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Descending projections from the nucleus raphe obscurus to pudendal motoneurons in the male rat.
- Source :
-
The Journal of comparative neurology [J Comp Neurol] 1998 Aug 10; Vol. 397 (4), pp. 458-74. - Publication Year :
- 1998
-
Abstract
- Previous physiological and behavioral studies have shown that the nucleus raphe obscurus (nRO) modulates pelvic floor reflex function (Yamanouchi and Kakeyama [1992] Physiol. Behav. 51:575-579; Beattie et al. [1996] Soc. Neurosci. Abstr. 22:722.4; Holmes et al. [1997] Brain Res. 759:197-204). In the present study, small injections of fluorescent tracers were used to investigate direct descending projections from the rostral and caudal portions of the brainstem nRO to retrogradely labeled pudendal motoneurons (MN) in the male rat. The caudal nRO projects into the ventral and lateral funiculi of the spinal cord, with arborizations in the thoracic intermediolateral cell column; in laminae VII, IX, and X of the lumbosacral cord; and in the sacral parasympathetic nucleus (SPN). Many identified external anal sphincter and ischiocavernosus MNs appeared to be in direct apposition with fibers originating from the caudal nRO; and more than half of the bulbospongiosus MNs that were identified appeared to receive such descending input. In addition to the nRO spinal autonomic and pudendal motoneuronal targets, projections were observed to regions of the intermediate gray that contain interneurons organizing the pelvic floor reflexes and to MN pools that are involved in functionally related somatic activities. Finally, several neurons in the lumbar enlargement were labeled retrogradely with FluoroRuby after injections into the nRO and the immediately adjacent reticular formation. Thus, the nRO may be in a position to modulate the coordinated actions of autonomic preganglionic and functionally related skeletal MN activity involved in sexual and eliminative reflex functions.
- Subjects :
- Animals
Autonomic Fibers, Preganglionic physiology
Dextrans
Efferent Pathways physiology
Fluorescent Dyes
Interneurons physiology
Lumbosacral Region
Male
Rats, Inbred Strains
Reflex physiology
Rhodamines
Spinal Cord physiology
Thorax
Motor Neurons physiology
Pelvis innervation
Raphe Nuclei physiology
Rats physiology
Synaptic Transmission physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9967
- Volume :
- 397
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- The Journal of comparative neurology
- Publication Type :
- Academic Journal
- Accession number :
- 9699910