Mice avoid the scent of men
Can ketamine have an antidepressant effect in mice? That depends, among other things, on whether a man or a woman administers the drug. The male smell makes the difference.
The scientists from the University of Maryland actually wanted to test how ketamine affects depressed mice. Studies had already suggested a soothing effect. However, Tedd Gould's team failed to replicate their own results as well as those of other research groups, and began to track it down.
In retrospect, a clear pattern emerged: if a male subject had administered ketamine to mice, an antidepressant effect emerged. If, on the other hand, the subject was a woman, there was no effect. The team already knew that the gender of the experimenter can influence the stress and behavioural responses of rodents. The group wanted to investigate this and started an experiment: randomly, either a man or a woman administered ketamine or a placebo to the animals. Then a third person subjected the rodents to a behavioural test. To everyone's surprise, only the mice that had received the ketamine from a man were actually less depressed. To be absolutely sure, the working group repeated the experiment several times with different people and also at other universities - the result was always the same.
In the following, Gould and his colleagues found that mice have an aversion to the smell of men and a preference for that of women. In addition, the animals were more susceptible to stress when touched by a male experimenter. And stress affects the effect of ketamine, the team found: Corticotropin-releasing hormone (CRH) mediates stress responses and is released in the entorhinal cortex in response to male scent. If the researchers increased CRH activity, this enhanced the antidepressant effect of ketamine. Many other unknown factors could have influenced the results, as the authors note in Nature Neuroscience. However, they recommend that the gender of the investigator be included in the methods section of animal studies and, if possible, that this variable be taken into account statistically. They also say the discovery could lead to new treatment approaches, such as the administration of ketamine in combination with substances that activate the CRH receptor.
Spectrum of Science
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Originalartikel auf Spektrum.deTitelbild: © unoL / Getty Images / iStock (Ausschnitt) Mäuse reagieren stressanfälliger bei einem Experiment, wenn ein Mann den Versuch durchführt (Symbolbild)
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