The sacral autonomic outflow is sympathetic

Abstract

A kinship between cranial and pelvic visceral nerves of vertebrates has been accepted for a century. Accordingly, sacral preganglionic neurons are considered parasympathetic, as are their targets in the pelvic ganglia that prominently control rectal, bladder, and genital functions. Here, we uncover 15 phenotypic and ontogenetic features that distinguish pre- and postganglionic neurons of the cranial parasympathetic outflow from those of the thoracolumbar sympathetic outflow in mice. By every single one, the sacral outflow is indistinguishable from the thoracolumbar outflow. Thus, the parasympathetic nervous system receives input from cranial nerves exclusively and the sympathetic nervous system from spinal nerves, thoracic to sacral inclusively. This simplified, bipartite architecture offers a new framework to understand pelvic neurophysiology as well as development and evolution of the autonomic nervous system.

Dual origin of enteric neurons in vagal Schwann cell precursors and the sympathetic neural crest

“…Since the major contribution of the sacral crest to the autonomic nervous system, the pelvic ganglion, is entirely sympathetic (31), the trunk crest is sympatho-enteric at both ends (Fig. 5).…”

The sacral parasympathetic system is actually sympathetic—and other updates on recent autonomic research

“…In their publication, Espinosa-Medina et al [1] also reported that various transcription factors in the sacral preganglionic neurons were indistinguishable from those of the thoracolumbar neurons, and much different from those found in the DMV. This transcription factor ''fingerprint'' lends further support to the notion that the sacral outflow is sympathetic from development.…”

“…This ''craniosacral'' outflow model of the parasympathetic system is based on several anatomical and physiological similarities between the outflow of the cranial and sacral autonomic nerves, namely that their target areas are more specific than those of the thoracolumbar sympathetic nerves, that they lack projections to the paravertebral sympathetic chain, and that they are sensitive to muscarinic antagonists. This doctrine has been disputed recently by Espinosa-Medina and colleagues in an article published in the November 2016 issue of Science [1].…”

The sacral autonomic outflow: against premature oversimplification

“…Based on these data, they have put forward the idea that the preganglionic and postganglionic neurons of the autonomic nervous system in the sacral spinal cord and in the pelvic ganglia are sympathetic and not parasympathetic [1]. This idea seemingly challenges the traditional view established originally by Langley [2,3] that the peripheral parasympathetic and sympathetic pathways are defined anatomically by the location of the preganglionic neurons in the spinal cord and brain stem.…”