Cellular Adaptation of the Rat Small Intestine after Proximal Enterectomy: Changes in Microvillous Enzymes and in the Secretory Component of Immunoglobulins

Abstract

ABSTRACT.To investigate the adaptation of functions expressed by the villous and crypt cell of the intestinal mucosa after intestinal resection, a 50% proximal enterectomy or a single transection was performed in 16 growing rats weighing 175-200 g. Ten days following the enterectomy, we determined the mucosal mass parameters (weight, protein, and DNA content), the activity of microvillous enzymes (lactase, sucrase, and aminopeptidase) in villus cells, and the concentration of the secretory component of immunoglobulins in crypt cells isolated from the proximal intestinal remnant. Mucosal hyperplasia was attested by the finding that mucosal weight, protein, and DNA content per cm of intestinal length were significantly ( p < 0.01) higher (+29 to +48%) in the resected group than in transected controls. The specific activity of lactase, sucrase, and aminopeptidase were significantly ( p < 0.05) lower (-23 to -56%) in villous cells isolated from the intestinal remnant of resected rats compared to controls. Sucrase activity was depressed in each cell fraction of the entire villous-crypt unit resulting in a lower villous to crypt gradient of enzyme activity. K, for the enzyme determined in villous cells was similar in both groups but the V,., was reduced proportionally to the enzyme activity in the resected group indicating less enzyme per cell. By contrast, the concentration of secretory component measured by an immunoradiometric assay in both villous and crypt cells was significantly ( p < 0.05) increased (+37 to 45%) following proximal enterectomy. Our data indicate that the response of the epithelial cell to intestinal resection varies according to the metabolic function and that the mechanism of adaptation at the cellular level is complex. (Pediatr Res 22: 29-33,1987)

Saccharomyces boulardii upgrades cellular adaptation after proximal enterectomy in rats

“…Animals underwent surgery under ether anaesthesia. The procedure of proximal enterectomy has been described in detail previously 6. Briefly, the small intestine was exteriorised through a small midline incision and measured.…”

“…The second group received by nasogastric intubation an equivalent volume (0.5 ml) of saline according to the same protocol. Day 8 after the operation was chosen for the investigations because at that time mucosal hyperplasia is already distinctly expressed while functional adaptation is depressed per unit of cell6 9 and occurs later on 9. Studies were approved by the animal ethics committee of the Catholic University of Louvain, Brussels, Belgium.…”

“…The morphological changes include increased circumference of the intestinal wall and mucosal hyperplasia 1-5. Although total disaccharidase activities normalised to gut length increase or remain unchanged compared with sham operated controls,1 4 5their specific activities measured in isolated villus cells are considerably decreased,6 7 suggesting that the enhanced hydrolase activity is due to an increased number of cells rather than to increased expression of enzyme molecules per cell. The same is true for nutrient absorption and transport mechanisms, which may increase or remain unchanged mainly as the result of increased mucosal mass rather than because of a net increase in absorptive capacity per enterocyte 8…”

Refeeding after starvation in the rat: comparative effects of lipids, proteins and carbohydrates on jejunal and ileal mucosal adaptation

“…The entire small intestine from the pylorus to the ileo-coecal valve was immediately excised and trimmed of fat and mesentery. After rinsing it in 0.9% cold saline, the total length was measured under fixed tension and divided into two equal segments, as described [16]. The proximal half was defined as the jejunum and the distal half as the ileum.…”

Keratinocyte Growth Factor Enhances Early Gut Adaptation in a Rat Model of Short Bowel Syndrome

“…Cellular absorptive and transport functions may be up‐regulated independent of this increase in cell mass (eg, α‐glucosidase and neural aminopeptidase activity, sodium‐glucose co‐transport) 10,11 . Changes in mucosal enzymes (ie, sucrase and alkaline phosphatase) provide some insight into the functionality of adaptation 12 . Intestinal trefoil protein (ITF) belongs to a family of novel peptides that have roles in mucosal cell migration and proliferation, as well as intestinal defense properties 13,14 .…”