Rat Experiment May Hold Key to Stress Management

By Middlebury Campus

Author: Meghan Keenan

Spring Break gave many students the opportunity to relax, de-stress and return to a normal routine far from the frenzy that consumed life during mid-terms. But wouldn’t life be so much easier if we could better understand where exactly this stress comes from and how better to deal with it? Research Scholar in Biology Dana Helmreich is currently working here at Middlebury to demystify the origin of stress and determine its most efficient and positive effects.
Beginning during her post-doctoral years at Michigan State in 1998, Helmreich has been conducting experiments to measure stress levels in rats in hopes of understanding the chemical effects of stress within the human body. Her main goal, she said, is to learn “whether all stress impacts the brain in the same way.” By examining the rats’ reactions to stressful situations, Helmreich seeks to pinpoint the mechanisms in the human brain and endocrine system that are affected by stress.
Her experiment places two rats in adjacent cages and differentiates between an “executive” and a “yoked” rat. The “executive” rat is administered a mild electric shock (a low-level, irritating buzzing sensation) which is terminated when the rat presses a lever. The “yoked” rat also receives a shock of equal intensity, but holds no control over the ending of the shock and relies completely on the “executive” rat to stop the shock. Using blood samples, Helmreich then tests hormone levels in areas such as the hypothalamus and thyroid to determine differences in the psychological responses between the two animals.
Helmreich has found that differences do exist both chemically and physically between the two animals. Chemically, a change in thyroid access for the animals causes hormones to be released in different levels, thereby affecting the animals’ response. Physically, the “yoked” animal tends to display signs of learned helplessness. Due to its lack of control in a stressful situation, such as the one created by the shock inducement, the “yoked” rat develops difficulties in learning new responses in new situations. Although these reactions may change according to what specific day or situation in which the rat is placed, the “yoked” rats do not generally develop positive reactions to stress and do not effectively learn to deal with new, stressful situations, Helmreich said.
So what does this all mean for stressed out students attempting to cram for exams? Helmreich notes that “a stress response is normal and when one can control stress, then stress provides energy.” By perceiving stress from a controlled perspective and by applying stress positively to a situation, a student can benefit from the activating powers of stress. However, problems arise when one loses control over stress and lets it take over one’s body. Normally, stress progresses on a bell curve of hormone levels, beginning at a low point and increasing until they reach a peak, where the hormone levels remain until they are brought under control by the body. The body begins to react negatively when the hormone levels remain at the peak level and are unable to return to lower, safer levels. One’s perception of and reaction to stress become extremely important in controlling the negative effects of stress.
Scientifically, this experiment provides many clues that will eventually help to unlock the mystery of stress. Ethically, though, experiments such as this one raise questions regarding the treatment of the rats and whether a benefit truly-exists that warrants placing the rats under potentially harmful conditions. According to Helmreich, however, the rats used in this experiment are “given the best care available.” In order to obtain the necessary grants for this experiment, Helmreich submitted protocols to both the federal government and to Middlebury’s chapter of the Institutional Animal Codes for Use and Care(IACUC). Headed by faculty member Chris Waters, the IACUC consists of Middlebury professors, as well as a licensed veterinarian from the Middlebury community, and reviews every experiment involving animals on campus. The IACUC also provides an extensive guidebook outlining the proper procedures concerning animal treatment.
Helmreich says she is genuinely interested in figuring out how the human brain works, and sees enough similarity between the brains of humans and rats to believe that her experiments will help the scientific community further understand the human brain’s inner workings. She administers the lowest level of stress stimulus possible to the rats and equates the feeling as not even nearing the intensity of the shock received by an electric dog fence. Although Helmreich has yet to come to a conclusion regarding the results of her experiment, she continues to look at stress effects so that one day people everywhere will be able to positively control their stress reactions.