| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2012: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2011: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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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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