Transneuronal labeling of neurons in the adult rat brainstem and spinal cord after injection of pseudorabies virus into the urethra

Abstract

Transneuronal tracing techniques were used to identify sites in the central nervous system involved in the neural control of urethral function. The distribution of virus-infected neurons was examined in the spinal cord and brainstem at various intervals (56-96 hours) following pseudorabies virus (PRV) injection into the urethra. In the lumbosacral (L6-S1) spinal cord at 56 hours, neurons containing PRV immunoreactivity (PRV-IR) were located in the region of the sacral parasympathetic nucleus (SPN), around the central canal, and in the dorsal commissure. Some animals also exhibited PRV-IR in cells in the L6 dorsolateral motor nucleus. At longer survival times (72-96 hours), PRV-IR cells were observed in the superficial and deeper laminae of the dorsal horn, and increased numbers of PRV-IR cells were consistently detected in the region of the SPN, around the central canal, and in the dorsal commissure. PRV-IR fiber-like staining also occurred along the lateral edge of the dorsal horn extending from Lissauer's tract to the region of the SPN. In rostral lumbar segments (L1-L2), PRV-IR cells were located in the region of the dorsal commissure and the intermediolateral cell nucleus (IML), around the central canal, and in the dorsal horn. After 72-84 hours, PRV-IR cells were also noted at more rostral levels of the neuraxis including the medulla, pons, midbrain, and diencephalon. At 72 hours, PRV-IR cells were consistently observed in Barrington's nucleus (pontine micturition center), nucleus raphe magnus (RMg), parapyramidal reticular formation, and the A5 and A7 regions. At 78-84 hours, additional regions exhibited PRV-IR cells, including the periaqueductal gray, locus coeruleus, the dorsal and ventral subcoeruleus alpha, and the red nucleus. A few cells were also located in the lateral hypothalamic area. This distribution of PRV-labeled cells in the spinal cord and brainstem is similar in many respects to the distribution of cells labeled in previous studies by PRV injection into the urinary bladder. This overlap of urethra and bladder neurons is consistent with the results of physiological experiments indicating a close coordination between the central nervous control of bladder and urethral activity.

Transplantation of Neuronal and Glial Restricted Precursors into Contused Spinal Cord Improves Bladder and Motor Functions, Decreases Thermal Hypersensitivity, and Modifies Intraspinal Circuitry

“…Several sites in the brainstem project serotonergic axons into the lumbosacral spinal cord. These pathways, particularly those projecting to the DL, have been implicated in the central control of bladder and urethra and recovery of bladder-external urethral sphincter coordination in SCI rats (Ding et al, 1995;Vizzard et al, 1995;Nadelhaft and Vera, 1996;Marson, 1997;Pikov and Wrathall, 2001). 5-HT-positive fibers in the DL were more densely distributed in NRP/GRP compared with OP-controls but less than in unoperated controls rats.…”

“…We also analyzed lumbosacral regions to determine whether these grafts would modify axonal growth from host pathways. Brainstem nuclei project corticotrophin releasing factor (CRF) containing axons (Valentino et al, 1996(Valentino et al, , 2000, serotonergic (Marson, 1997) and noradrenergic (Vizzard et al, 1995;Marson, 1997) axons to regions in the lumbosacral spinal cord, particularly the spinal parasympathetic nucleus (SPN) and the dorsolateral nucleus (DL) (Nadelhaft and Booth, 1984;Vizzard et al, 1995;Ding et al, 1997;Marson, 1997) that together coordinate the activity of the bladder and urethral sphincter (Pikov and Wrathall, 2001). Some of these modulatory pathways also project to locomotor centers in lumbar spinal cord.…”

The roles of herpes simplex virus in neuroscience

“…(Norgren Jr and Lehman, 1989;Strack and Loewy, 1990). However, careful analyses from several transneuronal tracing studies which contain proper controls have demonstrated the use of herpes viruses to identify transneuronal connections (for example, Strack et al, 1989;Spencer et al, 1990;Jansen et al, 1992;Loewy et al, 1991;Rotto-Percelay et al, 1992;Schramm et al, 1993;Hedner et al, 1993;Vizzard et al, 1995).…”

Neural Control of the Lower Urinary Tract

“…in several regions of the hypothalamus after injection of PRV into the LUT in animals (463,604,664). Histochemical studies using tracers also revealed that neurons in the PMC receive input from the caudal hypothalamus and that the paraventricular hypothalamic nucleus projects nonspecifically to all autonomic preganglionic motor neurons in the spinal cord, including the sacral parasympathetic and sphincter motor nuclei (270).…”

“…Transneuronal PRV tracing methods have also identified many populations of neurons in the rat brain that are involved in the control of bladder (460,462,463,604), urethra (664), and the EUS (402,461,462), including the PMC (Barrington's nucleus), PAG, medullary raphe nuclei, which contain serotonergic neurons; the locus coeruleus (LC), which contains noradrenergic neurons, and the A5 noradrenergic cell group (Fig. 11).…”