Objective: To apply stereotactic electrical stimulation of the pig brainstem and thus identify a pontine micturition centre.
Materials and methods: In 10 anaesthetized female Vietnamese minipigs a needle-electrode was positioned in the pontine region. Pressure responses in the lower urinary tract identified the micturition centre functionally during electrical stimulation. Stereotactic coordinates were recorded, and the needle visualized by fluoroscopy, magnetic resonance imaging (MRI) or histologically.
Results: The stimulation evoked responses similar to voiding, i.e. a urethral pressure decrease followed by a bladder pressure increase; or similar to a continence manoeuvre, i.e. urethral pressure increase and no change in bladder pressure. In a few cases a continence response was evoked by stimulating a site 1 mm away from the site where a voiding response was evoked. The electrode position was detected by the fluoroscopy-based stereotactic procedure followed by subsequent MRI (one animal), and by histological analysis, verifying it to be in the dorsolateral pontine region.
Conclusions: These results show that a pontine micturition centre exists in pigs similar to that described in rats, cats, dogs and humans.