Sad Fat Rats

Or “We are not alone”

Rats and mice are valuable experimental animals, as they share so much biologically with us – but they’re not particularly good subjects for studying Seasonal Affective Depression. Mice are nocturnal, and do most of their running around at times when their melatonin levels are high – when we’re safely asleep. Accordingly, two researchers, Prof. Noga Kronfeld-Schor of Tel Aviv University and, Prof. Haim Einat of the University of Minnesota decided to look at using a diurnal experimental subject, the Fat Sand Rat (Psammomys obesus) a relative of the gerbil native to the middle east and north africa.Sad Fat Rat

They found the rats would develop symptoms matching Winter Blues when given simulated shorter winter , and better yet would, respond to light therapy in a way simular to human sufferers. This doesn’t mean we’re any closer to effective treatments, but it is good to have an animal subject which behaves analogously to humans.

One important point to take away is that this helps us eliminate the possibility of light therapy’s efficacy being due to the placebo effect, as the sand rats are unlikely to have been able to divine the researcher’s intentions. There is, of course, the possibility that the sand rats are just depressed because people keep calling them fat.

Tal Ashkenazy, Haim Einat, Noga Kronfeld-Schor. We are in the dark here: induction of depression- and anxiety-like behaviours in the diurnal fat sand rat, by short daylight or melatonin injections. The International Journal of Neuropsychopharmacology, 2008; 12 (01): 83 DOI: 10.1017/S1461145708009115

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