; C( B5 |% x, H I5 Q% t/ r4 [* c' k; gPleasant stimulation of skin serves important social functions in mammals, but has received less attention from molecular neurobiologists than the response to noxious stimuli. Now David Anderson and colleagues have used calcium imaging in live mice to show that a small population of sensory neurons in hairy skin — expressing the G-protein-coupled receptor MRGPRB4 — responds specifically to strokes from a small paintbrush intended to simulate natural stroking or grooming, but not to pinching or poking stimuli, which activate a different population of sensory neurons expressing MRGPRD. Pharmacological stimulation of MRGPRB4+ neurons elicits positive reinforcing behavioural effects. The 'stroke-sensitive' neurons resemble C-tactile afferents, unmyelinated mechanoreceptive neurons found in hairy skin of humans and other mammals. The functional characterization of this novel population of neurons opens the way to identifying molecular transduction mechanisms and neural circuitry associated with a positive affective state — or pleasure. On the cover, monkeys by a river in Angkor, Cambodia (Roberto Westbrook/Blend Images/Corbis).; v- ^3 l5 u( r- @$ q! s 作者: yuhaoze 时间: 2013-2-1 13:30
