Intrinsic neuromuscular defects in the neurogenic bladder: IX. Effects of combined parasympathetic decentralization and hypogastric neurectomy on neuromuscular ultrastructure of the feline bladder base

Abstract

AbstractPrevious studies have shown that unilateral decentralization of the feline bladder by sacral ventral rhizotomy results in ultrastructural neuromuscular changes in the bladder base. In the present study, the neuromuscular ultrastructure of the feline bladder base was studied in twenty sexually mature adult male cats 1–4 and 6–10 weeks following bilateral sacral rhizotomy, alone and combined with hypogastric neurectomy. The former procedure resulted in initial degeneration of cholinergic axons with loss of their neuroeffector junctions, but the adrenergic axons and neuroeffector junctions were preserved; within 6–10 weeks, the bladder base became re‐innervated by regenerated cholinergic, increased adrenergic, and abundant probable copeptidergic axons. In contrast, combined sacral rhizotomy and hypogastric neurectomy resulted in persistent (up to 10 weeks) degeneration of both cholinergic and adrenergic axons with loss of their neuroeffector junctions, and no adrenergic hyperinnervation, with only a modest increase in probable copeptidergic axons in long‐term samples. Our observations indicate that intact efferent sympathetic pathways are essential for eventual cholinergic re‐innervation and adrenergic hyperinnervation of the decentralized bladder and suggest that the latter is an important factor in the development of vesical hypertonicity in lower‐motor neuron lesions. On this basis, we introduce the concept that two functional types of the lower motor neurogenic bladder–i.e., the hypertonic with intact and the normotonic with injured efferent sympathetic pathways–may be distinguishable morphologically by ultrastructural study of the vesical muscularis.