How Alcohol Blunts Ability Of Hamsters To 'Rise And Shine'

Chronic alcohol consumption blunts the biological clock’s ability to synchronize daily activities to light, disrupts natural activity patterns and continues to affect the body’s clock (circadian rhythm), even days after the drinking ends, according to a new study with hamsters.The study describes the changes that drinking can produce on the body’s master clock and how it affects behavior. The research provides a way to study human alcoholism using an animal model, said researcher Christina L. Ruby.

The study appears in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. Christina L. Ruby, Allison J. Brager, Marc A. DePaul, and J. David Glass, all of Kent State University, and Rebecca A. Prosser of the University of Tennessee, conducted the study. The American Physiological Society published the research.

Batteries not included

Alcohol consumption affects the master clock, located in the suprachiasmatic nucleus (SCN) section of the brain. This clock controls the circadian cycle, a roughly 24-hour cycle, which regulates sleeping and waking, as well as the timing of a variety of other physiological functions, such as hormonal secretions, appetite, digestion, activity levels and body temperature. The SCN synchronizes physiological functions so that they occur at the proper times and keeps these functions synchronized with daylight. Disruption of the clock dramatically increases the risks of developing cancer, heart disease, and depression, among other health problems.

The researchers used hamsters to find out how alcohol affects circadian rhythms. Although hamsters are nocturnal, light synchronizes their clocks, just as with humans. The animals were divided into three groups, differing only on what they drank. The control group received water only. A second group received water containing 10% alcohol and the third group received water containing 20% alcohol. Hamsters, when given a choice, prefer alcohol, which they metabolize quickly.

The animals drank as much as they wanted and lived in an environment that provided 14 hours of light and 10 hours of darkness each day.

Sleeping in

The researchers recorded the activity levels of the three groups throughout the day. Late in the dark cycle, about three hours before the nocturnal animals would normally be settling in to sleep, the researchers put on a low-level light for 30 minutes. The light was similar to the dim light of dawn. At another time, the groups received a brighter light, akin to the light in an office building. Hamsters exposed to the light late in their active cycle will normally settle down to sleep at the same time, but will wake up earlier. In effect, the light pushes their circadian clock forward.

In addition, the researchers tracked how long it takes alcohol to travel to the master clock in the brain. They also took regular readings of subcutaneous alcohol levels, which are akin to blood alcohol levels. In the final phase of the experiment, the hamsters that received alcohol were switched to regular water to examine the effects of withdrawal.

The study found that:

* The hamsters that drank alcohol had the hardest time shifting their rhythms after exposure to the dim light, and the more alcohol they drank, the harder it was to adjust. Exposure to dim light caused the water-only hamsters to wake up 72 minutes earlier than they normally would. The 10% alcohol group woke up 30 minutes earlier and the 20% alcohol group woke up only 18 minutes earlier.
* Exposure to bright light helped the alcohol-consuming hamsters to wake up sooner, greatly reducing the difference in wake up times among the groups. The control animals woke up 102 minutes earlier compared to the 20% alcohol group that woke up 84 minutes earlier.
* Total time spent active during the 24-hour period was the same for all three groups. However, the hamsters that consumed alcohol had fewer bouts of activity that lasted longer than the water-consuming controls. The control group had more bouts of activity over the course of the day.
* When the hamsters were withdrawn from alcohol for 2-3 days and then exposed to the same light treatment again, they woke up much earlier than the animals that had drunk only water. The hamsters that were withdrawn from alcohol woke up 126 minutes sooner compared to the water drinking controls, who advanced 66 minutes. This exaggerated response persisted even up to three days later, when the experiment ended.
* The hamsters drank the most heavily shortly after the beginning of the dark cycle, when they would naturally be most active. A peak in alcohol reached the suprachiasmatic nucleus in the brain 20 minutes later.

Human applications?

The researchers aim to apply the research to people, who also show circadian disruptions from drinking. Specifically, the study suggests the following:

* People who drink alcohol, particularly late into the night, may not respond to important light cues to keep their biological clocks in synch with daylight over the next 24 hours. Even low levels of alcohol may impair the response to light cues, said Ruby.
* After the first 24 hours, the circadian cycle continues to be affected, even without further consumption of alcohol.
* Exposure to bright light in the morning may reduce the disruption of alcohol to the biological clock.
* Chronic drinking continues to affect the biological clock even after withdrawal from alcohol. The hamsters withdrawn from alcohol woke up much earlier in response to light than they normally would, just like people who are trying to stop drinking. Getting a person’s circadian rhythm back in line after quitting may be why staying abstinent is so difficult.
* Chronic drinking may affect activity patterns, making drinkers less active at times of the day when they should be active and more active when they should not be, such as late at night.

Journal reference:

1. Christina L. Ruby, Allison J. Brager, Marc A. DePaul, Rebecca A. Prosser and J. David Glass. Chronic ethanol attenuates circadian photic phase resetting and alters nocturnal activity patterns in the hamster. AJP Regulatory Integrative and Comparative Physiology, 2009; 297 (3): R729 DOI: 10.1152/ajpregu.00268.2009

List Of Hazardous Chemicals In Smokeless Tobacco Is Expanded In New Study

Attention all smokeless tobacco users: It's time to banish the comforting notion that snuff and chewing tobacco are safe because they don't burn and produce inhalable smoke like cigarettes. A study that looked beyond the well-researched tobacco hazards, nitrosamines and nicotine, has discovered a single pinch –– the amount in a portion –– of smokeless tobacco exposes the user to the same amount of another group of dangerous chemicals as the smoke of five cigarettes.The research on polycyclic aromatic hydrocarbons (PAH) in smokeless tobacco was reported at the 238th National Meeting of the American Chemical Society (ACS). It adds to existing evidence that smokeless contains two dozen other carcinogens that cause oral and pancreatic cancers, the scientists say.

"This study once again clearly shows us that smokeless tobacco is not safe," said Irina Stepanov, Ph.D., who led the research team. "Our finding places snuff on the same list of major sources of exposure to polycyclic aromatic hydrocarbons as smoking cigarettes." PAHs are widespread environmental contaminants formed as a result of incomplete burning of wood, coal, fat in meat, and organic matter. PAHs form, for instance, during the grilling of burgers, steaks and other meat.

The findings come in the midst of a rise in both marketing and consumption of smokeless tobacco, which many consumers regard as less dangerous than other forms of tobacco. Estimates suggest that sales of moist snuff in the United States have doubled since the 1980s.

"The feeling of safety among some smokeless users is wrong," said Stepanov, a chemist with Masonic Cancer Center, University of Minnesota, Minneapolis. "A total of 28 carcinogens were identified in smokeless tobacco even before our study. Continued exposure to these over a period of time can lead to cancer. Now we have found even more carcinogens in snuff." In addition to the heightened cancer risk, she noted that chronic use of snuff leads to nicotine addiction, just as it does with cigarette smoking.

Stepanov said that until recently, scientists believed that only trace amounts of PAH existed in snuff because the tobacco was not burned when used. This assumption proved to be wrong. "Even though smokeless tobacco use does not involve burning, moist snuff is getting contaminated with PAH during its manufacturing," according to Stepanov. The most likely source of this contamination with PAH is the curing process that is used to turn tobacco leaves into snuff. This process is called 'fire-curing', and it puts tobacco into direct contact with the smoke generated by smoldering hardwoods –– a rich source of various PAHs.

Looking to the next project, she said the team is working on a study that will examine a wide range of smokeless tobacco brands to compare PAH levels among them.

Funding for Stepanov's research came from the National Cancer Institute and the National Institute on Drug Abuse to the Transdisciplinary Tobacco Use Research Center at the University of Minnesota. The research team working on this project includes Dr. Dorothy Hatsukami and Dr. Stephen Hecht, renowned experts in tobacco carcinogenesis and tobacco harm reduction.

Links Between Video-game Playing And Health Risks In Adults Found

While video gaming is generally perceived as a pastime for children and young adults, research shows that the average age of players in the United States is 35. Investigators from the Centers for Disease Control and Prevention (CDC), Emory University and Andrews University analyzed survey data from over 500 adults ranging in age from 19 to 90 in the Seattle-Tacoma area on health risks; media use behaviors and perceptions, including those related to video-game playing; and demographic factors. In an article published in the October 2009 issue of the American Journal of Preventive Medicine, they found measurable correlations between video-game playing and health risks.Participants reported whether they were players or nonplayers, and weekly usage was collected. Internet usage was assessed, as was the relative importance of the Internet as a social support. The personal determinants examined in this study included self-assessments of depression, personality, health status, physical and mental health, body mass index (BMI), and poor quality of life. Immersion in media environments was evaluated using the participants' estimates of the time they spent during a typical week surfing the Internet and watching TV, including videos and DVDs. The Seattle–Tacoma area was selected because of its size (13th largest US media market) and its Internet usage level is the highest in the nation.

A total of 45.1% of respondents reported playing video games. Female video-game players reported greater depression and lower health status than female nonplayers. Male video-game players reported higher BMI and more Internet use time than male nonplayers. The only determinant common to both female and male video-game players was greater reliance on the Internet for social support.

Writing in the article, Dr. James B Weaver III, PhD, MPH, National Center for Health Marketing, CDC, Atlanta, states, "As hypothesized, health-risk factors – specifically, a higher BMI and a greater number of poor mental-health days – differentiated adult video-game players from nonplayers. Video-game players also reported lower extraversion, consistent with research on adolescents that linked video-game playing to a sedentary lifestyle and overweight status, and to mental-health concerns. Internet community support and time spent online distinguished adult video-game players from nonplayers, a finding consistent with prior research pointing to the willingness of adult video-game enthusiasts to sacrifice real-world social activities to play video games. The data illustrate the need for further research among adults to clarify how to use digital opportunities more effectively to promote health and prevent disease."

In a commentary in the same issue, Brian A. Primack, MD, EdM, MS, from the University of Pittsburgh School of Medicine, applauds Weaver et al. for focusing on the current popularity of video games not only among youth, but also among adults. He suggests that many video games are different enough from original forms of play that they may be better defined as "playlike activities." He writes, "There are noteworthy differences between the oldest forms of play (e.g., chase games) and today's 'playlike activities.' These playlike activities may stimulate the right centers of the brain to be engaging ... However, the differences between today's 'playlike activities' and original forms of play may illuminate some of the observed health-related correlates discovered by Weaver, et al."

Dr. Primack observes that our greatest challenge will be maintaining the balance: "How do we simultaneously help the public steer away from imitation playlike activities, harness the potentially positive aspects of video games, and keep in perspective the overall place of video games in our society? There are massive, powerful industries promoting many playlike activities. And industry giants that can afford to will successfully tout the potential benefits of health-related products they develop. But who will be left to remind us that – for children and adults alike – Hide-And-Seek and Freeze Tag are still probably what we need most?"

The article is "Health-Risk Correlates of Video-Game Playing Among Adults" by James B Weaver III, PhD MPH; Darren Mays, MPH; Stephanie S Weaver, PhD, MPH; Wendi Kannenberg, MPH; Gary L Hopkins, MD DrPH; Dogan Eroglu, PhD; and Jay M Bernhardt, PhD MPH. The commentary is "Video Games: Play or 'Playlike Activity'?" by Brian A Primack, MD, EdM, MS. Both appear in the American Journal of Preventive Medicine, Volume 37, Issue 4 (October 2009) published by Elsevier.