Running increases ethanol preference

Conditioned ethanol aversion in rats induced by voluntary wheel running, forced swimming, and electric shock: an implication for aversion therapy of alcoholism

This study was planned to demonstrate rats' acquisition of aversion to ethanol solution consumed before voluntary running, forced swimming, or electric shock delivery. Wistar rats under water deprivation were allotted to four groups of eight rats each, and all rats were allowed to drink 5% ethanol solution for 15 min. Immediately after the ethanol drinking, rats of Group Run were put into the individual running wheels for 15 min, those of Group Swim were put into the individual swimming pools for 15 min, those of Group Shock received electric shocks for 15 min (15 0.45-mA shocks of 0.7s with the intershock interval of 1 min) in the individual small chambers, and those of Group Control were directly returned back to the home cages. This procedure was repeated for six days, followed by a two-day choice test of ethanol aversion where a bottle containing 5% ethanol solution and a bottle of tap water were simultaneously presented for 15 min. In the test, Groups Run, Swim, and Shock drank ethanol solution significantly less than tapwater, while Group Control drank both fluids equally. The effects of running, swimming, and shock were equivalent. The successful demonstration of acquired ethanol aversion induced by exercise (running and swimming) or shock in rats suggests an avenue for clinical application of exercise and shock treatments for human alcoholics, though there are many issues to be resolved before the practical use.

Endogenous opiates and behavior: 2002

This paper is the twenty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2002 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Decreased ethanol preference and wheel running in Nurr1-deficient mice

Nurr1 (Nr4a2) is a transcription factor expressed in dopamine cells from early development and throughout life. Null mutants for Nurr1 lack the ventral midbrain dopamine neurons and die soon after birth. Animals with a heterozygous deletion are viable and display no apparent abnormality. We have investigated the impact of heterozygous deletion of Nurr1 on ethanol consumption in adult mice as a model for drug-induced reward and on wheel running as a model for natural reward. Interestingly, Nurr1 heterozygous mice never developed high ethanol consumption nor did they develop as much running behaviour as did the wild-type animals. Thus, Nurr1 appears to have a key role for the reinforcing properties of ethanol and running that underlies the development of excessive reward-seeking behaviours characteristic for addiction. Quantitative trait loci mapping using C57Bl/6 and DBA/2 mice describe a locus for ethanol preference on chromosome 2, wherein Nurr1 is located. We found two dinucleotide repeats in the Nurr1 promoter that were longer in mice with low preference for ethanol (DBA/2 and 129/Sv) than in mice with high preference for ethanol (C57Bl/6J and C57Bl/6NIH). These sequential data are compatible with Nurr1 as a candidate gene responsible for the quantitative trait loci for ethanol preference on mouse chromosome 2. Together, our data thus imply involvement of Nurr1 in the transition to a state of high ethanol consumption as well as in the development of a high amount of wheel running in mice.

Circadian activity rhythms in high-alcohol-preferring and low-alcohol-preferring mice

The circadian periods of high-alcohol-preferring (HAP) and low-alcohol-preferring (LAP) selected lines of mice were compared. The mice were ethanol-naive. Circadian periods were calculated from records of running-wheel activity in constant dark. The number of daily wheel revolutions and body weights of the two lines of mice were also compared. The HAP line had a shorter period of wheel running than that of the LAP lines. The HAP mice also had a tendency to run more on wheels than did LAP mice. These findings support the suggestion that genes affecting ethanol consumption in mice have pleiotropic effects on circadian period.