Galanin is known to be associated with mental health. People born with genetically low levels of galanin are at unusually high risk of depression and anxiety disorders.
Several studies show that exercise increases the production of the substance. In the rat experiments, some of which were carried out in Dr. Wine hangers carried out, the researchers found that exercise resulted in an increase in galanin production in the animals' brains, particularly in a part of the brain known to be involved in physiological stress responses. Perhaps most interesting was that the rats' subsequent stress resistance is greater the more galanin is present.
For the new research, they collected healthy adult male and female mice and gave some of them access to exercise bikes in their cages. Others remained inactive. Mice generally seem to enjoy running, and those with wheels scurry several miles each day. After three weeks, the scientists looked for genetic markers for galanin in the mouse brain and found that these were much higher in runners, with greater mileage correlating with more galanin.
Then the scientists emphasized all of the animals by slightly shocking their paws while the mice were restrained and unable to run away. This method does not physically harm the mice, but rather scares them, which the scientists confirmed by checking the mice for stress hormones. They had risen.
The next day, scientists put runners and inactive animals in new situations to re-alarm them, including cages with light, open sections and dark, enclosed areas. Mice are prey and their natural response is to run into the dark and then, when they feel safe, explore the open spaces. The runners now reacted like normal, healthy mice and moved carefully towards the light. But the sedentary animals tended to crouch in the shadows, still too stressful to explore. They lacked resilience.
Finally, the researchers confirmed that galanin plays a crucial role in the stress resistance of the animals by breeding mice with unusually high substance levels. Like runners, these rodents responded to the stress of foot shocks with whole-body floods of stress hormones. But the next day, like the runners, they cautiously defy the well-lit parts of the light-dark cage, not ruthlessly, but with appropriate caution.
The result of these experiments is that abundant galanin appears to be critical to resilience, at least in rodents, says Rachel P. Tillage, Ph.D. Candidate in Dr. Weinshenker's lab who led the new study. And exercise enhances gallantry and strengthens the ability of animals to stand firm in the face of all the obstacles life and science present.