Intestinal calcium-binding protein 3 months after massive small bowel resection in the piglet

Nerve terminals containing neuropeptides decrease in number after massive proximal small bowel resection in the piglet

The aim of this study was to evaluate possible changes in the neuropeptide innervation pattern of the remaining porcine ileum following 75% proximal resection of the small intestine. Three-month-old piglets were operated on and two months postoperatively full-thickness specimens of the proximal part of the distal ileum wall were taken. Age-matched 3- and 5-month-old unoperated piglets were used as controls. The number and intensity of VIP-, galanin-, enkephalin-, substance P-, and somatostatin-containing nerve fibers were estimated in sections processed for immunofluorescence microscopy and subjected to quantitative scoring. The VIP-, galanin-, and enkephalin-immunoreactive fibers of the circular muscle layer and villi were also quantitated by computer-assisted morphometry. The number and intensity of VIP-immunoreactive fibers in the mucosa and circular muscle layer markedly decreased after resection as compared to 3-month-old and 5-month-old controls (P < 0.05). The galanin immunoreactivity index decreased significantly after resection in the circular muscle layer as compared to both control groups (P < 0.05). The increase in the number of enkephalin-immunoreactive nerve fibers that normally occurred from 3 to 5 months of age was inhibited by the resection. We were not able to see any differences in somatostatin or substance P immunoreactivity between the groups. The results suggest that massive resection induces significant changes in the neuropeptide-containing innervation of the remaining small intestine. These findings are compatible with altered motor activity and mucosa function in the remain intestine.

Intestinal and renal calcium-binding protein in rats with experimental short bowel syndrome

Intestinal calcium-binding protein (calbindin-D9K) and renal calcium-binding protein (calbindin-D28K) levels were measured by enzyme-linked immunoadsorbent assays in rats with short bowel syndrome induced by resection of about 85% of the small intestine. Rats with short bowel syndrome had significantly lower mucosal concentrations of calbindin-D9K (P less than 0.001) and a parallel reduction of both intestinal calcium absorption (P less than 0.001) and p-1,25-dihydroxyvitamin D (P less than 0.01) in spite of a general hypertrophy of the duodenal mucosa. Interestingly, the renal concentration of calbindin-D28K was significantly elevated (P less than 0.05) in rats with short bowel syndrome, a change apparently related to factors independent of vitamin D.

Measurement of the 10,000-molecular weight calcium-binding protein in small-intestinal biopsy specimens from patients with malabsorption syndromes

Calcium-binding protein (CaBP) (molecular weight, 10,000) was measured in small-intestinal biopsy specimens from 36 patients with malabsorption syndromes: short-bowel syndrome (n = 13), untreated coeliac disease (n = 4), coeliac disease in remission (n = 7), patients with intestinal bypass owing to morbid obesity (n = 5), and in patients with chronic diarrhoea of unknown cause (n = 7). Twelve patients with no signs of malabsorption who had the irritable bowel syndrome were used as controls. Patients with small-bowel resections showed reduced concentrations of CaBP (p less than 0.01) and low intestinal calcium absorption (p less than 0.05). Small amounts of CaBP were found in intestinal specimens from patients with coeliac disease in remission (p less than 0.01), and CaBP was almost undetectable in patients with a newly diagnosed coeliac disease and avillous jejunal biopsy findings (p less than 0.001). Patients with chronic diarrhoea and patients with an intestinal bypass had CaBP concentrations comparable to those of the control group. A direct correlation was found between CaBP and the fractional calcium absorption in all patients (p less than 0.05). CaBP may therefore be considered an indicator of the efficiency of the small intestine to absorb calcium.

Cholecalcin (a 9-kDa cholecalciferol-induced calcium-binding protein) messenger RNA. Distribution and induction by calcitriol in the rat digestive tract

In view of the possible physiological importance of the 9-kDa cholecalcin (a 9000-Mr cholecalciferol-induced calcium-binding protein) in the intestinal transport of calcium in mammals, the gene expression of this protein has been analysed. Its regulation in the digestive tract of the growing rat by calcitriol (1,25-dihydroxycholecalciferol) was studied using a specific cloned [32P]cDNA to 9-kDa cholecalcin. Northern hybridisation studies show that the cDNA sequence hybridises to a single 500-600-nucleotide species throughout the digestive tract and therefore demonstrate identical 9-kDa-cholecalcin mRNA processing in the whole of the intestine and caecum. The highest concentrations of cholecalcin mRNA occur in the duodenum, proximal jejunum and caecum. The observed differences in 9-kDa-cholecalcin mRNA levels correlate well with both the in vivo variations in cholecalcin itself and with the known intestinal sites of calcium absorption. The whole intestine is able to respond to exogenous calcitriol but the response of the distal intestine and caecum, as measured by the increase in cholecalcin mRNA and corresponding protein, was proportionally higher than in the duodenum. The rapid production of fully functional cholecalcin mRNA, which was detectable as early as 1 h after a single dose of calcitriol to vitamin-D-deficient rats, provides convincing evidence that calcitriol increases 9-kDa cholecalcin production by increasing cholecalcin gene expression at the transcriptional level.