Expression of 1,25(OH)₂D₃ metabolizing enzymes and of Ca²⁺transporters in the kidney of mice fed for three mo a high fructose, starch, or glucose diet containing normal Ca²⁺ levels.

<p>(A) Marked effects of excessive fructose intake on mRNA expression levels of renal 1,25(OH)₂D₃ metabolic enzymes, CYP27B1 and CYP24A1. (B) mRNA expression levels of renal TRPV6, CaBP28k, CaBP9k and PMCA1. All expression data were analyzed by real-time PCR using <i>EF1</i>α as a reference and normalized relative to levels seen in mice fed glucose diet. Data are means ± SEM (<i>n</i> = 5 per group). Differences (<i>P</i><0.05) among means are indicated by differences in superscript letters, as analyzed by 1-way ANOVA LSD. Thus, within a gene of interest, bars with superscript “a” are > bars with “b”. Chronic consumption of high fructose levels has dramatic effects on mRNA expression of renal 1,25(OH)₂D₃ metabolizing enzymes but not on Ca²⁺ transporter mRNA expression.</p

Effect of chronic fructose feeding on renal expression of 1,25(OH)₂D₃ metabolizing enzymes and of Ca²⁺transporters.

<p>Rats were fed for three mo a normal Ca²⁺ diet containing either 43% glucose or fructose. (<b>A</b>) mRNA expression level of renal 1,25(OH)₂D₃ metabolic enzymes, CYP27B1 and CYP24A1 (<b>B</b>) The protein abundance of CYP27B1 and CYP24B1 using β-actin as a reference. (<b>C</b>) mRNA expression levels of renal TRPV6, CaBP28k, CaBP9k and PMCA1. All expression data were analyzed by real-time PCR using <i>EF1</i>α as a reference and normalized relative to levels seen in rat fed glucose diet. Data are means ± SEM (<i>n</i> = 6 per group). Differences (<i>P</i><0.05) between means are indicated by asterisks. Chronic consumption of high fructose diets reduces mRNA and protein expression of CYP27B1.</p

Time course of the fructose-induced reduction in serum levels of 1,25-(OH)₂D₃ in adult rats fed for three mo a normal Ca²⁺ diet with either glucose or fructose.

<p>Glucose or Fructose = 43%. FGF  =  fibroblast growth factor, PTH  =  parathyroid hormone. <i>n</i> = 6 per group. Data are means ± SEM. Means with different superscript letters are significantly different from others in the same row (<i>P</i><0.05 by <i>posthoc</i> LSD test).</p

Fructose-fed mice demonstrate an inhibition of compensation for intestinal Ca²⁺transport rate and transporter expression induced by dietary Ca²⁺-deficiency.

<p>(A) Ca²⁺ transport was measured using everted duodenal sacs from mice fed diets containing either 43% glucose or fructose, in combination with either normal or low Ca²⁺. Active transepithelial Ca²⁺ transport from the luminal to the basolateral compartment was expressed as a ratio of the final quantity of ⁴⁵Ca²⁺ inside/outside of the everted gut sacs. (B) mRNA expression levels of intestinal Ca²⁺ (TRPV6, CaBP9k, PMCA1) transporters. All expression data were analyzed by real-time PCR using <i>EF1</i>α as a reference and then normalized to levels in mice fed a normal Ca²⁺-glucose diet (Nor Ca²⁺-G). Data are means ± SEM (<i>n</i> = 6 per group). Differences (<i>P</i><0.05) among means are indicated by differences in superscript letters, as analyzed by 1-way ANOVA LSD. Thus, within a gene of interest, bars with superscript “a” are > bars with “b” which in turn are > bars with “c”. Dietary fructose inhibits compensatory increases in Ca²⁺ transporter activity and expression induced by dietary Ca²⁺-deficiency.</p

Fructose inhibits compensatory increases in renal expression of the 1,25(OH)₂D₃ metabolizing enzyme CYP27B1 induced by dietary Ca²⁺deficiency in mice.

<p>(A) mRNA expression levels of renal CYP27B1 (1α-hydroxylase) and CYP24A1 (24-hydroxylase). (B) The protein abundance of CYP27B1 and CYP24A1, using β-actin as a reference. (C) mRNA expression levels of renal TRPV6, CaBP28k, CaBP9k and PMCA1. Nor  =  normal; G  =  glucose; F  =  fructose. All mRNA expression level data were analyzed by real-time PCR using <i>EF1</i>α as a reference and normalized to levels in mice fed glucose and normal Ca²⁺ diet. Data are means ± SEM (<i>n</i> = 5–6 per group). Differences (<i>P</i><0.05) among means are indicated by differences in superscript letters, as analyzed by 1-way ANOVA LSD. Thus, within a gene of interest, bars with superscript “a” are > bars with “b” which in turn > bars with “c”. Dietary fructose inhibits compensatory increases in renal expression of Ca²⁺ transporters and 1,25(OH)₂D₃ metabolizing enzymes induced by dietary Ca²⁺-deficiency.</p

Effects of age on expression of intestinal Ca²⁺ transporters and of renal 1,25(OH)₂D₃ metabolic enzymes in mice.

<p>A comparison of the expression levels of Ca²⁺ transporters (<b>A</b>) and 1,25(OH)₂D₃ metabolic enzymes (<b>B</b>) in four mo old mice after three mo of feeding on normal Ca²⁺ diet containing 63% glucose (from study 2) and in two mo old mice fed a normal Ca²⁺ diet containing 43% glucose for five wk (from study 1). All expression data were analyzed by real-time PCR using <i>EF1</i>α as a reference and normalized relative to levels seen in four mo old mice. Data are means ± SEM (<i>n</i> = 5–6 per group). Differences (<i>P</i><0.05) between means are indicated by asterisks. Expression of intestinal Ca²⁺ transporters decreases with age.</p

Chronic consumption of fructose has no significant effect on intestinal Ca²⁺ transport rate and transporter mRNA expression in mice fed for three mo a high fructose, starch, or glucose diet containing normal Ca²⁺ levels.

<p>(A) Active transduodenal Ca²⁺ transport from the luminal to the basolateral compartment was expressed as a ratio of the final quantity of (⁴⁵Ca²⁺ inside/⁴⁵Ca²⁺ outside) of the everted sacs of mice fed diets containing 63% fructose, glucose or starch. (B) mRNA expression levels of intestinal Ca²⁺ (TRPV6, CaBP9k, PMCA1) transporters. All expression data were analyzed by real-time PCR using <i>EF1</i>α as a reference and normalized relative to levels seen in mice fed glucose diet. Data are means ± SEM (<i>n</i> = 5 per group). Chronic consumption of high fructose levels has no significant effect on intestinal Ca²⁺ transport rate and transporter mRNA expression.</p

Blood chemistry of mice after consuming glucose- or fructose-based low and normal Ca^2<b>+</b> diets for five weeks.

<p>Normal Ca²⁺  = 0.5%; Low Ca²⁺  = 0.02%; Glucose or Fructose = 43%; FGF  =  fibroblast growth factor. <i>n</i> = 5–6 per group. Data are means ± SEM. Means with different superscript letters are significantly different from others in the same row (<i>P</i><0.05 by <i>posthoc</i> LSD test).</p

Correlation of serum sclerostin and bone volume (BV/TV) among sham, Nx+PTx 0.6% and Nx+PTx 1.2% groups.

<p>Nx+PTx: 5/6 nephrectomy and total parathyroidectomy.</p