Autonomic neuroscience : basic & clinical
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Effects of gentle skin stimulation of various segmental areas on the micturition contractions of the urinary bladder were examined in anesthetized male rats. The bladder was expanded by infusing saline via urethral cannula until the bladder produced rhythmic micturition contractions as a consequence of rhythmic burst discharges of vesical pelvic efferent nerves. Gentle stimulation was applied for 1 min by slowly rolling on top of skin with an elastomer "roller". ⋯ We recorded unitary afferent activity from cutaneous branches of the pudendal nerve and found that the fibers excited by stimulation were low-threshold mechanoreceptive Aβ, Aδ and C fibers. Discharge rates of afferent C fibers (7.9 Hz) were significantly higher than those of Aβ (2.2 Hz) and Aδ (2.9 Hz) afferents. The results suggest that low frequency excitation of low threshold cutaneous mechanoreceptive myelinated and unmyelinated fibers inhibits a vesico-pelvic parasympathetic reflex, mainly via release of opioids, leading to inhibition of micturition contraction.