A new Loyola study has found that exposing adolescent rats to binge amounts of alcohol permanently altered the system that produces hormones in response to stress. This disruption in stress hormones “might lead to behavioral and/or mood disorders in adulthood,” researchers reported.
Senior author Toni R. Pak, PhD, and colleagues reported their findings Nov. 15 at the annual meeting of the Society for Neuroscience in San Diego.
Though results from animal studies don’t directly translate to people, the findings do suggest a mechanism by which teenage binge drinking could cause mental health problems in adulthood, Pak said.
“Exposing young people to alcohol could permanently disrupt normal connections in the brain that need to be made to ensure healthy adult brain function,” Pak said.
Binge drinking is defined as a woman having at least four drinks or a man having at least five drinks on one occasion. Heavy binge drinkers can consume 10 to 15 drinks. Binge drinking typically begins around age 13 and peaks between 18 and 22, before gradually decreasing. Thirty-six percent of youths ages 18 to 20 reported at least one binge-drinking episode during the last 30 days, according to the Substance Abuse and Mental Health Services Administration.
The Loyola study examined the long-term effects of alcohol on the production of the stress hormone corticosterone in rats. (The equivalent stress hormone in humans is cortisol).
Humans and rats produce stress hormones in response to physical or psychological stress. For example, in a “fight-or-flight” situation, a jolt of cortisol provides a burst of energy and a lower sensitivity to pain, while suppressing functions that aren’t immediately needed, such as digestion. However, chronic exposure to cortisol and other stress hormones has been linked to depression, cardiovascular disease and other problems.
In the study, researchers exposed adolescent rats to an eight-day binge-drinking pattern: three days of alcohol bingeing, two days off, then three more days of bingeing. On binge days, rats were injected with enough alcohol to raise their blood-alcohol concentration to between 0.15 percent and 0.2 percent. (In humans such concentrations would be approximately 2 to 2.5 times higher than the 0.08 legal limit for driving.) A control group of rats received injections of saline.
One month later, when the rats were young adults, they were exposed to one of three regimens: saline injections, a one-time alcohol injection or a binge-pattern of alcohol exposure. Alcohol is a stressor for the body, so not surprisingly, the animals that had either a one-time or binge alcohol exposure produced more of the corticosterone stress hormone. A more significant finding is that among rats that had received alcohol during adolescence, there was a significantly larger spike in corticosterone when they received alcohol during adulthood. These rats also had a lower base level of corticosterone than rats that had remained sober during adolescence. These findings suggest that alcohol exposure during puberty permanently alters the system by which the brain triggers the body to produce stress hormones.
Pak is a molecular neurobiologist and an assistant professor in the Department of Cell and Molecular Physiology at Loyola University Chicago Stritch School of Medicine. Two members of her lab are co-authors of the study: first author Magdalena Przybycien-Szymanska, a PhD student, and Roberta Gillespie, a research assistant.
Based in the western suburbs of Chicago, Loyola University Health System is a quaternary care system with a 61-acre main medical center campus, the 36-acre Gottlieb Memorial Hospital campus and 28 primary and specialty care facilities in Cook, Will and DuPage counties. The medical center campus is conveniently located in Maywood, 13 miles west of the Chicago Loop and 8 miles east of Oak Brook, Ill. The heart of the medical center campus, Loyola University Hospital, is a 569-licensed-bed facility. It houses a Level 1 Trauma Center, a Burn Center and the Ronald McDonald® Children’s Hospital of Loyola University Medical Center. Also on campus are the Cardinal Bernardin Cancer Center, Loyola Outpatient Center, Center for Heart & Vascular Medicine and Loyola Oral Health Center as well as the LUC Stritch School of Medicine, the LUC Marcella Niehoff School of Nursing and the Loyola Center for Fitness. Loyola’s Gottlieb Memorial Hospital campus in Melrose Park includes the 264-bed community hospital, the Gottlieb Center for Fitness and the Marjorie G. Weinberg Cancer Care Center.