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Lesley Marson - One of the best experts on this subject based on the ideXlab platform.
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Identification of CNS Neurons Innervating the Levator Ani and Ventral Bulbospongiosus Muscles in Male Rats
The journal of sexual medicine, 2013Co-Authors: Amy D. Dobberfuhl, Hirotaka Sakamoto, Takumi Oti, Lesley MarsonAbstract:Abstract Introduction The pelvic striated muscles play an important role in mediating erections and ejaculation, and together these muscles compose a tightly coordinated neuromuscular system that is androgen sensitive and sexually dimorphic. Aim To identify spinal and brains neurons involved in the control of the levator ani (LA) and bulbospongiosus (BS) in the male adult and preadolescent rat. Methods Rats were anesthetized, and the transsynaptic retrograde tracer pseudorabies virus (PRV) was injected into the LA muscle of adults or the ventral BS muscle in 30‐day‐old rats. After 3–5 days rats were sacrificed, and PRV‐labeled neurons in the spinal cords and brains were identified using immunohistochemistry. The presence of gastrin‐releasing peptide (GRP) in the lumbar spinal neurons was examined. Main Outcomes Measures The location and number of PRV‐labeled neurons in the spinal cord and brain and GRP colocalization in the lumbar spinal cord. Results PRV‐labeled spinal interneurons were found distributed throughout T11‐S1 of the spinal cord, subsequent to dorsal medial motoneuron infection. The majority of spinal interneurons were found in the lumbosacral spinal cord in the region of the dorsal Gray Commissure and parasympathetic preganglionic neurons. Preadolescent rats had more PRV‐labeled spinal interneurons at L5‐S1 where the motoneurons were located but relatively less spread rostrally in the spinal cord compared with adults. Lumbar spinothalmic neurons in medial Gray of L3‐L4 co‐localized PRV and GRP. In the brain consistent labeling was seen in areas known to be involved in male sexual behavior including the ventrolateral medulla, hypothalamic paraventricular nucleus, and medial preoptic area. Conclusion Common spinal and brain pathways project to the LA and BS muscles in the rat suggesting that these muscles act together to coordinate male sexual reflexes. Differences may exist in the amount of synaptic connections/neuronal pathways in adolescents compared with adults. Dobberfuhl AD, Oti T, Sakamoto H, and Marson L. Identification of CNS neurons innervating the levator ani and ventral bulbospongiosus muscles in male rats. J Sex Med 2014;11:664–677.
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Spinal neurons activated in response to pudendal or pelvic nerve stimulation in female rats.
Brain research, 2008Co-Authors: J. Wiedey, M. Sipski Alexander, Lesley MarsonAbstract:The overlapping distribution of spinal neurons activated with either pudendal sensory nerve or pelvic nerve stimulation was examined in the female rat using c-fos immunohistochemistry. Pudendal sensory nerve stimulation resulted in a significant increase in fos-positive cells in the ipsilateral dorsal horn and bilaterally in the medial, lateral and intermediate Gray of L5-S1. Pelvic nerve stimulation resulted in significant increases of c-fos immunoreactive nuclei in the ipsilateral dorsal horn, lateral and intermediate Gray and bilaterally in the medial Gray of L5-S1. Co-distribution of fos immunoreactive nuclei with the vesicular glutamate transporters (VGlut2 and VGlut3) and neurokinin I receptors were found in distinct regions of the dorsal horn, medial and lateral Gray. Specific areas in the medial dorsal horn, dorsal Gray Commissure, laminae VI and X and dorsal lateral Gray were activated after stimulation of the pudendal sensory and pelvic nerves, suggesting these areas contain spinal neurons that receive both somatomotor and visceral inputs and are part of the intraspinal circuit that regulates sexual and voiding function.
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Spinal Control of Sexual Reflexes: An Overview from Studies in Animal Models
Topics in Spinal Cord Injury Rehabilitation, 2002Co-Authors: Lesley MarsonAbstract:Central nervous system control of female genital arousal and climax has been reviewed from data obtained in animal studies. Sensory inputs from the pelvic organs are mediated via the pudendal nerve (motor) and pelvic and hypogastric nerves (autonomic). The afferents of these nerves that relay sensory information terminate in L6-S1 and T13-L3. Interneurons located in the spinal Gray (T13-S1), especially in the dorsal Gray, Commissure and surrounding the intermediolateral cell column are important in relaying afferent information to spinal efferent neurons. These interneurons also send messages to the brain. Vagal innervation of the pelvic organs may supplement the spinal systems and may be important in relaying sensory information after spinal cord injury.
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oxytocinergic innervation of autonomic nuclei controlling penile erection in the rat
Neuroscience, 1999Co-Authors: F Veronneaulongueville, Olivier Rampin, Kevin E. Mckenna, Lesley Marson, M J Freundmercier, Y Tang, A Calas, M E Stoeckel, G Benoit, François GiulianoAbstract:Abstract In the rat, spinal autonomic neurons controlling penile erection receive descending pathways that modulate their activity. The paraventricular nucleus of the hypothalamus contributes oxytocinergic fibers to the dorsal horn and preganglionic sympathetic and parasympathetic cell columns. We used retrograde tracing techniques with pseudorabies virus combined with immunohistochemistry against oxytocin and radioligand binding detection of oxytocinergic receptors to evidence the oxytocinergic innervation of thoracolumbar and lumbosacral spinal neurons controlling penile erection. Spinal neurons labelled with pseudorabies virus transsynaptically transported from the corpus cavernosum were present in the intermediolateral cell column and the dorsal Gray Commissure of the thoracolumbar and lumbosacral spinal cord. Confocal laser scanning microscopic observation of the same preparations revealed close appositions between oxytocinergic varicosities and pseudorabies virus-infected neurons, suggesting strongly the presence of synaptic contacts. Electron microscopy confirmed this hypothesis. Oxytocin binding sites were present in the superficial layers of the dorsal horn, the dorsal Gray Commissure and the intermediolateral cell column in both the thoracolumbar and lumbosacral segments. In rats, stimulation of the paraventricular nucleus induces penile erection, but the link between the nucleus and penile innervation remains unknown. Our findings support the hypothesis that oxytocin, released by descending paraventriculo-spinal pathways, activates proerectile spinal neurons.
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5-Hydroxytryptamine2C receptors on spinal neurons controlling penile erection in the rat.
Neuroscience, 1999Co-Authors: Mircea Bancila, Daniel Vergé, Olivier Rampin, Jon R. Backstrom, Elaine Sanders-bush, Kevin E. Mckenna, Lesley Marson, André Calas, François GiulianoAbstract:Abstract The localization of 5-hydroxytryptamine 2C receptors in the lumbosacral spinal cord of the rat was investigated using selective antibodies raised against the carboxyl-terminal part of the rat receptor. The distribution of immunoperoxidase labelling at the light microscope level revealed numerous labelled neurons in the Gray matter, with a higher intensity in the sacral parasympathetic nucleus, the dorsal Gray Commissure and particularly the motoneurons of the ventral horn. Confocal microscope analysis showed that immunostaining was mainly intracellular (motoneurons), but could also be associated with the membrane of cell bodies and dendrites. Actually, electron microscope immunogold experiments demonstrated an exclusive staining of the cis -Golgi apparatus. Following pseudo-rabies virus transsynaptic retrograde labelling from the corpus cavernosum, labelled neurons were found in the sacral parasympathetic nucleus and the dorsal Gray Commissure of the L6–S1 segments. All virus-labelled neurons exhibited 5-hydroxytryptamine 2C receptor immunoreactivity. These results indicate that all parasympathetic preganglionic neurons and their related interneurons which contribute to the innervation of cavernosal tissue bear 5-hydroxytryptamine 2C receptors. In the sacral parasympathetic nucleus, most neurons which were retrogradely-labelled from the pelvic ganglion with Fast Blue also showed 5-hydroxytryptamine 2C receptor immunoreactivity. In the ventral horn, motoneurons retrogradely labelled from the ischiocavernosus muscle and the bulbospongiosus muscle, both of which are involved in erection and ejaculation, were also 5-hydroxytryptamine 2C receptor-immunopositive. The supraspinal serotoninergic control of erection at the lumbosacral level therefore appears to be strongly associated with the activation of 5-hydroxytryptamine 2C receptors, consistent with the proerectile properties of 5-hydroxytryptamine 2C agonists.
Irving Nadelhaft - One of the best experts on this subject based on the ideXlab platform.
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Separate urinary bladder and prostate neurons in the central nervous system of the rat: simultaneous labeling with two immunohistochemically distinguishable pseudorabies viruses
BMC Neuroscience, 2002Co-Authors: Irving Nadelhaft, Alejandro J Miranda-sousa, Pedro L. VeraAbstract:Background This work examines the central nervous system distribution of virus-labeled neurons from the rat urinary bladder and the prostate simultaneously within the same tissue sections. Two immunohistochemically distinct pseudorabies virus strains were simultaneously injected into male Sprague Dawley rats (~280 gm). One virus was injected into the bladder and the other into the prostate. After incubation intervals of 2.25, 2.5, 2.75, 3 and 4 days, sections from the spinal cord and brain were processed immunohistochemically to detect cells, within a single section, which were labeled separately by each virus or were labeled by both viruses. Results Each strain of virus labeled a separate population of neurons and some neurons were labeled by both strains. The majority of neurons labeled by virus from the urinary bladder were found in the L6-S1 spinal cord segments within the dorsal Gray Commissure, the intermediolateral area and the superficial dorsal horn. Neurons labeled by virus from the prostate were mainly found in the L1-L2 spinal cord segments in the dorsal Gray Commissure and the intermediolateral areas. Double-labeled interneurons in L1-L2 were mainly located in the intermediolateral area. In L6-S1 they were divided between the dorsal Gray Commissure and the intermediolateral area. Conclusions Spinal neurons innervating the bladder are clearly separate and different from those innervating the prostate. This difference also persists in the brain. In disagreement with previous reports, no direct anatomical evidence of parasympathetic innervation of the prostate was observed.
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separate urinary bladder and external urethral sphincter neurons in the central nervous system of the rat simultaneous labeling with two immunohistochemically distinguishable pseudorabies viruses
Brain Research, 2001Co-Authors: Irving Nadelhaft, P L VeraAbstract:Abstract This work examines the distribution, in the central nervous system, of virus-labeled neurons from the rat urinary bladder and the external urethral sphincter simultaneously within the same tissue sections. Two immunohistochemically distinct pseudorabies virus strains were injected into male Sprague–Dawley rats (∼280 g). One virus was injected into the bladder and the other into the external urethral sphincter. After incubation intervals of 2, 2.5 and 3 days, sections from the spinal cord and brain were treated immunohistochemically to detect cells which were labeled separately by each virus or were labeled by both viruses. The major result of these experiments is that each strain of virus labeled a separate population of neurons and that some neurons were labeled by both strains. In the lumbosacral cord, 3 days post-infection, neurons labeled by virus from the external urethral sphincter were found in Onuf’s nucleus, the dorsal Gray Commissure, and the superficial dorsal horn. Neurons labeled by virus from the urinary bladder were found in the L6–S1 and L1–L2 spinal cord segments within the dorsal Gray Commissure, the intermediolateral area and the superficial dorsal horn. Double-labeled interneurons were mainly located in the dorsal Gray Commissure although some were also found in the intermediolateral area and the superficial dorsal horn. In the medulla, external urethral sphincter neurons and bladder neurons and double-labeled neurons were found in the reticular region and the raphe. More rostrally, bladder neurons were located in the pontine micturition center and external urethral sphincter neurons were found in the locus coeruleus and subcoeruleus. A very small number of double-labeled neurons were found in the pontine micturition center and the locus coeruleus or subcoeruleus.
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Neurons in the rat brain and spinal cord labeled after pseudorabies virus injected into the external urethral sphincter.
The Journal of comparative neurology, 1996Co-Authors: Irving Nadelhaft, Pedro L. VeraAbstract:Male Sprague-Dawley rats, with their pelvic and hypogastric nerves transected, were infected with pseudorabies virus (PRV) injected into the external urethral sphincter. Animals were sacrificed at 2, 2.5, 3, and 4 days postinfection. Spinal cord and brain tissue were sectioned and processed by immunohistochemical techniques with antisera against PRV and choline acetyl transferase (CAT). At 2 days postinfection, virus-labeled neurons were found in the ventrolateral divisions of Onuf's nucleus and in the dorsal Gray Commissure (DGC). At progressively later incubation times, labeled neurons were found in the intermediolateral regions, the superficial layer of the dorsal horn, and the brainstem, in particular, the pontine micturition center. PRV/CAT-positive neurons were only found in Onuf's nucleus. Preganglionic neurons in the L6-S1 intermediolateral regions were CAT positive but PRV negative, thus suggesting that they are interneurons, not sacral parasympathetic preganglionic neurons. After 4 days, virus had spread to neurons in the paraventricular, preoptic, and even cortical regions. The distribution of these PRV-labeled brain neurons strongly resembled that obtained after the injection of PRV into the urinary bladder (Nadelhaft et al. [1992] Neurosci. Lett. 143:271-274). In both cases, neurons were labeled in the DGC in the spinal cord. The data therefore suggest that neurons in the DGC may be involved in the integrated control of the bladder and the external urethral sphincter.
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Central nervous system neurons infected by pseudorabies virus injected into the rat urinary bladder following unilateral transection of the pelvic nerve.
The Journal of comparative neurology, 1995Co-Authors: Irving Nadelhaft, Pedro L. VeraAbstract:Following the transection of one pelvic nerve and both hypogastric nerves, the urinary bladder of male Sprague-Dawley rats was injected with pseudorabies virus (PRV; Bartha strain). The central stump of the transected pelvic nerve was labelled with fast blue (FB), and rats were maintained for 2, 2. 5, and 3 days following viral infection. Tissue was processed with antisera against PRV and choline acetyltransferase (CAT). In the L6-S1 spinal cord, neurons in the ipsilateral intermediolateral area (IML) were labelled after 2 days. After 2. 5 days, labelled neurons were also found in the dorsal Gray Commissure (DGC), the ipsilateral superficial dorsal horn, and the contralateral IML area. After 3 days, many labelled neurons appeared in the superficiai dorsal horns and, bilaterally, in the L6-S1 dorsal root ganglia. In both IMLs, two groups of PRV-labelled neurons were found: (1) CAT-positive preganglionic cells and (2) smaller, CAT-negative cells located slightly dorsal to the preganglionic neurons. No other doubly stained neurons were found in the spinal cord. Contralateral DRG neurons stained for either PRV or FB or both. Ipsilateral DRG neurons stained only for PRV. PRV-immunoreactive (IR) neurons appeared in the brainstem only after 3 days. These were located primarily in the pontine micturition centers (equal numbers), the ventral locus coeruleus, and the raphe and lateral reticular areas. © 1995 Wiley-Liss, Inc.
Pedro L. Vera - One of the best experts on this subject based on the ideXlab platform.
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Separate urinary bladder and prostate neurons in the central nervous system of the rat: simultaneous labeling with two immunohistochemically distinguishable pseudorabies viruses
BMC Neuroscience, 2002Co-Authors: Irving Nadelhaft, Alejandro J Miranda-sousa, Pedro L. VeraAbstract:Background This work examines the central nervous system distribution of virus-labeled neurons from the rat urinary bladder and the prostate simultaneously within the same tissue sections. Two immunohistochemically distinct pseudorabies virus strains were simultaneously injected into male Sprague Dawley rats (~280 gm). One virus was injected into the bladder and the other into the prostate. After incubation intervals of 2.25, 2.5, 2.75, 3 and 4 days, sections from the spinal cord and brain were processed immunohistochemically to detect cells, within a single section, which were labeled separately by each virus or were labeled by both viruses. Results Each strain of virus labeled a separate population of neurons and some neurons were labeled by both strains. The majority of neurons labeled by virus from the urinary bladder were found in the L6-S1 spinal cord segments within the dorsal Gray Commissure, the intermediolateral area and the superficial dorsal horn. Neurons labeled by virus from the prostate were mainly found in the L1-L2 spinal cord segments in the dorsal Gray Commissure and the intermediolateral areas. Double-labeled interneurons in L1-L2 were mainly located in the intermediolateral area. In L6-S1 they were divided between the dorsal Gray Commissure and the intermediolateral area. Conclusions Spinal neurons innervating the bladder are clearly separate and different from those innervating the prostate. This difference also persists in the brain. In disagreement with previous reports, no direct anatomical evidence of parasympathetic innervation of the prostate was observed.
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Neurons in the rat brain and spinal cord labeled after pseudorabies virus injected into the external urethral sphincter.
The Journal of comparative neurology, 1996Co-Authors: Irving Nadelhaft, Pedro L. VeraAbstract:Male Sprague-Dawley rats, with their pelvic and hypogastric nerves transected, were infected with pseudorabies virus (PRV) injected into the external urethral sphincter. Animals were sacrificed at 2, 2.5, 3, and 4 days postinfection. Spinal cord and brain tissue were sectioned and processed by immunohistochemical techniques with antisera against PRV and choline acetyl transferase (CAT). At 2 days postinfection, virus-labeled neurons were found in the ventrolateral divisions of Onuf's nucleus and in the dorsal Gray Commissure (DGC). At progressively later incubation times, labeled neurons were found in the intermediolateral regions, the superficial layer of the dorsal horn, and the brainstem, in particular, the pontine micturition center. PRV/CAT-positive neurons were only found in Onuf's nucleus. Preganglionic neurons in the L6-S1 intermediolateral regions were CAT positive but PRV negative, thus suggesting that they are interneurons, not sacral parasympathetic preganglionic neurons. After 4 days, virus had spread to neurons in the paraventricular, preoptic, and even cortical regions. The distribution of these PRV-labeled brain neurons strongly resembled that obtained after the injection of PRV into the urinary bladder (Nadelhaft et al. [1992] Neurosci. Lett. 143:271-274). In both cases, neurons were labeled in the DGC in the spinal cord. The data therefore suggest that neurons in the DGC may be involved in the integrated control of the bladder and the external urethral sphincter.
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Central nervous system neurons infected by pseudorabies virus injected into the rat urinary bladder following unilateral transection of the pelvic nerve.
The Journal of comparative neurology, 1995Co-Authors: Irving Nadelhaft, Pedro L. VeraAbstract:Following the transection of one pelvic nerve and both hypogastric nerves, the urinary bladder of male Sprague-Dawley rats was injected with pseudorabies virus (PRV; Bartha strain). The central stump of the transected pelvic nerve was labelled with fast blue (FB), and rats were maintained for 2, 2. 5, and 3 days following viral infection. Tissue was processed with antisera against PRV and choline acetyltransferase (CAT). In the L6-S1 spinal cord, neurons in the ipsilateral intermediolateral area (IML) were labelled after 2 days. After 2. 5 days, labelled neurons were also found in the dorsal Gray Commissure (DGC), the ipsilateral superficial dorsal horn, and the contralateral IML area. After 3 days, many labelled neurons appeared in the superficiai dorsal horns and, bilaterally, in the L6-S1 dorsal root ganglia. In both IMLs, two groups of PRV-labelled neurons were found: (1) CAT-positive preganglionic cells and (2) smaller, CAT-negative cells located slightly dorsal to the preganglionic neurons. No other doubly stained neurons were found in the spinal cord. Contralateral DRG neurons stained for either PRV or FB or both. Ipsilateral DRG neurons stained only for PRV. PRV-immunoreactive (IR) neurons appeared in the brainstem only after 3 days. These were located primarily in the pontine micturition centers (equal numbers), the ventral locus coeruleus, and the raphe and lateral reticular areas. © 1995 Wiley-Liss, Inc.
Gert Holstege - One of the best experts on this subject based on the ideXlab platform.
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ultrastructural evidence for direct projections from the pontine micturition center to glycine immunoreactive neurons in the sacral dorsal Gray Commissure in the cat
The Journal of Comparative Neurology, 2001Co-Authors: Judith A M L Sie, Henk De Weerd, Bertil F.m. Blok, Gert HolstegeAbstract:During micturition, according to the concept of Blok, Holstege, and colleagues ([1997] Neurosci. Lett. 233:109-112), the pontine micturition center (PMC) elicits bladder contraction by way of direct excitation of the parasympathetic bladder motoneurons. At the same time, the PMC elicits relaxation of the external urethral sphincter (EUS) by excitation of gamma -aminobutyric acid (GABA)-ergic interneurons in the sacral dorsal Gray Commissure (DGC), which, in turn, inhibit EUS motoneurons. The question is whether the inhibitory neurotransmitter glycine is also involved in this system. The present study investigated, first, whether there are glycine immunoreactive interneurons in the sacral DGC and, second, whether they receive direct PMC afferents. Finally, it was determined whether glycine and GABA are colocalized in DGC interneurons. In two adult male cats, the PMC was identified by electrical stimulation. Subsequently, the identified region was injected with the anterograde tracer WGA-HRP. Sections of sacral cord segments were processed for light and electron microscopic detection of anterograde labeling, as well as for glycine and GABA, using postembedding immunogold labeling with antibodies. In total 128 labeled PMC terminals were found in the DGC, which contained many round vesicles and asymmetric synapses. About 31.3% (40 of 128) made contact with glycine-immunoreactive dendrites. Eleven of them were selected for serial sectioning, which showed that 54.6% (6 of 11) of the glycine-immunoreactive dendrites were also immunoreactive for GABA. The results demonstrate that the PMC projects directly to dendrites of interneurons in the sacral DGC, which are immunoreactive for both glycine and GABA. These interneurons are thought to inhibit the EUS motoneurons during micturition. J. Comp. Neurol. 429:631-637, 2001. (C) 2001 Wiley-Liss, Inc.
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Electrical stimulation of the sacral dorsal Gray Commissure evokes relaxation of the external urethral sphincter in the cat
Neuroscience letters, 1998Co-Authors: Bertil F.m. Blok, Jos Th. P. W. Van Maarseveen, Gert HolstegeAbstract:Stimulation of the pontine micturition center (PMC) results in micturition, i.e. an immediate relaxation of the urethral sphincter and a contraction of the detrusor muscle of the bladder. The PMC generates the bladder contraction by way of a direct excitatory pathway to the parasympathetic bladder motoneurons in the sacral cord. The idea is that the PMC produces the relaxation of the urethral sphincter via direct projections to GABAergic neurons in the dorsal Gray Commissure (DGC), which, in turn, inhibit the urethral sphincter motoneurons. According to this hypothesis, electrical stimulation in the DGC in three cats should result in relaxation of the urethral sphincter. The results were in total agreement with this concept. During DGC stimulation a sharp decrease of the urethral pressure was found, the strength of which depended completely on the amplitude of the electrical stimulation.
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The pontine micturition center projects to sacral cord GABA immunoreactive neurons in the cat
Neuroscience Letters, 1997Co-Authors: Bertil F.m. Blok, Henk De Weerd, Gert HolstegeAbstract:Stimulation of the pontine micturition center (PMC) results in micturition, i.e. an immediate relaxation of the bladder sphincter and a contraction of the detrusor muscle of the bladder. Earlier studies have shown that the bladder contraction is brought about by a direct excitatory pathway from the PMC to the parasympathetic bladder motoneurons in the sacral cord. How the PMC produces the inhibition of the bladder sphincter is not known. The present study in two adult male cats demonstrates at the ultrastructural level a direct pathway from the PMC to the dorsal Gray Commissure of the sacral cord. More than half (55%) of these terminals made contact with gamma amino butyric acid (GABA) immunoreactive neurons or somata, the others with non-GABA immunoreactive profiles. The PMC terminals contained many round vesicles, some dense cored vesicles and exclusively asymmetric synaptic clefts, which correspond with an excitatory pathway. A concept is put forward in which this pathway produces the relaxation of the bladder sphincter during micturition.
Alexander G. Rabchevsky - One of the best experts on this subject based on the ideXlab platform.
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Plasticity of lumbosacral propriospinal neurons is associated with the development of autonomic dysreflexia after thoracic spinal cord transection
The Journal of comparative neurology, 2008Co-Authors: Shaoping Hou, Hanad Duale, Adrian A. Cameron, Sarah M. Abshire, Travis S. Lyttle, Alexander G. RabchevskyAbstract:Complete thoracic (T) spinal cord injury (SCI) above the T6 level typically results in autonomic dysreflexia, an abnormal hypertensive condition commonly triggered by nociceptive stimuli below the level of SCI. Over-expression of nerve growth factor in the lumbosacral spinal cord induces profuse sprouting of nociceptive pelvic visceral afferent fibers that correlates with increased hypertension in response to noxious colorectal distension. After complete T4 SCI, we evaluated the plasticity of propriospinal neurons conveying visceral input rostrally to thoracic sympathetic preganglionic neurons. The anterograde tracer biotinylated dextran amine (BDA) was injected into the lumbosacral dorsal Gray Commissure (DGC) of injured/non-transected rats immediately after injury (acute) or 2 weeks later (delayed). At 1 or 2 weeks after delayed or acute injections, respectively, a higher density (p
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plasticity of lumbosacral propriospinal neurons is associated with the development of autonomic dysreflexia after thoracic spinal cord transection
The Journal of Comparative Neurology, 2008Co-Authors: Shaoping Hou, Hanad Duale, Adrian A. Cameron, Sarah M. Abshire, Travis S. Lyttle, Alexander G. RabchevskyAbstract:Complete thoracic (T) spinal cord injury (SCI) above the T6 level typically results in autonomic dysreflexia, an abnormal hypertensive condition commonly triggered by nociceptive stimuli below the level of SCI. Over-expression of nerve growth factor in the lumbosacral spinal cord induces profuse sprouting of nociceptive pelvic visceral afferent fibers that correlates with increased hypertension in response to noxious colorectal distension. After complete T4 SCI, we evaluated the plasticity of propriospinal neurons conveying visceral input rostrally to thoracic sympathetic preganglionic neurons. The anterograde tracer biotinylated dextran amine (BDA) was injected into the lumbosacral dorsal Gray Commissure (DGC) of injured/non-transected rats immediately after injury (acute) or 2 weeks later (delayed). At 1 or 2 weeks after delayed or acute injections, respectively, a higher density (p<0.05) of BDA+ fibers was found in thoracic dorsal Gray matter of injured versus non-transected spinal cords. For corroboration, fast blue (FB) or cholera toxin subunit beta (CTb) was injected into the T9 dorsal horns 2 weeks post-injury/non-transection. After 1 week transport, more retrogradely-labeled (p<0.05) DGC propriospinal neurons (T13-S1) were quantified in injured versus non-transected cords. We also monitored immediate early gene, c-fos, expression following colorectal distension and found increased (p<0.01) c-Fos+ cell numbers throughout the DGC after injury. Collectively, these results imply that, in conjunction with local primary afferent fiber plasticity, injury-induced sprouting of DGC neurons may be a key constituent in relaying visceral sensory input to sympathetic preganglionic neurons that elicit autonomic dysreflexia after high thoracic SCI.
