Exercise improves the ability to persevere through hard times. In a series of recent experiments, UGA neuroscientists have begun to unravel the link between long-term stress resilience and exercise.
The study, published in the journal Neuropharmacology, reveals that a neuropeptide, a molecule used by neurons to communicate with each other, is a necessary piece of the puzzle. That neuropeptide is called galanin.
Researchers demonstrated, in an animal model, that galanin protects neurons from degeneration caused by stress. When rats exercised, and galanin was blocked, the rats were as anxious as if they hadn’t exercised at all. Researchers also showed that galanin reverses the negative effects of stress among sedentary rats. The anatomical evidence suggests that galanin contributes to stress resilience by preserving the way neural connections are strengthened or weakened over time, a process called synaptic plasticity.
“We were able to show that stress, just a single exposure to stress, caused a decrease in synapse formation,” said Philip Holmes, the study’s principal investigator and a professor of psychology in the Franklin College of Arts and Sciences.
The team, which included the paper’s first author, Natale Sciolino, used mild foot shocks and a plus-shaped maze to measure anxiety-like behavior in the rats. Stressed rats that exercised or received galanin were more willing to explore the maze, a sign of resilience. Stressed sedentary rats, however, did not want to explore. In one experiment, researchers gave rats that exercised a drug to prevent the action of galanin, and these rats stayed put as often as the sedentary group.
“We found this protective effect of exercise, but we could block it with the galanin antagonist, so that was really exciting because that told us that galanin was necessary for the beneficial effects of exercise,” Holmes said.
Sciolino, who was finishing her doctorate at the time of the experiment, began investigating the connection between exercise and galanin after Holmes and David Weinshenker, a professor of human genetics at Emory University, received a grant from the National Institute on Drug Abuse for addiction research in 2010.
“We know that stress is the most common cause of relapse in people with drug dependence, and we were able to show that either exercise or galanin decreased relapse-like behavior in rats given cocaine, so the ability of exercise-induced galanin to reduce stress makes sense,” Weinshenker said.