An American team has highlighted, in mice, the role of neurons under the skin and followed their path to the center of the reward in the brain.
by Nathaniel Herzberg
The satisfaction of a massage, the delight of a touching, the sweetness of a caress … The ability of touch to cause almost immediate pleasure may seem obvious. For neuroscientists, however, it remains largely mysterious. The path that leads from our epidermis to the center of the reward, in the depths of our brain, remains strewn with questions.
in window An article published on January 23 in the review Cell , an American team announces that it has traced the complete route of what it calls “the touch of pleasure and sexual receptivity”. As always, these pioneering works were carried out on the mouse. But they display the promise of an understanding of the phenomenon in humans and even new treatments and manual therapies.
It all started in 2018, in the Ishmail Abdus-Saboor laboratory, at the University of Pennsylvania, in the United States. Specializing in the study of pain, the researcher had offered a young Thésarde, Leah Elias, to look at the role of specific sensory cells called MRGPRB4. Highlights in 2007, these neurons had no known utility. The student undertook to study them by optogenetics. This delicate but now usual technique consists in modifying the neurons in order to activate them then by a simple colorful light radius, and therefore to follow the effects. “To our big surprise, by activating these sensory neurons on the back of female mice, they took a posture of lordosis,” says the young researcher, now postdoctorating at Johns-Hopkins university.
GPR83 neurons, intermediate link
usual in the eyes of yoga enthusiasts and cat owners, lordosis, in mice, is the position taken by the female to promote penetration by a male. Should it be a feeling of pleasure? The team continued the experiment in a study chamber by activating the light on the animal, then extracted it from the room. When she did it again, the rodent went directly to the place where he had been enlightened. A serious index of the rewarding nature of the activation of these neurons.
Interrupted by the COVVI-19 pandemic, research resumed in 2021. This time, the team undertook to genetically modify the mice in order to remove the activity of the MRGPRB4 neurons. Not only has lordosis disappeared, but females have become hostile to the sexual approaches of males.
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