The pelvic organs receive no parasympathetic innervation

Area of Science:

• Neuroscience
• Autonomic Nervous System Research
• Pelvic Organ Innervation

Background:

• The pelvic organs have traditionally been understood to receive autonomic innervation via lumbar sympathetic and sacral parasympathetic pathways.
• These pathways were believed to converge at the pelvic ganglion, a structure conceptualized as a mix of sympathetic and parasympathetic neurons.

Purpose of the Study:

• To investigate the cellular composition and functional identity of neurons within the mouse pelvic ganglion.
• To re-evaluate the established model of pelvic organ innervation.

Main Methods:

• Single-cell RNA sequencing (scRNA-seq) was employed to analyze the transcriptomic profiles of pelvic ganglion neurons.
• Immunohistochemistry and tracing techniques were used to identify neuronal subtypes and their connections.

Main Results:

• The mouse pelvic ganglion comprises four distinct neuronal classes, genetically dissimilar from classical sympathetic and parasympathetic neurons.
• These neurons exhibit a genetic profile suggesting a closer relationship to sympathetic neurons.
• Lumbar preganglionic neurons synapse onto both noradrenergic and cholinergic cells within the pelvic ganglion, indicating they function as sympathetic relays.

Conclusions:

• Pelvic viscera are innervated not by parasympathetic or typical sympathetic neurons, but by a specialized extension of the sympathetic nervous system.
• This divergent sympathetic pathway is responsible for the unique functions of pelvic organs.