Thirst Reduces Stress Response: “The Watering Hole Effect”

Assuming this is conserved in humans, the following passage might suggest that it’s better that you walk into an interview a little bit thirsty:

“We’re calling this the Watering Hole Effect,” says Eric Krause, PhD, a research assistant professor in the basic science division of UC’s 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.”

Krause and his team dehydrated laboratory rats by giving them sodium chloride, 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,” says Krause.

“Also, in a social interaction paradigm with two rats interacting, we found them to be more interactive and less socially anxious.”

Further research, through examination of brain and blood samples from the rats, showed that 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 level, known as hypernatremia, limited stress responses by suppressing the release of the pro-stress hormone angiotensin II. Conversely, it increased the activity of oxytocin, an anti-stress hormone. (via.)

Thanks to hugthemonkey for pointing this one out on Twitter. Susan also posted a link to this interesting gem recently: A study led by Jillian O’Connor, a graduate student in the Department of Psychology, Neuroscience & Behaviour at McMaster University, found that people think they can predict whether a mate will cheat by listening to tone of voice.

Stress-related Gene (MKP-1 or MKP1), Depression, and Heat Stress

Duman’s team did whole genome scans on tissue samples from 21 deceased individuals who had been diagnosed with depression and compared gene expression levels to those of 18 individuals who had not been diagnosed with depression. They found that one gene called MKP-1 was increased more than two-fold in the brain tissues of depressed individuals.

This was particularly exciting, say the researchers, because the gene inactivates a molecular pathway crucial to the survival and function of neurons and its impairment has been implicated in depression as well as other disorders. Duman’s team also found that when the MKP-1 gene is knocked out in mice, the mice become resilient to stress. When the gene is activated, mice exhibit symptoms that mimic depression.

The finding that a negative regulator of a key neuronal signaling pathway is increased in depression also identifies MKP-1 as a potential target for a novel class of therapeutic agents, particularly for treatment resistant depression. (via.)

Interesting tidbits from elsewhere: