This study investigated the role of γ-aminobutyric acid subtype B (GABAB) receptors in tibial and pudendal neuromodulation of bladder overactivity induced by intravesical administration of dilute (0.5%) acetic acid (AA) in α-chloralose anesthetized cats. To inhibit bladder overactivity, tibial or pudendal nerve stimulation (TNS or PNS) was applied at 5 Hz and 2 or 4 times threshold (T) intensity for inducing toe or anal sphincter twitch. TNS at 2T or 4T intensity significantly (p<0.05) increased the bladder capacity to 173.8±16.2% or 198.5±24.1%, respectively, of control capacity. Meanwhile, PNS at 2T or 4T intensity significantly (p<0.05) increased the bladder capacity to 217±18.8% and 221.3±22.3% of control capacity, respectively. CGP52432 (a GABAB receptor antagonist) at intravenous dosages of 0.1-1 mg/kg completely removed the TNS inhibition in female cats but had no effect in male cats. CGP52432 administered intravenously also had no effect on control bladder capacity or the pudendal inhibition of bladder overactivity. These results reveal a sex difference of GABAB receptors in tibial neuromodulation of bladder overactivity in cats and that GABAB receptors are not involved in either pudendal neuromodulation or irritation-induced bladder overactivity.
- Copyright © 2016, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology