Modulation of cue value and the augmentation of heroin seeking in chronically food-restricted male rats under withdrawal.

Food restriction augments drug seeking in abstinent rats. The underlying motivational mechanisms, however, remain unclear. We hypothesized that caloric restriction enhances the incentive value attributed to drug-associated cues and, in turn, augments drug seeking.

Acute food deprivation-induced relapse to heroin seeking after short and long punishment-imposed abstinence in male rats.

Rational: Stress is a major trigger for drug relapse in humans and animal models, even after prolonged abstinence. However, animal models for stress-induced relapse were criticized for the lack of predictive and face validity.

Objectives: Here we investigated the effect of acute food deprivation stress in a novel stress-induced relapse model using voluntary, punishment-imposed abstinence from heroin.

Restrained eating and alcohol use: Testing drinking to cope and impulsivity as moderators.

The association between restrained eating and alcohol use remains poorly understood among undergraduates. Consistent with tension reduction theory, individuals with disordered eating may be motivated to drink alcohol to cope with negative emotionality. Perhaps what pushes them to drink despite restriction goals is impulsivity.

A Procedure to Study Stress-induced Relapse of Heroin Seeking after Punishment-imposed Abstinence.

The punishment-imposed abstinence procedure models the self-imposed abstinence that humans initiate due to the adverse consequences associated with drug-taking. This model has been implemented in experiments using different types of substances of abuse such as methamphetamine, cocaine, and alcohol. However, punishment-induced abstinence in heroin-trained animals has not been demonstrated.

The utility of maraviroc, an antiretroviral agent used to treat HIV, as treatment for opioid abuse? Data from MRI and behavioural testing in rats.

Background: Maraviroc is an antiretroviral agent and C-C chemokine coreceptor 5 (CCR5) antagonist that is currently used to treat human immunodeficiency virus. CCR5/μ-opioid receptor heterodimerization suggests that maraviroc could be a treatment for oxycodone abuse. We treated rats with maraviroc to explore its effect on oxycodone-seeking and its interference with the analgesic effects of oxycodone.

Assessing the Role of Corticothalamic and Thalamo-Accumbens Projections in the Augmentation of Heroin Seeking in Chronically Food-Restricted Rats.

Drug addiction is a chronic disorder characterized by compulsive drug seeking, and involves repetitive cycles of compulsive drug use, abstinence, and relapse. In both human and animal models of addiction, chronic food restriction increases rates of relapse. Our laboratory has reported a robust increase in drug seeking following a period of withdrawal in chronically food-restricted rats compared with sated controls.

A role for leptin and ghrelin in the augmentation of heroin seeking induced by chronic food restriction.

Rational: Caloric restriction increases the risk of relapse in abstinent drug users. Hormones involved in the regulation of energy balance and food intake, such as leptin and ghrelin, are implicated in drug-related behaviors.

Objectives: We investigated the role of leptin and ghrelin in the augmentation of heroin seeking induced by chronic food restriction.

The role of the paraventricular nucleus of the thalamus in the augmentation of heroin seeking induced by chronic food restriction.

Drug addiction is a chronic disorder that is characterized by compulsive drug seeking and involves cycling between periods of compulsive drug use, abstinence, and relapse. In both human addicts and animal models of addiction, chronic food restriction has been shown to increase rates of relapse. Previously, our laboratory has demonstrated a robust increase in drug seeking following a period of withdrawal in chronically food-restricted rats compared with sated rats.

Effects of chronic prenatal MK-801 treatment on object recognition, cognitive flexibility, and drug-induced locomotor activity in juvenile and adult rat offspring.

Background: Patients with schizophrenia display impaired cognitive functioning and increased sensitivity to psychomimetic drugs. The neurodevelopmental hypothesis of schizophrenia posits that disruption of the developing brain predisposes neural networks to lasting structural and functional abnormalities resulting in the emergence of such symptoms in adulthood. Given the critical role of the glutamatergic system in early brain development, we investigated whether chronic prenatal exposure to the glutamate NMDA receptor antagonist, MK-801, induces schizophrenia-like behavioural and neurochemical changes in juvenile and adult rats.

Exploring the role of locomotor sensitization in the circadian food entrainment pathway.

Food entrainment is the internal mechanism whereby the phase and period of circadian clock genes comes under the control of daily scheduled food availability. Food entrainment allows the body to efficiently realign the internal timing of behavioral and physiological functions such that they anticipate food intake. Food entrainment can occur with or without caloric restriction, as seen with daily schedules of restricted feeding (RF) or restricted treat (RT) that restrict food or treat intake to a single feeding time.

Effects of contingent and noncontingent nicotine on lever pressing for liquids and consumption in water-deprived rats.

Nicotine has been proposed to be a primary reinforcer and a reinforcement enhancer. To date, no studies have examined whether nicotine enhances consummatory behaviors or only operant responding (appetitive behaviors). Experiments were designed to test whether contingent and noncontingent nicotine enhance lever pressing for and consumption of fluids in water-deprived rats.

Augmentation of Heroin Seeking Following Chronic Food Restriction in the Rat: Differential Role for Dopamine Transmission in the Nucleus Accumbens Shell and Core.

Caloric restriction during drug abstinence increases the risk for relapse in addicts. In rats, chronic food restriction during a period of withdrawal following heroin self-administration augments heroin seeking. The mechanisms underlying this effect are largely unknown.

Effects of an acute cannabidiol treatment on cocaine self-administration and cue-induced cocaine seeking in male rats.

Cannabidiol is a non-psychoactive compound that is the second most abundant component of cannabis. It has been shown to have a potential therapeutic value for a wide range of disorders, including anxiety, psychosis, and depression. Recently, it was suggested that cannabidiol might be a potential treatment for heroin craving and relapse.

Food restriction-induced augmentation of heroin seeking in female rats: manipulations of ovarian hormones.

Rationale: Food restriction augments heroin seeking in chronically food-restricted male rats under withdrawal, an effect not yet examined in female rats. Importantly, women and female rats possess an increased vulnerability to drugs of abuse, which may be mediated by fluctuations in ovarian hormones.

Objectives: We investigated the role of estradiol and progesterone in augmented heroin seeking in chronically food-restricted female rats, under withdrawal.

A role for kappa-, but not mu-opioid, receptor activation in acute food deprivation-induced reinstatement of heroin seeking in rats.

Stress is considered to be one of the major triggers to drug relapse, even after prolonged periods of abstinence. In rats, the activation of stress-related brain systems, including corticotropin-releasing factor and norepinephrine, is critical for stress-induced reinstatement of extinguished drug seeking, an animal model for drug relapse. In addition, there are strong indications that activation of the endogenous opioid system is important for the effects of stress on drug seeking.

A procedure to study the effect of prolonged food restriction on heroin seeking in abstinent rats.

In human drug addicts, exposure to drug-associated cues or environments that were previously associated with drug taking can trigger relapse during abstinence. Moreover, various environmental challenges can exacerbate this effect, as well as increase ongoing drug intake. The procedure we describe here highlights the impact of a common environmental challenge, food restriction, on drug craving that is expressed as an augmentation of drug seeking in abstinent rats.

Is it stress? The role of stress related systems in chronic food restriction-induced augmentation of heroin seeking in the rat.

Drug addiction is a chronic disease characterized by recurring episodes of abstinence and relapse. The precise mechanisms underlying this pattern are yet to be elucidated, but stress is thought to be a major factor in relapse. Recently, we reported that rats under withdrawal and exposed to a mild chronic stressor, prolonged food restriction, show increased heroin seeking compared to sated controls.

Antagonism of the dopamine D1-like receptor in mesocorticolimbic nuclei attenuates acute food deprivation-induced reinstatement of heroin seeking in rats.

The neurotransmitter dopamine (DA) plays a critical role in both priming-and cue-induced reinstatement of extinguished drug-seeking behavior, but its role in stress-induced reinstatement is less clear. Our laboratory has recently demonstrated that systemic administration of the DA D1-like receptor antagonist, SCH 23390, attenuates acute food deprivation (FD) stress-induced reinstatement. The current study was designed to elucidate the brain regions critical to the effect of SCH 23390 on FD stress-induced reinstatement.

The effects of chronic food restriction on cue-induced heroin seeking in abstinent male rats.

Rationale And Objectives: Previous research with an animal model of relapse has shown that acute food deprivation will reinstate extinguished drug seeking. Recent evidence with humans, however, suggests that chronic food restriction rather than acute food deprivation is related to increases in drug taking and relapse, emphasizing a need for an animal model to elucidate the neural mechanisms mediating the effects of chronic food restriction on drug seeking. Here we studied the effects of chronic food restriction during a period of abstinence on heroin seeking in rats.

A limited role for ghrelin in heroin self-administration and food deprivation-induced reinstatement of heroin seeking in rats.

Food deprivation (FD) or restriction augments the locomotor activating and reinforcing effects of drugs of abuse. It has been proposed that these effects might be mediated by FD-induced increase in plasma levels of ghrelin, a 28-amino acid orexigenic peptide demonstrated to functionally interact with the mesolimbic dopaminergic system. However, a role for ghrelin has been demonstrated only with psychostimulant drugs and alcohol associated behaviors.

A role for neuropeptide Y Y5 but not the Y1-receptor subtype in food deprivation-induced reinstatement of heroin seeking in the rat.

Rational And Objectives: Neuropeptide Y (NPY), an orexigenic peptide that is released during periods of food restriction, has been shown to have a significant modulatory impact on drug-related behaviors. We have previously reported that both acute food deprivation (FD) and NPY injections can reinstate extinguished drug-seeking behavior, a proposed animal model of relapse to drug abuse. However, it is not clear whether the FD effect on drug seeking is dependent on NPY transmission.

Chronic food restriction augments the reinstatement of extinguished heroin-seeking behavior in rats.

Currently, there are no existing procedures that model in animals the situation where exposure to prolonged mild food restriction results in relapse to drug abuse. Here, reinstatement of extinguished heroin-seeking behavior was assessed in rats under extinction conditions. Ten, but not 7, days of food restriction (∼80% of sated body weight) induced reinstatement of heroin seeking, over and above the spontaneous recovery of the behavior.

Long-term physiological and behavioral effects of exposure to a highly palatable diet during the perinatal and post-weaning periods.

Environmental conditions promote weight gain in children and adults, with early nutritional states and the availability of energy condensed/high-fat palatable diets appearing to facilitate the development of obesity. Little is known about the extent to which prenatal and postnatal dietary manipulations alter the response of the adult offspring to high-fat, highly palatable diets. Here we exposed rat dams to highly palatable diet (supplemental diet, SD), rich in fat and sugars, during pregnancy and lactation, and assessed the potential interactions with the effects of a similar diet offered post-weaning on a range of physiological and behavioral parameters in the adult male offspring.

Role of CRF and other neuropeptides in stress-induced reinstatement of drug seeking.

A central problem in the treatment of drug addiction is high rates of relapse to drug use after periods of forced or self-imposed abstinence. This relapse is often provoked by exposure to stress. Stress-induced relapse to drug seeking can be modeled in laboratory animals using a reinstatement procedure.

Neuropeptide Y augments cocaine self-administration and cocaine-induced hyperlocomotion in rats.

Food restriction and deprivation are known to modulate drug-related behaviors. However, the mechanisms through which metabolic manipulations intercede the rewarding effects of drug reward are unknown. Neuropeptide Y (NPY) is thought to be critically involved in the regulation of energy balance.