title: Effect of electrical vs. chemical deep brain stimulation at midbrain sites on micturition in anaesthetized rats.
abstract: OBJECTIVE
  To understand how deep brain stimulation of the midbrain influences control of the urinary bladder.
  
  
  METHODS
  In urethane-anaesthetized male rats, saline was infused continuously into the bladder to evoke cycles of filling and voiding. The effect of electrical (0.1-2.0 ms pulses, 5-180 Hz, 0.5-2.5 V) compared to chemical stimulation (microinjection of D,L-homocysteic acid, 50 nL 0.1 M solution) at the same midbrain sites was tested.
  
  
  RESULTS
  Electrical stimulation of the periaqueductal grey matter and surrounding midbrain disrupted normal coordinated voiding activity in detrusor and sphincters muscles and suppressed urine output. The effect occurred within seconds was reversible and not secondary to cardiorespiratory changes. Bladder compliance remained unchanged. Chemical stimulation over the same area using microinjection of D,L-homocysteic acid (DLH) to preferentially activate somatodendritic receptors decreased the frequency of micturition but did not disrupt the coordinated pattern of voiding. In contrast, chemical stimulation within the caudal ventrolateral periaqueductal grey, in the area where critical synapses in the micturition reflex pathway are located, increased the frequency of micturition.
  
  
  CONCLUSIONS
  Electrical deep brain stimulation within the midbrain can inhibit reflex micturition. We suggest that the applied stimulus entrained activity in the neural circuitry locally, thereby imposing an unphysiological pattern of activity. In a way similar to the use of electrical signals to 'jam' radio transmission, this may prevent a synchronized pattern of efferent activity being transmitted to the spinal outflows to orchestrate a coordinated voiding response. Further experiments to record neuronal firing in the midbrain during the deep brain stimulation will be necessary to test this hypothesis.
authors.affiliation: School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK.
authors.forename: E
authors.initials: E
authors.lastname: Stone
authors.forename: J H
authors.initials: JH
authors.lastname: Coote
authors.forename: T A
authors.initials: TA
authors.lastname: Lovick
mesh_terms: D000818:Animals; D046690:Deep Brain Stimulation / Q000379:methods*; D004558:Electric Stimulation; D006710:Homocysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000502:physiology*; D014554:Urination / Q000187:drug effects / Q000502:physiology*
chemical_list: D006710:Homocysteine; C007956:homocysteic acid
keywords: D,L-homocysteic acid; deep brain stimulation; micturition; periaqueductal grey matter; rat