Glucagon-like peptide 2 therapy reduces negative effects of diarrhea on calf gut.

Damage to the intestinal epithelium reduces nutrient absorption and animal growth, and can have negative long-term health effects on livestock. Because the intestinotropic hormone glucagon-like peptide 2 (GLP-2) has been shown to contribute to gut integrity, reduce inflammation, and improve nutrient absorption, the present study was designed to determine whether administration of GLP-2 to calves with coccidiosis in the first month of life affects intestinal growth and mediates negative effects of the proinflammatory response. Holstein bull calves (n=19) were assigned to 4 treatment groups of 4 to 5 calves each: (1) infected with Eimeria bovis, GLP-2 treated; (2) noninfected, GLP-2 treated; (3) infected with E. bovis, buffer treated; and (4) noninfected, buffer treated. Infected calves received 100,000 to 200,000 sporulated E. bovis oocysts suspended in milk replacer on d 0 of the study. On d 18, calves in the GLP-2 groups received a subcutaneous injection of 50 μg of bovine GLP-2/kg of body weight twice daily for 10 d, and calves in the buffer-treated groups received an equivalent volume of sodium bicarbonate buffer only. On d 28, calves were slaughtered 2h after injection of 5-bromo-2'-deoxyuridine (BrdU). Intestinal tissues were measured and villus height, crypt depth, and BrdU immunostaining were evaluated in segments of the small intestine. Nitrotyrosine immunostaining, a measure of nitro-oxidative damage, was evaluated in the ileum and cecum. No GLP-2 treatment by E. bovis infection interaction was observed for any parameter measured, with the exception of nitrotyrosine immunostaining in the cecum. Large intestinal weight was greater in infected than noninfected calves and with GLP-2 treatment relative to buffer treatment. Calves that received GLP-2 also had greater small intestinal weight but no difference in cell proliferation, as assessed by BrdU labeling, relative to buffer-treated calves. No treatment effects were detected for villus height, crypt depth, or villus height:crypt depth ratio in segments of the small intestine. Protein tyrosine nitration was over 3-fold greater in the ileum and cecum of infected calves relative to noninfected calves, and GLP-2 therapy reduced tyrosine nitration in infected calves by 47% in the ileum and 69% in the cecum relative to buffer-treated calves. Treatment with GLP-2 promotes intestinal growth in neonatal calves and reduces the detrimental effects of nitro-oxidative stress in the ileocecum of calves with coccidiosis.