Autonomic neuropathy in BB rats and alterations in bladder function.

In vivo urinary bladder function was examined in BB rats after 4 and 6 mo of diabetes, and the data were correlated with morphometric changes in the pelvic and hypogastric nerves, which constitute the micturition reflex arc. After controlled bladder distension, diabetic animals revealed irregular bladder contractions at frequencies that were reduced to 33% of normal values and with significantly increased amplitudes. The abnormal micturition in diabetic animals was elicited at moderately elevated threshold volumes. These functional abnormalities of the diabetic bladder were associated with a progressive axonopathy of afferent myelinated sensory fibers and later-occurring axonal atrophy of unmyelinated efferent preganglionic fibers. These data suggest that diabetic urinary bladder dysfunction is initiated by a visceral sensory neuropathy involving the afferent limb of the micturition reflex arc.