Beta-cell mass adaptation to ileum nutrient flow. An experimental model.

The population with obesity has increased at an alarming rate during this century. Bariatric surgery has been demonstrated to be a good method to control weight and, most importantly, associated comorbidities, such as type 2 diabetes mellitus or high blood pressure. The reason why this happens even before losing significant weight remains unclear. Many authors believe that incretins play a main role, triggering special functions of the digestive tract. In reports, these hypotheses are known as foregut and hindgut theories. Initially, the theories were mutually exclusive; additionally, many other propositions have been analysed, according to different surgical techniques (e.g., bile acids and specific enterohormonal components). To elucidate the participation of the ileum, we developed a surgical technique to study the rapid response to nutrients in the ileum. Our goal was to study the stress functional test and histological changes in the pancreas that may explain the variations in glycaemic homeostasis in our rat model. After the oral glucose tolerance test, the experimental group presented an increased insulin release response with conserved glycaemia. We report an increasing beta-cell mass in the experimental group (+11.87 mg vs. +9.65 mg, respectively), while alpha-cell mass was not different. Based on transcription factors, the pathways that were increased were the proliferation process (as the number of PCNA-positive cells in the experimental group versus sham (+12.06 vs. +6.2 PCNA+ cells/mm²)) and transdifferentiation (ARX; +2.67 ARX+ cells/mm² in the experimental group vs. +2.04 ARX+ cells/mm² in the controls). We report the consequences of the rapid arrival of nonprocessed nutrients to the ileum on the endocrine cellular pancreas. The ileum could be a principal effector in the enterohormonal axis, which conditions endocrine pancreas cellularity.

A novel surgical technique focused on the study of the ileum: The preduodenal ileal transposition.

AIMS: Our main goal is to study the effects on the carbohydrate metabolism. Thus, we designed various experimental surgical models on healthy non-obese Wistar rats to reproduce several conditions. In this sense, we report a new experimental model. It is well known that bariatric surgery has important effects on the control of Type 2 Diabetes Mellitus. The underlying reasons are yet unknown, although the different theories focused in the release of different hormones after the pass of the nutrients through the tract. These released hormones have opposite effects that come together in a balanced glycemic metabolism. MATERIALS AND METHODS: After bariatric surgical techniques, the modified anatomy resulted in an imbalance of the secreted hormones. Wistar rats were randomized in two groups Sham and surgical group. Our model consisted on the transposition of the terminal ileum right after the pylorus. Weight gain, food intake, and basal glycemia were measured weekly. RESULTS: We did not obtain significant differences between both groups for these functional variables. CONCLUSIONS: This technique involved an early pass of the bolus through the ileum. The change on the luminal pH, along with the lack of enzymes to absorb the content, or the changes in the release of several hormones must be variables to the study. The mortality rate was assumable considering it was an experimental model on animals.

OBJETIVO: Crear un nuevo modelo quirúrgico experimental en ratas Wistar sanas no obesas para estudiar los efectos del metabolismo glucídico. Es bien sabido que las técnicas de cirugía bariátrica tienen un efecto importante sobre la resolución de la diabetes mellitus tipo 2. Se han invocado diferentes hipótesis, algunas centradas en el papel que tienen distintas hormonas secretadas por el propio tubo digestivo tras el paso de los nutrientes a su través, pero las razones últimas subyacentes permanecen desconocidas. El efecto contrapuesto de dichas hormonas consigue un efecto de control glucémico. El desequilibrio hormonal tras las alteraciones anatómicas de las cirugías bariátricas podría estar en la base de dicha mejora del metabolismo glucídico final. MATERIAL Y MÉTODOS: Las ratas fueron operadas en dos grupos (control quirúrgico y experimental) y se procedió a disponerles el íleon anastomosado al antro pilórico, previo al esfínter pilórico. Medimos distintos parámetros funcionales (ganancia de peso, ingesta y glucemias semanales). RESULTADOS: No obtuvimos diferencias significativas en la evolución de estos parámetros. CONCLUSIONES: Este modelo será útil para nuestro propósito de estudiar el íleon, en su componente secretor de enterohormonas, cuando el paso de los nutrientes se produzca tempranamente. La mortalidad fue asumible, dada la innovación técnica realizada.

A surgical study about jejunum: the exclusion to nutrients flow. A novel strategical technique

The bariatric surgery techniques applied in patients with obesity have reported a great ability to improve Type 2 Diabetes mellitus (T2DM). Some published data report an increasing betacell mass in some surgical processes. This mechanism was specially seen in the bariatric surgeries which affect the length of the small bowel. The intrinsic mechanism that links both phenomena seemed to be related to the enterohormonal secretion pattern. Many enteral hormones have been invoked as the effector of these mechanisms. Previous reports focused on the medial portion of jejunum, as the precise place in which some particular enterohormones determine the homeostatic glycemic improvement. Goto-Kakizaki diabetic male rats underwent surgery to exclude the 50% medial jejunum from the normal nutrients flow. This medial portion of jejunum was not resected, but anastomosed by both extremes to the abdominal wall, and a stoma was performed. This surgery wasnamed as Medial Jejunal Exclusion (MJE). We studied the functional parameters in a three-month survival period. In this sense basal glycaemia, weight increase and food intake were not modified between the surgical and control groups. The study presented a mortality of the 24%. This model was designed for the late study of serum and enterohormones release in this jejunal portion, excluded of nutrients flow. We report a new surgical technique, which appears to balance the homeostatic processes in order to maintain the survival of diabetic rats. Thus, this mechanism could be in the basis of T2DM improvement, and this novel surgical model will help study this precise portion of jejunum

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Pancreas is a preeminent source of ghrelin after sleeve gastrectomy in Wistar rats.

Many surgical techniques are employed in the treatment of severe obesity. A main consequence of these techniques is the improvement of type 2 Diabetes mellitus. Ghrelin is a gut hormone released in the gastric fundus and corpus, which has been related to diabetic improvement as mentioned in these papers. Sleeve gastrectomy and Roux-en Y Gastric Bypass are surgical techniques broadly employed in humans; both severely reduce the gastric surface. Paradoxically, the serum level of ghrelin in patients is preserved. We hypothesized about the role of embryonic pancreatic epsilon cells, which have the capacity to release ghrelin. We studied the changes in the epsilon cells and differentiation markers with immunostaining and ghrelin serum level and after surgery. We employed euglycemic male Wistar rats: two surgical groups (Sleeve gastrectomy and Roux-en Y Gastric Bypass) and two control groups. We reported a significant increase of ghrelin epsilon-cells in the pancreas and basal serum after Sleeve gastrectomy versus the control groups. The epsilon cellular increment was related to neogenesis, as the neurogenin-3 marker revealed. The Roux-en Y Gastric Bypass showed neither epsilon cell increase nor basal serum changes in ghrelin release. As a conclusion, we reported that the severe suppression of the fundus gastric produced the recovery of ghrelin released by the epsilon cells, which was indicative of an ontogenic embryonic pancreatic function.

The Leading Role of Peptide Tyrosine Tyrosine in Glycemic Control After Roux-en-Y Gastric Bypass in Rats.

AIMS: Roux-en-Y gastric bypass (RYGB) is one of the most effective surgical therapies for the rapid resolution of type 2 diabetes. However, the mechanisms underlying the entero-hormonal response after surgery and the role of peptide tyrosine tyrosine (PYY) in the restoration of normoglycemia are still not clear. METHODS: We reproduced the RYGB technique in Wistar and Goto-Kakizaki rats and performed serum hormonal, histological, and hormonal-infusion test. RESULTS: Using the diabetic Goto-Kakizaki (GK) rat model, we demonstrated that PYY plasma levels showed a remarkable peak approximately 30 min earlier than GLP-1 or GIP after mixed-meal administration in RYGB-operated rats with PYY. The GLP-1 and GIP areas under the curve (AUCs) increased after RYGB in GK rats. Additionally, the findings suggested that PYY (3-36) infusion led to increased GLP-1 and GIP plasma levels close to those obtained after a meal. Finally, the number of GLP-1-positive cells appeared to increase in the three segments of the small intestine in GK-RYGB-operated rats beyond the early presence of nutrient stimulation in the ileum. Nevertheless, PYY-positive cell numbers appeared to increase only in the ileum. CONCLUSION: At least in rats, these data demonstrate an earlier essential role for PYY in gut hormone regulation after RYGB. We understand that PYY contributes to GLP-1 and GIP release and there must be the existence of enteroendocrine communication routes between the distal and proximal small intestine.

The teaching of surface anatomy by body painting / Enseñanza de anatomía de superficie mediante la pintura corporal

The present project on learning surface anatomy through the body painting method was undertaken because anatomical knowledge supports medical practice. The appropriate anatomical training of the doctor depends on surface anatomy. We considered the renovation of teaching strategies and didactic resources to optimize the overall teaching- learning process. 189 first-year medical students, enrolled in the Trunk and Splanchnology course at the University of Cádiz (Spain) participated in this study. Students were divided into 5 groups each of 38-41 students. The students were asked to complete a satisfaction questionnaire supplied to each participant through an on-line platform. On the basis of the results, we recommend the body painting method as an alternative tool for learning surface and clinical anatomy.

El presente proyecto sobre el aprendizaje de la anatomía de superficie a través del método de pintura corporal se realizó debido a que el conocimiento anatómico apoya la práctica médica. El entrenamiento anatómico apropiado del médico depende de la anatomía de superficie. Consideramos la renovación de las estrategias de enseñanza y los recursos didácticos para optimizar el proceso general de enseñanza-aprendizaje. De este estudio participaron 189 estudiantes de primer año de medicina, matriculados en el curso de Troncal y Splanchnology en la Universidad de Cádiz (España). Los estudiantes fueron divididos en 5 grupos, cada uno de 38-41 estudiantes. Se les pidió a los estudiantes que completaran un cuestionario de satisfacción proporcionado a cada participante a través de una plataforma en línea. Sobre la base de los resultados, recomendamos el método de pintura corporal como una herramienta alternativa para el aprendizaje de la anatomía de superficie y clínica.

The histomorphometric parameters of endocrine pancreas after bariatric surgery in healthy animal models.

BACKGROUND: The aim of this study is to describe in depth how different bariatric surgeries affect to the cellularity of ß-cells in the pancreatic islet. There are much data regarding the possible physiological mechanisms involved in resolution of type 2 diabetes after bariatric surgery. But these data usually are controversial. We reported a direct influence of bariatric surgical technique on endocrine pancreas cellular turnover. Some surgeries increase proliferation processes of the ß-cells. Our objective is to report the histomorphometric mechanism that these techniques stimulate over the cellularity of pancreatic islet. METHOD: To this purpose, we used adult male Wistar rats to undergo the different techniques. We developed three surgical techniques (Sleeve gastrectomy and Y-Roux Gastric bypass as the most usual bariatric techniques, and a purely malabsorptive technique); moreover two control groups were performed (Sham and fasting controls). RESULTS: We completed a sequence of morphometric studies to conclude the behaviour of endocrine pancreatic ß-cell islet, correlating several histomorphometry parameters. CONCLUSION: Our purpose was to show a comprehensive interpretation to the consequences that bariatric surgeries had on the pancreatic islets cellularity. Moreover, we included the main tests to report the cellularity in histological samples.

GLP-1 mediated improvement of the glucose tolerance in the T2DM GK rat model after massive jejunal resection.

OBJECTIVE: The aim of this study was to clarify the role of the middle gut in the entero-pancreatic axis modification that leads to glucose improvement in the Goto-Kakizaki (GK) rat as a non-obese T2DM model. BACKGROUND: Bariatric surgery is considered an assured solution for type 2 Diabetes (T2DM). Enterohormones such as ghrelin, gastric inhibitory polypeptide and mainly glucagon-like peptide-1 (GLP-1) were recognized as key players in the physiophathological mechanisms associated with entero-pancreatic axis regulation and glucose tolerance improvement. However, the influence of anatomical arrangements post-bariatric surgery on this axis is still debatable. METHOD: To this purpose, 50% of small intestine resections were performed on GK rats (n = 6), preserving the proximal half of the jejunum and the ileum (IR50). Phenotypic and functional changes, such as performance in oral glucose tolerance tests, ileal release of GLP-1, beta-cell sensitivity to GLP-1, beta-cell mass, and turnover were characterized in IR50 and the surgical control group (Sham). RESULTS: The glucose tolerance was improved and ileal release of GLP-1 was enhanced four weeks after IR50 versus the control group rats. Beta-cell mass, beta-cell proliferation, and beta-cell sensitivity to GLP-1 were also increased in the pancreas of IR50 versus the control group rats. CONCLUSION: the jejunal exclusion increases beta-cell-mass and improves glucose tolerance by increasing in GLP-1 expression and number of receptors via the entero-pancreatic axis.

The main participation of the enterohormone GLP-1 after bariatric surgery.

BACKGROUND: Numerous hypotheses are called to explain the beneficial effect on glucose metabolism after bariatric surgery. Some authors advocate for the secretion and release of various substances with endocrine functions for the explanation on this event. One of the substances most marked as effector, with contrasting effects but controversial data, is GLP-1. METHODS: Our study was performed in healthy male Wistar rats, to avoid the absence of confounding factors such as T2DM and obesity. In order to know the adaptation of GLP-1 secretion after surgery 5 groups were designated: two control groups (fasting and surgical stress), and three surgical groups (gastric sleeve, 50% resection of the midgut and the Roux en Y gastric bypass). After three months the GLP-1 synthesis in the different portions of the small intestine and the expression of the membrane receptors in pancreatic islet cells were studied by immunohistochemical techniques. RESULTS: There was a significant increase in the number of secretory cells in ileum, duodenum and jejunum in mixed (RYGB) and malabsorptive (RI50) surgical groups. An elevation of pancreatic receptors signal was also observed in the same techniques versus controls. CONCLUSIONS: Our data indicate that intestinal secretion of GLP-1 and its sensitivity to the pancreatic changes were increased like a response of an adaptive effect to the mechanical aggression of the digestive tube and as alteration of nutrient flow after surgery.

La controvertida participación del GLP-1 en los mecanismos fisiológicos desencadenados tras cirugía bariátrica / The controversial participation of GLP-1 in the physiological mechanisms unchained after bariatric surgery

RESUMEN: Numerosas hipótesis se invocan para explicar el efecto beneficioso sobre el metabolismo glucídico tras la cirugía bariátrica. Algunos autores abogan por la secreción y liberación de distintas sustancias con funciones endocrinas (enterohormonas). Una de las sustancias más señaladas como efector, con efectos contrastados pero datos controvertidos, es el GLP-1. Nuestro estudio se realizó en ratas Wistar macho sanas, para evitar la ausencia de factores de confusión como son la DMT2 y la obesidad. Para conocer el mapa de adaptación a la secreción de GLP-1 tras la cirugía, se designaron 5 grupos: dos grupos control (de ayuno y de estrés quirúrgico); y tres grupos quirúrgicos (gastrectomía vertical, resección del 50 % del intestino medio y el Bypass gástrico con montaje en Y de Roux). Después de tres meses se estudiaron mediante técnicas inmunohistoquímicas el patrón de síntesis de GLP-1 en las distintas porciones del intestino delgado. También se estudió la expresión de los receptores de membrana en las células de los islotes pancreáticos. Se observó la existencia de un significativo aumento del número de células secretoras en íleon, duodeno y yeyuno en los grupos quirúrgicos de técnicas mixtas (RYGB) y malabsortivas (RI50). Igualmente se observó una elevación de los receptores pancreáticos en las mismas técnicas frente a los controles. Nuestros datos indican que la secreción intestinal de GLP-1 y su sensibilidad a nivel pancreáticas están aumentada, como efecto adaptativo a la agresión mecánica del tubo y a la alteración del flujo de nutrientes tras la cirugía.

SUMMARY: Numerous hypotheses are invoked to explain the beneficial effect on glucose metabolism after bariatric surgery. Some authors advocate for the secretion and release of various substances with endocrine functions (enterohormones). One of the substances most marked as effector, with contrasting effects but controversial data, is Glucagon-like peptide-1 GLP-1. Our study was performed in healthy male Wistar rats, to avoid the absence of confounding factors such as DMT2 and obesity. In order to know the map of adaptation to GLP-1 secretion after surgery, five groups were designated: Two control groups (fasting and surgical stress); and three surgical groups (vertical sleeve gastrectomy, 50 % midgut resection and Roux-en-Y gastric bypass). After three months, the GLP-1 synthesis pattern was studied by immunohistochemical techniques in the different portions of the small digestive tract. The expression of membrane receptors in pancreatic islet cells was also studied. There was a significant increase in the number of secretory cells in ileum, duodenum and jejunum in mixed surgical (RYGB) and malabsorptive (RI50) groups. An elevation of pancreatic receptors was also observed in the same techniques against controls. Our data indicated that intestinal secretion of GLP1 and its sensitivity to the pancreatic level were increased, both to an adaptive effect to the mechanical aggression of the digestive tube and to the alteration of nutrient flow after surgery.

Bariatric surgery influences ß-cell turnover in non obese rats.

BACKGROUND: The aim of this study was to investigate the relation between the different bariatric surgeries and pancreatic ß-cell turnover. MATERIAL AND METHODS: We used healthy adult male Wistar rats to undergo the different techniques. Three surgical techniques were developed (malabsorptive, Sleeve gastrectomy and Roux-Y Gastric Bypass-), together with two control groups (Sham and fasting control). Pancreatic ß-cell mass was measured, as well as apoptosis, proliferation and neogenesis related to cellular turnover. Otherwise, we measured the functional issues to elucidate the physiological role that these surgical techniques trigger in the carbohydrate metabolism (e.g. food intake, weight gain, intraperitoneal glucose tolerance test, and basal glycaemia). Results included the differences in phenotypes of the rat after the surgery. The rats did not show important differences in glycaemic parameters between the surgical groups. The ß-cell mass presented modifications related with proliferation processes. A significant increase of ß-cell mass in the malabsorptive technique was reported. On the other hand, the peripheral resistance to insulin tended to be reduced in rats which underwent malabsorptive and mixed techniques. CONCLUSION: This work showed an increase in ß-cell mass after the resection of an important portion of small bowel. The Roux-Y Gastric Bypass produced a non-significant increase in ß-cell mass. We considered that these implications of surgery over the endocrine pancreas must be one of the mechanisms related to the improvement of type 2 Diabetes mellitus following bariatric surgery.