2012 Fiscal Year Final Research Report
Investigation for novel nerve circuit related to urinary urgency in cold environmental stimulation
| Project/Area Number |
23791771
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Urology
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| Research Institution | Nagoya City University |
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Principal Investigator |
TAKADA Masa 名古屋市立大学, 大学院・医学研究科, 研究員 (60468254)
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| Project Period (FY) |
2011 – 2012
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| Keywords | 過活動膀胱 / 神経回路 / 尿意切迫感 / 後根神経節 / 一次知覚感覚神経線維 / 二分岐軸索 / 逆行性神経トレーサー |
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| Research Abstract |
Cold sensation occasionally evokes urinary urgency. Earlier studies in rats have reported the marked hyperactivity of the detrusor muscle owing to cold stress. There may be a solid link between the temperature reception of the skin and the bladder response. Bladder contraction can be provoked by manual stimulation of certain areas within sacral and lumbar dermatomes in patients with spinal cord injury; such trigger voiding also suggests close interactions between these organs. To reveal the mechanism of urinary urgency evoked by cold sensation, we investigated the convergence of the primary sensory afferents of the skin and bladder. Dichotomizing afferents of L6-S1 dorsal root ganglion neurons that innervate the skin and bladder was constantly observed with retrograde neuron tracers in rats. In-situ hybridization revealed that approximately 8.0% of the double-labeled cells expressed transient receptor potential channel melastatin member 8 (TRPM8) transcripts in the dorsal root ganglions. Cold and menthol stimuli to the skin generated bladder nerve responses conducted through dichotomizing axons. Taken together, TRPM8-expressing sensory neurons with dichotomizing axons projecting to the skin and bladder may be responsible for the urinary urgency evoked by cold sensation.
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