Previous studies have shown that @entity3775 inhibits @entity560 -dependent @entity460 absorption. The mechanism involves reduced sensitivity to @entity3873 and reduced expression of the @entity460 transport protein, calbindin-D28k. Reduced expression of calbindin protein may be due to decreased levels of calbindin mRNA. To test this hypothesis, we measured calbindin mRNA levels in chicks fed diets with and without added @entity3775 . Groups of chicks were fed one of four diets: control, control plus @entity3775 , low @entity460 , or low @entity460 plus @entity3775 . A fifth group was fed a @entity560 -free diet as a negative control. Calbindin protein was measured by immunoblotting. Serum @entity460 and inorganic @entity3151 were determined. Intestinal mRNA was isolated and assayed by slot-blot hybridization to a @entity941 -conjugated oligonucleotide probe complementary to calbindin-D28k mRNA. Antifluorescein antibodies conjugated to alkaline phosphatase were used to detect hybrids and mRNA levels were quantified by densitometry. Specificity of the probe was verified by Northern analysis. Intestinal calbindin protein was greater in the control plus @entity3775 group than in controls, but no difference in calbindin mRNA was observed. These changes were associated with small decreases in serum @entity3151 and @entity460 , suggesting a postranscriptional effect of @entity3775 . Chicks fed the low @entity460 diet had greater intestinal calbindin protein and mRNA levels relative to the control group in association with a 45% decrease in serum @entity460 . In contrast, no difference in calbindin protein, and significantly less mRNA were found in the low @entity460 plus @entity3775 group compared with controls, despite a decrease in serum @entity460 similar to that of chicks fed the low @entity460 diet without @entity3775 . These results show that in chicks fed a low @entity460 diet, @entity3775 intake decreases transcription and/or stability of intestinal calbindin mRNA, and that @entity3775 may inhibit the expression of @entity560 -dependent genes.

XXXX toxicity alters the regulation of calbindin-D28k protein and mRNA expression in chick intestine.

@entity3775 :: ('MESH:D000535', 'Chemical') :: ['aluminum'] @entity3873 :: ('MESH:D002117', 'Chemical') :: ['1,25-dihydroxycholecalciferol'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity941 :: ('MESH:D019793', 'Chemical') :: ['fluorescein'] @entity3151 :: ('MESH:D010758', 'Chemical') :: ['phosphorus'] @entity560 :: ('MESH:D014807', 'Chemical') :: ['vitamin D']
@entity3775 :: (MESH:D000535,Chemical) :: ['Aluminum']
