Effect of leptin on intestinal re-growth following massive small bowel resection in rat

Recent evidence suggests that the adipose tissue-derived cytokine leptin (LEP) is involved in modulation of growth and differentiation of normal small intestine. The purpose of the present study was to evaluate the effects of parenteral LEP on structural intestinal adaptation, cell proliferation and apoptosis in a rat model of short bowel syndrome (SBS). Male Sprague-Dawley rats were divided into three experimental groups: Sham rats underwent bowel transection and re-anastomosis, SBS-rats underwent a 75% small bowel resection, and SBS-LEP-rats underwent bowel resection and were treated with LEP given subcutaneously at a dose of 20 μg/kg, once daily, from day 3 through 14. Parameters of intestinal adaptation (bowel and mucosal weights, mucosal DNA and protein, villus height and crypt depth in jejunum and ileum), enterocyte proliferation and enterocyte apoptosis were determined on day 15 following operation. Ileal tissue samples were taken for detection of bax and bcl-2 gene expression using RT-PCR technique. Statistical analysis was performed using the non-parametric Kruskal–Wallis ANOVA test, with P<0.05 considered statistically significant. Treatment with subcutaneous LEP resulted in a significant increase in jejunal (17%, P<0.05) and ileal (13%, P<0.05) bowel weight, jejunal (10%, P<0.05) and ileal (25%, P<0.05) mucosal weight, jejunal (26%, P<0.05) and ileal (38%, P<0.05) mucosal DNA, ileal (25%, P<0.05) mucosal protein, jejunal (41%, P<0.05) and ileal (21%, P<0.05) villus height, jejunal (37%, P<0.05) crypt depth, and jejunal (24%, P<0.05) and ileal (21%, P<0.05) enterocyte proliferation compared to SBS-animals. Enterocyte apoptosis increased significantly after bowel resection in jejunum and ileum compared to sham animals and was accompanied by an increased bax gene expression and a decreased bcl-2 gene expression in ileal samples. SBS-LEP rats showed a trend toward a decrease in enterocyte apoptosis in ileum and a mild decrease in bax gene expression compared to SBS-untreated animals. In conclusion, in a rat model of SBS parenteral LEP stimulates structural intestinal adaptation. Increased cell proliferation and decreased cell death via apoptosis may be responsible for this increased cell mass.     

Effect of subcutaneous insulin on intestinal adaptation in a rat model of short bowel syndrome

Insulin has been shown to influence intestinal structure and absorptive function. The purpose of the present study was to evaluate the effects of parenteral insulin on structural intestinal adaptation, cell proliferation, and apoptosis in a rat model of short bowel syndrome (SBS). Male Sprague-Dawley rats were divided into three experimental groups: sham rats underwent bowel transection and reanastomosis, SBS rats underwent a 75% small bowel resection, and SBS-INS rats underwent a 75% small bowel resection and were treated with insulin given subcutaneously at a dose of 1 U/kg, twice daily, from day 3 through day 14. Parameters of intestinal adaptation, enterocyte proliferation, and enterocyte apoptosis were determined on day 15 following operation. SBS rats demonstrated a significant increase in jejunal and ileal bowel and mucosal weight, villus height and crypt depth, and cell proliferation index compared with the sham group. SBS-INS animals demonstrated higher jejunal and ileal bowel and mucosal weights, jejunal and ileal mucosal DNA and protein, and jejunal and ileal crypt depth compared with SBS animals. SBS-INS rats also had a greater cell proliferation index in both jejunum and ileum and a trend toward a decrease in enterocyte apoptotic index in jejunum and ileum compared with the SBS untreated group. In conclusion, parenteral insulin stimulates structural intestinal adaptation in a rat model of SBS. Increased cell proliferation is the main mechanism responsible for increased cell mass.     

Effect of dietary fat on early morphological intestinal adaptation in a rat with short bowel syndrome

Among factors promoting mucosal hyperplasia after bowel resection, long-chain fatty acids may have a special role. The purpose of the present study was to evaluate the effects of high-fat diet (HFD) on early intestinal adaptation in rats with short bowel syndrome (SBS). Male Sprague-Dawley rats underwent either a bowel transection with re-anastomosis (Sham rats) or 75% small bowel resection (SBS rats). Animals were randomly assigned to one of three groups: Sham rats fed normal chow (Sham-NC); SBS rats fed NC (SBS-NC); and SBS rats fed HFD (SBS-HFD). Rats were killed on days 3 or 14. Body weight and parameters of intestinal adaptation (overall bowel and mucosal weight, mucosal DNA and protein, villus height, and crypt depth) were determined at time of killing. By day 3, SBS-HFD rats demonstrated higher duodenal and jejunal bowel and mucosal weights and ileal villus height and jejunal crypt depth vs SBS-NC rats. By day 14 SBS-HFD rats continued to demonstrate increased duodenal and jejunal bowel weight and duodenal mucosal weight vs SBS-NC animals. We conclude that early exposure to HFD both augmented and accelerated structural bowel adaptation in a rat model of SBS.     

Epidermal growth factor and bombesin act synergistically to support intestinal adaptation in rats with massive small bowel resection

Intestinal adaptation is the most important event in short bowel syndrome following a massive small bowel resection. Effects of various growth factors and their synergism have been well documented in intestinal adaptation. This study aimed to compare the effect of two different trophic agents, epidermal growth factor (EGF) and bombesin (BBS), on intestinal adaptation following massive intestinal resection. Sprague–Dawley male rats were assigned to one of four groups after a 75% small bowel resection. Either EGF (90 g/kg), BBS (10 g/kg), EGF+BBS, or bovine serum albumin (BSA) were injected subcutaneously three times a day. The animals were killed 10 days after the operation. Weight loss and morphologic parameters such as mucosal thickness, villus height, crypt depth, villus-to-crypt ratio, and muscularis propria height were measured. In the EGF+BBS group, mucosal thickness was found to be significantly increased compared with the other study groups (p<0.05). Similarly, villus height was significantly increased only in the EGF+BBS group (p<0.05). In the BBS group, both villus height and mucosal thickness showed a slight increase, but the values were not statistically significant compared with the vehicle-treated group. There were no significant differences in any of the remaining parameters between the groups. The results of this study indicate that the gut hormones EGF and BBS act synergistically in facilitating the adaptive response of the remnant ileum to massive intestinal resection.     

Neonatal short bowel syndrome: 'rectal feeding' in order to stimulate intestinal growth

Short bowel syndrome (SBS) is characterized by a state of malabsorption following extensive resection of the small bowel, resulting in insufficient nutritive supply requiring artificial nutrition with long-term parenteral nutrition. Here we present an illustrative case report of a premature infant born with gastroschisis and SBS, who was treated with enteral refeeding via rectum. The infant developed during the period of rectal feeding with jejunostomy loses bowel lengthening and could be fed orally within a few months after birth. Rectal feeding with ostomy loses could stimulate bowel growth and adaptation in neonatal SBS.
Conclusion: The purpose of this report is to describe an illustrative case of short bowel syndrome due to gastroschisis and to share a novel technique of rectal feeding to stimulate bowel growth and adaptation.     

Effect of a valine-rich diet on a rat model of short bowel syndrome

It has been recently reported that valine, which was one of the branched chain amino acids, enhanced liver regeneration after a hepatectomy in rats. The aim of this study is to investigate the effect of enteral valine supplementation on the intestinal adaptation of short bowel syndrome using a rat model. Seven-week-old male Lewis rats underwent a 90% small bowel resection. The rats were randomly divided into two groups; Group V (valine-rich diet which contains valine, five times as the normal amount of valine as that found in standard rat chow) and Group S (standard rat chow), according to the diet each group received. The rats were killed and evaluated at the operative day, and postoperative days (POD) 7, 14, 30, and 60, respectively. The parameters of estimation were body weight (BW), a blood amino acids analysis, a urine organic acids analysis and a morphological examination of the residual small intestines. The BW and the intestinal wet weight, jejunal crypt depth and proliferating cell nuclear antigen positive cells in Group V at POD 7 were significantly higher than in Group S, while those in the Group V at POD 30 and 60 were smaller than in Group S. The urine methylmalonic acid (MMA) level in Group V at POD 30 and 60 was much higher than in Group S. The valine-rich diet was thus found to enhance intestinal regeneration after a small bowel resection in the acute phase. However, the long-term valine-rich diet supplementation was found to disturb the intestinal adaptation, which might be caused by the high production of MMA due to the valine-rich diet. This is the first report in which valine was used as a promoter of intestinal adaptation.     

Intestinal adaptation in short-bowel syndrome

After massive resection of the small intestine the remannt mucosa has an important capacity to enlarge the absorptive surface for the digestion, hydrolysis and absorption of nutrients. This intestinal adaptation is achieved by the interaction of various factors. Oral nutrients together with pancreatic biliary secretions stimulate the mucosa to become hyperplastic. Secondary to these luminal factors hormones play an important role in the adaptive process. Among the hormones, enteroglucagon is the most important growth promoting agent together with other growth factors such as epidermal growth factor, prostaglandin E₂ and human growth hormone analogues, e.g. plerocercoid growth factor from the plerocercoid larvae of the tapeworm Spirometra mansonoides. The intestinal enterocyte is the target of these factors and within the cell the synthesis of polyamines, which are responsible for rapid growth, is the most essential step for the development of hyperplasia after resection. The rate limiting enzyme for polyamine synthesis ornithine decarboxylase (ODC) reacts to trophic stimuli with an increased activity. Thereafter rapid accumulation of tissue polyamines occurs. Blockade of ODC by specific inhibitors is accompanied by absence of intestinal hyperplasia after resection. Therefore it is concluded that ODC plays a key role in the intestinal adaptation of the remnant small bowel. To start and enhance intestinal hyperplasia after resection in patients with short bowel syndrome introduction of oral nutrition as soon as possible after operation is very important. On account of gastric acid hypersecretion the use of H₂ receptor blocking agents is recommended. A decreased intestinal transit time is treated with loperamide. Adequate nutritional support by enteral and (home) parenteral feeding is the prerequisite for the initiation and development of intestinal adaption in short bowel syndrome.Abbreviations CCK cholecystokinin - CCPR crypt cell production rate - DFMO alpha difluoromethyl-ornithine - EGF epidermal growth factor - FFA free fatty acids - hGH human growth hormone - LCT long chain triglycerides - MCT medium chain triglycerides - ODC ornithine decarboxylase - PBS pancreatic biliary secretion - PGE prostaglandin E₂ - PGF pleroceroid growth factor     

Management of short bowel syndrome in infancy

Short bowel syndrome (SBS) is a reduction in functioning bowel length which is most often a result of surgical resection. Risk factors in the neonatal period include necrotising enterocolitis, small bowel atresia and gastroschisis. With increasing survival of preterm infants there is an increase in incidence. Management is dependent on the use of parenteral nutrition to maintain fluid and electrolyte homeostasis and promote growth and development with the longer term aim being to promote intestinal adaptation to achieve partial or complete enteral autonomy. In this review we discuss the incidence, aetiology, pathophysiology, medical and surgical treatments and outcome.     

Management of intestinal failure

Intestinal failure (IF) occurs when the body is unable to sustain its energy and fluid requirements without support, due to loss of functional small bowel. Prolonged IF is seen after large intestinal resection and described as short bowel syndrome (SBS). The hallmark of the management is parental nutrition (PN), which is costly and may be associated with the well-recognized problems of parental nutrition associated liver disease (PNALD) and line related sepsis. Cessation of PN at the earliest possible stage is desirable but for this enteral autonomy has to be achieved first. Intestinal adaptation occurs when the remaining gut goes through morphological changes increasing its absorptive capacity. Factors such as intraluminal nutrients, gastrointestinal secretions and hormones facilitate adaptation. Enteral feeds are a potent stimulant to adaptation, and should be started as soon as the clinical situation permits. Some drugs are thought to increase intestinal adaptation. These include glutamine, growth hormone and glucagon like peptide-2, but there is a paucity of pediatric data to guide their use. In some cases surgical bowel lengthening procedures can be performed to increase the absorptive surface area. An isolated liver transplantation may be required if the liver has sustained irreversible damage but intestinal autonomy seems achievable. When prolonged PN is either unsustainable or associated with unacceptable side effects, small bowel transplantation should be considered as a treatment option.     

Surgical therapy for short bowel syndrome

Patients with short bowel syndrome (SBS) suffer tremendous morbidity secondary to prolonged hospitalization and chronic parenteral nutrition (TPN). Overall, the majority of infants will adapt and ultimately become independent of TPN, but this process may require many months or years. Reasons for continued TPN dependency include bowel dysmotility, bacterial overgrowth, insufficient adaptation, or very short bowel length. It is this subpopulation of patients who may benefit from surgical procedures that optimize intestinal adaptation and increase the mucosal absorptive surface area. The goal of this review article is to summarize the process of intestinal adaptation and then to outline the surgical principles and techniques available to surgeons who treat this complicated group of patients.     

Radiological aspects of the small bowel after extensive resection in children

The authors present radiological aspects of small bowel after extensive resection. They describe the main phenomena related to compensatory hypertrophy: dilatation of the loops, muscosal fold thickening and motor disturbances. The main complications demonstrated by the radiological examination are presented; gallstones, non-functionning anastomosis, bacterial overgrowth.     

Growth-factor enhancement of compromised gut function following massive small-bowel resection

 Our laboratory has shown that epidermal growth factor (EGF) and hepatocyte growth factor (HGF) can improve the function of normal rat small intestine. This study was designed to evaluate the role of these growth factors on the residual small intestine following massive (80%) small bowel resection. Our data demonstrate that EGF and HGF can enhance intestinal substrate absorption and mucosal mass beyond that which occurs with intestinal adaptation. These growth factors may be beneficial in the management of children with short bowel syndrome. Accepted: 13 December 1999     

Oral arginine improves intestinal recovery following ischemia-reperfusion injury in rat

Arginine and nitric oxide are critical to the normal physiology of the gastrointestinal tract and maintain the mucosal integrity of the intestine in various intestinal disorders. In the present study, we evaluate the effects of oral arginine (ARG) supplementation on intestinal structural changes, enterocyte proliferation, and apoptosis following intestinal ischemia–reperfusion (IR) in the rat. Male Sprague–Dawley rats were divided into three experimental groups: sham rats underwent laparotomy and superior mesenteric artery mobilization, IR rats underwent superior mesenteric artery occlusion for 30 min following by 24 h of reperfusion, and IR-ARG rats were treated with enteral arginine given in drinking water (2%) 48 h before and following IR. Intestinal structural changes, enterocyte proliferation, and enterocyte apoptosis were determined 24 h following IR. A nonparametric Kruskal–Wallis ANOVA test was used for statistical analysis with p <0.05 considered statistically significant. IR rats demonstrated a significant decrease in bowel weight in duodenum and jejunum, mucosal weight in jejunum and ileum, and villus height in jejunum and ileum compared with control animals. IR rats also had a significantly lower cell proliferation index in jejunum and ileum and a higher apoptotic index in ileum compared with control rats. IR-ARG animals demonstrated greater duodenal and jejunal bowel weight; duodenal, jejunal, and ileal mucosal weight; and jejunal and ileal cell proliferation index compared with IR animals. In conclusion, oral ARG administration improves mucosal recovery following IR injury in the rat.     

Intestinal epithelial cell proliferation is dependent on the site of massive small bowel resection

Early intestinal adaptation after massive small bowel resection (SBR) is driven by increased epithelial cell (EC) proliferation. There is a clear clinical difference in the post-operative course of patients after the loss of proximal (P) compared to distal (D) small bowel. This study examined the effects of the site of SBR on post-resectional intestinal adaptation, and investigated the potential mechanisms involved. C57BL/6J mice (n = 7/group) underwent: (1) 60% P-SBR, (2) 60% D-SBR, (3) 60% mid (M)-SBR and (4) SHAM-operation (transection/reanastomosis). Mice were sacrificed at 7 days after surgery and ECs and adjacent mucosal lymphocytes (IELs) isolated. Adaptation was assessed in both jejunum and ileum by quantification of villus height, crypt depth, villus cell size, crypt cell size (microns), goblet cell number, and EC proliferation (%BrdU incorporation). Proliferation signalling pathways including keratinocyte growth factor (KGF)/KGFR₁, IL-7/IL-7R, and epidermal growth factor receptor (EGFR) were measured by RT-PCR. Expression of IL-7 was further analysed by immunofluorescence. Data were analyzed using ANOVA. All three SBR models led to significant increases in villus height, crypt depth, goblet cell numbers and EC proliferation rate when compared to respective SHAM groups. The strongest morphometric changes were found for jejunal segments after M-SBR and for ileal segments after P-SBR. Furthermore, morphometric analysis showed that at 1-week post-resection a tremendous increase in EC numbers occurred in jejunal villi (cell hyperplasia), whereas a significant increase in EC size predominated in ileal villi (cell hypertrophy). mRNA expression of KGF, KGFR₁, IL-7R, and EGFR showed a significant increase only after D-SBR, whereas IL-7 increased significantly after SBR in all investigated models, and this was confirmed by immunofluorescence studies. Early intestinal adaptation shows distinct differences depending on the site of SBR, and is predominately driven by cell hyperplasia in jejunal villi and cell hypertrophy in ileal villi. However, the exact mechanisms, which guide these signalling pathways are still unclear.     

Nutritional supplementation with transforming growth factor-beta inhibits intestinal adaptation after massive small bowel resection in a rat

Introduction  

Transforming growth factor beta (TGF-β) has been shown to affect epithelial cell differentiation and proliferation through epithelial-mesenchymal and epithelial-immune cell interaction. In the present study, we evaluated the effect of TGF-β2-enriched polymeric diet (Modulen) on enterocyte turnover in a rat model of short bowel syndrome (SBS).     

The effect of intestinal plication on intestinal transit time in rats

Short bowel syndrome (SBS) can occur after extensive intestinal resections. In SBS, the aim of surgical techniques is to prolong intestinal transit time (ITT) and to increase the absorptive surface. This experimental study was conducted to research the effect of extramucosal intestinal plication on ITT in rats. Thirty Sprague-Dawley rats were divided into three groups. In the control group, barium solution was administrated by gavage. Forty-five minutes later, the rats were sacrificed, and the total length of their small bowels (SBs) and the distance of the barium in the SBs were measured. The ratio of the distance of the barium to the length of the SB was calculated, and the ITT was found for normal rats. Intestinal plication (made with three seromuscular sutures at the same level: one on the antimesenteric side, and two on the lateral sides of the bowel) and laparotomy and bowel manipulation were carried out in the study and sham groups, respectively, and ITT was measured by the same method after 1 week. A one-way ANOVA test was used to compare the groups in terms of body weight, total length of the SB, distance of the barium in the SB, and the ratio of this distance to the length of the SB. The rats were statistically homogeneous in terms of body weight and total length of the SB ( p >0.05). The distances of the barium in the small bowel in the control, sham, and study groups were 73.4±8.5 cm, 77.5±6.8 cm, and 56.3±3.6 cm, respectively. The distances of barium in the SB in the study group were statistically shorter than in the other groups ( p <0.05). The ratios of the distance of the barium to the length of the SB in the control, sham, and study groups were 65.8±7.3, 66.4±4.5, and 49.9±3.8, respectively. In the study group, this ratio was also statistically lower than in the other groups ( p <0.05). Extramucosal intestinal plication retarded ITT significantly in the study group compared with the other groups. This technique does not entail any risk of morbidity and mortality; therefore, it can be used in the treatment of SBS.Presented at XX Annual Meeting of Turkish Association of Pediatric Surgeons, 15–19 October 2002, Mersin, Turkey.     

Oral insulin stimulates intestinal epithelial cell turnover following massive small bowel resection in a rat and a cell culture model

Purpose  

We have recently reported that oral insulin (OI) stimulates intestinal adaptation after bowel resection and that OI enhances enterocyte turnover in correlation with insulin receptor expression along the villus–crypt axis. The purpose of the present study was to evaluate the effect of OI on intestinal epithelial cell proliferation and apoptosis in a rat model of short bowel syndrome (SBS) and in a cell culture model.