IU study uncovers hamster habits

Running on stationary wheels and scurrying through plastic mazes appears to be only the beginning of notable hamster activities. \nIn an experiment, IU Assistant Professor of Biology Gregory Demas found illness in Siberian hamsters suppresses hunger, but the animals continue to hoard food. The study was released Oct. 17 by the Indiana Academy of Science.\nThe IAS publishes a yearly journal and "encourages young scientists to participate," IU spokesman David Bricker said.\nThe experiment was headed by Demas with the aid of undergraduate research scientists Al Durazzo and Kevin Proud. \n"There appears to be an important biological link between energy availability and immune function and likely disease resistance," Demas said.\nFunding was provided by an IU Undergraduate Research and Creative Activity Partnership grant to Durazzo and Proud, along with a North American Association for the Study of Obesity research grant to Demas. Conducted over the course of about six months, the study explored the behavior of Siberian hamsters because of their extensive foraging abilities. \n"Unlike more commonly studied rodents (rats, house mice) in which food hoarding is not a substantial part of their behavioral repertoire, Siberian hamsters are prodigious hoarders and can hoard four to five times more food than they actually consume," Demas said.\nA group of control hamsters were compared to those who were injected with pathogenic materials. The hamsters in the experimental group continued their foraging habits at levels similar to their previous frequency. This questions the notion that illness causes a complete aversion to food. \nIn the past, scientists have shown how the immune system causes increased body temperature as well as increased sleep. Many have theorized that decreased food intake during illness is symbolic of a lost motivation to consume food.\nThe new findings suggest the possibility of specifically treating loss of hunger in order to combat weight loss throughout prolonged illnesses. A study released by Demas in March showed that minor decreases in fat tissues have the potential to increase susceptibility to disease. \nReduced food intake has also been shown to be part of an adaptive response that allows an organism to overcome infection, Demas said.\nParticular nutrients such as zinc and iron, although beneficial for the immune system, can benefit the growth of many pathogens as well. The natural defense of decreasing initial food intake is productive as long as the illness does not persist for an extended period of time. If it does, and fat reserves like those in the March study are depleted, the defense may become counterproductive.\nIn the hunger study, the hamsters returned to their usual consumption rates after gaining back their original health. This suggests that they had enough stored fat to avoid increased susceptibility and also to triumph over the illness by essentially starving it. \n"Because sick humans display many of the same symptoms as non-human animals, these results have the potential to provide important clues as to the physiological and behavioral mechanisms of sickness in humans," Demas said.\nIAS meetings have been held annually for more than 100 years and members recognize the importance of continued research and technology. The potential links between animals and humans add to the importance of this scientific aim. According to IAS' Web site, it shares a desire to ensure that science and scientists play a major role in the growth of Indiana.\nAll of the rodents used in the study were treated in accordance with the guidelines set forth by the National Institute of Health for the ethical and humane treatment of animals. In addition, the project was sanctioned by the local Institutional Animal Care and Use Committee.\n-- Contact staff writer Tim Callahan at tmcallah@indiana.edu.