Tumor necrosis factor-α expression and intestinal ALP activity in the duodenum of zinc-deficient rats

Summary Recently it was reported that alkaline phosphatase (ALP) reduces the toxicity of lipopolysaccharide (LPS) a toxin of Gram‑negative bacteria. Therefore we examined the change in ALP activity and induction of tumor necrosis fac‑ tor‑α (TNF‑α) in the duodenum of zinc‑deficient rats. Fifty‑six Sprague‑Dawley rats were divided into two groups fed diets containing 0 % (zinc‑deficient group) or 0.01 % (control group) zinc. Blood and duodenal mucosa samples (5 cm below the stomach) were obtained every week for four weeks for ALP and TNF‑α analyses. At one week the serum ALP and intestinal ALP activities in the zinc‑deficient group were significantly lower than in the control group and decreased further over four weeks. TNF‑α was detected in the duodenum of the zinc‑deficient rats at four weeks but not in the control group. This study shows that dietary zinc deficiency induces the expression of TNF‑α protein in the duodenal mucosa; one cause of this response is a marked reduction in the detoxification of LPS by intestinal ALP.