Modulation of feline bladder and distal urethral responses to dorsal sacral root stimulation by intrathecal administration of a kappa(1)-opioid agonist

Objectives. We examined bladder and distal urethral responses to sacral dorsal root (SDR) electrostimulation with simultaneous intrathecal administration of a kappa(1)-opiate agonist. Methods. Experiments were conducted on 14 spinally intact and 6 chronic spinally transected decerebrated mongrel cats. In the chronically spinalized cats, midthoracic complete spinal cord transection was performed 6 to 8 weeks before the electrostimulation experiments. Sympathetic denervation was carried out by cutting 6 the sympathetic chain and the hypogastric nerve bilaterally. Proximal ends of the cut S1-3DR were stimulated, and bladder pressure and urethral perfusion pressure changes were recorded before and after drug administration. Results, The S2DR electrostimulation in spinally intact cats produced the best vesical contraction, but with dyssynergic urethral response. The magnitude and the pattern of the response changed with the different stimulation parameters. U-50, 488H, a selective kappa(1)-opiate receptor agonist, decreased significantly the bladder and the urethral responses to S2DR stimulation in spinally intact but not in chronic spinally transected cats. Nor-BNI, a kappa antagonist, reversed these responses in spinally intact cats. Conclusions. Our results showed that it is feasible to produce bladder contraction with SDR stimulation and suggest that kappal receptors may have a role in bladder and distal urethral reflexes at the suprasacral level. (C) 1997, Elsevier Science Inc.