Spinal pathways mediate coordinated bladder/urethral sphincter activity during reflex micturition in decerebrate and spinalized neonatal rats.

Coordination between the urinary bladder and the external urethral sphincter is necessary for normal voiding. However, it is uncertain whether the spinal cord or brainstem generates this coordination. Bladder and urethral sphincter activity were examined during reflex voiding induced by perineal stimulation or bladder distension in decerebrate non-spinalized and spinalized 15 to 26-day-old neonatal rats. Perineal stimulation induced voiding and coordinated bladder/sphincter activity in both types of rats, indicating that spinal pathways can generate coordinated voiding behavior. The discoordination observed during voiding induced by bladder distension in spinalized pups may be due to the loss of descending pathways or to the emergence of detrimental spinal reflexes.