“Enkephalinergic Neurons Gate Sex-Specific Control of Voluntary Micturition”

Lower urinary tract (LUT) control is a vital physiological function, governed by a complex interplay between neural circuits and muscle activity. This regulation depends on brainstem circuits, with Barrington’s nucleus (Bar) acting as a central hub. Here, we construct a transcriptional atlas of Bar to resolve the neuronal diversity and characterize a distinct excitatory, enkephalinergic population (Bar ^Penk ). Using in vivo calcium imaging and optogenetics, we show that Bar ^Penk neurons are selectively active during voiding and promote external urethral sphincter (EUS) relaxation. Chemogenetic activation of these neurons elicits an aberrant micturition phenotype in male but not female mice, while conditional ablation disrupts voluntary scent-marking behavior. Moreover, anatomical tracing reveals that Bar ^Penk projections target spinal regions critical for LUT control and receive convergent input from areas involved in visceromotor control and behavioral state processing. These findings position Bar ^Penk neurons as a specialized brainstem population that integrates internal state and environmental cues to shape context-dependent urinary behavior in a sex-specific manner.