Abstract:

Objective To investigate the effect of 5-hydroxytryptamine (5-HT) on the spontaneous and mechanosensitive activity of bladder afferent nerves. Methods The effects of intravesical instillation of different concentrations of 5-HT on the spontaneous and distension-induced pelvic afferent nerve activity were observed in the isolated rat bladder/pelvic nerve preparations. Results At rest, with the bladder empty, there was little background activity (<10 imp/s) in the pelvic nerve branch innervating the bladder. During ramp distension, the afferent nerve activity increased progressively as the intravesical pressure rose. Intraluminal instillation of 0.1 mL 5-HT (1 to 30 μmol/L) caused an increase of the ongoing afferent discharge and potentiated the low threshold (0-15 mmHg) mechanosensory responses in a concentration-dependent manner. Conclusion 5-HT directly activates low threshold bladder afferent fibers in the pelvic nerve, and can potentiate their mechanosensitivity.

Key words: 5-hydroxytryptamine receptor, bladder afferent nerve, mechanosensitivity, bladder/pelvic nerve preparations