Accumbens dopamine-acetylcholine balance in approach and avoidance

Cholinergic mu-opioid receptor deletion alters reward preference and aversion-resistance

The endogenous opioid system has been implicated in alcohol consumption and preference in both humans and animals. The mu opioid receptor (MOR) is expressed on multiple cells in the striatum, however little is known about the contributions of specific MOR populations to alcohol drinking behaviors. The current study used mice with a genetic deletion of MOR in cholinergic cells (ChAT-Cre/Oprm1fl/fl) to examine the role of MORs expressed in cholinergic interneurons (CINs) in home cage self-administration paradigms. Male and female ChAT-Cre/Oprm1fl/fl mice were generated and heterozygous Cre+ (knockout) and Cre- (control) mice were tested for alcohol consumption in two drinking paradigms: limited access "Drinking in the Dark" and intermittent access. Quinine was added to the drinking bottles in the DID experiment to test aversion-resistant, "compulsive" drinking. Nicotine and sucrose drinking were also assessed so comparisons could be made with other rewarding substances. Cholinergic MOR deletion did not influence consumption or preference for ethanol (EtOH) in either drinking task. Differences were observed in aversion-resistance in males with Cre + mice tolerating lower concentrations of quinine than Cre-. In contrast to EtOH, preference for nicotine was reduced following cholinergic MOR deletion while sucrose consumption and preference was increased in Cre+ (vs. Cre-) females. Locomotor activity was also greater in females following the deletion. These results suggest that cholinergic MORs participate in preference for rewarding substances. Further, while they are not required for consumption of alcohol alone, cholinergic MORs may influence the tendency to drink despite negative consequences.

Preliminary investigation of the administration of biperiden to reduce relapses in individuals with cocaine/crack user disorder: A randomized controlled clinical trial

BACKGROUND

Several studies have demonstrated that ACh modulates the dopaminergic circuit in the nucleus accumbens, and its blockade appears to be associated with the inhibition of the reinforced effect or the increase in dopamine caused by cocaine use. The objective of this study was to evaluate the effect of biperiden (a muscarinic receptor antagonist with a relatively higher affinity for the M1 receptor) on crack/cocaine use relapse compared to a control group that received placebo.

METHODS

This study is a double-blind, randomized, placebo-controlled clinical trial. The intervention group received 2 mg of biperiden, 3 times a day, for a period of 3 months. The control group received identical placebo capsules, at the same frequency and over the same period. All participants were followed for a period of six months.

RESULTS

The sample comprised 128 people, with 61 in the control group and 67 in the biperiden group. Lower substance consumption was observed in the group that received biperiden treatment two (bT2 = -2.2 [-3.3; -1.0], p < 0.001) and six months (bT4 = -6, 2 [-8.6; -3.9], p < 0.001) after the beginning of the intervention. The biperiden group had a higher latency until a possible first day of consumption, in the same evaluation periods (bT2 = 0.26 [0.080; 0.44], p = 0.004; bT4 = 0.63 [0.32; 0.93], p < 0.001).

CONCLUSIONS

Despite the major limitations of the present study, the group that received biperiden reduced the number of days of cocaine/crack use and showed an increase in the latency time for relapse. More studies are needed to confirm the utility of this approach.

Pharmacokinetic and pharmacodynamic studies of nicotine in rat brain: a simultaneous investigation of nicotine metabolites and the release of neurotransmitters in vivo

Introduction: The body's ability to metabolize nicotine and the disposition of nicotine in the brain are important determinants of its exposure. Limited knowledge about the near real-time changes of neurochemicals during the brain nicotine metabolic process hinders the recognition of its multiple neuropharmacological effects. Methods: An online microdialysis coupled with UHPLC-HRMS/MS method for the in vivo multi-analysis of nicotine metabolites and several neurotransmitters in rat brain was developed. Whether the systemic modulation of metabolic enzyme CYP2B would modulate nicotine pharmacokinetics and local neurochemical effects was further investigated. Results: The dynamic profiles of over 10 nicotine metabolites and neurotransmitters were simultaneously obtained after a single injection of nicotine (2 mg·kg-1, i.p.) using the new method. Proadifen pretreatment (50 mg·kg-1·d-1, i.p., 4 days) caused significant inhibition of brain CYP2B1 activity. When exposed to nicotine, the brain C max of nicotine was 1.26 times higher and the levels of nicotine metabolites, nornicotine, and nicotine-N-oxide, were decreased by 85.3% and 34.4% in proadifen-pretreated rats. The higher level of brain nicotine induced a greater release of dopamine, serotonin, glutamate, and γ-amino-butyric acid in the nucleus accumbens. The concentrations of nicotine and dopamine were positively correlated, and the average levels of γ-amino-butyric acid and serotonin were 2.7 and 1.2 times higher, respectively, under the inhibition of nicotine metabolism. Discussion: These results demonstrated that inhibiting nicotine metabolism in rats can enhance the residence of brain nicotine and its local neurotransmitter effects. The metabolic activity of nicotine under different physiological conditions could regulate nicotine's bioavailability and its resulting pharmacology.

Striosomes and Matrisomes: Scaffolds for Dynamic Coupling of Volition and Action

Striosomes form neurochemically specialized compartments of the striatum embedded in a large matrix made up of modules called matrisomes. Striosome-matrix architecture is multiplexed with the canonical direct-indirect organization of the striatum. Striosomal functions remain to be fully clarified, but key information is emerging. First, striosomes powerfully innervate nigral dopamine-containing neurons and can completely shut down their activity, with a following rebound excitation. Second, striosomes receive limbic and cognition-related corticostriatal afferents and are dynamically modulated in relation to value-based actions. Third, striosomes are spatially interspersed among matrisomes and interneurons and are influenced by local and global neuromodulatory and oscillatory activities. Fourth, striosomes tune engagement and the motivation to perform reinforcement learning, to manifest stereotypical behaviors, and to navigate valence conflicts and valence discriminations. We suggest that, at an algorithmic level, striosomes could serve as distributed scaffolds to provide formats of the striatal computations generated through development and refined through learning. We propose that striosomes affect subjective states. By transforming corticothalamic and other inputs to the functional formats of the striatum, they could implement state transitions in nigro-striato-nigral circuits to affect bodily and cognitive actions according to internal motives whose functions are compromised in neuropsychiatric conditions.

Neuroproteomic mapping of kinases and their substrates downstream of acetylcholine: finding and implications

INTRODUCTION

Since the emergence of the cholinergic hypothesis of Alzheimer's disease (AD), acetylcholine has been viewed as a mediator of learning and memory. Donepezil improves AD-associated learning deficits and memory loss by recovering brain acetylcholine levels. However, it is associated with side effects due to global activation of acetylcholine receptors. Muscarinic acetylcholine receptor M1 (M1R), a key mediator of learning and memory, has been an alternative target. The importance of targeting a specific pathway downstream of M1R has recently been recognized. Elucidating signaling pathways beyond M1R that lead to learning and memory holds important clues for AD therapeutic strategies.

AREAS COVERED

This review first summarizes the role of acetylcholine in aversive learning, one of the outputs used for preliminary AD drug screening. It then describes the phosphoproteomic approach focused on identifying acetylcholine intracellular signaling pathways leading to aversive learning. Finally, the intracellular mechanism of donepezil and its effect on learning and memory is discussed.

EXPERT OPINION

The elucidation of signaling pathways beyond M1R by phosphoproteomic approach offers a platform for understanding the intracellular mechanism of AD drugs and for developing AD therapeutic strategies. Clarifying the molecular mechanism that links the identified acetylcholine signaling to AD pathophysiology will advance the development of AD therapeutic strategies.

Continuous cholinergic-dopaminergic updating in the nucleus accumbens underlies approaches to reward-predicting cues

The ability to learn Pavlovian associations from environmental cues predicting positive outcomes is critical for survival, motivating adaptive behaviours. This cued-motivated behaviour depends on the nucleus accumbens (NAc). NAc output activity mediated by spiny projecting neurons (SPNs) is regulated by dopamine, but also by cholinergic interneurons (CINs), which can release acetylcholine and glutamate via the activity of the vesicular acetylcholine transporter (VAChT) or the vesicular glutamate transporter (VGLUT3), respectively. Here we investigated behavioural and neurochemical changes in mice performing a touchscreen Pavlovian approach task by recording dopamine, acetylcholine, and calcium dynamics from D1- and D2-SPNs using fibre photometry in control, VAChT or VGLUT3 mutant mice to understand how these signals cooperate in the service of approach behaviours toward reward-predicting cues. We reveal that NAc acetylcholine-dopaminergic signalling is continuously updated to regulate striatal output underlying the acquisition of Pavlovian approach learning toward reward-predicting cues.

Leptin Promotes Striatal Dopamine Release via Cholinergic Interneurons and Regionally Distinct Signaling Pathways

Dopamine (DA) is a critical regulator of striatal network activity and is essential for motor activation and reward-associated behaviors. Previous work has shown that DA is influenced by the reward value of food, as well as by hormonal factors that reguate food intake and energy expenditure. Changes in striatal DA signaling also have been linked to aberrant eating patterns. Here we test the effect of leptin, an adipocyte-derived hormone involved in feeding and energy homeostasis regulation, on striatal DA release and uptake. Immunohistochemical evaluation identified leptin receptor (LepR) expression throughout mouse striatum, including on striatal cholinergic interneurons (ChIs) and their extensive processes. Using fast-scan cyclic voltammetry (FSCV), we found that leptin causes a concentration-dependent increase in evoked extra-cellular DA concentration ([DA]o) in dorsal striatum (dStr) and nucleus accumbens (NAc) core and shell in male mouse striatal slices, and also an increase in the rate of DA uptake. Further, we found that leptin increases ChI excitability, and that the enhancing effect of leptin on evoked [DA]o is lost when nicotinic acetylcholine (ACh) receptors are antagonized or when examined in striatal slices from mice lacking ACh synthesis. Evaluation of signaling pathways underlying leptin's action revealed a requirement for intracellular Ca2+, and the involvement of different downstream pathways in dStr and NAc core versus NAc shell. These results provide the first evidence for dynamic regulation of DA release and uptake by leptin within brain motor and reward pathways, and highlight the involvement of ChIs in this process.SIGNIFICANCE STATEMENT Given the importance of striatal dopamine (DA) in reward, motivation, motor behavior and food intake, identifying the actions of metabolic hormones on DA release in striatal subregions should provide new insight into factors that influence DA-dependent motivated behaviors. We find that one of these hormones, leptin, boosts striatal DA release through a process involving striatal cholinergic interneurons (ChIs) and nicotinic acetylcholine (ACh) receptors. Moreover, we find that the intracellular cascades downstream from leptin receptor (LepR) activation that lead to enhanced DA release differ among striatal subregions. Thus, we not only show that leptin regulates DA release, but also identify characteristics of this process that could be harnessed to alter pathologic eating behaviors.

Cognitive control, motivation and fatigue: A cognitive neuroscience perspective

The present article provides a unified systematic account of the role of cognitive control, motivation and dopamine pathways in relation to the development of fatigue. Since cognitive fatigue is considered to be one aspect of the general control system that manages goal activity in the service of motivational requirements (Hockey, 2011), our focus is also broader than fatigue itself. The paper shall therefore first focus on the motivation-control interactions at the level of networks of the brain. A motivational control network is argued to play a critical role in shaping goal-directed behavior, in conjunction with dopamine systems that energize the network. Furthermore, motivation-control interactions as implemented in networks of the brain provide an important element to elucidate how decision making weighs both the anticipated benefits and costs of control operations, in optimal and suboptimal conditions such as mental fatigue. The paper further sketches how fatigue affects the connectivity of large-scale networks in the brain during effortful exercition, in particular the high-cost long striatal-cortical pathways, leading to a global reduction of integration in the brain's network architecture. The resulting neural state within these networks then enters as interoceptive information to systems in the brain that perform cost-benefit calculations. Based on these notions we propose a unifying cost-benefit model, inspired by influential insights from the current neuroscience literature of how fatigue changes the motivation to perform. The model specifies how the reward value, effort costs and fatigue aspects of task performance converge in the medial prefrontal cortex to calculate the net motivation value of stimuli and select the appropriate actions.

Applying a Fast-Scan Cyclic Voltammetry to Explore Dopamine Dynamics in Animal Models of Neuropsychiatric Disorders

Progress in the development of technologies for the real-time monitoring of neurotransmitter dynamics has provided researchers with effective tools for the exploration of etiology and molecular mechanisms of neuropsychiatric disorders. One of these powerful tools is fast-scan cyclic voltammetry (FSCV), a technique which has progressively been used in animal models of diverse pathological conditions associated with alterations in dopamine transmission. Indeed, for several decades FSCV studies have provided substantial insights into our understanding of the role of abnormal dopaminergic transmission in pathogenetic mechanisms of drug and alcohol addiction, Parkinson’s disease, schizophrenia, etc. Here we review the applications of FSCV to research neuropsychiatric disorders with particular attention to recent technological advances.

At the heart of the interoception network: Influence of the parasubthalamic nucleus on autonomic functions and motivated behaviors

The parasubthalamic nucleus (PSTN), a small nucleus located on the lateral edge of the posterior hypothalamus, has emerged in recent years as a highly interconnected node within the network of brain regions sensing and regulating autonomic function and homeostatic needs. Furthermore, the strong integration of the PSTN with extended amygdala circuits makes it ideally positioned to serve as an interface between interoception and emotions. While PSTN neurons are mostly glutamatergic, some of them also express neuropeptides that have been associated with stress-related affective and motivational dysfunction, including substance P, corticotropin-releasing factor, and pituitary adenylate-cyclase activating polypeptide. PSTN neurons respond to food ingestion and anorectic signals, as well as to arousing and distressing stimuli. Functional manipulation of defined pathways demonstrated that the PSTN serves as a central hub in multiple physiologically relevant networks and is notably implicated in appetite suppression, conditioned taste aversion, place avoidance, impulsive action, and fear-induced thermoregulation. We also discuss the putative role of the PSTN in interoceptive dysfunction and negative urgency. This review aims to synthesize the burgeoning preclinical literature dedicated to the PSTN and to stimulate interest in further investigating its influence on physiology and behavior.

Phosphoproteomic of the acetylcholine pathway enables discovery of the PKC-β-PIX-Rac1-PAK cascade as a stimulatory signal for aversive learning

Acetylcholine is a neuromodulator critical for learning and memory. The cholinesterase inhibitor donepezil increases brain acetylcholine levels and improves Alzheimer's disease (AD)-associated learning disabilities. Acetylcholine activates striatal/nucleus accumbens dopamine receptor D2-expressing medium spiny neurons (D2R-MSNs), which regulate aversive learning through muscarinic receptor M1 (M1R). However, how acetylcholine stimulates learning beyond M1Rs remains unresolved. Here, we found that acetylcholine stimulated protein kinase C (PKC) in mouse striatal/nucleus accumbens. Our original kinase-oriented phosphoproteomic analysis revealed 116 PKC substrate candidates, including Rac1 activator β-PIX. Acetylcholine induced β-PIX phosphorylation and activation, thereby stimulating Rac1 effector p21-activated kinase (PAK). Aversive stimulus activated the M1R-PKC-PAK pathway in mouse D2R-MSNs. D2R-MSN-specific expression of PAK mutants by the Cre-Flex system regulated dendritic spine structural plasticity and aversive learning. Donepezil induced PAK activation in both accumbal D2R-MSNs and in the CA1 region of the hippocampus and enhanced D2R-MSN-mediated aversive learning. These findings demonstrate that acetylcholine stimulates M1R-PKC-β-PIX-Rac1-PAK signaling in D2R-MSNs for aversive learning and imply the cascade's therapeutic potential for AD as aversive learning is used to preliminarily screen AD drugs.

Muscarinic signaling regulates voltage-gated potassium channel KCNQ2 phosphorylation in the nucleus accumbens via protein kinase C for aversive learning

The nucleus accumbens (NAc) plays critical roles in emotional behaviors, including aversive learning. Aversive stimuli such as an electric foot shock increase acetylcholine (ACh) in the NAc, and muscarinic signaling appears to increase neuronal excitability and aversive learning. Muscarinic signaling inhibits the voltage-dependent potassium KCNQ current which regulates neuronal excitability, but the regulatory mechanism has not been fully elucidated. Phosphorylation of KCNQ2 at threonine 217 (T217) and its inhibitory effect on channel activity were predicted. However, whether and how muscarinic signaling phosphorylates KCNQ2 in vivo remains unclear. Here, we found that PKC directly phosphorylated KCNQ2 at T217 in vitro. Carbachol and a muscarinic M1 receptor (M1R) agonist facilitated KCNQ2 phosphorylation at T217 in NAc/striatum slices in a PKC-dependent manner. Systemic administration of the cholinesterase inhibitor donepezil, which is commonly used to treat dementia, and electric foot shock to mice induced the phosphorylation of KCNQ2 at T217 in the NAc, whereas phosphorylation was suppressed by an M1R antagonist. Conditional deletion of Kcnq2 in the NAc enhanced electric foot shock induced aversive learning. Our findings indicate that muscarinic signaling induces the phosphorylation of KCNQ2 at T217 via PKC activation for aversive learning.

In vivo blockade of 5HT3 receptors in the infralimbic medial prefrontal cortex enhances fear extinction in a rat model of PTSD

Objectives

Treatments that reverse deficits in fear extinction are promising for the management of post-traumatic stress disorder (PTSD). 5-Hydroxytryptamine type 3 (5-HT3) receptor is involved involved in the extinction of fear memories. The present work aims to investigate the role of 5HT3 receptors in the infralimbic part of the medial prefrontal cortex (IL-mPFC) in extinction of conditioned fear in the single prolonged stress (SPS) model of PTSD in rats.

Materials and Methods

The effect of SPS administration was evaluated on the freezing behavior in contextual and cued fear conditioning models. After the behavioral tests, levels of 5HT3 transcription in IL-mPFC were also measured in the same animals using the real-time RT-PCR method. To evaluate the possible role of local 5HT3 receptors on fear extinction, conditioned freezing was evaluated in another cohort of animals that received local microinjections of ondansetron (a 5HT3 antagonist) and ondansetron plus a 5HT3 agonist (SR 57227A) after extinction sessions.

Results

Our findings showed that exposure to SPS increased the freezing response in both contextual and cued fear models. We also found that SPS is associated with increased expression of 5HT3 receptors in the IL-mPFC region. Ondansetron enhanced the fear of extinction in these animals and the enhancement was blocked by the 5HT3 agonist, SR 57227A.

Conclusion

It seems that up-regulation of 5HT3 receptors in IL-mPFC is an important factor in the neurobiology of PTSD and blockade of these receptors could be considered a potential treatment for this condition.

Addiction-related neuroadaptations following chronic nicotine exposure

The addiction-relevant molecular, cellular, and behavioral actions of nicotine are derived from its stimulatory effects on neuronal nicotinic acetylcholine receptors (nAChRs) in the central nervous system. nAChRs expressed by dopamine-containing neurons in the ventral midbrain, most notably in the ventral tegmental area (VTA), contribute to the reward-enhancing properties of nicotine that motivate the use of tobacco products. nAChRs are also expressed by neurons in brain circuits that regulate aversion. In particular, nAChRs expressed by neurons in the medial habenula (mHb) and the interpeduncular nucleus (IPn) to which the mHb almost exclusively projects regulate the "set-point" for nicotine aversion and control nicotine intake. Different nAChR subtypes are expressed in brain reward and aversion circuits and nicotine intake is titrated to maximally engage reward-enhancing nAChRs while minimizing the recruitment of aversion-promoting nAChRs. With repeated exposure to nicotine, reward- and aversion-related nAChRs and the brain circuits in which they are expressed undergo adaptations that influence whether tobacco use will transition from occasional to habitual. Genetic variation that influences the sensitivity of addiction-relevant brain circuits to the actions of nicotine also influence the propensity to develop habitual tobacco use. Here, we review some of the key advances in our understanding of the mechanisms by which nicotine acts on brain reward and aversion circuits and the adaptations that occur in these circuits that may drive addiction to nicotine-containing tobacco products.

Converging vulnerability factors for compulsive food and drug use

Highly palatable foods and substance of abuse have intersecting neurobiological, metabolic and behavioral effects relevant for understanding vulnerability to conditions related to food (e.g., obesity, binge eating disorder) and drug (e.g., substance use disorder) misuse. Here, we review data from animal models, clinical populations and epidemiological evidence in behavioral, genetic, pathophysiologic and therapeutic domains. Results suggest that consumption of highly palatable food and drugs of abuse both impact and conversely are regulated by metabolic hormones and metabolic status. Palatable foods high in fat and/or sugar can elicit adaptation in brain reward and withdrawal circuitry akin to substances of abuse. Intake of or withdrawal from palatable food can impact behavioral sensitivity to drugs of abuse and vice versa. A robust literature suggests common substrates and roles for negative reinforcement, negative affect, negative urgency, and impulse control deficits, with both highly palatable foods and substances of abuse. Candidate genetic risk loci shared by obesity and alcohol use disorders have been identified in molecules classically associated with both metabolic and motivational functions. Finally, certain drugs may have overlapping therapeutic potential to treat obesity, diabetes, binge-related eating disorders and substance use disorders. Taken together, data are consistent with the hypotheses that compulsive food and substance use share overlapping, interacting substrates at neurobiological and metabolic levels and that motivated behavior associated with feeding or substance use might constitute vulnerability factors for one another. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.

Motivational competition and the paraventricular thalamus

Although significant progress has been made in understanding the behavioral and brain mechanisms for motivational systems, much less is known about competition between motivational states or motivational conflict (e.g., approach - avoidance conflict). Despite being produced under diverse conditions, behavior during motivational competition has two signatures: bistability and metastability. These signatures reveal the operation of positive feedback mechanisms in behavioral selection. Different neuronal architectures can instantiate this selection to achieve bistability and metastability in behavior, but each relies on circuit-level inhibition to achieve rapid and stable selection between competing tendencies. Paraventricular thalamus (PVT) is identified as critical to this circuit level inhibition, resolving motivational competition via its extensive projections to local inhibitory networks in the ventral striatum and extended amygdala, enabling adaptive responding under motivational conflict.

Unchanged food approach-avoidance behaviour of healthy men after oxytocin administration

The oxytocinergic system has been assumed to contribute to food intake, possibly via interactions with dopamine. However, so far, it is unknown whether oxytocin influences the underlying motivational behaviour towards food. In the present study, we used a food-based approach-avoidance task (AAT) in a randomised, placebo-controlled, double-blind, cross-over design to compare intranasal oxytocin with a placebo. In the AAT, participants pushed or pulled a joystick when images of foods with a high or low craving rating were presented, where differences in response times typically reflect approach and avoidance motivational biases towards positively and negatively valence stimuli, respectively. Thirty-three healthy male participants (age = 25.12 ± 3.51 years; body mass index = 24.25 ± 2.48 kg/m² ) completed the two-session study, one with placebo and the other with oxytocin. We used mixed-effects models to investigate effects of treatment (oxytocin, placebo), response type (approach, avoid) and stimulus (high, low craving). The results showed that both approach and avoid responses tended to be faster for foods higher in craving compared to foods lower in craving. Most importantly, we did not observe any significant effects of oxytocin compared to placebo in motivational behaviour towards food. Our study demonstrates a general response bias towards foods with different craving values, which could have implications for future studies investigating food-related behaviour. We discuss possible explanations for the null effects of oxytocin and suggest further investigation of the relationship between oxytocin, dopamine and food-reward processing.

Food Addiction and Psychosocial Adversity: Biological Embedding, Contextual Factors, and Public Health Implications

The role of stress, trauma, and adversity particularly early in life has been identified as a contributing factor in both drug and food addictions. While links between traumatic stress and substance use disorders are well documented, the pathways to food addiction and obesity are less established. This review focuses on psychosocial and neurobiological factors that may increase risk for addiction-like behaviors and ultimately increase BMI over the lifespan. Early childhood and adolescent adversity can induce long-lasting alterations in the glucocorticoid and dopamine systems that lead to increased addiction vulnerability later in life. Allostatic load, the hypothalamic-pituitary-adrenal axis, and emerging data on epigenetics in the context of biological embedding are highlighted. A conceptual model for food addiction is proposed, which integrates data on the biological embedding of adversity as well as upstream psychological, social, and environmental factors. Dietary restraint as a feature of disordered eating is discussed as an important contextual factor related to food addiction. Discussion of various public health and policy considerations are based on the concept that improved knowledge of biopsychosocial mechanisms contributing to food addiction may decrease stigma associated with obesity and disordered eating behavior.

Aging impairs perceptual decision-making in mice: integrating computational and neurobiological approaches

Decision-making is one of the cognitive domains which has been under-investigated in animal models of cognitive aging along with its neurobiological correlates. This study investigated the latent variables of the decision process using the hierarchical drift-diffusion model (HDDM). Neurobiological correlates of these processes were examined via immunohistochemistry. Young (n = 11, 4 months old), adult (n = 10, 10 months old), and old (n = 10, 18 months old) mice were tested in a perceptual decision-making task (i.e. two-alternative forced-choice; 2AFC). Observed data showed that there was an age-dependent decrease in the accuracy rate of old mice while response times were comparable between age groups. HDDM results revealed that age-dependent accuracy difference was a result of a decrease in the quality of evidence integration during decision-making. Significant positive correlations observed between evidence integration rate and the number of tyrosine hydroxylase positive (TH+) neurons in the ventral tegmental area (VTA) and axon terminals in dorsomedial striatum (DMS) suggest that decrease in the quality of evidence integration in aging is related to decreased function of mesocortical and nigrostriatal dopamine.

Cingulate-basal ganglia-thalamo-cortical aspects of catatonia and implications for treatment

The catatonic syndrome is an example of a multifactorial neurobehavioral disorder that causes much morbidity and mortality but also has the potential to unlock the mystery of how motivation and movement interact to produce behavior. In this chapter, an attempt is made to understand better the catatonic syndrome through the lens of neurobiology and neuropathophysiology updated by recent studies in molecular biology, genomics, inflammasomics, neuroimaging, neural network theory, and neuropsychopathology. This will result in a neurostructural model for the catatonic syndrome that centers on paralimbic regions including the anterior and midcingulate cortices, as they interface with striatal and thalamic nodes in the salience decision-making network. Examination of neurologic disorders like the abulic syndrome, which includes in its extreme catatonic form, akinetic mutism, will identify the cingulate cortex and paralimbic neighbors as regions of interest. This exploration has the potential to unlock mysteries of the brain cascade from motivation to movement and to clarify catatonia therapeutics. Such a synthesis may also help us discern meaning inherent in this complex neurobehavioral syndrome.

Nucleus Accumbens Cholinergic Interneurons Oppose Cue-Motivated Behavior

BACKGROUND

Environmental reward-predictive stimuli provide a major source of motivation for adaptive reward pursuit behavior. This cue-motivated behavior is known to be mediated by the nucleus accumbens (NAc) core. The cholinergic interneurons in the NAc are tonically active and densely arborized and thus well suited to modulate NAc function. However, their causal contribution to adaptive behavior remains unknown. Here we investigated the function of NAc cholinergic interneurons in cue-motivated behavior.

METHODS

We used chemogenetics, optogenetics, pharmacology, and a translationally analogous Pavlovian-to-instrumental transfer behavioral task designed to assess the motivating influence of a reward-predictive cue over reward-seeking actions in male and female rats.

RESULTS

The data show that NAc cholinergic interneuron activity critically opposes the motivating influence of appetitive cues. Chemogenetic inhibition of NAc cholinergic interneurons augmented cue-motivated behavior. Optical stimulation of acetylcholine release from NAc cholinergic interneurons prevented cues from invigorating reward-seeking behavior, an effect that was mediated by activation of β2-containing nicotinic acetylcholine receptors.

CONCLUSIONS

NAc cholinergic interneurons provide a critical regulatory influence over adaptive cue-motivated behavior and therefore are a potential therapeutic target for the maladaptive cue-motivated behavior that marks many psychiatric conditions, including addiction and depression.

Randomized placebo-controlled trial of galantamine in individuals with cocaine use disorder

No pharmacotherapies are approved for the treatment of cocaine use disorder (CUD). Galantamine, a cholinesterase inhibitor, has shown initial promise for cocaine use reduction in methadone-maintained individuals with CUD and cognitive improvement in abstinent individuals with past CUD. However, galantamine has not previously tested in individuals with current CUD and no comorbid opioid use disorder or methadone maintenance. The goal of this 13-week, double-blind, placebo-controlled, randomized controlled trial was to test the efficacy of galantamine (8 mg or 16 mg/day; extended release (ER)) for reducing cocaine use and improving cognitive function in individuals with cocaine use disorder (CUD). Ninety-three treatment-seeking cocaine users were randomized to placebo (n = 32), 8 mg/day galantamine (n = 31) or 16 mg/day galantamine (n = 30). The medication was well-tolerated with minimal reports of side-effects. However, there were no significant treatment group differences in cocaine use outcomes (as measured by self-report or urines). The 16 mg galantamine group had a greater improvement in working memory capacity (Backwards Digit Span), but there were no other significant treatment group differences on key cognitive outcomes. These findings did not provide support for the efficacy of galantamine as a treatment for cocaine use in this sample of individuals with CUD.

An insular view of the social decision-making network

Social animals must detect, evaluate and respond to the emotional states of other individuals in their group. A constellation of gestures, vocalizations, and chemosignals enable animals to convey affect and arousal to others in nuanced, multisensory ways. Observers integrate social information with environmental and internal factors to select behavioral responses to others via a process call social decision-making. The Social Decision Making Network (SDMN) is a system of brain structures and neurochemicals that are conserved across species (mammals, reptiles, amphibians, birds) that are the proximal mediators of most social behaviors. However, how sensory information reaches the SDMN to shape behavioral responses during a social encounter is not well known. Here we review the empirical data that demonstrate the necessity of sensory systems in detecting social stimuli, as well as the anatomical connectivity of sensory systems with each node of the SDMN. We conclude that the insular cortex is positioned to link integrated social sensory cues to this network to produce flexible and appropriate behavioral responses to socioemotional cues.

Striatal Cholinergic Interneurons Are a Novel Target of Corticotropin Releasing Factor

Cholinergic interneurons (CINs) are critical regulators of striatal network activity and output. Changes in CIN activity are thought to encode salient changes in the environment and stimulus-response-outcome associations. Here we report that the stress-associated neuropeptide corticotropin releasing factor (CRF) produces a profound and reliable increase in the spontaneous firing of CINs in both dorsal striatum and nucleus accumbens (NAc) through activation of CRF type 1 receptors, production of cAMP and reduction in spike accommodation in male mice. The increase of CIN firing by CRF results in the activation muscarinic acetylcholine receptors type 5, which mediate potentiation of dopamine transmission in the striatum. This study provides critical mechanistic insight into how CRF modulates striatal activity and dopamine transmission in the NAc to likely account for CRF facilitation of appetitive behaviors.SIGNIFICANCE STATEMENT Although the presence of CRF receptors in the dorsal and ventral striatum has been acknowledged, the cellular identity and the functional consequences of receptor activation is unknown. Here we report that striatal cholinergic interneurons express CRF-R1 receptors and are acutely activated by the neuropeptide CRF that is released in response to salient environmental stimuli. Cholinergic interneurons make <1% of the cells in the striatum but are critical regulators of the striatal circuitry and its output. CRF's fast and potent activation of cholinergic interneurons could have far reaching behavioral implications across motivated behaviors controlled by the striatum.

Persistent Alterations of Accumbal Cholinergic Interneurons and Cognitive Dysfunction after Adolescent Intermittent Ethanol Exposure

Adolescent binge drinking renders young drinkers vulnerable to alcohol use disorders in adulthood; therefore, understanding alcohol-induced brain damage and associated cognitive dysfunctions is of paramount importance. Here we investigated the effects of binge-like adolescent intermittent ethanol (AIE) exposure on nonspatial working memory, behavioral flexibility and cholinergic alterations in the nucleus accumbens (NAc) in male and female rats. On postnatal days P25-57 rats were intubated with water or ethanol (at a dose of 5 g/kg) on a 2-day-on/2-day-off cycle and were then tested in adulthood on social recognition and probabilistic reversal learning tasks. During the social recognition task AIE-treated rats spent similar amounts of time interacting with familiar and novel juveniles, indicating an impaired ability to sustain memory of the familiar juvenile. During probabilistic reversal learning, AIE-treated male and female rats showed behavioral inflexibility as indicated by a higher number of trials needed to complete three reversals within a session, longer response latencies for lever selection, and for males, a higher number of errors as compared to water-treated rats. AIE exposure also reduced the number of cholinergic interneurons in the NAc in males and females. These findings indicate AIE-related pathologies of accumbal cholinergic interneurons and long lasting cognitive-behavioral deficits, which may be associated with cortico-striatal hypofunction.

Longitudinal changes in striatum and sub-threshold positive symptoms in individuals with an 'at risk mental state' (ARMS)

Recent studies have revealed that several psychotic symptom changes observed in the 'at risk mental state' (ARMS) are associated with changes in the striatum. We investigated if structural changes in the striatum are associated with recovery of sub-threshold psychotic symptoms in subjects with an ARMS who did not develop psychosis (ARMS-N). Sixteen healthy controls and 42 subjects with an ARMS participated in this study. Striatal volumes (caudate, putamen, and nucleus accumbens) were analyzed using MRI. The sub-threshold psychotic symptoms of the subjects with an ARMS were measured using the SOPS. Imaging and symptoms were reevaluated after 52 weeks. Significant right putamen volume reduction was observed at the follow-up in ARMS-N subjects. Improvement in sub-threshold positive symptoms significantly correlated with an increase in volume in the right accumbens at follow up. No relationship was found for negative symptoms. From these findings, the association between improvement in sub-threshold positive symptoms and an increase in the volume of the right accumbens may suggest that changes in the accumbens, which is a major site for dopamine innervation, are associated with symptom recovery. These findings may point to neurobiological resilience that may be associated with lower transition to psychosis.

Cholinergic system in sleep regulation of emotion and motivation

Sleep profoundly regulates our emotional and motivational state of mind. Human brain imaging and animal model studies are providing initial insights on the underlying neural mechanisms. Here, we focus on the brain cholinergic system, including cholinergic neurons in the basal forebrain, ventral striatum, habenula, and brain stem. Although much is learned about cholinergic regulations of emotion and motivation, less is known on their interactions with sleep. Specifically, we present an anatomical framework that highlights cholinergic signaling in the integrated reward-arousal/sleep circuitry, and identify the knowledge gaps on the potential roles of cholinergic system in sleep-mediated regulation of emotion and motivation. Sleep impacts every aspect of brain functions. It not only restores cognitive control, but also retunes emotional and motivational regulation [1]. Sleep disturbance is a comorbidity and sometimes a predicting factor for various psychiatric diseases including major depressive disorder, anxiety, post-traumatic stress disorder, and drug addiction [2-9]. Although it is well recognized that sleep prominently shapes emotional and motivational regulation, the underlying neural mechanisms remain elusive. The brain cholinergic system is essential for a diverse variety of functions including cognition, learning and memory, sensory and motor processing, sleep and arousal, reward processing, and emotion regulation [10-14]. Although cholinergic functions in cognition, learning and memory, motor control, and sleep and arousal have been well established, its interaction with sleep in regulating emotion and motivation has not been extensively studied. Here we review current evidence on sleep-mediated regulation of emotion and motivation, and reveal knowledge gaps on potential contributions from the cholinergic system.

Intracerebral injection of R-(-)-Apomorphine into the nucleus accumbens decreased carbachol-induced 22-kHz ultrasonic vocalizations in rats

Rats can produce ultrasonic vocalizations (USVs) in a variety of different contexts that signal their emotional state to conspecifics. Under distress, rats can emit 22-kHz USVs, while during positive pro-social interactions rats can emit frequency-modulated (FM) 50-kHz USVs. It has been previously reported that rats with increasing emission of FM 50-kHz USVs in anticipation of rewarding electrical stimulation or positive pro-social interaction decrease the number of emitted 22-kHz USVs. The purpose of the present investigation was to determine, in a pharmacological-behavioural experiment, if the positive emotional arousal of the rat indexed by the number of emitted FM 50-kHz USVs can decrease the magnitude of a subsequent negative emotional state indexed by the emission of 22-kHz USVs. To induce a positive emotional state, an intracerebral injection of a known D₁/D₂ agonist R-(-)-apomorphine (3.0 μg/0.3 μl) into the medial nucleus accumbens shell was used, while a negative emotional state was induced by intracerebral injection of carbachol (1.0 μg/0.3 μl), a known broad-spectrum muscarinic agonist, into the anterior hypothalamic-medial preoptic area. Our results demonstrated that initiation of a positive emotional state was able to significantly decrease the magnitude of subsequently expressed negative emotional state measured by the number of emitted 22-kHz USVs. The results suggest the neurobiological substrates that initiate positive emotional state indirectly antagonize the brain regions that initiate negative emotional states.

Neuropharmacology of compulsive eating

Compulsive eating behaviour is a transdiagnostic construct observed in certain forms of obesity and eating disorders, as well as in the proposed construct of 'food addiction'. Compulsive eating can be conceptualized as comprising three elements: (i) habitual overeating, (ii) overeating to relieve a negative emotional state, and (iii) overeating despite adverse consequences. Neurobiological processes that include maladaptive habit formation, the emergence of a negative affect, and dysfunctions in inhibitory control are thought to drive the development and persistence of compulsive eating behaviour. These complex psychobehavioural processes are under the control of various neuropharmacological systems. Here, we describe the current evidence implicating these systems in compulsive eating behaviour, and contextualize them within the three elements. A better understanding of the neuropharmacological substrates of compulsive eating behaviour has the potential to significantly advance the pharmacotherapy for feeding-related pathologies.This article is part of a discussion meeting issue 'Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists'.

The high efficacy of muscarinic M4 receptor in D1 medium spiny neurons reverses striatal hyperdopaminergia

The opposing action of dopamine and acetylcholine has long been known to play an important role in basal ganglia physiology. However, the quantitative analysis of dopamine and acetylcholine signal interaction has been difficult to perform in the native context because the striatum comprises mainly two subtypes of medium-sized spiny neurons (MSNs) on which these neuromodulators exert different actions. We used biosensor imaging in live brain slices of dorsomedial striatum to monitor changes in intracellular cAMP at the level of individual MSNs. We observed that the muscarinic agonist oxotremorine decreases cAMP selectively in the MSN subpopulation that also expresses D₁ dopamine receptors, an action mediated by the M₄ muscarinic receptor. This receptor has a high efficacy on cAMP signaling and can shut down the positive cAMP response induced by dopamine, at acetylcholine concentrations which are consistent with physiological levels. This supports our prediction based on theoretical modeling that acetylcholine could exert a tonic inhibition on striatal cAMP signaling, thus supporting the possibility that a pause in acetylcholine release is required for phasic dopamine to transduce a cAMP signal in D1 MSNs. In vivo experiments with acetylcholinesterase inhibitors donepezil and tacrine, as well as with the positive allosteric modulators of M₄ receptor VU0152100 and VU0010010 show that this effect is sufficient to reverse the increased locomotor activity of DAT-knockout mice. This suggests that M₄ receptors could be a novel therapeutic target to treat hyperactivity disorders.

p11 in Cholinergic Interneurons of the Nucleus Accumbens Is Essential for Dopamine Responses to Rewarding Stimuli

A recent study showed that p11 expressed in cholinergic interneurons (CINs) of the nucleus accumbens (NAc) is a key regulator of depression-like behaviors. Dopaminergic neurons projecting to the NAc are responsible for reward-related behaviors, and their function is impaired in depression. The present study investigated the role of p11 in NAc CINs in dopamine responses to rewarding stimuli. The extracellular dopamine and acetylcholine (ACh) levels in the NAc were determined in freely moving male mice using in vivo microdialysis. Rewarding stimuli (cocaine, palatable food, and female mouse encounter) induced an increase in dopamine efflux in the NAc of wild-type (WT) mice. The dopamine responses were attenuated (cocaine) or abolished (food and female mouse encounter) in constitutive p11 knock-out (KO) mice. The dopamine response to cocaine was accompanied by an increase in ACh NAc efflux, whereas the attenuated dopamine response to cocaine in p11 KO mice was restored by activation of nicotinic or muscarinic ACh receptors in the NAc. Dopamine responses to rewarding stimuli and ACh release in the NAc were attenuated in mice with deletion of p11 from cholinergic neurons (ChAT-p11 cKO mice), whereas gene delivery of p11 to CINs restored the dopamine responses. Furthermore, chemogenetic studies revealed that p11 is required for activation of CINs in response to rewarding stimuli. Thus, p11 in NAc CINs plays a critical role in activating these neurons to mediate dopamine responses to rewarding stimuli. The dysregulation of mesolimbic dopamine system by dysfunction of p11 in NAc CINs may be involved in pathogenesis of depressive states.

Sugar Addiction: From Evolution to Revolution

The obesity epidemic has been widely publicized in the media worldwide. Investigators at all levels have been looking for factors that have contributed to the development of this epidemic. Two major theories have been proposed: (1) sedentary lifestyle and (2) variety and ease of inexpensive palatable foods. In the present review, we analyze how nutrients like sugar that are often used to make foods more appealing could also lead to habituation and even in some cases addiction thereby uniquely contributing to the obesity epidemic. We review the evolutionary aspects of feeding and how they have shaped the human brain to function in "survival mode" signaling to "eat as much as you can while you can." This leads to our present understanding of how the dopaminergic system is involved in reward and its functions in hedonistic rewards, like eating of highly palatable foods, and drug addiction. We also review how other neurotransmitters, like acetylcholine, interact in the satiation processes to counteract the dopamine system. Lastly, we analyze the important question of whether there is sufficient empirical evidence of sugar addiction, discussed within the broader context of food addiction.

Racing the clock: The role of circadian rhythmicity in addiction across the lifespan

Although potent effects of psychoactive drugs on circadian rhythms were first described over 30 years ago, research into the reciprocal relationship between the reward system and the circadian system - and the impact of this relationship on addiction - has only become a focus in the last decade. Nonetheless, great progress has been made in that short time toward understanding how drugs of abuse impact the molecular and physiological circadian clocks, as well as how disruption of normal circadian rhythm biology may contribute to addiction and ameliorate the efficacy of treatments for addiction. In particular, data have emerged demonstrating that disrupted circadian rhythms, such as those observed in shift workers and adolescents, increase susceptibility to addiction. Furthermore, circadian rhythms and addiction impact one another longitudinally - specifically from adolescence to the elderly. In this review, the current understanding of how the circadian clock interacts with substances of abuse within the context of age-dependent changes in rhythmicity, including the potential existence of a drug-sensitive clock, the correlation between chronotype and addiction vulnerability, and the importance of rhythmicity in the mesocorticolimbic dopamine system, is discussed. The primary focus is on alcohol addiction, as the preponderance of research is in this area, with references to other addictions as warranted. The implications of clock-drug interactions for the treatment of addiction will also be reviewed, and the potential of therapeutics that reset the circadian rhythm will be highlighted.

Designing selective modulators for the nicotinic receptor subtypes: challenges and opportunities

Nicotinic receptors are membrane proteins involved in several physiological processes. They are considered suitable drug targets for various CNS disorders or conditions, as shown by the large number of compounds which have entered clinical trials. In recent years, nonconventional agonists have been discovered: positive allosteric modulators, allosteric agonists, site-specific agonists and silent desensitizers are compounds able to modulate the receptor interacting at sites different from the orthodox one, or to desensitize the receptor without prior opening. While these new findings can further complicate the pharmacology of these proteins and the design and optimization of ligands, they undoubtedly offer new opportunities to find drugs for the many therapeutic indications involving nicotinic receptors.

Accumbal Cholinergic Interneurons Differentially Influence Motivation Related to Satiety Signaling

Satiety, rather than all or none, can instead be viewed as a cumulative decrease in the drive to eat that develops over the course of a meal. The nucleus accumbens (NAc) is known to play a critical role in this type of value reappraisal, but the underlying circuits that influence such processes are unclear. Although NAc cholinergic interneurons (CINs) comprise only a small proportion of NAc neurons, their local impact on reward-based processes provides a candidate cell population for investigating the neural underpinnings of satiety. The present research therefore aimed to determine the role of NAc-CINs in motivation for food reinforcers in relation to satiety signaling. Through bidirectional control of CIN activity in mice, we show that when motivated by food restriction, increasing CIN activity led to a reduction in palatable food consumption while reducing CIN excitability enhanced food intake. These activity-dependent changes developed only late in the session and were unlikely to be driven by the innate reinforcer strength, suggesting that CIN modulation was instead impacting the cumulative change in motivation underlying satiety signaling. We propose that on a circuit level, an overall increase in inhibitory tone onto NAc output neurons played a role in the behavioral results, as activating NAc-CINs led to an inhibition of medium spiny neurons that was dependent on nicotinic receptor activation. Our results reveal an important role for NAc-CINs in controlling motivation for food intake and additionally provide a circuit-level framework for investigating the endogenous cholinergic circuits that signal satiety.

Effects of adolescent methamphetamine and nicotine exposure on behavioral performance and MAP-2 immunoreactivity in the nucleus accumbens of adolescent mice

The neurotoxic effects of methamphetamine (MA) exposure in the developing and adult brain can lead to behavioral alterations and cognitive deficits in adults. Previous increases in the rates of adolescent MA use necessitate that we understand the behavioral and cognitive effects of MA exposure during adolescence on the adolescent brain. Adolescents using MA exhibit high rates of nicotine (NIC) use, but the effects of concurrent MA and NIC in the adolescent brain have not been examined, and it is unknown if NIC mediates any of the effects of MA in the adolescent. In this study, the long-term effects of a neurotoxic dose of MA with or without NIC exposure during early adolescence (postnatal day 30-31) were examined later in adolescence (postnatal day 41-50) in male C57BL/6J mice. Effects on behavioral performance in the open field, Porsolt forced swim test, and conditioned place preference test, and cognitive performance in the novel object recognition test and Morris water maze were assessed. Additionally, the effects of MA and/or NIC on levels of microtubule associated-2 (MAP-2) protein in the nucleus accumbens and plasma corticosterone were examined. MA and NIC exposure during early adolescence separately decreased anxiety-like behavior in the open field test, which was not seen following co-administration of MA/NIC. There was no significant effect of early adolescent MA and/or NIC exposure on the intensity of MAP-2 immunoreactivity in the nucleus accumbens or on plasma corticosterone levels. These results show that early adolescent MA and NIC exposure separately decrease anxiety-like behavior in the open field, and that concurrent MA and NIC exposure does not induce the same behavioral change as either drug alone.

A cholinergic basal forebrain feeding circuit modulates appetite suppression

Atypical food intake is a primary cause of obesity and other eating and metabolic disorders. Insight into the neural control of feeding has previously focused mainly on signalling mechanisms associated with the hypothalamus, the major centre in the brain that regulates body weight homeostasis. However, roles of non-canonical central nervous system signalling mechanisms in regulating feeding behaviour have been largely uncharacterized. Acetylcholine has long been proposed to influence feeding owing in part to the functional similarity between acetylcholine and nicotine, a known appetite suppressant. Nicotine is an exogenous agonist for acetylcholine receptors, suggesting that endogenous cholinergic signalling may play a part in normal physiological regulation of feeding. However, it remains unclear how cholinergic neurons in the brain regulate food intake. Here we report that cholinergic neurons of the mouse basal forebrain potently influence food intake and body weight. Impairment of cholinergic signalling increases food intake and results in severe obesity, whereas enhanced cholinergic signalling decreases food consumption. We found that cholinergic circuits modulate appetite suppression on downstream targets in the hypothalamus. Together our data reveal the cholinergic basal forebrain as a major modulatory centre underlying feeding behaviour.

Botulinum Toxin A for Controlling Obesity

Rapid growth of the overweight population and the number of obese individuals in recent decades suggests that current strategies based on diet, exercise, and pharmacological knowledge are not sufficient to address this epidemic. Obesity is the result of a high caloric intake and energy storage, not counterbalanced by an equally important energy expense. Botulinum toxin type A (BoNT-A) use is rapidly expanding to include treatment of a variety of ophthalmological, gastrointestinal, urological, orthopedic, dermatological, secretory, painful, and cosmetic disorders. Many studies evaluating the effect of BoNT-A in gastric antrum e/o fundus for the treatment of obesity have been published. This treatment modality was based on the observation that gastric injection of BoNT-A in laparatomized rats induced a significant reduction of food intake and body weight. These studies have been published yielding debated results. Differences in the selection of patients, the doses of BoNT-A, the method of administration of the toxin, and the instruments of evaluation of some parameters among these studies may be the cause. In this review, it will study the state-of-the-art use of BoNT-A in obesity basic science models and review the clinical evidence on the therapeutic applications of BoNT-A for obesity.

Adolescent Emotional Maturation through Divergent Models of Brain Organization

In this article we introduce the hypothesis that neuropsychological adolescent maturation, and in particular emotional management, may have opposing explanations depending on the interpretation of the assumed brain architecture, that is, whether a componential computational account (CCA) or a dynamic systems perspective (DSP) is used. According to CCA, cognitive functions are associated with the action of restricted brain regions, and this association is temporally stable; by contrast, DSP argues that cognitive functions are better explained by interactions between several brain areas, whose engagement in specific functions is temporal and context-dependent and based on neural reuse. We outline the main neurobiological facts about adolescent maturation, focusing on the neuroanatomical and neurofunctional processes associated with adolescence. We then explain the importance of emotional management in adolescent maturation. We explain the interplay between emotion and cognition under the scope of CCA and DSP, both at neural and behavioral levels. Finally, we justify why, according to CCA, emotional management is understood as regulation, specifically because the cognitive aspects of the brain are in charge of regulating emotion-related modules. However, the key word in DSP is integration, since neural information from different brain areas is integrated from the beginning of the process. Consequently, although the terms should not be conceptually confused, there is no cognition without emotion, and vice versa. Thus, emotional integration is not an independent process that just happens to the subject, but a crucial part of personal growth. Considering the importance of neuropsychological research in the development of educational and legal policies concerning adolescents, we intend to expose that the holistic view of adolescents is dependent on whether one holds the implicit or explicit interpretation of brain functioning.

Cocaine cardiovascular effects and pharmacokinetics after treatment with the acetylcholinesterase inhibitor donepezil

BACKGROUND

In rodents, cholinesterase inhibitors can cause sustained decreases in the reinforcing effects of cocaine. Nonetheless, cocaine is metabolized by butyrylcholinesterase (BuChE), raising concerns that cholinesterase inhibition could increase its peripheral concentrations, perhaps augmenting toxicity. Although donepezil is approved for use in patients and selective for inhibiting acetylcholinesterase over BuChE, no studies have reported cocaine bioavailability in human subjects receiving donepezil.

METHODS

Twelve cocaine-dependent veterans received three days of treatment with either oral placebo or 5 mg daily of donepezil, followed by cross-over to the opposite treatment. During both oral treatments, double-blind intravenous cocaine was administered at .0, .18, and .36 mg/kg in a laboratory setting, followed by determinations of heart rate, blood pressure, and plasma concentrations of cocaine and major metabolites.

RESULTS

Intravenous cocaine produced dose-related increases in systolic blood pressure that were most pronounced over the initial 30 minutes after treatment. Oral donepezil attenuated drug-induced elevations of systolic blood pressure following low-dose cocaine (.18 mg/kg). No significant difference in blood pressure following treatment with placebo or donepezil after high-dose cocaine (.36 mg/kg). Peak values of blood pressure and heart rate were unaffected by donepezil. Plasma concentrations of cocaine and metabolites did not differ in donepezil- and placebo-treated participants.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

We conclude that donepezil can attenuate drug-induced increases in systolic blood pressure following low-dose cocaine, but does not otherwise modify the cardiovascular effects of intravenous cocaine. Clinically significant changes in cocaine bioavailability and cardiovascular effects do not occur following this dose of donepezil. (Am J Addict 2016;25:392-399).

Neuronal Nicotinic Acetylcholine Receptor Modulators Reduce Sugar Intake

Excess sugar consumption has been shown to contribute directly to weight gain, thus contributing to the growing worldwide obesity epidemic. Interestingly, increased sugar consumption has been shown to repeatedly elevate dopamine levels in the nucleus accumbens (NAc), in the mesolimbic reward pathway of the brain similar to many drugs of abuse. We report that varenicline, an FDA-approved nicotinic acetylcholine receptor (nAChR) partial agonist that modulates dopamine in the mesolimbic reward pathway of the brain, significantly reduces sucrose consumption, especially in a long-term consumption paradigm. Similar results were observed with other nAChR drugs, namely mecamylamine and cytisine. Furthermore, we show that long-term sucrose consumption increases α4β2 * and decreases α6β2* nAChRs in the nucleus accumbens, a key brain region associated with reward. Taken together, our results suggest that nAChR drugs such as varenicline may represent a novel treatment strategy for reducing sugar consumption.

Neuromodulation, Emotional Feelings and Affective Disorders

Affective disorders such as anxiety, phobia and depression are a leading cause of disabilities worldwide. Monoamine neuromodulators are used to treat most of them, with variable degrees of efficacy. Here, we review and interpret experimental findings about the relation of neuromodulation and emotional feelings, in pursuit of two goals: (a) to improve the conceptualisation of affective/emotional states, and (b) to develop a descriptive model of basic emotional feelings related to the actions of neuromodulators. In this model, we hypothesize that specific neuromodulators are effective for basic emotions. The model can be helpful for mental health professionals to better understand the affective dynamics of persons and the actions of neuromodulators - and respective psychoactive drugs - on this dynamics.