Biological and Biomedical Sciences Program, Cornell University, Ithaca, NY 14853, USA.
Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA; Cornell Neurotech, Cornell University, Ithaca, NY 14853, USA.
Curr Biol. 2023 Nov 20;33(22):4926-4936.e4. doi: 10.1016/j.cub.2023.09.071. Epub 2023 Oct 20.
Sexual stimulation triggers changes in female physiology and behavior, including sexual satiety and preparing the uterus for pregnancy. Serotonin (5-HT) is an important regulator of reproductive physiology and sexual receptivity, but the relationship between sexual stimulation and 5-HT neural activity in females is poorly understood. Here, we investigated dorsal raphe 5-HT neural activity in female mice during sexual behavior. We found that 5-HT neural activity in mating females peaked specifically upon male ejaculation and remained elevated above baseline until disengagement. Artificial intravaginal mechanical stimulation was sufficient to elicit increased 5-HT neural activity but the delivery of ejaculatory fluids was not. Distal penis expansion ("penile cupping") at ejaculation and forceful expulsion of ejaculatory fluid each provided sufficient mechanical stimulation to elicit 5-HT neuron activation. Our study identifies a female ejaculation-specific signal in a major neuromodulatory system and shows that intravaginal mechanosensory stimulation is necessary and sufficient to drive this signal.
性刺激会引发女性生理和行为的变化，包括性满足和为怀孕做准备。血清素（5-HT）是生殖生理学和性接受度的重要调节剂，但性刺激和女性 5-HT 神经活动之间的关系还知之甚少。在这里，我们研究了雌性小鼠在性行为期间中缝背核 5-HT 神经活动。我们发现，交配雌性的 5-HT 神经活动在雄性射精时特异性地达到峰值，并保持在基线以上，直到分离。人工阴道内机械刺激足以引起 5-HT 神经活动增加，但射精时并不需要传递精液。射精时的远端阴茎扩张（“阴茎杯状”）和射精时的强力射出精液都提供了足够的机械刺激，引起 5-HT 神经元激活。我们的研究在一个主要的神经调质系统中确定了一个与女性射精特异性相关的信号，并表明阴道内机械感觉刺激是必要且充分的驱动因素。
