Systems NeuroscienceIntraspinal sprouting of unmyelinated pelvic afferents after complete spinal cord injury is correlated with autonomic dysreflexia induced by visceral pain
Section snippets
Animals and surgery
All animal housing conditions, surgical procedures and post-operative care techniques were conducted according to the University of Kentucky Institutional Animal Care and Use Committee and the National Institutes of Health animal care guidelines to ensure minimizing the number of animals used and any potential suffering. Adult female Wistar rats (ā¼200ā250 g) were anesthetized with a mixture of ketamine (80 mg/kg, i.p.; Fort Dodge Animal Health, Fort Dodge, IA, USA) and xylazine (10 mg/kg, i.p.;
Autonomic dysreflexia: noxious CRD-induced changes in MAP and HR
In all three selected rats with T4-transection, CRD performed 2 weeks post-SCI elicited MAP increases accompanied by reduced HR characteristic of autonomic dysreflexia (data not shown). These results are in accordance with what we have published (Cameron et al., 2006).
Unmyelinated CGRP+ afferents
In both T4-transected and sham rats, CGRP immunoreactivity was predominately expressed in fibers and punctate terminals in three regions: the superficial dorsal horn (laminae IāII), medial gray matter (above the central canal), as
Discussion
Utilizing neuronal tract tracing and immunohistochemical methods, the major finding in the present study is that only unmyelinated pelvic visceral afferent fiber sprouting occurs in the L/S level following high T spinal cord transection. In addition, following CTb injections into the distal colon, the density of labeled colonic afferents at the L6/S1 spinal level was significantly enhanced at 3 weeks post-injury compared with sham spinal cords. Furthermore, virtually all CTb-labeled colonic
Conclusion
In summary, the present study demonstrates that following high T SCI the selective sprouting of CGRP+ unmyelinated nociceptive pelvic afferents into the L/S spinal cord correlates with the development of autonomic dysreflexia. Furthermore, CTb injections into the distal colon predominantly labeled unmyelinated pelvic visceral afferent fibers, in contrast to previous studies in which myelinated somatic afferent fibers were labeled with CTb. Our results demonstrate that the sprouting of
Acknowledgments
This work was supported by grants from KSCHIRT #3-11 (A.G.R.), NIH/NINDS R01 NS049901-01 (A.G.R.) and P30 NS051220. Authors are grateful for the technical expertise of Travis Lyttle, MS and Joseph Whelan, MS.
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2019, Respiratory Physiology and NeurobiologyCitation Excerpt :An appreciation for the capacity of the spinal cord to undergo extensive functional neuroplasticity following injury has increased in recent years, as well as an understanding of the significance and ramifications of the same (Fouad and Tse, 2008; Lane et al., 2008b; Darian-Smith, 2009). Contribution of interneurons to neuroplasticity has been demonstrated across several studies in a variety of settings (Krassioukov et al., 2002; de Groat and Yoshimura, 2006d; Llewellyn-Smith et al., 2006; Rabchevsky, 2006; Zinck and Downie, 2006; Hou et al., 2008a, b). This has been well-demonstrated in the locomotor system, wherein long and short propriospinal interneurons serve differential roles in motor recovery following spinal cord injury.
Sprouting of afferent and efferent inputs to pelvic organs after spinal cord injury
2024, Journal of Neuropathology and Experimental Neurology
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Authors contributed equally.
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Present address: Center for Neural Repair, Department of Neurosciences, University of California, San Diego Biomedical Science Building, Rm. 4033, 9500 Gilman Dr. La Jolla, CA 92093-0626.