PARASYMPATHETIC PREGANGLIONIC NEURONS IN THE SPINAL-CORD INVOLVED IN UTERINE INNERVATION ARE CHOLINERGIC AND NITRIC OXIDE-CONTAINING

Background: The purpose of this study was to elucidate parasympathetic preganglionic neurons in the spinal cord that project axons in pathwa ys to the uterus and to reveal their neurotransmitter phenotype. Metho ds: ''Uterine-related'' neurons were identified by using a combination of retrograde axonal tracers: (1) Fluorogold injected into the gangli a of termination of preganglionic fibers, and (2) a transganglionic ax onal tracer (pseudorabies virus) injected into the uterus. Immunohisto chemistry was used to reveal virus-labeled neurons and their neurotran smitter marker. Results: Double-labeled (Fluorogold + pseudorabies vir us) ''uterine'' preganglionic neurons were identified in the sacral pa rasympathetic nucleus of the rat lumbosacral spinal cord, Subpopulatio ns of neurons in the sacral parasympathetic nucleus were shown to be i mmunoreactive for choline acetyltransferase or nitric oxide synthase. Double-staining immunohistochemistry (for pseudorabies virus + neurotr ansmitter enzyme) revealed that some of the uterine-related preganglio nic neurons were cholinergic and some nitric oxide synthase-containing . Conclusions: These results demonstrate a subpopulation of preganglio nic parasympathetic neurons in the sacral parasympathetic nucleus that are involved in uterine innervation. In addition, both acetylcholine and nitric oxide could be used to modify activity in the postganglioni c neurons, which directly innervate the uterus. (C) 1995 Wiley-Liss, I nc.