanding of the etiology and pathophysiology of insomnia, and the lack of appropriate animal models for screening new compounds. As the main homeostatic, circadian, and neurochemical modulations of sleep remain essentially similar between humans and rodents, rodent models are often used to elucidate the mechanisms of insomnia and to develop novel therapeutic targets. In this article, we focus on several rodent models of insomnia induced by stress, diseases, drugs, disruption of the circadian clock, and other means such as genetic manipulation of specific neuronal activity, respectively, which could be used to screen for novel hypnotics. Moreover, important advantages and constraints of some animal models are discussed. Finally, this review highlights that the rodent models of insomnia may play a crucial role in novel drug development to optimize the management of insomnia.

Armodafinil as a Potential Pharmacological Treatment for Attention Deficit Hyperactivity Disorder in Adults: A Review

INTRODUCTION

Armodafinil is a psychostimulant that promotes alertness, and it has been shown to improve attention, memory, and fatigue in healthy adults and adults with neurodevelopmental conditions that share symptoms with Attention Deficit Hyperactivity Disorder (ADHD). It is generally well tolerated and safe, and most of the adverse events reported are considered not serious. However, the available evidence on the efficacy of armodafinil for the treatment of ADHD in adults is scarce.

OBJECTIVE

The present review aims to perform a systematized search of the available evidence on the possible therapeutic benefit of armodafinil treatment in adult patients with ADHD.

METHODS

A literature review using PubMed was conducted to compile and summarize the available clinical and scientific evidence on the possible use of armodafinil as a pharmacological treatment in adult patients with ADHD.

RESULTS

From the 86 articles reviewed, the available evidence showed that both acute and chronic treatment with armodafinil can improve wakefulness, memory, impulse control, and executive functions in adults with sleep disorders and other conditions. In addition, evidence of improvement in cognitive functions and mood alterations in other neuropsychiatric conditions was shown.

CONCLUSION

Armodafinil could be useful for the treatment of ADHD in adults, according to the review of the literature from both pre-clinical and clinical studies.

Synthesis of Metal-Free Chiral Covalent Organic Framework for Visible-Light-Mediated Enantioselective Photooxidation in Water

Although chiral covalent organic frameworks (CCOFs) presence grows in thermal asymmetric catalysis, their application in equally important asymmetric photocatalysis has yet to begin. Herein, we first report a propargylamine-linked and quaternary ammonium bromide decorated porphyrin-CCOF which can highly promote visible-light-driven enantioselective photooxidation of sulfides to sulfoxides in water and in air. This methodology has also been applied to the synthesis of (R)-modafinil, a wakefulness-promoting medication used for the treatment of excessive sleepiness. This research might open a new way for the application of CCOFs in asymmetric photocatalysis.

Activation of the GABAergic Parafacial Zone Maintains Sleep and Counteracts the Wake-Promoting Action of the Psychostimulants Armodafinil and Caffeine

We previously reported that acute and selective activation of GABA-releasing parafacial zone (PZVgat) neurons in behaving mice produces slow-wave-sleep (SWS), even in the absence of sleep deficit, suggesting that these neurons may represent, at least in part, a key cellular substrate underlying sleep drive. It remains, however, to be determined if PZVgat neurons actively maintain, as oppose to simply gate, SWS. To begin to experimentally address this knowledge gap, we asked whether activation of PZVgat neurons could attenuate or block the wake-promoting effects of two widely used wake-promoting psychostimulants, armodafinil or caffeine. We found that activation of PZVgat neurons completely blocked the behavioral and electrocortical wake-promoting action of armodafinil. In some contrast, activation of PZVgat neurons inhibited the behavioral, but not electrocortical, arousal response to caffeine. These results suggest that: (1) PZVgat neurons actively maintain, as oppose to simply gate, SWS and cortical slow-wave-activity; (2) armodafinil cannot exert its wake-promoting effects when PZVgat neurons are activated, intimating a possible shared circuit/molecular basis for mechanism of action; (3) caffeine can continue to exert potent cortical desynchronizing, but not behavioral, effects when PZVgat neurons are activated, inferring a shared and divergent circuit/molecular basis for mechanism of action; and 4) PZVgat neurons represent a key cell population for SWS induction and maintenance.

Differential effects of environment-induced changes in body temperature on modafinil's actions against methamphetamine-induced striatal toxicity in mice

Methamphetamine (METH) exposure can produce hyperthermia that might lead to toxicity and death. Modafinil is a wake-promoting compound that is also been prescribed off-label to treat METH dependence. Modafinil has shown neuroprotective properties against METH harmful effects in animal models. The goal of the present study was to test if the prevention of hyperthermia might play a role on the neuroprotective actions of modafinil against METH toxicity using various ambient temperatures. METH was administered to female C57BL/6 mice in a binge regimen: 4 × 5 mg/kg, 2 h apart; modafinil (90 mg/kg) was injected twice, 1 h before first and fourth METH injections. Drugs were given at cold ambient temperature (14 °C) or hot ambient temperature (29 °C). Body temperature was measured during treatments. Brains were dissected out 6 days after treatments and processed for tyrosine hydroxylase (TH), dopamine transporter (DAT), GFAP and c-Fos immunohistochemistry. Exposure to hot ambient temperature exacerbated METH toxicity evidenced by striatal reductions in TH and DAT and increased GFAP immmunoreactivity. Modafinil counteracted reductions in TH and DAT, but failed to block astroglial activation. At both ambient temperatures tested modafinil did induce increments in GFAP, but the magnitude was significantly lower than the one induced by METH. Both drugs induced increases in c-Fos positive nuclei; modafinil did not block this effect. Our results suggest that protective effects of modafinil against METH-induced neurotoxicity may be dependent, in part, to its hypothermic effects. Nevertheless, modafinil maintained some protective properties on METH-induced alterations in the striatum at different ambient temperatures.

The neurobiology of modafinil as an enhancer of cognitive performance and a potential treatment for substance use disorders

RATIONALE AND OBJECTIVES

Modafinil (MOD) and its R-enantiomer (R-MOD) are approved medications for narcolepsy and other sleep disorders. They have also been used, off-label, as cognitive enhancers in populations of patients with mental disorders, including substance abusers that demonstrate impaired cognitive function. A debated nonmedical use of MOD in healthy individuals to improve intellectual performance is raising questions about its potential abuse liability in this population.

RESULTS AND CONCLUSIONS

MOD has low micromolar affinity for the dopamine transporter (DAT). Inhibition of dopamine (DA) reuptake via the DAT explains the enhancement of DA levels in several brain areas, an effect shared with psychostimulants like cocaine, methylphenidate, and the amphetamines. However, its neurochemical effects and anatomical pattern of brain area activation differ from typical psychostimulants and are consistent with its beneficial effects on cognitive performance processes such as attention, learning, and memory. At variance with typical psychostimulants, MOD shows very low, if any, abuse liability, in spite of its use as a cognitive enhancer by otherwise healthy individuals. Finally, recent clinical studies have focused on the potential use of MOD as a medication for treatment of drug abuse, but have not shown consistent outcomes. However, positive trends in several result measures suggest that medications that improve cognitive function, like MOD or R-MOD, may be beneficial for the treatment of substance use disorders in certain patient populations.

Addiction-related gene regulation: risks of exposure to cognitive enhancers vs. other psychostimulants

The psychostimulants methylphenidate (Ritalin, Concerta), amphetamine (Adderall), and modafinil (Provigil) are widely used in the treatment of medical conditions such as attention-deficit hyperactivity disorder and narcolepsy and, increasingly, as "cognitive enhancers" by healthy people. The long-term neuronal effects of these drugs, however, are poorly understood. A substantial amount of research over the past two decades has investigated the effects of psychostimulants such as cocaine and amphetamines on gene regulation in the brain because these molecular changes are considered critical for psychostimulant addiction. This work has determined in some detail the neurochemical and cellular mechanisms that mediate psychostimulant-induced gene regulation and has also identified the neuronal systems altered by these drugs. Among the most affected brain systems are corticostriatal circuits, which are part of cortico-basal ganglia-cortical loops that mediate motivated behavior. The neurotransmitters critical for such gene regulation are dopamine in interaction with glutamate, while other neurotransmitters (e.g., serotonin) play modulatory roles. This review presents (1) an overview of the main findings on cocaine- and amphetamine-induced gene regulation in corticostriatal circuits in an effort to provide a cellular framework for (2) an assessment of the molecular changes produced by methylphenidate, medical amphetamine (Adderall), and modafinil. The findings lead to the conclusion that protracted exposure to these cognitive enhancers can induce gene regulation effects in corticostriatal circuits that are qualitatively similar to those of cocaine and other amphetamines. These neuronal changes may contribute to the addiction liability of the psychostimulant cognitive enhancers.

Mephedrone (4-methylmethcathinone, 'meow'): acute behavioural effects and distribution of Fos expression in adolescent rats

Mephedrone (4-methylmethcathinone) is a novel recreational drug that has rapidly increased in popularity in recent years. Users report mephedrone as having the stimulant-like qualities of methamphetamine and cocaine, combined with the prosocial, entactogenic effects of 3,4-methylenedioxymethamphetamine (MDMA). Anecdotal and case study reports indicate that mephedrone may have the potential to engender compulsive patterns of use as well as toxicity in overdose. However, there have been almost no neuropharmacological investigations of the drug up to this point. Here we examined the effects of two different mephedrone doses [15 and 30 mg/kg, intraperitoneal (IP)] relative to the well-known stimulant methamphetamine (2 mg/kg IP) in adolescent rats. Rats were injected, assessed for locomotor activity for 60 minutes and then tested in a 10-minute social preference test (measuring time spent in close proximity to a real rat versus a dummy rat). Their brains were then processed using Fos immunohistochemistry to determine patterns of brain activation. Results showed that mephedrone caused profound locomotor hyperactivity at both dose levels while tending to reduce social preference. Patterns of Fos expression with mephedrone resembled a combination of those observed with methamphetamine and MDMA, with particularly strong Fos expression in the cortex, dorsal and ventral striatum, ventral tegmental area (typical of both MDMA and methamphetamine) and supraoptic nucleus (typical of MDMA). These results demonstrate for the first time the powerful stimulant effects of mephedrone in animal models and its capacity to activate mesolimbic regions. These results also provide some empirical basis to user reports that mephedrone subjectively resembles a MDMA/methamphetamine hybrid.

Modulation of fronto-cortical activity by modafinil: a functional imaging and fos study in the rat

Modafinil (MOD) is a wake-promoting drug with pro-cognitive properties. Despite its increasing use, the neuronal substrates of MOD action remain elusive. In particular, animal studies have highlighted a putative role of diencephalic areas as primary neuronal substrate of MOD action, with inconsistent evidence of recruitment of fronto-cortical areas despite the established pro-cognitive effects of the drug. Moreover, most animal studies have employed doses of MOD of limited clinical relevance. We used pharmacological magnetic resonance imaging (phMRI) in the anesthetized rat to map the circuitry activated by a MOD dose producing clinically relevant plasma exposure, as here ascertained by pharmacokinetic measurements. We observed prominent and sustained activation of the prefrontal and cingulate cortex, together with weaker but significant activation of the somatosensory cortex, medial thalamic domains, hippocampus, ventral striatum and dorsal raphe. Correlation analysis of phMRI data highlighted enhanced connectivity within a neural network including dopamine projections from the ventral tegmental area to the nucleus accumbens. The pro-arousing effect of MOD was assessed using electroencephalographic recording under anesthetic conditions comparable to those used for phMRI, together with the corresponding Fos immunoreactivity distribution. MOD produced electroencephalogram desynchronization, resulting in reduced delta and increased theta frequency bands, and a pattern of Fos induction largely consistent with the phMRI study. Altogether, these findings show that clinically relevant MOD doses can robustly activate fronto-cortical areas involved in higher cognitive functions and a network of pro-arousing areas, which provide a plausible substrate for the wake-promoting and pro-cognitive effects of the drug.

Good night and good luck: norepinephrine in sleep pharmacology

Sleep is a crucial biological process that is regulated through complex interactions between multiple brain regions and neuromodulators. As sleep disorders can have deleterious impacts on health and quality of life, a wide variety of pharmacotherapies have been developed to treat conditions of excessive wakefulness and excessive sleepiness. The neurotransmitter norepinephrine (NE), through its involvement in the ascending arousal system, impacts the efficacy of many wake- and sleep-promoting medications. Wake-promoting drugs such as amphetamine and modafinil increase extracellular levels of NE, enhancing transmission along the wake-promoting pathway. GABAergic sleep-promoting medications like benzodiazepines and benzodiazepine-like drugs that act more specifically on benzodiazepine receptors increase the activity of GABA, which inhibits NE transmission and the wake-promoting pathway. Melatonin and related compounds increase sleep by suppressing the activity of the neurons in the brain's circadian clock, and NE influences the synthesis of melatonin. Antihistamines block the wake-promoting effects of histamine, which shares reciprocal signaling with NE. Many antidepressants that affect the signaling of NE are also used for treatment of insomnia. Finally, adrenergic receptor antagonists that are used to treat cardiovascular disorders have considerable sedative effects. Therefore, NE, long known for its role in maintaining general arousal, is also a crucial player in sleep pharmacology. The purpose of this review is to consider the role of NE in the actions of wake- and sleep-promoting drugs within the framework of the brain arousal systems.

Armodafinil

Armodafinil is the R-enantiomer of modafinil, a wake-promoting agent, that primarily affects areas of the brain involved in controlling wakefulness. Once-daily armodafinil was effective in improving wakefulness in adult patients with excessive sleepiness associated with obstructive sleep apnoea/hypopnoea syndrome (OSA) [despite treatment of the underlying condition], narcolepsy or shift work sleep disorder (SWSD) in four large (n > 195), double-blind, multinational trials of 12 weeks' duration. Compared with placebo, mean sleep latency (coprimary endpoint) was significantly improved with armodafinil 150 or 250 mg once daily in patients with OSA or narcolepsy, and with armodafinil 150 mg once daily in patients with SWSD, as assessed by the Multiple Sleep Latency Test (MSLT) or the Maintenance of Wakefulness Test (MWT). Furthermore, a significantly higher proportion of armodafinil than placebo recipients achieved a response (at least a minimal improvement) on the Clinical Global Impressions of Change (CGI-C) scale at study end in these four trials (coprimary endpoint). Once-daily armodafinil was generally well tolerated in adult patients with excessive sleepiness associated with OSA (despite treatment of the underlying condition), narcolepsy or SWSD.