Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China.
Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China.; Department of Dermatology, The 958(th) Hospital of PLA, Chongqing, 400020, China.
Exp Neurol. 2022 Aug;354:114101. doi: 10.1016/j.expneurol.2022.114101. Epub 2022 Apr 30.
Itch is an unpleasant sensation that induces the desire to scratch. Except for a sketchy map focusing on neural mechanisms underlying itch processing being drawn at the peripheral and spinal level over the past decades, the brain mechanisms remain poorly understood. Several previous studies indicated that anterior cingulate cortex (ACC) and prelimbic cortex (PrL), two subregions of the medial prefrontal cortex (mPFC) play an important role in regulating itch processing. However, the knowledge about whether infralimbic cortex (IL), another subregion of mPFC, is involved in modulating itch processing remains unclear. Here, we showed that the activity of IL excitatory pyramidal neurons was significantly elevated during itch-related scratching, and pharmacogenetic inhibition of IL pyramidal neurons significantly impaired itch-related scratching. Moreover, IL-medial striatum (MS) projections were verified as a critical neural pathway for modulating itch processing. Therefore, the present study firstly presents the regulatory function of IL pyramidal neurons during itch processing and also reveals that IL-MS projections are involved in modulating the itch processing.
痒是一种不愉快的感觉，会引起搔抓的欲望。除了过去几十年在周围和脊髓水平上对瘙痒处理的神经机制进行了粗略的研究外，大脑机制仍知之甚少。几项先前的研究表明，扣带前皮质 (ACC) 和前扣带皮层 (PrL)，即内侧前额叶皮质 (mPFC) 的两个亚区，在调节瘙痒处理中起着重要作用。然而，关于 mPFC 的另一个亚区——下边缘皮层 (IL) 是否参与调节瘙痒处理的知识尚不清楚。在这里，我们表明，在与瘙痒相关的搔抓过程中，IL 兴奋性锥体神经元的活动显著升高，而 IL 锥体神经元的药理学抑制显著损害了与瘙痒相关的搔抓。此外，还验证了 IL-内侧纹状体 (MS) 投射作为调节瘙痒处理的关键神经通路。因此，本研究首次提出了 IL 锥体神经元在瘙痒处理过程中的调节作用，也揭示了 IL-MS 投射参与调节瘙痒处理。
