April 26, 2013

Longer Days Bring ‘Winter Blues’—For Rats, Not Humans




Most of us are familiar with the “winter blues,” the depression-like symptoms known as “seasonal affective disorder,” or SAD, that occurs when the shorter days of winter limit our exposure to natural light and make us more lethargic, irritable and anxious. But for rats it’s just the opposite.

Biologists at UC San Diego have found that rats experience more anxiety and depression when the days grow longer. More importantly, they discovered that the rat’s brain cells adopt a new chemical code when subjected to large changes in the day and night cycle, flipping a switch to allow an entirely different neurotransmitter to stimulate the same part of the brain.