Troubleshooting in animal models of colitis: The use of a novel electrocautery model.
BACKGROUND
Experimental colitis induced by chemical agents leads to upregulation of inflammatory cytokines in distant unaffected small intestine and to a decrease in nutrient absorption. To preclude any possible proximal diffusion of these chemicals, we designed a novel method for ulcer induction in the colon by electrocautery.


METHODS
Under light anesthesia, a colonic ulcer was induced in rats by a special electrocautery probe introduced in the descending colon through the rectum allowing the injection of a controlled electrolytic current. A direct current (3-7 mA) was delivered through the electrodes for 30s and then for another 30s after reversing the polarity of the electrodes. Then, the probe was moved for a distance of +/-0.5 cm and the current injection was repeated. Rats were sacrificed at various time intervals after ulcer induction (3-96 h). Samples from colon and jejunum were taken for histological assessment and determination, by ELISA, of the levels of interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha). In other groups of animals, jejunal amino acid absorption was determined in vivo at 24 and 48 h post electrocautery.


RESULTS
A colonic ulcer persisted for 72 h after cauterization. A significant upregulation of the levels of different cytokines was observed in the colon and jejunum post cauterization and persisted for at least 48 h. In the jejunum, IL-1beta increased from 81+/-9 to 652+/-110 (p<0.01) and 243+/-47 (p<0.05) pg/mg protein at 24 and 48 h, respectively. Similarly, jejunal TNF-alpha levels increased by approximately 2 folds at 24 and 48 h post ulcer induction (p<0.05). A similar but higher increase in cytokines was observed in the colon. Jejunal alanine absorption (0.2+/-0.02 micromol/20 min/cm) decreased significantly at 24 and 48 h after colitis induction (0.12+/-0.01 and 0.14+/-0.02, respectively; p<0.01).


CONCLUSIONS
This model may be used as an alternative or a complement to chemical models of colitis.
Mourad
F H
FH
Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon. fmourad@aub.edu.lb
Barada
K A
KA
Noutsi
B
B
Saade
N E
NE
D000409:Alanine / Q000378:metabolism; D000818:Animals; D003093:Colitis, Ulcerative / Q000473:pathology*; D003106:Colon / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004564:Electrocoagulation; D004797:Enzyme-Linked Immunosorbent Assay; D053583:Interleukin-1beta / Q000378:metabolism; D007408:Intestinal Absorption / Q000502:physiology; D007421:Intestine, Small / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016207:Cytokines; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D000409:Alanine