[Wakefulness-promoting agents for severe fatigue: to use or not to use?] / Medicatie tegen ernstige aanhoudende vermoeidheid.

About 20% of adults experience excessive daytime sleepiness or severe fatigue. Causes include somatic conditions, psychiatric disorders, and medication or drug use. Treatment depends on the underlying cause. If sleepiness persists despite optimal treatment of the underlying condition, exclusion of other causes, and behavioral interventions, wakefulness-promoting agents may be considered. However, no established pharmacological strategy exists for symptomatic treatment. Modafinil and stimulants like methylphenidate may offer some benefit based on experiences with narcolepsy or idiopathic hypersomnia. Studies in specific patient groups (e.g., multiple sclerosis, Parkinson's disease, traumatic brain injury, cancer-related fatigue) show variable results. The use of wakefulness-promoting agents is discouraged for addressing unexplained fatigue, as seen in the context of chronic fatigue syndrome.

Modafinil, an atypical CNS stimulant?

Modafinil is a central nervous system stimulant approved for the treatment of narcolepsy and sleep disorders. Due to its wide range of biochemical actions, modafinil has been explored for other potential therapeutic uses. Indeed, it has shown promise as a therapy for cognitive disfunction resulting from neurologic disorders like ADHD, and as a smart drug in non-medical settings. The mechanism(s) of actions underlying the therapeutic efficacy of this agent remains largely elusive. Modafinil is known to inhibit the dopamine transporter, thus decreasing dopamine reuptake following neuronal release, an effect shared by addictive psychostimulants. However, modafinil is unique in that only a few cases of dependence on this drug have been reported, as compared to other psychostimulants. Moreover, modafinil has been tested, with some success, as a potential therapeutic agent to combat psychostimulant and other substance use disorders. Modafinil has additional, but less understood, actions on other neurotransmitter systems (GABA, glutamate, serotonin, norepinephrine, etc.). These interactions, together with its ability to activate selected brain regions, are likely one of the keys to understand its unique pharmacology and therapeutic activity as a CNS stimulant. In this chapter, we outline the pharmacokinetics and pharmacodynamics of modafinil that suggest it has an "atypical" CNS stimulant profile. We also highlight the current approved and off label uses of modafinil, including its beneficial effects as a treatment for sleep disorders, cognitive functions, and substance use disorders.

Contingency management plus acceptance and commitment therapy for initial cocaine abstinence: Results of a sequential multiple assignment randomized trial (SMART).

BACKGROUND: This study tested an adaptive intervention for optimizing abstinence outcomes over phases of treatment for cocaine use disorder using a SMART design. Phase 1 assessed whether 4 weeks of contingency management (CM) improved response with the addition of Acceptance and Commitment Therapy (ACT). Phase 2 assessed pharmacological augmentation with modafinil (MOD) vs. placebo (PLA) for individuals not achieving abstinence during Phase 1. METHOD: For Phase 1 of treatment, participants (N=118) were randomly allocated to ACT+CM or Drug Counseling (DC+CM), the comparison condition. At week 4, treatment response was defined as the submission of six consecutive cocaine-negative urine drug screens (UDS). Phase 1 non-responders were re-randomized to MOD or PLA as adjunct to their initial treatment. Phase 1 responders continued receiving their initial treatment. Primary outcomes included response rate and proportion of cocaine-negative UDS for Phase 1 and 2. Analyses used Bayesian inference with 80% pre-specified as the posterior probability (PP) threshold constituting moderate evidence that an effect exists. RESULTS: Phase 1 response was higher in the ACT+CM group (24.5%) compared to the DC+CM group (17.5%; PP = 84.5%). In Phase 2, the proportion of cocaine-negative UDS among Phase 1 responders did not differ by initial treatment (PP = 61.8%) but remained higher overall compared to Phase 1 non-responders (PPs > 99%). No evidence of an effect favoring augmentation with MOD was observed. DISCUSSION: Adding ACT to CM increased abstinence initiation. Initial responders were more likely to remain abstinent compared to initial non-responders, for whom modafinil was not an effective pharmacotherapy augmentation strategy.

Idiopathic hypersomnia with a video recording of a spontaneous sleep attack: A case report.

RATIONALE: Although patients with central disorders of hypersomnolence (CDH) exhibit characteristic symptoms of hypersomnia frequently, it takes 5 to 15 years from the onset for its diagnosis due to the lack of symptom recognition. Here, we present a case of idiopathic hypersomnia (IH), a CDH, wherein early diagnosis was aided by a video footage of a spontaneous sleep attack. PATIENT CONCERNS: A 21-year-old man lost consciousness while driving and experienced an accident. He had complained of excessive daytime sleepiness (EDS) over half a year. During his hospitalization for close monitoring of the loss of consciousness, an in-room surveillance camera captured a 14-minutes long spontaneous sleep attack, during which he experienced general muscle weakness and loss of consciousness without warnings or convulsions leading to a fall from the bed. There were no abnormalities in vital signs. DIAGNOSES: There was no significant cataplexy and less than 2 sleep-onset rapid eye movements (SOREM) in 2 sleep latency tests, with a mean sleep latency of 2.1 and 4.6 minutes. Other sleep deprivation syndromes were excluded from differential diagnosis and finally, a diagnosis of IH was confirmed according to the criteria of the Third Edition of the International Classification of Sleep Disorders. During the course of the disease, attention-deficit/hyperactive disorder (ADHD) and a gaming disorder also diagnosed. INTERVENTIONS: Pharmacological treatment with modafinil was administered for IH and methylphenidate for ADHD. Cognitive behavioral therapy was performed for the gaming disorder. OUTCOMES: The EDS improved, and sleep attacks were no longer observed. The disruption of daily life caused by the gaming disorder was also reduced. LESSONS: Video recordings of sleep attacks are beneficial for identifying the cause of loss of consciousness. Home video recordings may be helpful in the early diagnosis of IH.

Application of novel metal organic framework-deep eutectic solvent/molecularly imprinted polymer multiple monolithic fiber for solid phase microextraction of amphetamines and modafinil in unauthorized medicinal supplements with GC-MS.

The goal of this research is the development of multiple monolithic fiber-solid phase microextraction (MMF-SPME) using a new integrated fiber for the determination of amphetamine derivatives and modafinil from unauthorized medicinal supplements. For this purpose, a monolithic fiber of metal organic framework MIL-Al (53)-deep eutectic solvent (DES)/molecularly imprinted polymers (MOF-DES/MIP) was synthesized. To find optimum microextraction conditions gas chromatography-mass spectrometer (GC-MS) was used and the influences of effective variables were investigated using one factor at a time method. After that, the significant variables were optimized using a Box-Behnken design (BBD) combined with a desirability function (DF). Under optimized conditions (desorption solvent=1500 µL of 1-octanol, pH=3.5, extraction time=35 min, [NaCl]=0% w/v and stirring rate=600 rpm), calibration graphs of analytes were linear in a concentration range of 0.1-400 µg L-1 with correlation coefficients > 0.9966. Limits of detection and quantification were in the ranges of 0.023-0.033 µg L-1 and 0.088-0.113 µg L-1, respectively. This procedure was successfully employed in determining target analytes in spiked and unspiked unauthorized medicinal supplement samples with recoveries ranging from 95.14 to 104.63%.

Selenium alleviates modafinil-induced neurobehavioral toxicity in rat via PI3K/Akt/mTOR/GSK3B signaling pathway and suppression of oxidative stress and apoptosis: in vivo and in silico study.

Nonmedical use of modafinil (MOD) led to increased rates of overdose toxicity, road accidents, addiction, withdrawal, suicide, and mental illnesses. The current study aims to determine the probable MOD brain toxicity and elucidate the possible role of selenium (Se) in ameliorating the neurotoxicity in rat models. Fifty-four male Albino rats were randomly assigned into nine groups. The groups were G1 (control negative), G2 (Se0.1), G3 (Se0.2), G4 (MOD300), G5 (MOD600), G6 (Se0.1 + MOD300), G7 (Se0.2 + MOD300), G8 (Se0.1 + MOD600), and G9 (Se0.2 + MOD600). After finishing the experiment, blood and brain tissue were harvested for biochemical and histological investigation. Neurobehavior parameters were assessed. Tissue neurotransmitter levels and oxidative stress markers were assessed. Gene expression of PI3K/Akt/mTOR-GSK3B, orexin, and orexin receptor2 was measured by qRT-PCR. Histological and immunohistochemistry assessments, as well as molecular docking, were carried out. MOD-induced neurobehavioral toxicity exhibited by behavioral and cognitive function impairments, which are associated with decreased antioxidant activities, increased MDA levels, and decreases in neurotransmitter levels. Brain levels of mRNA expression of PI3K, Akt, and mTOR were decreased, while GS3K, orexin, and orexin receptors were significantly elevated. These disturbances were confirmed by histopathological brain changes with increased silver and Bax immunostaining and decreased crystal violet levels. MOD induced neurotoxic effects in a dose-dependent manner. Compared with the MOD groups, SE coadministration significantly attenuates MOD-induced toxic changes. Docking study shows the protective role of Se as an apoptosis inhibitor and inflammation inhibitor. In conclusion, Se could be used as a biologically effective antioxidant compound to protect from MOD neurobehavioral toxicity in Wistar rats by reversing behavioral alterations, inflammation, apoptosis, and oxidative injury.

Headache improves with armodafinil.

This case report recounts the details of a patient diagnosed with narcolepsy and cataplexy whose headaches improved once treatment with armodafinil began. The clinical significance of this report lies in the fact that armodafinil is known to cause headaches, at least initially. But perhaps through a reduced need for caffeine and/or a regulation of sleep/wake, armodafinil may reduce headache frequency and severity. CITATION: Barone DA. Headache improves with armodafinil. J Clin Sleep Med. 2024;20(3):469-470.

Pharmacokinetics of Novel Dopamine Transporter Inhibitor CE-123 and Modafinil with a Focus on Central Nervous System Distribution.

S-CE-123, a novel dopamine transporter inhibitor, has emerged as a potential candidate for cognitive enhancement. The objective of this study was to compare the tissue distribution profiles, with a specific focus on central nervous system distribution and metabolism, of S-CE-123 and R-modafinil. To address this objective, a precise liquid chromatography-high resolution mass spectrometry method was developed and partially validated. Neuropharmacokinetic parameters were assessed using the Combinatory Mapping Approach. Our findings reveal distinct differences between the two compounds. Notably, S-CE-123 demonstrates a significantly superior extent of transport across the blood-brain barrier (BBB), with an unbound brain-to-plasma concentration ratio (Kp,uu,brain) of 0.5, compared to R-modafinil's Kp,uu,brain of 0.1. A similar pattern was observed for the transport across the blood-spinal cord barrier. Concerning the drug transport across cellular membranes, we observed that S-CE-123 primarily localizes in the brain interstitial space, whereas R-modafinil distributes more evenly across both sides of the plasma membrane of the brain's parenchymal cells (Kp,uu,cell). Furthermore, our study highlights the substantial differences in hepatic metabolic stability, with S-CE-123 having a 9.3-fold faster metabolism compared to R-modafinil. In summary, the combination of improved BBB transport and higher affinity of S-CE-123 to dopamine transporters in comparison to R-modafinil makes S-CE-123 a promising candidate for further testing for the treatment of cognitive decline.

COMPARATIVE ANALYSIS OF EFFECTIVENESS OF OBESITY TREATMENT IN PRIMARY CARE USING PATIENT-ORIENTED APPROACH WITH MOTIVATIONAL COUNSELING FOR LIFESTYLE CORRECTION AND ITS COMBINATION WITH ARMODAFINIL THERAPY IN PATIENTS WITH CONCOMITANT SHIFT WORK SLEEP DISORDER.

OBJECTIVE: Aim: Conduct a comparative analysis of effectiveness of obesity treatment in primary care using patient-oriented approach with motivational counseling for lifestyle correction and its combination with armodafinil therapy in patients with concomitant shift work sleep disorder. PATIENTS AND METHODS: Materials and Methods: 75 patients with obesity were studied, 38 patients had shift work disorder. Patients were divided into 2 groups: I (37 patients with obesity treated with motivational counseling) and II (38 patients with obesity and shift work disorder treated additionally with armodafinil 150 mg daily). The examination was at baseline, after 1st, 3th and 6th months. Statistical analysis was provided. RESULTS: Results: After 1 month of treatment, there were improvement of eating behavior, level of anxiety and depression, prognosis of diabetes development. At 3rd month, more pronounced changes were observed in 2nd group: 10% body weight loss, changes in eating behavior, sleep quality, anxiety level (p<0.05). After 6 months, examined indicators in both groups normalized, but dynamics in 2nd group was more significant; armodafinil-treated group had significantly better results in body weight loss, BMI, WC, HC, ConI, AVI, BPs, HOMA index, serotonin, leptin, levels of anxiety and depression, eating behavior, daytime dysfunction, level of sleepiness, quality of life and risk of developing diabetes. CONCLUSION: Conclusions: The use of armofafinil in addition to patientoriented motivational counseling in lifestyle correction ("5 As" and "5R") in patients with obesity connected with shift work disorder and excessive daytime sleepiness allows to reduce body weight by more than 16,52%, in contrast to isolated use of the same technique of motivational counseling in obese patients without sleep disorder (only 5,51%).

Recovery Mimicking “Ideal” CPAP Adherence Does Not Improve Wakefulness or Cognition in Chronic Murine Models of OSA: Effect of Wake-Promoting Agents

Introduction: Obstructive sleep apnea (OSA) is a chronic condition characterized by intermittent hypoxia (IH) and sleep fragmentation (SF). OSA can induce excessive daytime sleepiness (EDS) and is associated with impaired cognition and anxiety. Solriamfetol (SOL) and modafinil (MOD) are widely used wake-promoting agents in OSA patients with EDS. Methods: Male C57Bl/6J mice were exposed to SF along with sleep controls (SC) or to IH and room air (RA) controls during the light (inactive) phase for 4 and 16 weeks, respectively. Both IH and SF exposures were then discontinued to mimic “ideal” continuous positive airway pressure (CPAP) adherence. All groups were then randomly assigned to receive once daily intraperitoneal injections of SOL, MOD, or vehicle (VEH) for 6 days. Sleep/wake activity was assessed along with tests of explicit memory, anxiety and depression were performed before and after treatments. Results: IH and SF exposures increased sleep percentage in the dark phase and reduced wake bouts lengths (i.e., EDS), and induced cognitive deficits and impulsivity in mice. Both SOL and MOD treatments effectively mitigated EDS when combined with recovery, while recovery alone did not improve EDS over the 6-day period. Furthermore, improvements explicit memory emerged only after SOL. Conclusion: Chronic IH and SF induce EDS in young adult mice that is not ameliorated by recovery except when combined with either SOL or MOD. SOL, but not MOD, significantly improves IH-induced cognitive deficits. Thus, SOL emerges as a viable adjuvant medication for residual EDS in OSA along with its positive impact on cognition. (AU)

Consciousness Recovery in Traumatic Brain Injury: A Systematic Review Comparing Modafinil and Amantadine.

OBJECTIVES: Acute traumatic brain injury is one of the most common causes of death and disability. Reduction in the level of consciousness is a significant complication that can impact morbidity. Glasgow Coma Scale (GCS) is the most widely used method of assessing the level of consciousness. Neurostimulants such as amantadine and modafinil are common pharmacologic agents that increase GCS in patients with brain trauma. This study aimed to compare the effectiveness of these 2 drugs. METHODS: This systematic review obtained articles from Google Scholar, PubMed, Scopus, Embase, and MEDLINE databases. Extensive searches were conducted separately by 4 individuals in 3 stages. Ultimately, 16 clinical trials, cohort studies, case reports, and case series articles were obtained after reading the title, abstract, and full text and considering the exclusion criteria. The data of the final article were entered into the analysis table. This study was registered with PROSPERO (registration number CRD42022334409) and conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: Amantadine seems to be associated with a higher overall response rate. In contrast, modafinil is associated with the most remarkable change in GCS score during treatment. However, the number of clinical trials with high quality and sample size has not been satisfactory to compare the effectiveness of these 2 drugs and their potential side effects. CONCLUSIONS: The authors recommend additional double-blind clinical trials are needed to be conducted with a larger sample size, comparing amantadine with modafinil to delineate the efficacy and adverse effects, both short and long term.

Open-label placebo treatment does not enhance cognitive abilities in healthy volunteers.

The use of so-called 'smart drugs' such as modafinil to improve cognitive performance has recently attracted considerable attention. However, their side effects have limited user enthusiasm. Open-label placebo (OLP) treatment, i.e., inert treatments that are openly disclosed to individuals as having no active pharmacological ingredient, has been shown to improve various medical symptoms and conditions, including those related to cognitive performance. OLP treatment could therefore be an exciting alternative to pharmacological cognitive enhancers. Here, we used a randomized-controlled design to investigate the effect of a 21-day OLP treatment on several sub-domains of cognitive performance in N = 78 healthy volunteers. Subjective and objective measures of cognitive performance as well as different measures of well-being were obtained before and after the treatment period. Using a combination of classic Frequentist and Bayesian analysis approaches showed no additional benefit from OLP treatment in any of the subjective or objective measures of cognitive performance. Our study thus highlights possible limitations of OLP treatment in boosting cognitive performance in healthy volunteers. These findings are discussed in the light of expectancy-value considerations that may determine OLP efficacy.

A novel mesna-based electrochemical sensor embellished with silver nanoparticles for ultrasensitive analysis of modafinil.

Modafinil (MOD) is a CNS stimulant used for the treatment of narcolepsy, shift work sleep disorder, excessive daytime sleepiness, and post-COVID 19 neurological symptoms. In the literature, there is no report of square wave voltammetric (SWV) methods being used for the determination of MOD. This study describes, for the first time, the construction and evaluation of the analytical performance of a novel sensor for ultrasensitive SWV detection of MOD. The sensor was constructed by integration of silver nanoparticles (AgNPs) on Mesna (MSN) layers over a pencil graphite electrode (PGE) surface. The interface and morphological characteristics of the fabricated AgNPs@MSN/PGE sensor were investigated via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). This sensor was found to enhance the electro-oxidation of MOD. The combination of AgNPs@MSN/PGE with SWV enabled the determination of MOD in its bulk form and in pharmaceutical and biological matrices at the nanomolar scale (LOD = 28.59 nM) with excellent recoveries. This study represents the first report describing an electrochemical procedure for MOD detection in human plasma. The established SWV method was also validated, and the results were consistent with ICH criteria. Finally, the presented SWV procedure provides a facile, sensitive, rapid, and cost-effective approach compared to other existing methods.

Recovery Mimicking "Ideal" CPAP Adherence Does Not Improve Wakefulness or Cognition in Chronic Murine Models of OSA: Effect of Wake-Promoting Agents.

INTRODUCTION: Obstructive sleep apnea (OSA) is a chronic condition characterized by intermittent hypoxia (IH) and sleep fragmentation (SF). OSA can induce excessive daytime sleepiness (EDS) and is associated with impaired cognition and anxiety. Solriamfetol (SOL) and modafinil (MOD) are widely used wake-promoting agents in OSA patients with EDS. METHODS: Male C57Bl/6J mice were exposed to SF along with sleep controls (SC) or to IH and room air (RA) controls during the light (inactive) phase for 4 and 16 weeks, respectively. Both IH and SF exposures were then discontinued to mimic "ideal" continuous positive airway pressure (CPAP) adherence. All groups were then randomly assigned to receive once daily intraperitoneal injections of SOL, MOD, or vehicle (VEH) for 6 days. Sleep/wake activity was assessed along with tests of explicit memory, anxiety and depression were performed before and after treatments. RESULTS: IH and SF exposures increased sleep percentage in the dark phase and reduced wake bouts lengths (i.e., EDS), and induced cognitive deficits and impulsivity in mice. Both SOL and MOD treatments effectively mitigated EDS when combined with recovery, while recovery alone did not improve EDS over the 6-day period. Furthermore, improvements explicit memory emerged only after SOL. CONCLUSION: Chronic IH and SF induce EDS in young adult mice that is not ameliorated by recovery except when combined with either SOL or MOD. SOL, but not MOD, significantly improves IH-induced cognitive deficits. Thus, SOL emerges as a viable adjuvant medication for residual EDS in OSA along with its positive impact on cognition.

Pitolisant-supported bridging during drug holidays to deal with tolerance to modafinil in patients with narcolepsy.

STUDY OBJECTIVES: Modafinil is a common treatment for excessive daytime sleepiness (EDS) in narcolepsy. The long-term use of modafinil can lead to tolerance with the loss of efficacy and the continuous increase of its dose. Pharmacological strategies to deal with the tolerance to modafinil are lacking. We investigated the efficacy and safety of pitolisant-supported bridging during drug holidays in patients with tolerance to modafinil. METHODS: Narcolepsy patients on monotherapy with modafinil who developed symptoms of tolerance were eligible. The following alternating therapy regimen was established: Monday to Friday patients continued on modafinil whereas Saturday and Sunday they switched to pitolisant to "bridge" the EDS symptoms. Patients were assessed at baseline and after three months with the Epworth Sleepiness Scale (ESS) and the Ullanlinna Narcolepsy Scale (UNS). Health-related quality of life (HrQol) was evaluated by EuroQol5D. Adverse events were documented in the patients' diaries. RESULTS: 41 patients aged 30.9 ± 5.6 years were included. After three months of the alternating therapy regimen, the symptoms of tolerance decreased and the modafinil dose could be reduced by 41% (p < 0.01) resulting in better safety. The EDS improved on ESS (baseline: 18.2 ± 4.2, follow-up: 12.6 ± 4.0, p < 0.0001) and UNS (baseline: 25.8 ± 7.9, follow-up: 18.9 ± 5.9, p < 0.0001). The HrQol increased significantly. CONCLUSION: Patients with tolerance to modafinil could benefit from pitolisant-supported bridging during drug holidays. This alternating pharmacological strategy proved to be safe and helped to reduce EDS and to decrease the modafinil dose. Further randomized controlled studies are required to evaluate the different strategies to deal with the tolerance to modafinil. CLINICAL TRIAL REGISTRATION NUMBER: Clinical Trials.gov Identifier NCT05321355.

Collaborative rp-hplc method development for modafinil and scopolamine hydrobromide in sublingual tablets: involving key industry players

Objective: This research aims to develop and validate a collaborative RP-HPLC method, with input from key industry players, for the simultaneous determination of modafinil and scopolamine hydrobromide in compound sublingual tablets. The focus is on ensuring the safety and efficacy of these substances for enhancing the physical and cognitive fitness of athletes and players. Method: Utilizing a C18 chromatographic column (200mm×4.6mm, 5μm), the method employs a mobile phase of acetonitrile-water (25:75) with 0.02mol/L ammonium acetate and 0.02% triethylamine, pH adjusted to 6.0. The flow rate was set at 1 mL/min, detection at 225 nm wavelength, and an injection volume of 20 μL.Results: Scopolamine hydrobromide showed a linear range of 1-50 μg/mL, with a standard curve equation of A=0.2187C+0.0708 (R²=0.9993), and modafinil exhibited a range of 10-500 μg/mL, with A=0.6702C-1.6855 (R²=0.9993). Both substances demonstrated average recoveries of over 99%, within acceptable variance limits, signifying reliable quantification for fitness-related applications. Conclusion: The developed method is sensitive, precise, accurate, and reproducible, conforming to the standards of the Chinese Pharmacopoeia (2020 edition). It is particularly valuable for monitoring the quality of substances used by athletes and players to ensure their safe application in enhancing fitness and performance. The method benefits significantly from the collaboration with industry experts, addressing the specific needs of fitness and sports professionals (AU)

Atomoxetine promotes incentive value of modafinil and sensitizes exploratory behavior.

Substance dependence is a disorder that alters the functioning of the nervous system due to frequent abuse of drugs. The role of dopamine in the addictive effect of psychostimulants is well known; however, the involvement of the noradrenergic system is still unclear and poorly understood, though drugs like cocaine and amphetamines are known to exert significant activity on this system. The drug modafinil (MOD) has no proven addictive effect. It promotes wakefulness by acting mainly on the dopaminergic system and, to a lesser degree, the noradrenergic (NOR) system. Atomoxetine (ATX) is a non-stimulant drug that acts only on the NOR system, enhancing its activity. The aims of the present study were to analyze the effect of co-activating the DA and NOR systems (with MOD and ATX, respectively) on motor activity and exploratory behavior, and to examine the possible emergence of rewarding properties of MOD and an MOD+ATX mixture. Male Wistar rats at postnatal day 60 were treated chronically (16 days) with either monotherapy with 2ATX, 4ATX, or 60MOD mg/kg, two combinations of these substances -60MOD + 2ATX and 60MOD + 4ATX- or a vehicle. The rats co-administered with 60MOD + 4ATX reduced the rearing behavior frequency induced by MOD, but this behavior was sensitized by self-administration of the MOD+ATX mixture after chronic treatment. The rats pre-treated with 60MOD + 4ATX showed higher self-administration of MOD and greater activity on an operant task to obtain the MOD+ATX mixture. In addition, the 60MOD, 2ATX, and 60MOD + 2ATX groups showed sensitization of exploratory behavior after ingesting the mixture. Results suggest that the noradrenergic system enhances the incentive value of MOD and a MOD+ATX mixture, while also playing an important role in the sensitization of exploratory behavior.

Restoring connexin-36 function in diabetogenic environments precludes mouse and human islet dysfunction.

The secretion of insulin from ß-cells in the islet of Langerhans is governed by a series of metabolic and electrical events, which can fail during the progression of type 2 diabetes (T2D). ß-cells are electrically coupled via connexin-36 (Cx36) gap junction channels, which coordinates the pulsatile dynamics of [Ca2+ ] and insulin release across the islet. Factors such as pro-inflammatory cytokines and free fatty acids disrupt gap junction coupling under in vitro conditions. Here we test whether gap junction coupling and coordinated [Ca2+ ] dynamics are disrupted in T2D, and whether recovery of gap junction coupling can recover islet function. We examine islets from donors with T2D, from db/db mice, and islets treated with pro-inflammatory cytokines (TNF-α, IL-1ß, IFN-É£) or free fatty acids (palmitate). We modulate gap junction coupling using Cx36 over-expression or pharmacological activation via modafinil. We also develop a peptide mimetic (S293) of the c-terminal regulatory site of Cx36 designed to compete against its phosphorylation. Cx36 gap junction permeability and [Ca2+ ] dynamics were disrupted in islets from both human donors with T2D and db/db mice, and in islets treated with pro-inflammatory cytokines or palmitate. Cx36 over-expression, modafinil treatment and S293 peptide all enhanced Cx36 gap junction coupling and protected against declines in coordinated [Ca2+ ] dynamics. Cx36 over-expression and S293 peptide also reduced apoptosis induced by pro-inflammatory cytokines. Critically, S293 peptide rescued gap junction coupling and [Ca2+ ] dynamics in islets from both db/db mice and a sub-set of T2D donors. Thus, recovering or enhancing Cx36 gap junction coupling can improve islet function in diabetes. KEY POINTS: Connexin-36 (Cx36) gap junction permeability and associated coordination of [Ca2+ ] dynamics is diminished in human type 2 diabetes (T2D) and mouse models of T2D. Enhancing Cx36 gap junction permeability protects against disruptions to the coordination of [Ca2+ ] dynamics. A novel peptide mimetic of the Cx36 c-terminal regulatory region protects against declines in Cx36 gap junction permeability. Pharmacological elevation in Cx36 or Cx36 peptide mimetic recovers [Ca2+ ] dynamics and glucose-stimulated insulin secretion in human T2D and mouse models of T2D.