OBES SURG DOI 10.1007/s11695-014-1549-7
ORIGINAL CONTRIBUTIONS
Side-to-Side Jejunoileal Bypass Induces Better Glucose-Lowering Effect than End-to-Side Jejunoileal Bypass on Nonobese Diabetic Rats Jinyuan Duan & Cai Tan & Hang Xu & Shaolin Nie
# Springer Science+Business Media New York 2014
Abstract Background Jejunoileal bypass (JIB) can markedly ameliorate diabetes in obese patients and rodents. The aim of this study is to systematically evaluate the role of the operational manner and the retained distal small bowel length in mediating changes in glucose homeostasis after intestinal bypass surgeries in nonobese diabetic rats. Methods Streptozotocin-induced diabetic rats underwent side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL), end-to-side jejunoileal bypass (ESJIB), proximal small bowel resection (PBR), and sham operation. Each operational manner included two subgroups, in which 30 cm (L-30) or 40 cm (L-40) distal small bowel was retained. Main outcome measures were fasting blood glucose levels (FBG), insulin sensitivity, serum insulin, glucagon-like peptide-1 (GLP-1), bilirubin (BIL), and total bile acids (TBA) levels.
J. Duan (*) Department of General Surgery, The First Affiliated Hospital of Soochow University, No.188 Shizi Road, Suzhou, Jiangsu Province 215006, People’s Republic of China e-mail: [email protected] C. Tan Department of Women’s Health, Maternal and Child Health Hospital of Jiangxi Province, Nanchang 330006, China e-mail: [email protected] H. Xu Department of Breast and Thyroid Surgery, Haikou Peoples’s Hospital, Central South University Xiangya School of Medicine Affiliated Haikou Hospital, Haikou 570208, China e-mail: [email protected] S. Nie Department of Intestinal Surgery, Hunan Provincial Tumor Hospital, The Affiliated Tumor Hospital of Central South University Xiangya School of Medicine, Changsha 410013, China e-mail: [email protected]
Results Global food intake in the sham group was higher than in the operation groups, and global body weight and food intake in the SSJIBL group were higher than in the ESJIB and PBR groups. Global body weight and food intake in L-40 group were higher than in L-30 group. The SSJIBL procedure induced better improvement in glucose homeostasis and insulin sensitivity than the ESJIB and PBR procedures, and L-30 group showed better antidiabetic effects than L-40 group. Serum GLP-1, BIL, and TBA levels in SSJIBL group were higher than in ESJIB and PBR groups. Conclusions This study shows that side-to-side jejunoileal bypass induced better glucose-lowering effects than end-toside jejunoileal bypass and proximal small bowel resection, and intestinal bypass surgery that retained shorter distal small bowel yielded better antidiabetic effects. Keywords Diabetes . Jejunoileal bypass . Side-to-side anastomosis . End-to-side anastomosis . Proximal small bowel resection
Introduction In the late 1960s and early 1970s, jejunoileal bypass (JIB) was performed frequently as a bariatric surgical option for massive obesity; however, this technique had become obsolete by the mid-1980s due to the serious complications which was mainly induced by blind loop syndrome [1]. The end-to-side jejunoileal bypass necessitates transection of the jejunum, including all intrinsic neural and muscular tissues that are responsible for propagation of the controlling electrical activity, thus dividing the jejunal limb from the native pacemaker. As a result, the ectopic pacemakers are generated in the middle
OBES SURG
of the bypassed limb and are paced at a much lower frequency and, occasionally, in an oral direction, leading to stagnation of the intestinal contents and subsequent bacterial overgrowth in the bypassed loop [2], which has been known to be the key cause of blind loop syndrome. With a degree of clinical success, a number of surgeons have used proximal loop ligation during the loop esophagojejunostomy after total gastrectomy to prevent blind loop syndrome [3]. The “uncut Roux” reconstructive technique has been found to be successful in promoting myoelectric continuity in the aboral direction and preventing the formation of ectopic pacemakers [4]. Inspired by these idea, we designed a new jejunoileal bypass procedure that we termed “side-to-side jejunoileal bypass plus proximal loop ligation” or SSJIBL [5]. However, to date, very little systematic work has been done to study the comparison of curative effect between side-to-side and end-to-side jejunoileal bypass on diabetes. Furthermore, we assumed that the length of retained distal small bowel might also be a determinant of antidiabetic effects after jejunoileal bypass. To investigate the above problems, we developed three experimental intestinal procedures using streptozotocin (STZ)-induced diabetic rats, a widely used animal model of nonobese diabetes. The three experimental intestinal procedures were side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL or SS), end-to-side jejunoileal bypass (ESJIB or ES), and proximal small bowel resection (PBR or BR), respectively. Meanwhile, each intestinal procedure had two subgroups, in which 30 cm (L-30) or 40 cm (L-40) distal small bowel was retained separately. The antidiabetic effect of the three intestinal procedures (SSJIB, ESJIB, and PBR) and two subgroups (L-30 and L-40) was then compared with each other to determine the contributions of the operational manner and the retained distal small bowel length to the improvement in glucose homeostasis after surgical procedures.
Materials and Methods Animals’ Model The experiments were carried out in accordance with and were approved by the Ethical Committee on Animal Experimentation of Xiangya Medical College, Central South University of Science and Technology, China (Permit number: S249). A total of 120 male Sprague-Dawley (SD) rats weighting 258 ± 11 g were purchased from the Central South University Xiangya School of Medicine Animal Department [SPF, Certification number×20102288]. The rats were housed 1 per cage in a room with a 12/12-h light/dark cycle and a temperature of 22 to 25 °C. Water and standard rodent chow were given to the rats ad libitum. The rats were
acclimated for 1 week, followed by an intraperitoneal injection of 65 mg/kg [6] streptozotocin (STZ, Sigma, St. Louis, MO, USA). Seventy-two hours after STZ injection, rats with a non-fasting blood glucose level above 300 mg/dl [7] were considered to be diabetic rats and were selected for further studies. Surgical Groups One week after the STZ injection body weight, food intake, fasting blood glucose level (FBG), and oral glucose tolerance test (OGTT) were measured before surgery. The STZ-induced diabetic rats were divided into eight treatment groups according to two parameters: operational manner (operation) and retained distal small bowel length (length). The operation includes SS, ES, BR, and sham operation, and the length includes 30 cm (L-30) and 40 cm (L-40). Therefore, a total of 96 diabetic rats were randomized into the following treatment groups: SS-30 (n=12), SS-40 (n=12), ES-30 (n=12), ES-40 (n=12), BR-30 (n=12), BR-40 (n= 12), Sham-30 (n=12), and Sham-40 (n=12). The allocation of rats to each group and surviving numbers over time, out to 12 weeks postoperative, are shown in Table 1. Surgical Techniques After an overnight fast with free access to water, animals were anesthetized with 10 % chloral hydrate solution (300 mg/kg body weight). The abdomen was shaved, and the peritoneal cavity was accessed via a 4-cm midline incision. Side-to-Side Jejunoileal Bypass Plus Proximal Loop Ligation For SSJIBL group (Fig. 1a), the entire small bowel (from the ligament of Treitz to the ileocecal valve, the usual length of the rat’s jejunoileum varied from 104 to 119 cm) was measured along the antimesenteric border, a point 40 cm (SS-40) or 30 cm (SS-30) proximal to the ileocecal valve was used as the Table 1 Allocation of rats to surgical treatment group and surviving numbers over time SS-30 SS-40 ES-30 ES-40 BR-30 BR-40 Sham Before surgery 1 week 2 weeks 4 weeks 6 weeks 12 weeks
12 10 10 10 10 10
12 11 11 11 11 11
12 10 9 8 8 8
12 10 10 10 10 9
12 11 10 9 8 8
12 10 10 9 9 9
24 21 20 20 20 18
Causes of death during the study period included intestinal obstruction (n=4), anastomotic leakage (n=14), intestinal intussusceptions (n=1), diabetic complication (n=3), and unknown causes (n=1)
OBES SURG
Fig. 1 Operations. a, b Schematic and operative photograph of the sideto-side jejunoileal bypass plus proximal loop ligation (SSJIBL or SS) model. Physiological characteristics of the procedure included (1) preservation of 30 or 40-cm distal small intestine, (2) exclusion of about 60 or 70 % of proximal-to-mid small intestine, (3) an isoperistaltic side-to-side anastomosis between the proximal jejunum (at 6 cm distal to the Treitz ligament) and the ileum, (4) luminal occlusion at the first portion of the bypassed segment using a ligation of 0 silk suture. c End-to-side jejunoileal bypass (ESJIB or ES).
Physiological characteristics of the procedure included preservation of (1) the same distal small intestine and exclusion of the same proximal-to-mid small intestine as in SSJIBL, (2) an end-to-side anastomosis between the proximal jejunum and the ileum. d Proximal small bowel resection (PBR or BR). Physiological characteristics of the procedure included preservation of (1) the same distal small intestine and exclusion of the same proximal-to-mid small intestine as in SSJIBL and ESJIB, (2) an end-to-end anastomosis between the proximal jejunum and the ileum
reference point. Starting proximally from this point to 6 cm distal to the Treitz ligament, about 60 or 70 % of the length of the entire small bowel was bypassed and bowel continuity was restored by an isoperistaltic side-to-side anastomosis between the proximal jejunum and the ileum. The luminal occlusion was performed at the first portion of the bypassed segment using a ligation of 0 silk suture (ETHICON SA86G, Johnson & Johnson) (Fig. 1b). The distance between anastomosis and luminal occlusion was minimized in order to avoid a blind pouch. Enteric anastomoses were performed with a single layer of interrupted 7–0 nylon suture (Hangzhou Huawei Medical Treatment Articles Co., Ltd). The abdominal cavity was closed with 3–0 silk suture (ETHICON SA84G, Johnson & Johnson).
End-to-Side Jejunoileal Bypass For ESJIB group, like SSJIBL group, 40 cm (ES-40) or 30 cm (ES-30) of the ileum was preserved and jejunoileal end-to-side anastomosis was established using the first 6 cm of the jejunum (measured from the Treitz ligament) and the ileum, thus bypassing about 60 or 70 % of the small intestine (Fig. 1c). Partial Proximal Small Bowel Resection For PBR group, a point 40 cm (BR-40) or 30 cm (BR-30) proximal to the ileocecal valve was used as the reference point. Starting proximally from this point, about 60 or 70 % of the length of the entire small bowel was resected, and bowel
OBES SURG
continuity was restored by an end-to-end anastomosis between the proximal jejunum (at 6 cm distal to the Treitz ligament) and the ileum (Fig. 1d). Sham Operations For the sham operations, abdominal incisions and two transections of intestine were performed at 6 cm distal to the Treitz ligament and 30 cm (Sham-30) or 40 cm (Sham-40) proximal to the ileocecal valve, with no removal or bypass. All transections were immediately followed by end-to-end anastomosis in the original position.
rat specific enzyme-linked immunosorbent assay (ELISA) with antibodies obtained from Wuhan Xinqidi Biological Technology Co., Ltd (Wuhan, China). All rats were killed after overnight fasting under chloral hydrate anesthetic on the final morning of the 12-week period, and blood was collected from the hearts of the animals into centrifuge tubes containing coagulant for estimation of serum total bilirubin (TBIL), direct bilirubin (DBIL), and total bile acids (TBA). The analytical tests were performed by the biochemical laboratory of The Second Xiangya Hospital. Statistical Analysis
Postoperative Care All rats were given 10-ml sterile saline subcutaneously after operation, and the animals were put in individual cages to recover from anesthesia. All rats were fasted for 24 h. Free access to tap water was allowed from the first postoperative day to the end of experiment, and the standard rodent chow was provided 1 day after surgery. Measurement of Body Weight and Food Intake Body weight and food intake were measured at baseline and postoperative weeks 1, 2, 4, 6, 8, 10, and 12. Biochemical Tests Glucose levels were measured by an electronic glucometer (Accu-Chek Performa ®, Roche Diagnostic, Switzerland) on blood obtained via the tail vein of conscious rats. For the fasting blood glucose level (FBG), the food were taken away from the 8:00 AM, after 8 h of fasting, the glucose level were measured at 16:00 PM before surgery and at 1, 2, 4, 6, 8, 10, and 12 weeks postoperation. An insulin tolerance test (ITT) was performed to evaluate insulin sensitivity in conscious rats at 2 and 12 weeks postoperatively by measuring glucose levels before and 15, 30, 45, 60, 90, and 120 min after intraperitoneal injection of 0.5 IU/kg human insulin (Wanbang Biopharmaceuticals, Jiangsu, China). Serum insulin and glucagon-like peptide-1 (GLP-1) levels were measured on blood obtained via ophthalmic venous plexus of conscious rats at baseline and 30 min after 1 g/kg glucose (20 % dextrose) gavage at 12 weeks postoperatively. Blood samples were placed in tubes containing 12 trypsin inhibitory unit (TIU)/ml aprotinin (Sangon Biotech (Shanghai) Co., Ltd., Catalogue AD0153, Shanghai, China). Tubes containing blood samples were immediately centrifuged at 3000 rpm for 13 min. Serum was removed immediately and stored at −80 °C until analysis. Fasting and glucosestimulated insulin and GLP-1 levels were determined using a
Data are expressed as means±standard deviation. All statistical analyses were performed with SPSS Version 20.0 and the level of significance was set at 0.05. Considering that there was no significant difference of body weight, food intake, FBG, OGTT, ITT, and other observed results between two sham groups, Sham-30 and Sham-40 groups were combined into one group (Sham) in order to facilitate statistics and statements. Generalized linear mixed models (GLMMs) were constructed to the longitudinal measurements of changes over time in body weight, food intake, FBG, and insulin tolerance. Following Bonferroni test was performed for pairwise comparisons between groups. One-way analysis of variance (ANOVA) was performed to evaluate difference of serum insulin and GLP-1 levels, and serum TBIL, DBIL, and TBA levels.
Results Body Weight Control Evolution of the average body weights of operated groups and sham group rats after surgery was shown in Fig. 2. By GLMMs, (1) ES-30 (242 g, 95 % confidence interval (CI) 237–248 g) and BR-30 (240 g, 95 % CI 235–245 g) rats showed lower global body weight than sham (271 g, 95 % CI 267–276 g) rats (post hoc Bonferroni, P=0.006 and P= 0.008 for ES-30 and BR-30 versus sham group), whereas rats in SS-40 (290 g, 95 % CI 284–296 g) showed higher global body weight than sham rats (post hoc Bonferroni, P=0.003) (Fig. 2a); though the ES-40 (276 g, 95 % CI 271–281 g) and BR-40 (278 g, 95 % CI 271–285 g)-operated rats exhibited higher global body weight than sham operated rats, no significant difference was detected (post hoc Bonferroni, P=0.479 and P=0.283 for ES-40 and BR-40 versus sham group); (2) the global body weight in SS (274 g, 95 % CI 271–280 g) group was higher than in ES (258 g, 95 % CI 253–263 g) and BR (259 g, 95 % CI 254–265 g) groups (post hoc Bonferroni,
OBES SURG
Daily Intake of Food Evolution of the average food intakes of operated groups and sham groups rats after surgery was shown in Fig. 3. By
Fig. 2 Body weight. Body weight curves (a treatment groups, b operation groups, c length groups). SS side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL), ES end-to-side jejunoileal bypass (ESJIB), BR proximal small bowel resection (PBR). Rats had SS or ES or BR surgery, retained 30 cm (SS-30, ES-30, and BR-30) or 40 cm (SS-40, ES-40, and BR-40) distal small bowel. L-30 group includes SS-30, ES30, and BR-30 groups; L-40 group includes SS-40, ES-40, and BR-40 groups. * All Ps0.05 for ES-40, BR-40, and SS-30 versus sham group; ** Both Ps 0.05 between ES and BR groups; *** Both Ps
ORIGINAL CONTRIBUTIONS
Side-to-Side Jejunoileal Bypass Induces Better Glucose-Lowering Effect than End-to-Side Jejunoileal Bypass on Nonobese Diabetic Rats Jinyuan Duan & Cai Tan & Hang Xu & Shaolin Nie
# Springer Science+Business Media New York 2014
Abstract Background Jejunoileal bypass (JIB) can markedly ameliorate diabetes in obese patients and rodents. The aim of this study is to systematically evaluate the role of the operational manner and the retained distal small bowel length in mediating changes in glucose homeostasis after intestinal bypass surgeries in nonobese diabetic rats. Methods Streptozotocin-induced diabetic rats underwent side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL), end-to-side jejunoileal bypass (ESJIB), proximal small bowel resection (PBR), and sham operation. Each operational manner included two subgroups, in which 30 cm (L-30) or 40 cm (L-40) distal small bowel was retained. Main outcome measures were fasting blood glucose levels (FBG), insulin sensitivity, serum insulin, glucagon-like peptide-1 (GLP-1), bilirubin (BIL), and total bile acids (TBA) levels.
J. Duan (*) Department of General Surgery, The First Affiliated Hospital of Soochow University, No.188 Shizi Road, Suzhou, Jiangsu Province 215006, People’s Republic of China e-mail: [email protected] C. Tan Department of Women’s Health, Maternal and Child Health Hospital of Jiangxi Province, Nanchang 330006, China e-mail: [email protected] H. Xu Department of Breast and Thyroid Surgery, Haikou Peoples’s Hospital, Central South University Xiangya School of Medicine Affiliated Haikou Hospital, Haikou 570208, China e-mail: [email protected] S. Nie Department of Intestinal Surgery, Hunan Provincial Tumor Hospital, The Affiliated Tumor Hospital of Central South University Xiangya School of Medicine, Changsha 410013, China e-mail: [email protected]
Results Global food intake in the sham group was higher than in the operation groups, and global body weight and food intake in the SSJIBL group were higher than in the ESJIB and PBR groups. Global body weight and food intake in L-40 group were higher than in L-30 group. The SSJIBL procedure induced better improvement in glucose homeostasis and insulin sensitivity than the ESJIB and PBR procedures, and L-30 group showed better antidiabetic effects than L-40 group. Serum GLP-1, BIL, and TBA levels in SSJIBL group were higher than in ESJIB and PBR groups. Conclusions This study shows that side-to-side jejunoileal bypass induced better glucose-lowering effects than end-toside jejunoileal bypass and proximal small bowel resection, and intestinal bypass surgery that retained shorter distal small bowel yielded better antidiabetic effects. Keywords Diabetes . Jejunoileal bypass . Side-to-side anastomosis . End-to-side anastomosis . Proximal small bowel resection
Introduction In the late 1960s and early 1970s, jejunoileal bypass (JIB) was performed frequently as a bariatric surgical option for massive obesity; however, this technique had become obsolete by the mid-1980s due to the serious complications which was mainly induced by blind loop syndrome [1]. The end-to-side jejunoileal bypass necessitates transection of the jejunum, including all intrinsic neural and muscular tissues that are responsible for propagation of the controlling electrical activity, thus dividing the jejunal limb from the native pacemaker. As a result, the ectopic pacemakers are generated in the middle
OBES SURG
of the bypassed limb and are paced at a much lower frequency and, occasionally, in an oral direction, leading to stagnation of the intestinal contents and subsequent bacterial overgrowth in the bypassed loop [2], which has been known to be the key cause of blind loop syndrome. With a degree of clinical success, a number of surgeons have used proximal loop ligation during the loop esophagojejunostomy after total gastrectomy to prevent blind loop syndrome [3]. The “uncut Roux” reconstructive technique has been found to be successful in promoting myoelectric continuity in the aboral direction and preventing the formation of ectopic pacemakers [4]. Inspired by these idea, we designed a new jejunoileal bypass procedure that we termed “side-to-side jejunoileal bypass plus proximal loop ligation” or SSJIBL [5]. However, to date, very little systematic work has been done to study the comparison of curative effect between side-to-side and end-to-side jejunoileal bypass on diabetes. Furthermore, we assumed that the length of retained distal small bowel might also be a determinant of antidiabetic effects after jejunoileal bypass. To investigate the above problems, we developed three experimental intestinal procedures using streptozotocin (STZ)-induced diabetic rats, a widely used animal model of nonobese diabetes. The three experimental intestinal procedures were side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL or SS), end-to-side jejunoileal bypass (ESJIB or ES), and proximal small bowel resection (PBR or BR), respectively. Meanwhile, each intestinal procedure had two subgroups, in which 30 cm (L-30) or 40 cm (L-40) distal small bowel was retained separately. The antidiabetic effect of the three intestinal procedures (SSJIB, ESJIB, and PBR) and two subgroups (L-30 and L-40) was then compared with each other to determine the contributions of the operational manner and the retained distal small bowel length to the improvement in glucose homeostasis after surgical procedures.
Materials and Methods Animals’ Model The experiments were carried out in accordance with and were approved by the Ethical Committee on Animal Experimentation of Xiangya Medical College, Central South University of Science and Technology, China (Permit number: S249). A total of 120 male Sprague-Dawley (SD) rats weighting 258 ± 11 g were purchased from the Central South University Xiangya School of Medicine Animal Department [SPF, Certification number×20102288]. The rats were housed 1 per cage in a room with a 12/12-h light/dark cycle and a temperature of 22 to 25 °C. Water and standard rodent chow were given to the rats ad libitum. The rats were
acclimated for 1 week, followed by an intraperitoneal injection of 65 mg/kg [6] streptozotocin (STZ, Sigma, St. Louis, MO, USA). Seventy-two hours after STZ injection, rats with a non-fasting blood glucose level above 300 mg/dl [7] were considered to be diabetic rats and were selected for further studies. Surgical Groups One week after the STZ injection body weight, food intake, fasting blood glucose level (FBG), and oral glucose tolerance test (OGTT) were measured before surgery. The STZ-induced diabetic rats were divided into eight treatment groups according to two parameters: operational manner (operation) and retained distal small bowel length (length). The operation includes SS, ES, BR, and sham operation, and the length includes 30 cm (L-30) and 40 cm (L-40). Therefore, a total of 96 diabetic rats were randomized into the following treatment groups: SS-30 (n=12), SS-40 (n=12), ES-30 (n=12), ES-40 (n=12), BR-30 (n=12), BR-40 (n= 12), Sham-30 (n=12), and Sham-40 (n=12). The allocation of rats to each group and surviving numbers over time, out to 12 weeks postoperative, are shown in Table 1. Surgical Techniques After an overnight fast with free access to water, animals were anesthetized with 10 % chloral hydrate solution (300 mg/kg body weight). The abdomen was shaved, and the peritoneal cavity was accessed via a 4-cm midline incision. Side-to-Side Jejunoileal Bypass Plus Proximal Loop Ligation For SSJIBL group (Fig. 1a), the entire small bowel (from the ligament of Treitz to the ileocecal valve, the usual length of the rat’s jejunoileum varied from 104 to 119 cm) was measured along the antimesenteric border, a point 40 cm (SS-40) or 30 cm (SS-30) proximal to the ileocecal valve was used as the Table 1 Allocation of rats to surgical treatment group and surviving numbers over time SS-30 SS-40 ES-30 ES-40 BR-30 BR-40 Sham Before surgery 1 week 2 weeks 4 weeks 6 weeks 12 weeks
12 10 10 10 10 10
12 11 11 11 11 11
12 10 9 8 8 8
12 10 10 10 10 9
12 11 10 9 8 8
12 10 10 9 9 9
24 21 20 20 20 18
Causes of death during the study period included intestinal obstruction (n=4), anastomotic leakage (n=14), intestinal intussusceptions (n=1), diabetic complication (n=3), and unknown causes (n=1)
OBES SURG
Fig. 1 Operations. a, b Schematic and operative photograph of the sideto-side jejunoileal bypass plus proximal loop ligation (SSJIBL or SS) model. Physiological characteristics of the procedure included (1) preservation of 30 or 40-cm distal small intestine, (2) exclusion of about 60 or 70 % of proximal-to-mid small intestine, (3) an isoperistaltic side-to-side anastomosis between the proximal jejunum (at 6 cm distal to the Treitz ligament) and the ileum, (4) luminal occlusion at the first portion of the bypassed segment using a ligation of 0 silk suture. c End-to-side jejunoileal bypass (ESJIB or ES).
Physiological characteristics of the procedure included preservation of (1) the same distal small intestine and exclusion of the same proximal-to-mid small intestine as in SSJIBL, (2) an end-to-side anastomosis between the proximal jejunum and the ileum. d Proximal small bowel resection (PBR or BR). Physiological characteristics of the procedure included preservation of (1) the same distal small intestine and exclusion of the same proximal-to-mid small intestine as in SSJIBL and ESJIB, (2) an end-to-end anastomosis between the proximal jejunum and the ileum
reference point. Starting proximally from this point to 6 cm distal to the Treitz ligament, about 60 or 70 % of the length of the entire small bowel was bypassed and bowel continuity was restored by an isoperistaltic side-to-side anastomosis between the proximal jejunum and the ileum. The luminal occlusion was performed at the first portion of the bypassed segment using a ligation of 0 silk suture (ETHICON SA86G, Johnson & Johnson) (Fig. 1b). The distance between anastomosis and luminal occlusion was minimized in order to avoid a blind pouch. Enteric anastomoses were performed with a single layer of interrupted 7–0 nylon suture (Hangzhou Huawei Medical Treatment Articles Co., Ltd). The abdominal cavity was closed with 3–0 silk suture (ETHICON SA84G, Johnson & Johnson).
End-to-Side Jejunoileal Bypass For ESJIB group, like SSJIBL group, 40 cm (ES-40) or 30 cm (ES-30) of the ileum was preserved and jejunoileal end-to-side anastomosis was established using the first 6 cm of the jejunum (measured from the Treitz ligament) and the ileum, thus bypassing about 60 or 70 % of the small intestine (Fig. 1c). Partial Proximal Small Bowel Resection For PBR group, a point 40 cm (BR-40) or 30 cm (BR-30) proximal to the ileocecal valve was used as the reference point. Starting proximally from this point, about 60 or 70 % of the length of the entire small bowel was resected, and bowel
OBES SURG
continuity was restored by an end-to-end anastomosis between the proximal jejunum (at 6 cm distal to the Treitz ligament) and the ileum (Fig. 1d). Sham Operations For the sham operations, abdominal incisions and two transections of intestine were performed at 6 cm distal to the Treitz ligament and 30 cm (Sham-30) or 40 cm (Sham-40) proximal to the ileocecal valve, with no removal or bypass. All transections were immediately followed by end-to-end anastomosis in the original position.
rat specific enzyme-linked immunosorbent assay (ELISA) with antibodies obtained from Wuhan Xinqidi Biological Technology Co., Ltd (Wuhan, China). All rats were killed after overnight fasting under chloral hydrate anesthetic on the final morning of the 12-week period, and blood was collected from the hearts of the animals into centrifuge tubes containing coagulant for estimation of serum total bilirubin (TBIL), direct bilirubin (DBIL), and total bile acids (TBA). The analytical tests were performed by the biochemical laboratory of The Second Xiangya Hospital. Statistical Analysis
Postoperative Care All rats were given 10-ml sterile saline subcutaneously after operation, and the animals were put in individual cages to recover from anesthesia. All rats were fasted for 24 h. Free access to tap water was allowed from the first postoperative day to the end of experiment, and the standard rodent chow was provided 1 day after surgery. Measurement of Body Weight and Food Intake Body weight and food intake were measured at baseline and postoperative weeks 1, 2, 4, 6, 8, 10, and 12. Biochemical Tests Glucose levels were measured by an electronic glucometer (Accu-Chek Performa ®, Roche Diagnostic, Switzerland) on blood obtained via the tail vein of conscious rats. For the fasting blood glucose level (FBG), the food were taken away from the 8:00 AM, after 8 h of fasting, the glucose level were measured at 16:00 PM before surgery and at 1, 2, 4, 6, 8, 10, and 12 weeks postoperation. An insulin tolerance test (ITT) was performed to evaluate insulin sensitivity in conscious rats at 2 and 12 weeks postoperatively by measuring glucose levels before and 15, 30, 45, 60, 90, and 120 min after intraperitoneal injection of 0.5 IU/kg human insulin (Wanbang Biopharmaceuticals, Jiangsu, China). Serum insulin and glucagon-like peptide-1 (GLP-1) levels were measured on blood obtained via ophthalmic venous plexus of conscious rats at baseline and 30 min after 1 g/kg glucose (20 % dextrose) gavage at 12 weeks postoperatively. Blood samples were placed in tubes containing 12 trypsin inhibitory unit (TIU)/ml aprotinin (Sangon Biotech (Shanghai) Co., Ltd., Catalogue AD0153, Shanghai, China). Tubes containing blood samples were immediately centrifuged at 3000 rpm for 13 min. Serum was removed immediately and stored at −80 °C until analysis. Fasting and glucosestimulated insulin and GLP-1 levels were determined using a
Data are expressed as means±standard deviation. All statistical analyses were performed with SPSS Version 20.0 and the level of significance was set at 0.05. Considering that there was no significant difference of body weight, food intake, FBG, OGTT, ITT, and other observed results between two sham groups, Sham-30 and Sham-40 groups were combined into one group (Sham) in order to facilitate statistics and statements. Generalized linear mixed models (GLMMs) were constructed to the longitudinal measurements of changes over time in body weight, food intake, FBG, and insulin tolerance. Following Bonferroni test was performed for pairwise comparisons between groups. One-way analysis of variance (ANOVA) was performed to evaluate difference of serum insulin and GLP-1 levels, and serum TBIL, DBIL, and TBA levels.
Results Body Weight Control Evolution of the average body weights of operated groups and sham group rats after surgery was shown in Fig. 2. By GLMMs, (1) ES-30 (242 g, 95 % confidence interval (CI) 237–248 g) and BR-30 (240 g, 95 % CI 235–245 g) rats showed lower global body weight than sham (271 g, 95 % CI 267–276 g) rats (post hoc Bonferroni, P=0.006 and P= 0.008 for ES-30 and BR-30 versus sham group), whereas rats in SS-40 (290 g, 95 % CI 284–296 g) showed higher global body weight than sham rats (post hoc Bonferroni, P=0.003) (Fig. 2a); though the ES-40 (276 g, 95 % CI 271–281 g) and BR-40 (278 g, 95 % CI 271–285 g)-operated rats exhibited higher global body weight than sham operated rats, no significant difference was detected (post hoc Bonferroni, P=0.479 and P=0.283 for ES-40 and BR-40 versus sham group); (2) the global body weight in SS (274 g, 95 % CI 271–280 g) group was higher than in ES (258 g, 95 % CI 253–263 g) and BR (259 g, 95 % CI 254–265 g) groups (post hoc Bonferroni,
OBES SURG
Daily Intake of Food Evolution of the average food intakes of operated groups and sham groups rats after surgery was shown in Fig. 3. By
Fig. 2 Body weight. Body weight curves (a treatment groups, b operation groups, c length groups). SS side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL), ES end-to-side jejunoileal bypass (ESJIB), BR proximal small bowel resection (PBR). Rats had SS or ES or BR surgery, retained 30 cm (SS-30, ES-30, and BR-30) or 40 cm (SS-40, ES-40, and BR-40) distal small bowel. L-30 group includes SS-30, ES30, and BR-30 groups; L-40 group includes SS-40, ES-40, and BR-40 groups. * All Ps0.05 for ES-40, BR-40, and SS-30 versus sham group; ** Both Ps 0.05 between ES and BR groups; *** Both Ps
