Effects of pruritogens and algogens on rostral ventromedial medullary ON and OFF cells
Effects of pruritogens and algogens on rostral ventromedial medullary ON and OFF cells
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DOI：
10.1152/jn.00208.2018
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发表时间：
2018-11-01
影响因子：
2.5
通讯作者：
Carstens, E.
中科院分区：
文献类型：
--
作者：
Follansbee, T.;Akiyama, G. T.;Carstens, E.
延髓头端腹内侧（RVM）ON和OFF细胞被认为分别促进和抑制脊髓伤害性传递。然而，目前尚不清楚ON和OFF细胞如何响应瘙痒刺激或它们如何有助于脊髓瘙痒信号的下行调节。在戊巴比妥钠麻醉的小鼠中，在RVM中从ON和OFF细胞中进行单单位记录，通过它们各自的增加或减少的放电来识别，这些放电发生在由爪捏引起的伤害性后肢缩回之前。皮内组胺对RVMON细胞的兴奋率为75%（21/28）。氯喹皮内注射组为50%（10/20），辣椒素皮内注射组为75%（27/36）。大多数化学反应单位也响应于施加到注射后爪的抓挠刺激。少数ON细胞对皮内注射媒介物（盐水：5/32;吐温2/17）有反应，但仍对抓挠有反应。对于OFF细胞。皮内组胺和搔抓抑制32%（6/19），其余组胺无作用。皮内注射氯喹抑制44%（4/9）的OFF细胞，皮内注射辣椒素抑制61%（11/18）的OFF细胞。少数OFF细胞受到溶剂的影响（吐温：1例受抑制，7例未受影响;生理盐水：3例受兴奋，1例受抑制，8例未受影响）。对一种化学物质有反应的ON和OFF细胞通常也对其他化学物质有反应，而对第一种化学物质无反应的细胞往往对其他化学物质没有反应。这些结果表明，上行性伤害感受信号激活RVM ON细胞并抑制RVM OFF细胞。这些作用被认为分别促进和抑制脊柱疼痛传递。目前尚不清楚是否脊髓瘙痒传输同样modulated.NEW &值得注意的是，延髓头端腹内侧（RVM）包含ON和OFF细胞，分别是兴奋和抑制的伤害性刺激，并有下降的预测，促进和抑制脊髓伤害性传递。皮内注射致敏原组胺和氯喹以及致敏原辣椒素，可使大多数RVM ON细胞兴奋，而OFF细胞则受到抑制。这些结果表明，瘙痒刺激会激活RVM神经元，这可能会引起脊髓瘙痒传递的下降调节。
Rostroventromedial medulla (RVM) ON and OFF cells are thought to facilitate and inhibit spinal nociceptive transmission, respectively. However, it is unknown how ON and OFF cells respond to pruritic stimuli or how they contribute to descending modulation of spinal itch signaling. In pentobarbital sodium-anesthetized mice, single-unit recordings were made in RVM from ON and OFF cells identified by their respective increase or decrease in firing that occurred just before nocifensive hindlimb withdrawal elicited by paw pinch. Of RVM ON cells, 75% (21/28) were excited by intradermal histamine. 50% (10/20) by intradermal chloroquine, and 75% (27/36) by intradermal capsaicin. Most chemically responsive units also responded to a scratch stimulus applied to the injected hindpaw. Few ON cells responded to intradermal injection of vehicle (saline: 5/32; Tween 2/17) but still responded to scratching. For OFF cells. intradermal histamine and scratching inhibited 32% (6/19) with no effect of histamine in the remainder. Intradermal chloroquine inhibited 44% (4/9) and intradermal capsaicin inhibited 61% (11/18) of OFF cells. Few OFF cells were affected by vehicles (Tween: 1 inhibited, 7 unaffected; saline: 3 excited, 1 inhibited, 8 unaffected). Both ON and OFF cells that responded to one chemical usually also responded to others, whereas units unresponsive to the first-tested chemical tended not to respond to others. These results indicate that ascending pruriceptive signals activate RVM ON cells and inhibit RVM OFF cells. These effects are considered to facilitate and disinhibit spinal pain transmission, respectively. It is currently not clear if spinal itch transmission is similarly modulated.NEW & NOTEWORTHY The rostroventromedial medulla (RVM) contains ON and OFF cells that are, respectively, excited and inhibited by noxious stimuli and have descending projections that facilitate and inhibit spinal nociceptive transmission. Most RVM ON cells were excited, and OFF cells inhibited, by intradermal injection of the pruritogens histamine and chloroquine, as well as the algogen capsaicin. These results indicate that itchy stimuli activate RVM neurons that presumably give rise to descending modulation of spinal itch transmission.