Pleasurable touch is paramount during social behavior, including sexual encounters. However, the identity and precise role of sensory neurons that transduce sexual touch remain unknown. A population of sensory neurons labeled by developmental expression of the G protein-coupled receptor Mrgprb4 detects mechanical stimulation in mice. Here, we study the social relevance of Mrgprb4-lineage neurons and reveal that these neurons are required for sexual receptivity and sufficient to induce dopamine release in the brain. Even in social isolation, optogenetic stimulation of Mrgprb4-lineage neurons through the back skin is sufficient to induce a conditioned place preference and a striking dorsiflexion resembling the lordotic copulatory posture. In the absence of Mrgprb4-lineage neurons, female mice no longer find male mounts rewarding: sexual receptivity is supplanted by aggression and a coincident decline in dopamine release in the nucleus accumbens. Together, these findings establish that Mrgprb4-lineage neurons initiate a skin-to-brain circuit encoding the rewarding quality of social touch.

令人愉悦的触摸在社交行为（包括性接触）中至关重要。然而，传导性接触的感觉神经元的身份和确切作用仍然未知。由 G 蛋白偶联受体 Mrgprb4 发育表达标记的感觉神经元群可检测小鼠的机械刺激。在这里，我们研究了 Mrgprb4 谱系神经元的社会相关性，并揭示这些神经元是性接受所必需的，并且足以诱导大脑中多巴胺的释放。即使在社会隔离的情况下，通过背部皮肤对 Mrgprb4 谱系神经元进行光遗传学刺激也足以诱导条件性位置偏好和类似于前凸交配姿势的惊人背屈。在缺乏 Mrgprb4 谱系神经元的情况下，雌性小鼠不再觉得雄性坐骑有回报：性接受能力被攻击性所取代，伏隔核中多巴胺释放同时下降。总之，这些发现表明，Mrgprb4 谱系神经元启动了编码社交接触的奖励质量的皮肤到大脑回路。