How Researchers Measure a Mouse's Mood

You know what they say: give a mouse a Zoloft and he'll ask for a Prozac. Give a mouse a Prozac and he'll ask for a Lexapro. But how do researchers determine if the anti-depressent they're developing is actually effective before giving it to people?

It's difficult determining how sad a mouse is because, "a mouse can't tell you how it's feeling," Michael Kaplitt of Cornell Medical College told Scientific American. So, as "Lifting the Black Cloud" author, Robin Henig, explains, the scientific community has developed as series of tests that gauge the animal's mood via proxy. This allows them to determine the general efficiency of a drug's effects.

The Forced Swimming test measures how much "will to live" the animal possesses. It's placed in a water-filled cylinder from which escape is difficult. The longer the mouse swims, the stronger its interpreted will is. If it immediately gives up, the behavior is deemed, "depression-like." And yes, of course the mouse is retrieved from the water before sinking or incurring any harm.

The Tail Suspension test involves hanging a mouse upside down from its tail. The longer the mouse struggles, the less depressed researchers deem it. Less struggling means more depression. However, after giving mice anti-depressants, the animals will struggle longer than before.

The Sugar Water doesn't test depression through negative stimuli like the two methods above, but rather it tests stress levels via a positive stimulus. Mice will almost always consume larger amounts of sugar water than regular water if presented with both. It's like asking an eight-year-old if he wants soda or water. However, mice suffering from chronic stress show no preference to the sweet stuff.

Obviously, these aren't perfect tests. However, until we finish developing machine-readable mice or at least teach them to speak, these methods are the best available for anti-depressant development. [SA via BoingBoing]

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