IDENTIFICATION OF CENTRAL-NERVOUS-SYSTEM NEURONS THAT INNERVATE THE BLADDER BODY, BLADDER BASE, OR EXTERNAL URETHRAL SPHINCTER OF FEMALE RATS - A TRANSNEURONAL TRACING STUDY USING PSEUDORABIES VIRUS

Transneuronal tracing techniques were used to identify the putative sp inal and brainstem neurons involved in continence and voiding in the f emale rat. Pseudorabies virus, Bartha's K strain, was injected into ei ther the external urethral sphincter, the bladder base, or the bladder body. After 3-5 days, the rats were perfused with fixative, and virus -labelled cells were identified by using immunohistochemistry. Externa l urethral sphincter (EUS) injections resulted in labelling of pudenda l motoneurons in the dorsolateral nucleus of L6. Putative spinal inter neurons were found in the medial cord from T13 to S1 and in the latera l gray of T13-L2 and L5-S1. After both bladder base and bladder body i njections, the majority of pseudorabies virus-labelled cells were foun d in the lateral gray and medial cord of L6-S1. A number of those foun d in the intermediolateral cell column resembled the parasympathetic p reganglionic neurons; the remaining neurons in the lateral and medial gray were presumed to be interneurons. Very few pseudorabies virus-lab elled cells were found rostral to T10. In the brainstem, transneuronal ly labelled cells were found in the parapyramidal medullary reticular formation, Barrington's nucleus, raphe magnus, raphe pallidus, subcoer uleus pars alpha, locus coeruleus, the A5 noradrenergic cell group, an d ventromedial periaqueductal gray after all injection sites. Pseudora bies virus-labelled cells were also seen in the forebrain following th e longest survival times; areas consistently labelled included the lat eral hypothalamus, the parvocellular region of the paraventricular nuc leus, and the medial preoptic area. These studies indicate that there is a substantial overlap of central nervous system neurons that innerv ate the EUS and the bladder in the female. (C) 1997 Wiley-Liss, Inc.