Abstract
Barrington's nucleus (Bar), which controls micturition behavior through downstream projections to the spinal cord, contains two types of projection neurons, BarCRH and BarESR1, that have different functions and target different spinal circuitry. Both types of neurons project to the L6-S1 spinal intermediolateral (IML) nucleus, whereas BarESR1 neurons also project to the dorsal commissural nucleus (DCN). To obtain more information about the spinal circuits targeted by Bar, we used patch-clamp recording in spinal slices from adult mice in combination with optogenetic stimulation of Bar terminals. Recording of opto-evoked excitatory postsynaptic currents (oEPSCs) in 1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine, 4-chlorobenzenesulfonate (DiI)-labeled lumbosacral preganglionic neurons (LS-PGNs) revealed that both Bar neuronal populations make strong glutamatergic monosynaptic connections with LS-PGNs, whereas BarESR1 neurons also elicited smaller-amplitude glutamatergic polysynaptic oEPSCs or polysynaptic opto-evoked inhibitory postsynaptic currents (oIPSCs) in some LS-PGNs. Optical stimulation of BarCRH and BarESR1 terminals also elicited monosynaptic oEPSCs and polysynaptic oIPSCs in sacral DCN neurons, some of which must include interneurons projecting to either the IML or ventral horn. Application of capsaicin increased opto-evoked firing during repetitive stimulation of Bar terminals through the modulation of spontaneous postsynaptic currents in LS-PGNs. In conclusion, our experiments have provided insights into the synaptic mechanisms underlying the integration of inputs from Bar to autonomic circuitry in the lumbosacral spinal cord that may control micturition.NEW & NOTEWORTHY Photostimulation of BarCRH or BarESR1 axons in the adult mouse spinal cord elicits excitatory or inhibitory postsynaptic responses in multiple cell types related to the autonomic nervous system including preganglionic neurons (PGNs) in the lumbosacral intermediolateral nucleus and interneurons in the lumbosacral dorsal commissure nucleus. Integration of excitatory inputs from Bar and from visceral primary afferents in PGNs may be important in the regulation of micturition behavior.
Highlights
Activity of the pelvic viscera including the urogenital organs and distal bowel is controlled by autonomic pathways in the lumbosacral spinal cord
In BarESR1 stimulation experiments opto-evoked excitatory postsynaptic currents (oEPSCs) elicited in 8 of 11 cells were suppressed by TTX application and reversed by TTX þ 4-action potentials (APs) application (À182.6 ± 58.9 pA, À3.1 ± 2.0 pA, À230.4 ± 76.0 pA, respectively; n = 8; Fig. 3, E and F), but in the remaining 3 cells the responses were not reversed by TTX þ 4-AP (À130.2 ± 21.3, –1.6 ± 1.6, and À5.1 ± 3.0 pA, respectively; Supplemental Fig. S6). These results indicate that BarESR1 has polysynaptic connections to lumbosacral preganglionic neurons (LS-preganglionic neurons (PGNs)), as well as the monosynaptic connections that were detected in the BarCRH pathway
Barrington’s nucleus (Bar), which contains at least two types of neurons (BarCRH and BarESR1) that send axons to the lumbosacral spinal cord, potentially controls various types of pelvic organ functions including those of the urogenital system
Summary
Activity of the pelvic viscera including the urogenital organs and distal bowel is controlled by autonomic pathways in the lumbosacral spinal cord. Lumbosacral parasympathetic preganglionic neurons (LS-PGNs) that send axons through the pelvic nerves induce micturition, defecation, and penile erection, whereas lumbar sympathetic PGNs that send axons into the sympathetic chain and hypogastric nerves modulate these functions. At the level of the spinal cord, PGN activity is regulated by primary afferent input from the peripheral organs and by segmental interneuronal circuitry. These reflex mechanisms are in turn regulated by input from the brain. An important supraspinal pathway for the regulation of micturition [1,2,3,4,5] and possibly other pelvic visceral functions [6, 7] originates in Barrington’s nucleus (Bar) located in the rostral pons. Bar contains two types of spinal projection neurons identified by the expression of either corticotropinreleasing hormone (CRH, BarCRH) or estrogen receptor 1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
