C-Fos in enteric nerves after extrinsic denervation of guinea pig ileum.
BACKGROUND
Gastrointestinal function is controlled partly by an interaction between extrinsic (sympathetic, parasympathetic, sensory) and intrinsic (enteric) nerves. However, normal gut function occurs in the absence of extrinsic innervation as enteric nerves adapt to the loss of extrinsic nerves from the gut wall. Expression of the proto-oncogene product, c-Fos, is a signal for activity-dependent changes in gene expression and immunocytochemical detection of c-Fos is used as a marker for changes in neuronal activity. The purpose of this study was to determine if enteric neurons in guinea pig ileum respond to loss of extrinsic innervation by expressing c-Fos protein.


METHODS
Fos protein was localized using immunohistochemical methods and an antiserum raised against synthetic Fos. Segments of ileum were extrinsically denervated by crushing the mesenteric nerves in anesthetized animals or by treating animals with 6-hydroxydopamine (6-OH-DA) or capsaicin to destroy sympathetic and extrinsic sensory nerves, respectively.


RESULTS
One week after surgical extrinsic denervation of loops of ileum, 12 +/- 1 nuclei/submucosal ganglion and 114 +/- 6 nuclei/myenteric ganglion contained Fos immunoreactivity (ir). These values were greater (P < 0.05) than those from unoperated segments from the same animals (4 +/- 1 Fos-ir nuclei/submucosal ganglion and 13 +/- 4 Fos-ir nuclei/myenteric ganglion) or from sham-operated segments. Significantly more nuclei contained Fos-ir at 4, 7, 10, and 24 weeks after denervation. Finally, capsaicin or 6-OH-DA treatment increased the number of Fos-ir nuclei in enteric ganglia.


CONCLUSIONS
These data suggest that Fos expression may be part of the adaptation of enteric nerves to extrinsic denervation.
Yunker
A M
AM
Department of Pharmacology and Toxicology and Neuroscience Program, Michigan State University, East Lansing, Michigan, 48824, USA.
Paupore
E J
EJ
Galligan
J J
JJ
D000818:Animals; D003714:Denervation; D017615:Enteric Nervous System / Q000378:metabolism*; D005724:Ganglia / Q000378:metabolism; D006168:Guinea Pigs; D007082:Ileum / Q000294:innervation*; D008297:Male; D009197:Myenteric Plexus / Q000378:metabolism; D009475:Neurons, Afferent / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D012016:Reference Values; D013368:Submucous Plexus / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000502:physiology
D016760:Proto-Oncogene Proteins c-fos