Barrington's nucleus: a century of progress identifying neurons that control micturition

Barrington's nucleus (Bar) is a small population of neurons in the brainstem that elicit micturition. Its function was localized a century ago using focal lesions in cats. Bar neurons form a small cluster in the dorsal pontine tegmentum, medial to the locus coeruleus. Their axons project to the lumbosacral spinal cord, where they stimulate neurons that contract the bladder and relax the external urethral sphincter. Bar neurons are glutamatergic, with subpopulations expressing Crh (BarCrh) or Esr1 (BarEsr1). BarCrh neurons promote bladder contraction, while BarEsr1 neurons may trigger sphincter relaxation in addition to bladder contraction. These neurons integrate information from many other brain regions, which form a larger network controlling micturition. Expanding our knowledge of this network will enhance understanding and future treatment of neurologic diseases that impair bladder control. Here, we review advances in our understanding from J.F. Barrington's original work a century ago to now.