a white ratScientists have established that exercise can alter the brain’s structure, but what about a lack of exercise? A study from Wayne State University School of Medicine, in collaboration with other institutions, documented changes in the brain in a group of sedentary rats. The findings may lead to greater understanding of how a sedentary lifestyle affects humans.

The focus of the study was a part of the brain called the rostral ventrolateral medulla, which manages the sympathetic nervous system. This area of the brain has primarily been studied in animals, but imaging studies suggest that humans have the same region performing similar functions. The sympathetic nervous system takes its cues for blood flow and other tasks from the rostral ventrolateral medulla, but when its messages are garbled, the result can be high blood pressure or heart disease.

The researchers monitored 12 rats for three months. Half of the rats lived in cages equipped with a running wheel, while the other half did not have access to a wheel. After the three months passed, the rats were injected with a dye designed to color a particular type of neuron. The scientists analyzed the rats’ brains, using a computer program to create a digital model.

There were significant differences between the two groups of rats, especially in the shape of the neurons in the rostral ventrolateral medulla. While the active rats’ brains stayed essentially the same, the sedentary rats had an abnormally large amount of neuronal growth; the neurons sprouted an excessive number of branches, forming connections to other healthy neurons. This made the rats more sensitive to stimuli and resulted in unnecessary signals to the sympathetic nervous system.

Although the study is limited in scope, it adds to the body of knowledge about the brain’s neuroplasticity, especially in regards to exercise or a lack thereof. The results indicate that sedentary behavior affects the brain at the cellular level, which is a big step in understanding just what exercise does for the body.

This study is published in The Journal of Comparative Neurology.

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