Yonsei Med J.  2008 Jun;49(3):479-485. 10.3349/ymj.2008.49.3.479.

c-fos Expression in Bladder-Specific Spinal Neurons after Spinal Cord Injury Using Pseudorabies Virus

• Im YJ
• Hong CH
• Jin MH
• Lee BH
• Han SW

• KMID: 724265
• DOI: http://doi.org/10.3349/ymj.2008.49.3.479

Abstract

PURPOSE
c-fos expression in spinal neurons that are activated by lower urinary tract stimulation are not organ specific. In this experiment, we demonstrated changes of c-fos expression in bladder-specific preganglionic neurons (PGNs) and interneurons using pseudorabies virus (PRV). MATERIALS AND METHODS: Forty Sprague-Dawley rats were used. We identified the neuronal pathway associated with the bladder by injecting PRV into the detrusor. An immunohistochemical method was used to stain Fos-protein encoded by the c-fos gene. Immunofluorescent staining for PRV was performed to evaluate changes in bladder-specific spinal neurons. RESULTS: Immunofluorescent staining with choline acetyltransferase (ChAT) revealed that the sacral parasympathetic nucleus (SPN) regions contained 9.8 PGNs/ section. In rats with chronic spinal cord injury by intravesical saline instillation, 82.4+/-10.3% of PGNs in SPN exhibited Fos-immunoreactive (IR). Two and a half days after PRV infection, PRV-IR PGNs were observed at 5.4 PGNs/ section, and 2.7+/-1.6% of them exhibited Fos-IR. Unlike ChAT-IR PGNs, PRV-IR PGNs are bladder-specific neurons and PRV-IR and Fos-IR cells found in the back of PRV-IR PGNs are bladder- specific interneurons. Three days after PRV infection, we observed many PRV-IR and Fos-IR cells in the dorsal commissure. These neurons are interneurons distributed in the bladder. CONCLUSION: We confirmed that in chronic spinal cord injury, the patterns of c-fos expression in bladder-specific spinal neurons were similar to those in voiding-reflex related spinal neurons, which had already been demonstrated earlier. We believe that our methodology can be applied to study interactions between voiding and other organs as well, such as the urethra and prostate.

Keyword

Neurons; bladder; pseudorabies virus; c-fos protein

MeSH Terms

Animals
Female
Herpesvirus 1, Suid/*physiology
Immunohistochemistry
Interneurons/cytology/metabolism
Neurons/cytology/*metabolism
Proto-Oncogene Proteins c-fos/*metabolism
Rats
Rats, Sprague-Dawley
Spinal Cord Injuries/*physiopathology
Urinary Bladder/cytology/*metabolism/virology

Figure

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  Fig. 1 Fluorescent photomicrographs of an L6 spinal cord section. Virus-labeled bladder neuron (green) at 3 days postinfection (A). ChAT-IR cells (green cytoplasm) in the SPN (B). Scale bar: 100 µm.

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  Fig. 2 Co-localization of c-fos, ChAT, and PRV in the L6-S1 segments. Double immunofluorescent staining showed that Fos-IR cells (red nuclei) were co-localized with ChAT-IR cells (green cytoplasm) in the region of the SPN (A). Fos (red) co-localized with PRV (green) after 2.5 days postinfection in the SPN. Based on the location of the cells, PRV-IR cells in the circle corresponded to PGNs. PRV-IR PGNs exhibited Fos-IR (arrow) (B). Merged immunofluorescence showed that Fos (red) was co-localized with PRV (green) in the DCM (C). Scale bar: 50 µm.

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