New research in mice finds that a single workout activates a brain circuit associated with a lower appetite, lower blood sugar levels, and better metabolism. Moreover, this effect lasted for 2 days after the workout. The findings may help improve blood sugar metabolism in people with diabetes.
In excess of 30 million U.S. adults have diabetes, and more than 84 million have prediabetes. According to the CDC, prediabetes can evolve into diabetes within 5 years.
Controlling blood sugar levels with physical activity and diet is key to managing or preventing diabetes. However, new research suggests that we may need less physical activity than we might think to achieve these health benefits.
Dr. Kevin Williams, a neuroscientist at the University of Texas Southwestern in Dallas, is the corresponding and last author of the new study. Dr. Williams and colleagues examined the effects of a single bout of exercise on two types of neurons in mice.
The neurons make up the so-called melanocortin brain circuit, which humans share with rodents. The neurons in the circuit are hypothalamic pro-opiomelanocortin (POMC) neurons and neuropeptide Y/agouti-related peptide (NPY/AgRP) neurons.
Scientists have linked POMC neurons with a lower appetite, reduced blood sugar levels, and a more active metabolism. NPY/AgRP neurons, on the other hand, have an association with an increase in appetite and a slower metabolism.
Dr. Williams and colleagues published their findings in the journal Molecular Metabolism.
How exercise improves glucose metabolism
Scientists have previously studied the properties of the melanocortin brain circuit in relation to diet and fasting, but they have not investigated how physical exercise affects these neurons.
So, Dr. Williams and team examined the brain activity and neuronal firing rate in transgenic mice after a workout consisting of three, consecutive, 20-minute sessions of treadmill running.
They found that the single bout of exercise activated rodents’ POMC neurons, but deactivated the appetite-boosting NPY/AgRP neurons. The scientists noticed these neuronal changes lasted for up to 2 days.
“It doesn’t take much exercise to alter the activity of these neurons,” explains Dr. Williams. The researchers also trained the mice for periods ranging from zero to 10 days and found that the neuronal effects lasted longer if the training period was longer.
Finally, the metabolism-boosting POMC neurons stayed active for longer if they also expressed leptin receptors. Leptin is a metabolic hormone that previous research has shown is of benefit to the synapses of POMC neurons.
“Based on our results, we would predict that getting out and exercising even once in a semi-intense manner can reap benefits that can last for days, in particular with respect to glucose metabolism.”
Dr. Kevin Williams
Findings may benefit people with diabetes
The rodents also lost their appetite after the workout. This effect lasted for up to 6 hours after working out. Dr. Williams comments, “This result may explain at the neural circuit level why many people don’t feel hungry immediately after exercise.”
Dr. Williams continues to comment on the benefits of the findings for metabolic conditions. “This research is not just for improving fitness,” he says, adding, “A better understanding of neural links to exercise can potentially help a number of conditions affected by glucose regulation.”
“It is possible that activating melanocortin neurons may hold therapeutic benefits for patients one day, especially for [people with diabetes] who need improved blood-glucose regulation.”
Dr. Kevin Williams