Galanin and neurokinin-1 receptor immunoreactive [corrected] spinal neurons controlling the prostate and the bulbospongiosus muscle identified by transsynaptic labeling in the rat.
Ejaculation requires the coordination of sympathetic, parasympathetic and somatic neural outputs. Timely occurrence of the emission and expulsion of sperm results from an interplay between spinal nuclei innervating the seminal tract and the sexual accessory glands including the prostate on the one hand, and on the other hand perineal striated muscles, particularly the bulbospongiosus muscle. A group of cells essential for ejaculation, located around the central canal and referred to as lumbar spinothalamic neurons have been recently identified. Lumbar spinothalamic neurons are immunoreactive for galanin and neurokinin-1 receptor. In order to investigate the anatomical relationships between lumbar spinothalamic neurons and both the prostate and the bulbospongiosus muscle, pseudorabies virus retrograde tracing technique was used combined with immunohistochemistry. Three to five days after pseudorabies virus injection in the bulbospongiosus muscle or the prostate in male rats, spinal cord sections were processed for double immunofluorescence against pseudorabies virus and galanin or neurokinin-1 receptor. Immunocytochemical experiments against pseudorabies virus and choline acetyltransferase were also performed to discriminate between motoneurons and preganglionic neurons, or interneurons. Spinal sections were examined with confocal laser scanning microscope. Three days after pseudorabies virus injection within the prostate and the bulbospongiosus muscle, sympathetic preganglionic neurons and motoneurons of the dorsomedial nucleus were retrogradely labeled, respectively. Five days after pseudorabies virus injection, transsynaptically labeled choline acetyltransferase-negative neurons were found mainly located in the medial gray surrounding the central canal from L1 to S1. At the L3-L4 level, most of transsynaptically labeled neurons were immunoreactive for galanin and to a lesser extent for neurokinin-1 receptor, strongly suggesting that they could be the lumbar spinothalamic cells. We have thus evidenced connections between these cells and motoneurons of the dorsomedial nucleus and both sympathetic and parasympathetic preganglionic neurons innervating the bulbospongiosus muscle and the prostate, respectively. These anatomical data reinforce the crucial role for lumbar spinothalamic cells in coordinating the spinal control of ejaculation.
Xu
C
C
Groupe de Recherche en Urologie, UPRESS EA 1602, Faculté de Médecine Paris-Sud, Le Kremlin-Bicêtre, France.
Yaici
E D
ED
Conrath
M
M
Blanchard
P
P
Leclerc
P
P
Benoît
G
G
Vergé
D
D
Giuliano
F
F
D000818:Animals; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004542:Ejaculation / Q000502:physiology*; D007150:Immunohistochemistry; D008161:Lumbosacral Region; D008297:Male; D018613:Microscopy, Confocal; D018482:Muscle, Skeletal / Q000294:innervation; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D011467:Prostate / Q000294:innervation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044088:Receptors, Galanin / Q000378:metabolism*; D018040:Receptors, Neurokinin-1 / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology
D044088:Receptors, Galanin; D018040:Receptors, Neurokinin-1; D002795:Choline O-Acetyltransferase