Elevated Sodium Levels Inhibit Stress Response

CINCINNATIElevated levels of sodium blunt the bodys natural responses to stress by inhibiting stress hormones that would otherwise be activated in stressful situations, according to a new study published in the Journal of Neuroscience.

"We're calling this the Watering Hole Effect," said Eric Krause, PhD, a research assistant professor in the basic science division of the University of Cincinnatis department of psychiatry and behavioral neuroscience and first author of the study. "When you're thirsty, you have to overcome some amount of fear and anxiety to approach a communal water source. And you want to facilitate those interactions that way everyone can get to the water source."

Researchers at the University of Cincinnati dehydrated laboratory rats by giving them sodium chloride and then exposed them to stress. Compared with a control group, the rats that received the sodium chloride secreted fewer stress hormones and also displayed a reduced cardiovascular response to stress. Their blood pressure and heart rate did not go up as much in response to stress as the control group's, and they returned to resting levels more quickly. In a social interaction paradigm with two rats interacting, The rats also were more interactive and less socially anxious in a social interaction paradigm. The researchers also examined brain and blood samples from the rats and found the same hormones that act on kidneys to compensate for dehydration also act on the brain to regulate responsiveness to stressors and social anxiety.

The elevated sodium levelhypernatremialimited stress responses by suppressing the release of the pro-stress hormone angiotensin II. Conversely, it increased the activity of the anti-stress hormone oxytocin.