Co-administration of amphetamine with alcohol results in decreased alcohol withdrawal severity in adolescent rats

Alcohol withdrawal and amphetamine co-use in an animal model for attention deficit hyperactivity disorder

Background: Non-medical use of amphetamine and other stimulants prescribed for treatment of attention deficit/hyperactivity disorder (ADHD) is of special concern when combined with alcohol consumption. In a previous study, we modeled chronic ethanol-amphetamine co-use in adolescent Long-Evans (LE) rats and provided evidence that amphetamine attenuates alcohol withdrawal symptoms.Objectives: This project modeled co-use of amphetamine with alcohol in adolescents with ADHD-like symptoms by examining ethanol-amphetamine administration in adolescent Spontaneously Hypertensive Rats (SHR), an experimental model for the study of ADHD. Withdrawal symptoms were compared among SHR and two control rat strains, LE and Wistar Kyoto (WKY).Methods: At postnatal day 32, parallel groups of 12-24 male SHR, WKY and LE rats were administered a liquid diet containing ethanol (3.6%) and/or amphetamine (20 mg/L). Following administration periods up to 26 days, rats were withdrawn from their treatment and tested for overall severity of alcohol withdrawal symptoms, general locomotor activity, and anxiety-like behavior.Results: Overall withdrawal severity was lower for SHR than for LE (p < .001) or WKY (p = .027). Co-consumption of amphetamine decreased withdrawal severity for LE (p = .033) and WKY (p = .011) but not SHR (p = .600). Only WKY showed increased anxiety-like behavior during withdrawal (p = .031), but not after amphetamine co-administration (p = .832).Conclusion: Alcohol withdrawal severity may be attenuated when co-used with amphetamine. However, as a model for ADHD, SHR adolescents appeared resistant to developing significant signs of alcohol withdrawal following alcohol consumption. Whether alcohol withdrawal symptoms are attenuated or absent, potential consequences could include a decreased awareness of an emerging problem with alcohol use.

The co-use of nicotine and prescription psychostimulants: A review of their behavioral and neuropharmacological interactions

BACKGROUND

Nicotine is commonly co-used with other psychostimulants. These high co-use rates have prompted much research on interactions between nicotine and psychostimulant drugs. These studies range from examination of illicitly used psychostimulants such as cocaine and methamphetamine to prescription psychostimulants used to treat attention deficit hyperactivity disorder (ADHD) such as methylphenidate (Ritalin™) and d-amphetamine (active ingredient of Adderall™). However, previous reviews largely focus on nicotine interactions with illicitly used psychostimulants with sparse mention of prescription psychostimulants. The currently available epidemiological and laboratory research, however, suggests high co-use between nicotine and prescription psychostimulants, and that these drugs interact to modulate use liability of either drug. The present review synthesizes epidemiological and experimental human and pre-clinical research assessing the behavioral and neuropharmacological interactions between nicotine and prescription psychostimulants that may contribute to high nicotine-prescription psychostimulant co-use.

METHODS

We searched databases for literature investigating acute and chronic nicotine and prescription psychostimulant interactions. Inclusion criteria were that participants/subjects had to experience nicotine and a prescription psychostimulant compound at least once in the study, in addition to assessment of their interaction.

RESULTS AND CONCLUSIONS

Nicotine clearly interacts with d-amphetamine and methylphenidate in a variety of behavioral tasks and neurochemical assays assessing co-use liability across preclinical, clinical, and epidemiological research. The currently available research suggests research gaps examining these interactions in women/female rodents, in consideration of ADHD symptoms, and how prescription psychostimulant exposure influences later nicotine-related outcomes. Nicotine has been less widely studied with alternative ADHD pharmacotherapy bupropion, but we also discuss this research.

Sequential Changes in Brain Glutamate and Adenosine A1 Receptors May Explain Severity of Adolescent Alcohol Withdrawal after Consumption of High Levels of Alcohol

There is an excellent correlation between the age when alcohol consumption begins and the likelihood of lifelong problems with alcohol abuse. Alcohol use often begins in adolescence, a time marked by brain development and maturation of numerous brain systems. Rats are an important model, wherein the emergence of alcohol withdrawal symptoms serves as a gauge of dependency following chronic alcohol consumption. Previous work has shown that adolescent Long-Evans rats consume high levels of alcohol and develop a severe alcohol withdrawal syndrome when fed alcohol as part of a liquid diet. Acutely, alcohol inhibits two important excitatory receptors for glutamate (NMDA and AMPA) and may further decrease glutamate activity through modulatory adenosine receptors. The present study focuses on potential adaptive changes in expression of these receptors that may create a receptor imbalance during chronic alcohol consumption and lead to severe overexcitation of the adolescent brain during alcohol withdrawal. Levels of brain expression of NMDA, AMPA, and adenosine A1 and A2a receptors were determined by Western blotting after adolescent rats consumed an alcohol-containing liquid diet for 4, 11, or 18 days. Severity of alcohol withdrawal was also assessed at these time points. Levels increased for both AMPA and NMDA receptors, significant and approaching maximal by day 11. In contrast, A1 receptor density showed a slow decline reaching significance at 18 days. There were no changes in expression of adenosine A2a receptor. The most severe withdrawal symptoms appear to coincide with the later downregulation of adenosine A1 receptors coming on top of maximal upregulation of excitatory AMPA and NMDA glutamate receptors. Thus, loss of adenosine "brakes" on glutamate excitation may punctuate receptor imbalance in alcohol-consuming adolescents by allowing the upregulation of the excitatory receptors to have full impact during early alcohol withdrawal.