AB299. SPR-26 Micturition and defecation behavior following pelvic decentralization in a canine model

Objective: We demonstrated motor reinnervation of the decentralized canine urinary bladder by increased detrusor pressure induced by electrical stimulation of the transferred genitofemoral or femoral nerves in 21 of 28 animals. We previously reported evidence of bladder and bowel fullness sensation in these new neuronal pathways based on observation of micturition and defecation postures in the reinnervated animals. Our focus here was to determine whether these postures are eliminated in decentralized animals.

Methods: The pelvis was decentralized by bilateral transection of the hypogastric nerves and all spinal nerve roots caudal to L7 in 6 female canines. A separate group of 6 female canines was decentralized identically with the additional bilateral transection of L7 dorsal roots. Video surveillance of the housing cages allowed measurement of the frequency and duration of urination and defecation postures at monthly intervals post operatively (PO) by observers blinded to the surgical interventions.

Results: In the 6 animals with intact L7 dorsal roots, 3 displayed micturition postures 1 month, 6/6 at 2 and 3 months and 5/6 at 4 months PO. In the 6 animals with the additional L7 dorsal root transections, micturition postures were observed in 2/6 at 1 and 2 months and 3/6 at 3 and 4 months PO. In the L7 dorsal root intact animals, defecation postures were observed in 0/6 at 1 month and 2/6 at 2, 3 and 4 months PO. In the L7 dorsal root transected group, 1/6 showed defecation postures at 1 and 2 months but not at 4 months, and 1/6 showed these postures at 3 and 4 months PO.

Conclusions: In the L7 dorsal root intact animals, although half were unable to sense bladder fullness and 0/6 could not sense bowel fullness at 1 month PO, all were able to sense bladder fullness at 2 and 3 months and all but 1 at 4 months PO, suggesting sprouting of sensory bladder innervation likely from the remaining lower lumbar dorsal root fibers. Fewer dogs with L7 dorsal root transected were able to detect bladder fullness. The ability of 3/6 animals in the L7 dorsal root transected group to sense bladder fullness at 2–4 months PO may be from sensory nerve sprouting or variations in the bladder sensory innervation, as we described previously. Bowel fullness sensation appears to be primarily mediated by sacral sensory innervation.

Funding Source(s): NIH 1R01NS070267

Keywords: Innervation; bladder; colon; neural plasticity; dog