A Single Exposure to Amphetamine Is Sufficient to Induce Long-Term Behavioral, Neuroendocrine, and Neurochemical Sensitization in Rats

Drugs of abuse activate the reward circuitry of the mesocorticolimbic system, and it has been hypothesized that drug exposure triggers synaptic plasticity of glutamatergic synapses onto dopamine (DA) neurons of the ventral tegmental area. Here, we show that just a 2 h in vivo exposure to amphetamine is sufficient to potentiate these synapses, measured as an increase in the synaptic AMPAR/NMDAR ratio. We tested the prediction that an increase in GluR1-containing AMPA receptors would result in an increase in GluR1 homomeric receptors at synapses, but were unable to observe any evidence of the predicted rectification in DA neurons from animals treated with amphetamine. We also examined the possibility of increased AMPA receptor insertion in the membrane, but did not detect a significant increase in biotinylated surface GluR1. We conclude that amphetamine induces rapid changes in synaptic AMPAR/NMDAR ratios, suggesting that potentiation of glutamatergic synapses is a relatively early event in the series of neuroadaptations in response to drugs of abuse.

Section: A Single Dose Of Amphetamine Alters Glutamatergic Synapses Isupporting

confidence: 92%

Rapid Synaptic Plasticity of Glutamatergic Synapses on Dopamine Neurons in the Ventral Tegmental Area in Response to Acute Amphetamine Injection

Faleiro

Jones

Kauer

2004

“…Animals were dialyzed at least twice, first following the administration of saline and 671 days later following the administration of AMPH. Considering evidence suggesting that even a single dose of AMPH produces sensitizing effects (Vanderschuren et al, 1999), the effects of saline-'challenges' were always tested first. In the event that dialysis sessions preceded by saline administration did not result in detectable levels of ACh as a result of probe failure or severed tubing, a maximum of two additional sessions were conducted in order to generate a complete data set for each animal.…”

Section: Microdialysis Methodsmentioning

confidence: 99%

Toward a Neuro-Cognitive Animal Model of the Cognitive Symptoms of Schizophrenia: Disruption of Cortical Cholinergic Neurotransmission Following Repeated Amphetamine Exposure in Attentional Task-Performing, but Not Non-Performing, Rats

Kozak

Martı́nez

Young

et al. 2007

Impairments in attentional functions and capacities represent core aspects of the cognitive symptoms of schizophrenia. Attentional performance has been demonstrated to depend on the integrity and activity of cortical cholinergic inputs. The neurobiological, behavioral, and cognitive effects of repeated exposure to psychostimulants model important aspects of schizophrenia. In the present experiment, prefrontal acetylcholine (ACh) release was measured in attentional task-performing and non-performing rats pretreated with an escalating dosing regimen of amphetamine (AMPH) and following challenges with AMPH. In non-performing rats, pretreatment with AMPH did not affect the increases in ACh release produced by AMPH-challenges. In contrast, attentional task performanceassociated increases in ACh release were attenuated in AMPH-pretreated and AMPH-challenged rats. This effect of repeated AMPH exposure on ACh release was already present before task-onset, suggesting that the loss of cognitive control that characterized these animals' performance was a result of cholinergic dysregulation. The findings indicate that the demonstration of repeated AMPH-induced dysregulation of the prefrontal cholinergic input system depends on interactions between the effects of repeated AMPH exposure and cognitive performance-associated recruitment of this neuronal system. Repeated AMPH-induced disruption of prefrontal cholinergic activity and attentional performance represents a useful model to investigate the cholinergic mechanisms contributing to the cognitive impairments of schizophrenia.

“…Although most of the referenced studies are in vivo by design, in vitro studies have also been used to isolate various biological mechanisms from the living organism (Bolanos et al, 2000(Bolanos et al, , 2002Vanderschuren et al, 1999).…”

Section: Overview Of Animal Models Of Addictionmentioning

confidence: 99%

“…Behavioral sensitization refers to the progressive increase in the locomotor stimulant properties of a drug following chronic drug administration and is considered a long-term neuro adaptation important for the maintenance of drug dependence (Kalivas et al, 1998;Robinson and Berridge, 1993;Vanderschuren et al, 1999). Cocaine-induced sensitization occurs through the stimulation of D 1 receptors on cortical afferents to the VTA, which, in turn, induces glutamate release.…”

Section: Cocaine-induced Sensitizationmentioning

confidence: 99%

The Role of Acetylcholine in Cocaine Addiction

Williams

Adinoff²

2007

160

138

Central nervous system cholinergic neurons arise from several discrete sources, project to multiple brain regions, and exert specific effects on reward, learning, and memory. These processes are critical for the development and persistence of addictive disorders. Although other neurotransmitters, including dopamine, glutamate, and serotonin, have been the primary focus of drug research to date, a growing preclinical literature reveals a critical role of acetylcholine (ACh) in the experience and progression of drug use. This review will present and integrate the findings regarding the role of ACh in drug dependence, with a primary focus on cocaine and the muscarinic ACh system. Mesostriatal ACh appears to mediate reinforcement through its effect on reward, satiation, and aversion, and chronic cocaine administration produces neuroadaptive changes in the striatum. ACh is further involved in the acquisition of conditional associations that underlie cocaine self-administration and context-dependent sensitization, the acquisition of associations in conditioned learning, and drug procurement through its effects on arousal and attention. Long-term cocaine use may induce neuronal alterations in the brain that affect the ACh system and impair executive function, possibly contributing to the disruptions in decision making that characterize this population. These primarily preclinical studies suggest that ACh exerts a myriad of effects on the addictive process and that persistent changes to the ACh system following chronic drug use may exacerbate the risk of relapse during recovery. Ultimately, ACh modulation may be a potential target for pharmacological treatment interventions in cocaine-addicted subjects. However, the complicated neurocircuitry of the cholinergic system, the multiple ACh receptor subtypes, the confluence of excitatory and inhibitory ACh inputs, and the unique properties of the striatal cholinergic interneurons suggest that a precise target of cholinergic manipulation will be required to impact substance use in the clinical population.