Brainstem neurons coordinate the bladder and urethra sphincter for urination

Abstract Urination, a vital and conserved process of emptying urine from the urinary bladder in mammals, requires precise coordination between the bladder and external urethral sphincter (EUS) that is tightly controlled by a complex neural network. However, the specific subpopulation of neurons that accounts for such coordination remains unidentified, limiting the development of target-specific therapies for certain urination disorders, e.g., detrusor-sphincter dyssynergia. Here, we find that cells expressing estrogen receptor 1 (ESR1+) in the pontine micturition center (PMC) initiate voiding when activated and suspend ongoing voiding when suppressed, each at 100% reliability. Transection of the pelvic nerve does not impair PMCESR1+ neurons’ control of the EUS via the pudendal nerve, whereas transection of the pudendal nerve does not impair their control of the bladder via the pelvic nerve. Anatomically, PMCESR1+ neurons consist of three distinct spinal-projection-based subpopulations: one targeting the sacral parasympathetic nucleus (SPN), one innervating the dorsal gray commissure (DGC), and a third that projects to both regions, thereby enforcing the coordination of bladder contraction and sphincter relaxation in a rigid temporal sequence. Thus, we identify a cell type in the brainstem that controls the bladder-urethra coordination for urination. Competing Interest Statement The authors have declared no competing interest. Footnotes (1) We repeated retrograde tracing using CTB-647 to verify precise targeting of SPN and DGC neurons, as shown in the new Figure 7. (2) We performed dual retrograde tracing combined with fiber photometry or optogenetic activation to investigate the role of PMC dual-projecting neurons in the control of urination, as shown in Figure supplements 11 and 12. (3) We conducted new experiments activating PMCESR1+ neurons after PDNx to assess their role in urination, as shown in new Figure 6. (4) We added a more detailed analysis of the dynamics of neural responses in PMCESR1+ neurons in Figure supplements 3F and 3G. (5) We analyzed peak Ca2+ signals in the PMC during and after the onset of EMG bursting, as shown in Figure supplement 4F. (6) We added a comparison of spontaneous and light-induced spikes in PMCESR1+ neurons, as shown in Figure supplements 3B and 3C. (7) We expanded the Discussion to address how PMCESR1+ neurons coordinate bladder contraction and sphincter relaxation to control both the initiation and suspension of urination.