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The hypothalamus is an integrated energy sensing system interfacing with higher motivational structures of the mesocorticolimbic dopamine (DA) system. This interconnectivity is ...strictly regulated by a number of orexigenic hypothalamic neuropeptides, including especially ghrelin, orexins and neuropeptide Y (NPY), enabling the latter to modulate salient events of natural and chemical reinforcers. In this review we aim to analyse the current knowledge on these three orexigenic neuropeptide systems that are involved in the DAergic regulation of psychostimulant behaviours. We will first review the co-existing interactions between ghrelin, orexins and NPY in hypothalamic nuclei. We will next outline whether these neuropeptides can affect DAergic neurotransmission by either regulating the firing rate of DA neurons in the ventral tegmental area (VTA) or by presynaptically interacting on the DAergic nerve terminals. Finally, we will underscore the main studies that outlined the involvement of ghrelin, orexins and NPY with rewarding, reinforcing and incentive properties of natural reinforcers and drugs of abuse. The reciprocal hypothalamic interaction of ghrelin, orexins and NPY might represent a new central view on neuronal mechanisms regulating the behavioural phenomenology of addiction maintained by the DA system.
Orexin-expressing neurons are present in hypothalamic nuclei and send projections toward mesolimbic regions such as the nucleus accumbens (NAc), a key brain region implicated in the processing of the ...motivational significance of reinforcers. Recent evidence found that activation of the orexin system can lead to a state of hyperarousal that may facilitate drug craving or contribute to vulnerability to drug relapse. This study aimed at assessing the effects of the orexin-1 receptor antagonist SB-334867 1-(2-methylbenzoxazol-6-yl)-3-1,5naphthyridin-4-yl-urea hydrochloride on amphetamine-induced dopamine (DA) release in the shell subregion of the NAc by means of
in vivo microdialysis in freely moving rats. Since behavioral sensitization is thought to play a role in the maintenance of compulsive drug use, we also tested the effect of SB-334867 on the expression of sensitization to the locomotor activating effects of amphetamine. Acute administration of SB-334867 (30
mg/kg SC) significantly reduced the acute effects of amphetamine (1
mg/kg IP) on extracellular DA levels in the NAc shell. The expression of amphetamine sensitization was also significantly reduced by acute SB-334867 treatment. Altogether our findings show that selective orexin-1 antagonism both reduces the acute effects of amphetamine on DA outflow in the NAc shell and decreases the expression of locomotor sensitization to the repeated, intermittent administration of amphetamine.
There is evidence that serotonin2C (5-HT2C) receptors can modulate some behavioural effects of nicotine, but the generality of this action is not known. To analyse the influence of the 5-HT2C agonist ...Ro-60-0175 on responses to nicotine in the five-choice serial reaction time task (5-CSRTT) and on its discriminative stimulus effect; these procedures constitute models for attention-enhancing and subjective effects of nicotine, respectively. In the 5-CSRTT, rats were trained to obtain food reinforcers by detecting light stimuli and then challenged with Ro-60-0175 (0.3-0.8 mg/kg) and nicotine (0.2 mg/kg). For drug discrimination studies, rats were trained to discriminate nicotine (0.2 mg/kg) from saline in a two-lever procedure using a tandem schedule of food reinforcement. In the 5-CSRTT, nicotine positively influenced most response indices, confirming previous results. Ro-60-0175 increased response latencies and omission errors and reduced anticipatory responding but had little effect on response accuracy; importantly, it counteracted the effects of nicotine on response speed and omission errors. Pentobarbitone (10-14 mg/kg) also slowed performance of the 5-CSRTT but did not weaken the nicotine-induced enhancement of performance. In the drug discrimination procedure, Ro-60-0175 was not generalised with nicotine but shifted the nicotine dose-response curve to the right in a dose-related manner. The data suggest that selective occupancy of 5-HT2C receptors can attenuate some effects of nicotine in the 5-CSRTT and weaken the nicotine discriminative stimulus; these effects cannot be explained by a sedative action of Ro-60-0175. PUBLICATION ABSTRACT
Preclinical evidence suggests an important role of the brain orexin system in behaviours related to drug addiction. This study aimed at assessing the effect of the orexin-1 receptor antagonist ...SB-334867 on aspects of psychostimulant-conditioned behaviours that are thought to contribute to the maintenance of and relapse to psychostimulant drug use. Rats were first allowed to nose poke for cocaine infusions associated with a cue light presentation (conditioned stimulus; CS) over five daily sessions. Subsequently, drug-free rats were tested for the acquisition of a new response in which presses on a novel active lever led to the presentation of the previously paired CS. We tested SB-334867 in two conditions, SB-334867 was given either before each cocaine self-administration or before the initial four sessions of acquisition for a novel instrumental responding paired with the CS (conditioned reinforcement). The effect of SB-334867 was also tested on the expression of conditioned place preference to d-amphetamine. The rats treated with SB-334867 before each cocaine self-administration session subsequently showed reduced active lever pressing compared with controls in the initial days of the conditioned reinforcement. In the second study, untreated rats showed normal acquisition of discriminated responding preferential for the lever providing the cocaine cue. In contrast, SB-334867 decreased the number of active lever pressing (compared with the control) with significant effects in all sessions. Finally, SB-334867 blocked the expression of d-amphetamine-induced conditioned place preference. These results suggest that orexin-1 receptor antagonism could offer therapeutic potential in reducing the impact of psychostimulant-predictive stimuli that contribute to compulsive drug seeking in human drug users.
Lamotrigine is suggested to have potential as an add-on treatment for patients with schizophrenia. Supporting evidence comes from the efficacy of the drug in models of psychotic-like behaviour ...induced by N-methyl-D-aspartate (NMDA) receptor antagonists, such as phencyclidine (PCP). These drugs enhance levels of the monoamines in the cortex, which may contribute to their psychotomimetic effects. The ability of lamotrigine to prevent these neurochemical changes has not been examined. We studied PCP-evoked overflow of noradrenaline, dopamine and serotonin in the medial prefrontal cortex of awake rats using microdialysis. Rats were administered lamotrigine or vehicle, followed by PCP. Locomotor activity was also recorded before and after drug treatment. Lamotrigine did not have an influence on basal levels of the monoamines, but significantly reduced PCP-evoked overflow of dopamine and serotonin; PCP-evoked overflow of noradrenaline was also reduced by lamotrigine, but not to a significant degree. In contrast, PCP-induced hyperactivity was unaffected by lamotrigine. It is concluded that lamotrigine can modify PCP-evoked monoamine overflow in the cortex, consistent with an ability to prevent the psychotomimetic effects of NMDA receptor antagonists in rodents and humans. The dissociation between monoamine overflow and locomotor activity suggests the involvement of different brain circuits; relevance to the treatment of schizophrenia is also discussed.
In the striatum, dopamine and acetylcholine (ACh) modulate dopamine release by acting, respectively, on dopamine D(2) autoreceptors and nicotinic ACh (nACh) heteroreceptors localized on dopaminergic ...nerve terminals. The possibility that functional interactions exist between striatal D(2) autoreceptors and nACh receptors was studied with in vivo microdialysis in freely moving rats. Local perfusion of nicotine in the ventral striatum (shell of the nucleus accumbens) produced a marked increase in the extracellular levels of dopamine, which was completely counteracted by co-perfusion with either the non-alpha(7) nACh receptor antagonist dihydro-beta-erythroidine or the D(2-3) receptor agonist quinpirole. Local perfusion of the D(2-3) receptor antagonist raclopride produced an increase in the extracellular levels of dopamine, which was partially, but significantly, counteracted by coperfusion with dihydro-beta-erythroidine. These findings demonstrate a potent crosstalk between G protein-coupled receptors and ligand-gated ion channels in dopaminergic nerve terminals, with the D(2) autoreceptor modulating the efficacy of non-alpha(7) nACh receptor-mediated modulation of dopamine release. We further demonstrate physical interactions between beta(2) subunits of non-alpha(7) nicotinic acetylcholine receptors and D(2) autoreceptors in co-immunoprecipitation experiments with membrane preparations from co-transfected mammalian cells and rat striatum. These results reveal that striatal non-alpha(7) nicotinic acetylcholine receptors form part of heteromeric dopamine autoreceptor complexes that modulate dopamine release.
Industrial robots, automated manufacturing, and efficient logistics processes are at the heart of the upcoming fourth industrial revolution. While there are seminal studies on the vulnerabilities of ...cyber-physical systems in the industry, as of today there has been no systematic analysis of the security of industrial robot controllers. We examine the standard architecture of an industrial robot and analyze a concrete deployment from a systems security standpoint. Then, we propose an attacker model and confront it with the minimal set of requirements that industrial robots should honor: precision in sensing the environment, correctness in execution of control logic, and safety for human operators. Following an experimental and practical approach, we then show how our modeled attacker can subvert such requirements through the exploitation of software vulnerabilities, leading to severe consequences that are unique to the robotics domain. We conclude by discussing safety standards and security challenges in industrial robotics.
BACKGROUND Delayed union, malunion, and nonunion are serious complications in the healing of fractures. Predicting the risk of nonunion before or after surgery is challenging. AIM To compare the most ...prevalent predictive scores of nonunion used in clinical practice to determine the most accurate score for predicting nonunion. METHODS We collected data from patients with tibial shaft fractures undergoing surgery from January 2016 to December 2020 in three different trauma hospitals. In this retrospective multicenter study, we considered only fractures treated with intramedullary nailing. We calculated the tibia FRACTure prediction healING days (FRACTING) score, Nonunion Risk Determination score, and Leeds-Genoa Nonunion Index (LEG-NUI) score at the time of definitive fixation. RESULTS Of the 130 patients enrolled, 89 (68.4%) healed within 9 months and were classified as union. The remaining patients (n = 41, 31.5%) healed after more than 9 months or underwent other surgical procedures and were classified as nonunion. After calculation of the three scores, LEG-NUI and FRACTING were the most accurate at predicting healing. CONCLUSION LEG-NUI and FRACTING showed the best performances by accurately predicting union and nonunion.
In modern factories, “controlled” manufacturing systems, such as industrial robots, CNC machines, or 3D printers, are often connected in a control network, together with a plethora of heterogeneous ...control devices. Despite the obvious advantages in terms of production and ease of maintenance, this trend raises non-trivial cybersecurity concerns. Often, the devices employed are not designed for an interconnected world, but cannot be promptly replaced: In fact, they have essentially become legacy systems, embodying design patterns where components and networks are accounted as trusted elements. In this paper, we take a holistic view of the security issues (and challenges) that arise in designing and securely deploying controlled manufacturing systems, using industrial robots as a case study—indeed, robots are the most representative instance of a complex automatically controlled industrial device. Following up to our previous experimental analysis, we take a broad look at the deployment of industrial robots in a typical factory network and at the security challenges that arise from the interaction between operators and machines; then, we propose actionable points to secure industrial cyber-physical systems, and we discuss the limitations of the current standards in industrial robotics to account for active attackers.
The gut-hormone ghrelin endogenously binds to the ghrelin receptor (GHS-R) to promote foraging and feeding behaviours mainly via the hypothalamic arcuate nucleus (ARC). GHS-Rs are also expressed in ...midbrain dopaminergic neurons of the ventral tegmental area (VTA) suggesting that ghrelin may modulate the mesolimbic dopamine (DA) system. In support of this hypothesis, previous results have shown that intraventricular administration of ghrelin in rats increases DA levels in the nucleus accumbens (NAc). In the present study, the systemic doses of ghrelin capable of triggering central activation were first determined, and growth hormone (GH) levels were used as a marker of ghrelin-induced activation. Similar dose regimen was then used to measure ghrelin-induced effects on extracellular levels of monoamines in the shell and core subdivisions of the NAc using microdialysis in freely moving rats. We show that subcutaneous (s.c.) administration of ghrelin produced an increase in basal plasmatic ghrelin concentrations that was paralleled by enhanced GH secretion. In addition, a significant increase in extracellular levels of DA was observed specifically in the NAc shell, with no effect in the core subdivision. Extracellular serotonin (5-HT) levels were also affected in the shell subregion, but without reaching statistical significance. Increased extracellular DA levels in the NAc shell have been typically associated with the acute reinforcing effects of addictive drugs. The present findings therefore suggest that systemic ghrelin may modulate the valence of reinforcers such as food and drugs of abuse by interfering with mesolimbic DA activity.
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