Effect of intestinal inflammation on neuronal survival and function in the dorsal motor nucleus of the vagus.
BACKGROUND
The effects of intestinal inflammation on the central nervous system are unknown. The dorsal motor nucleus of the vagus (DMNV) integrates peripheral and central signals and sends efferent signals to the gastrointestinal system. The purpose of this study was to determine the effects of intestinal inflammation on the DMNV in an animal model and in vitro.


METHODS
Carbocyanine dye (DiI) was injected into the stomach wall of rats to label retrogradely the neurons of the DMNV. Colitis was induced with trinitrobenzene sulfonic acid (TNBS). Tissue was examined under fluorescent microscopy. In vitro studies were performed using primary culture of DMNV neurons. Cell proliferation was measured by BrdU incorporation. Apoptosis was measured by an enzyme sandwich-linked immunosorbent assay. Single-cell cytoplasmic calcium transients were determined using the fluorescence dye fura-2-AM. Reverse transcriptase-polymerase chain reaction of glutamate receptor was performed.


RESULTS
Animals treated with TNBS ate less and lost weight compared with controls. Microscopic analysis demonstrated a 77% decrease in DiI labeling in the DMNV of TNBS animals compared with controls. Cell proliferation in DMNV neurons after 24-hour exposure to the cytokines interleukin- (IL)-1 beta, IL-6, or tumor necrosis factor- (TNF)-alpha was significantly decreased. Similarly, apoptosis of DMNV neurons after 24 hours of incubation with IL-1 beta or TNF-alpha was significantly increased, but no changes resulted with IL-6. Exposure to each cytokine resulted in decreased glutamate-induced intracellular calcium transients. Transcription of glutamate receptor was decreased after 24-hour exposure to TNF-alpha.


CONCLUSIONS
DMNV neurons projecting to the stomach are reduced in number after induction of colitis in rats. In vitro, proinflammatory cytokines diminish DMNV cellular proliferation, increase apoptosis, and alter calcium responses to glutamate. These results indicate that intestinal inflammation affects adversely neuronal survival and function in the DMNV.
Ammori
John B
JB
Department of Surgery, University of Michigan, Ann Arbor, MI 48109-0346, USA.
Zhang
Wei-Zhen
WZ
Li
Ji-Yao
JY
Chai
Biao-Xin
BX
Mulholland
Michael W
MW
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000032:analysis; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003092:Colitis / Q000139:chemically induced / Q000473:pathology*; D016207:Cytokines / Q000494:pharmacology; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000473:pathology*; D009474:Neurons / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013270:Stomach / Q000294:innervation; D014302:Trinitrobenzenesulfonic Acid; D014630:Vagus Nerve / Q000473:pathology*
D016207:Cytokines; D014302:Trinitrobenzenesulfonic Acid; D002118:Calcium