Division of Biological Principles, Department of Physiology, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
Department of Basic Veterinary Science, Laboratory of Physiology, Joint Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
J Smooth Muscle Res. 2023;59:28-33. doi: 10.1540/jsmr.59.28.
Distinct sex differences in the prevalence and symptoms of abnormal bowel habits in patients with irritable bowel syndrome (IBS) have been reported. We have elucidated the sex differences in the regulation of colorectal motility via the central nervous system. Noxious stimuli in the colorectum of anesthetized male rats enhance colorectal motility by activating monoaminergic neurons in descending pain inhibitory pathways from the brainstem to the lumbosacral spinal cord. These monoaminergic neurons release serotonin and dopamine into the lumbosacral spinal cord, resulting in the increment of colorectal motility. In female rats, in contrast, noxious stimuli in the colorectum have no effect on colorectal motility. We clarified that GABAergic inhibition in the lumbosacral spinal cord masks the enhancement of colorectal motility induced by monoamines in female animals. Considering that IBS patients often show visceral hypersensitivity and hyperalgesia, our studies suggest that differences in the descending neurons that respond to painful stimuli are involved in various sex differences in abnormal bowel habits.
已经有报道称，在肠易激综合征（IBS）患者中，异常肠道习惯的发生率和症状存在明显的性别差异。我们已经阐明了通过中枢神经系统对结直肠运动的调节存在性别差异。麻醉雄性大鼠结直肠内的有害刺激通过激活从脑干到腰骶脊髓的下行疼痛抑制通路中的单胺能神经元来增强结直肠运动。这些单胺能神经元将 5-羟色胺和多巴胺释放到腰骶脊髓中，导致结直肠运动增加。相比之下，在雌性大鼠中，结直肠内的有害刺激对结直肠运动没有影响。我们已经阐明，腰骶脊髓中的 GABA 能抑制掩盖了单胺类物质在雌性动物中引起的结直肠运动增强。考虑到 IBS 患者常表现出内脏高敏感性和痛觉过敏，我们的研究表明，对疼痛刺激做出反应的下行神经元的差异可能与异常肠道习惯的各种性别差异有关。
