Intrinsic Denervation Research Articles

A new experimental model of intrinsic denervation in ileum from wistar rats through intramural microinjections of benzalkonium chloride

ABSTRACT: Extensive literature is available about the intrinsic denervation of segments of the digestive tube through the application of CB in the serosa of the viscera. However, this technique has some disadvantages like causing peritonitis, flanges and high mortality, limiting its use in humans. The aim of the present study was to evaluate the feasibility of benzalkonium chloride (CB) to induce intrinsic chemical denervation, through applications of CB in the intramural ileum of wistar rats, as well as deepen the knowledge about the evolution of neuronal injury caused in the process. We used 40 rats, divided into two groups (control-GC and benzalkonium-GB) of 20 animals each, divided into four sub-groups according to the time of postoperative assessment of 24, 48 hours, 30 and 90 days. The animals were submitted to intramural microinjections of sterile saline solution 0.9% (GC) or benzalkonium chloride (GB) in ileal portion, and subsequent histopathological analysis and immunohistochemistry for evaluation of neuronal injury. A significant decrease (p<0.05) was found of the neuronal myenteric count over time in groups, GB3, GB4 and GB2. The specific positive immunolabeling for H2AX and Caspase-3 confirmed the results obtained in the histopathological evaluation, denoting the ignition of irreversible cell injury in 24 hours, evolving into neuronal apoptosis in 48 hours after application of the CB 0.3%. Under the conditions in which this work was conducted, it can be concluded that the application of CB 0.3% by means of microinjections intramural in the ileal wall is able to induce intrinsic chemical denervation of the diverticulum of wistar rats and that the main mechanism of neuronal death is induction of apoptosis.

Sa1959 Angiogenesis Occurs Very Early During the Colonic Chemical Carcinogenesis and Is Attenuated by Intrinsic Denervation of the Colon

Sa1959 Angiogenesis Occurs Very Early During the Colonic Chemical Carcinogenesis and Is Attenuated by Intrinsic Denervation of the Colon

The Incretin Response After Successful Islet Transplantation

The Incretin Response After Successful Islet Transplantation

Do neuro‐humoral signaling molecules participate in colorectal carcinogenesis/cancer progression?

AbstractSignaling molecules in the gastrointestinal (GI) tract, as released from intrinsic, or extrinsic neurons, or from local endocrine cells may serve as positive or negative growth factors, and it has been suggested that such could participate also in colorectal carcinogenesis/cancer progression. Sporadic colorectal cancer arises from an initially benign adenoma, which, in turn, develops from the stem cell compartment, located in the bottom of the crypts of the colorectal mucosa. It was recently demonstrated in rat that intrinsic denervation of the colon appeared to be protective against chemically induced carcinogenesis. Of the various GI signaling molecules, noradrenaline (NA) and substance P (SP) may be of particular importance as growth factors involved in colorectal cancer. In the current issue of Neurogastroenterology and Motility, Graf et al. demonstrate that in benign, human colon polyps, there was a loss of innervation compared with adjacent mucosa, affecting efferent, noradrenergic, as well as sensory, SP‐ergic fibers, while there was an increase in SP‐immunoreactive non‐neuronal cells in the polyps. The results obtained could suggest that loss of mucosal innervation, due to e.g. luminal, pro‐inflammatory stimuli, could result in unbalanced pro‐tumorigenic stimulation of the stem cell region by non‐neuronal SP. The current findings may be important for the further understanding of the development of sporadic colorectal cancer.

Effects of denervation at ileocecal junction and ileocecal resection in dogs

To investigate neural regulation at the ileocecal junction (ICJ) and motility changes after ileocecal resection (ICR). Previous studies showed normal basal motility at the ICJ directly by force transducers in dogs, but these observations were limited to normal contractile activity. Continuous strain gauge recordings of stomach, terminal ileum, ileocecal sphincter (ICS), and colon were performed in dogs. The dogs were divided into four groups, namely control (CONT), extrinsic denervation at ICJ (ED), intrinsic denervation at ICJ (ID), and ICR groups. Colonic activity was recorded 2 h before a meal, in the early postprandial period (first 2 h), and in the late postprandial period (4-6 h after a meal). The meal lasted 5 min. Motility index was significantly increased at the ICS (P = 0.0056) and proximal colon (P = 0.0059) after feeding. However, such changes were not observed in the ED and ID groups. The amplitude of contractions at proximal colon in the interdigestive state was significantly decreased by ED. In the ID and ICR groups, the numbers of nonmigrating contractions were significantly decreased (P < 0.05), and colonic migrating motor complex (CMMC) ratio was significantly higher than that of the CONT group (P < 0.001). The dogs in these two groups had diarrhea. Gastrocolonic response at the ICJ may require both intrinsic and extrinsic innervation. When ID was performed, CMMC ratio increased. As a result, intraluminal water absorption may have decreased. ID may be one of the causes of diarrhea after ICR.

Intrinsic denervation of the colon is associated with a decrease of some colonic preneoplastic markers in rats treated with a chemical carcinogen

Denervation of the colon is protective against the colon cancer; however, the mechanisms involved are unknown. We tested the hypothesis that the denervated colonic mucosa could be less responsive to the action of the chemical carcinogen dimethylhydrazine (DMH). Three groups of 32 male Wistar rats were treated as follows: group 1 (G1) had the colon denervated with 0.3 mL 1.5 mM benzyldimethyltetradecylammonium (benzalkonium chloride, BAC); G2 received a single ip injection of 125 mg/kg DMH; G3 was treated with BAC + the same dose and route of DMH. A control group (Sham, N = 32) did not receive any treatment. Each group was subdivided into four groups according to the sacrifice time (1, 2, 6, and 12 weeks after DMH). Crypt fission index, ss-catenin accumulated crypts, aberrant crypt foci, and cell proliferation were evaluated and analyzed by ANOVA and the Student t-test. G3 animals presented a small number of aberrant crypt foci and low crypt fission index compared to G2 animals after 2 and 12 weeks, respectively. From the second week on, the index of ss-catenin crypt in G3 animals increased slower than in G2 animals. From the 12th week on, G2 animals presented a significant increase in cell proliferation when compared to the other groups. Colonic denervation plays an anticarcinogenic role from early stages of colon cancer development. This finding can be of importance for the study of the role of the enteric nervous system in the carcinogenic process.

Efeitos da desnervação intrínseca do jejuno após enterectomia extensa na síndrome do intestino curto em ratos

To investigate the effects of intrinsic denervation of the jejunum after the extensive intestinal resection in rats. Thirty male Wistar rats were distributed into three groups, depending on the experimental procedure: Group C (control), Group R (resection) and Group D (resection plus denervation). The body weight gain and a histomorphometric study of the jejunal mucosa were performed. The mean body weight of the group D animals showed a higher increase when compared to group R (D=312.2+/-21 g and R=196.7+/-36.2g). The number of jejunum myenteric neurons was smaller in group D (344.8+/-34.8 neurons/mm) when compared to other groups (R=909.0+/-55.5 and C=898.5+/-73.3). A hyperplasia of the jejunum mucosal epithelium was observed in the group D but also in the group R (R=7.3+/-3.9 mm2 and D=10.8+/-4.3 mm2), when compared to group C (C=5.8+/-3.0 mm2). The epithelial cell proliferation of the jejunum was higher in group D animals (48.7%) when compared to the other groups (R=31.9% and C=23.6%). The denervated animals presented an increase the body weight gain and mucosal cell proliferation responses when compared to the control group. This experimental model may provide new strategies for the surgical treatment of the short bowel syndrome.

Um modelo experimental de ablação do Sistema Nervoso Intrínseco Cardíaco reduz a contratilidade do coração de ratos

OBJETIVO: A função do Sistema Nervoso Intrínseco Cardíaco e o seu papel na doença cardíaca permanecem pobremente compreendidos. Sabe-se que o cloreto de benzalcônio (CB) induz a desnervação intrínseca do tubo digestivo. O objetivo deste estudo foi tentar produzir um modelo experimental de desnervação intrínseca do coração utilizando o CB. MÉTODO: Trinta ratos Wistar foram submetidos à aplicação intrapericárdica de CB (0,3%) e trinta animais controle receberam a solução salina. Após 15 dias, os animais foram divididos em três grupos, com 10 animais tratados e 10 controles em cada. Os animais do grupo I foram submetidos a estudo radiológico e histopatológico. A área cardíaca e o índice cardiotorácico (ICT) foram medidos nas radiografias. Os animais do grupo II foram submetidos a estudo hemodinâmico com registro da pressão arterial, freqüência cardíaca e débito cardíaco. No grupo III, a integridade da inervação parassimpática extrínseca do coração foi avaliada por estimulação vagal direita. O sistema de condução foi avaliado pelo ECG basal. RESULTADOS: A aplicação de CB acarretou aumento do ICT, da área cardíaca, pressão arterial e débito cardíaco, bem como do peso ponderal e do fígado. Nestes animais, a análise histopatológica mostrou redução do número de neurônios atriais e congestão passiva crônica do fígado. A estimulação vagal não mostrou diferenças entre os grupos experimentais. CONCLUSÃO: A ablação do sistema nervoso intrínseco propiciou o aparecimento de cardiopatia dilatada com insuficiência cardíaca direita e esquerda. Esse modelo experimental inédito deverá nortear futuros estudos na tentativa da elucidação da relação entre lesão neuronal e miocardiopatia.

Effects of intrinsic denervation on intestinal morphology in rats with short-bowel syndrome.

When benzalkonium chloride solution (BACs) is locally applied, to the serosal surface of the intestine, it causes intrinsic denervation (ID) of the myenteric plexus (MP), changes intestinal morphology, and slows intestinal passage by prolonging small-bowel transit time. These effects of ID suggest that chemically-induced bowel denervation may be useful in the treatment of short-bowel syndrome (SBS). How ID affects intestinal morphology in rats with SBS has not previously been investigated. A 75%-80% mid-small-bowel resection was performed in 20 rats with mean body weight 247 +/- 30 g. The proximal and distal 2 cm of the resected bowel were examined histologically. After intestinal continuity was maintained by end-to-end anastomosis, a 2-cm jejunal segment was marked with silk sutures to form the test segment. BACs 0.1% was applied to 10 of the 20 test segments according to the modified Fox method, resulting in MP destruction (G1). Saline solution was applied to the other 10 test segments to form the control group (G2). Three months later, the rats were killed and the jejunal, ileal, and test segments were evaluated morphologically. Results were expressed as mean +/- standard deviation. The Wilcoxon parametric test was performed to compare the groups during the operation and after death, while the Mann Whitney U-test was used to compare the data in G1 and G2. No intestinal obstruction was observed in either group. In G1, the body weight increased by 19.1% and the total small-intestinal lengthening was 62.2% (P < 0.05). In the test segment of G1, 75% of the ganglia in the MP were destroyed and villus height, crypt depth, intestinal muscle thickness, number of enterocytes, and villus density increased compared to G2. In the ileal segments of G1, there was an increase of 28.8% in intestinal diameter, 14% in muscle thickness, and 15% in villus density (P < 0.05). No change was observed in the untreated jejunal segments of G1 and G2. Thus, ID of the MP after segmental BACs application of the jejunal level: (1) does not cause intestinal obstruction after 3 months; (2) the increase in bowel diameter in the test and ileal segments increases the absorptive surface of the mucosa; (3) the morphologic changes in the test and ileal segments verify an increase in intestinal adaptation; and (4) BACs application in rats with SBS is an easy procedure with no morbidity or mortality, and can be used to increase intestinal adaptation in rats with SBS.

Effect of selective gastric intrinsic denervation on gastric motility in turkeys

The effect of selectively denervating portions of the myenteric plexus on gastroduodenal (GD) motility was examined in domestic turkeys (Meleagris gallopavo). The neural network beneath the lateral or medial side of the isthmus between the glandular stomach and the muscular stomach was denervated by application of 1% benzalkonium chloride (BC). Image intensification radiology (IIR) was performed postsurgically on the research subjects to observe GD contractions and to analyze aberrations. Two trials were performed. The first employed temporal controls by checking GD motility in all treated birds before and after BC had taken effect. The second trial controlled for the trauma associated with the surgical procedure by applying 0.9% saline solution in lieu of BC in four turkeys. The normal GD contractions sequence as confirmed by these controls was thin muscle contraction, duodenal contraction and outflow, thick muscle contraction, and, finally, glandular stomach contraction. Ablation of the nerves beneath the medial or lateral side of the isthmus resulted in the same abnormality in GD motility, namely a lack of thick muscle contractions. These results indicate that the entire myenteric plexus associated with the isthmus must remain intact for proper GD motility to take place. Furthermore, it can be inferred that initiation and regulation of the thick muscle pair acts via nerves encircling the isthmus. Secondary regulatory mechanisms controlling GD motility may exist and should be tested through future investigation.

Intrinsic Myenteric Denervation: A New Model to Increase the Intestinal Absorptive Surface in Short-Bowel Syndrome

Introduction. Short-bowel syndrome (SBS) is caused by resection of massive portions of the small intestine and is characterized by symptoms related to malabsorption, of which severe weight loss is the most apparent. Surgical treatments for SBS are not yet satisfactory. In rats, the myenteric denervation by benzalkonium chloride (BAC) leads to development of megaileum with visceral dilatation and mucosal hyperplasia and increases the intestinal transit time. Such operation in the remaining intestinal segment after massive small bowel resection could increase the duration of contact between luminal nutrients and ileal mucosal epithelium, and furthermore, it could increase the superficial area of the mucosa. Thus, our aim in this study was to evaluate the epithelial morphology and body weight changes of animals after intrinsic ileal denervation associated with extensive small intestine resection.Material and methods. Wistar rats were submitted to resection of 80% of small intestinal length (Group R). Another group (B) of animals also received topical serosal application of BAC 0.3%. Control animals were submitted to simulated surgery (Group C). Animals were weighed weekly and sacrificed after 90 days. Intestinal walls were collected for histological procedure and morphometry.Results. At the end of the experimental period all groups showed weight increase, which was reduced in the R group (P < 0.01). Interestingly, the denervated Group B showed a marked increase in weight, similar to the control animals. Morphometric analysis of the mucosal layer area showed a major increase in mucosal surface area, mainly in Group B.Conclusions. Our results showed that the ileal intrinsic denervation associated with massive intestinal resection induced an increase in the superficial absorptive area and was able to improve the postsurgical conditions for the animals, with accentuated weight increase. This procedure may be a useful model for further studies related to the role of the enteric nervous system on intestinal adaptations after extensive resections and may provide a new approach for the surgical treatment of short-bowel syndrome.

Megacolon in Rats

Four months of sigmoid colon intrinsic denervation of young male Wistar rats resulted in typical megacolon. Average 46.0% denervation of the Auerbach plexus was obtained by serosal application of benzalkonium chloride (0.2% v/v). Denervation was assessed by ganglion cell counts in a 480-nm extension of the treated segment. Increased thickness of the megacolon wall was due to muscle hypertrophy (+117.4%) and mucosal hyperplasia (+53.9%) as shown by morphometry. The potential usefulness of this experimental model is emphasized.

Contribution of Partial Pancreatectomy, Systemic Hormone Delivery, and Duct Obliteration to Glucose Regulation in Canine Pancreas: Importance in Pancreas Transplantation

Our aim was to isolate and determine the contribution of partial pancreatectomy, systemic delivery of pancreatic hormones, and duct obliteration to glucose regulation after segmental pancreas transplantation in dogs. Fasting, postprandial, and intravenous glucose-stimulated glucose, insulin, glucagon, pancreatic polypeptide (PP), and cholecystokinin (CCK) and intravenous bombesin-stimulated PP levels were studied in beagles at three successive intervals in a crossover design. The first was 6 wk after partial (approximately 70%) pancreatectomy with intact regular enteric exocrine drainage from the duodenal pancreatic remnant, the next was 2 wk after venous transposition with systemic delivery of pancreatic hormones, and the third was 6 wk after in situ duct obliteration of the remnant. With partial pancreatectomy, K values were modestly diminished (30%), and a concomitant reduction of second-phase intravenous glucose-stimulated insulin release was observed. Other parameters were not significantly affected. Venous transposition doubled peripheral plasma levels of insulin under all conditions. Fasting glucose, PP, and CCK levels decreased slightly. Other parameters were not affected. Duct obliteration of the systemic draining pancreatic remnants seriously impaired glucose sensitivity, resulting in a 50% reduction of K values and fasting and sustained postprandial hyperglycemia (approximately 8 mM) and a 70-50% reduction (acute and overall responses, respectively) of intravenous glucose-stimulated insulin. Fasting hormone and postprandial insulin, glucagon, and CCK levels were not affected. The postprandial PP response was severely reduced, and bombesin-stimulated PP release was abolished by duct obliteration. We conclude that histological changes associated with duct obliteration are the major determinants of glucose regulation in segmental pancreas transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired acid secretion and pancreatic polypeptide release in some patients with achalasia

Achalasia is characterized by an intrinsic denervation of the esophagus. It is not known whether this process extends to other parts of the gastrointestinal tract. By means of the modified sham feeding test, we studied the innervation of the stomach and the pancreas in 13 patients with achalasia. We compared the results with those from a group of 15 healthy controls and a group of 10 vagotomized patients. We saw two patterns of response in the achalasia group: 6 patients secreted acid and released pancreatic polypeptide, as did the controls. The other 7 patients neither secreted acid nor released pancreatic polypeptide after modified sham feeding, as did the vagotomized patients. We conclude that some patients with achalasia have denervation of the stomach and pancreas, as assessed by the modified sham feeding test. These differences are unrelated to age, sex, and duration and severity of the disease or treatment. Interestingly, all patients who responded normally developed reflux esophagitis after dilatation. Besides being an interesting pathophysiologic observation, the response to modified sham feeding can help identify those patients at greater risk of developing reflux esophagitis after esophageal dilatation.

Choline acetyltransferase activity of rabbit ileum wall. The effects of extrinsic and intrinsic denervation and of combined experimental hypertrophy.

(1970). Choline Acetyltransferase Activity of Rabbit Ileum Wall. the Effects of Extrinsic and Intrinsic Denervation and of Combined Experimental Hypertrophy. Archives Internationales de Physiologie et de Biochimie: Vol. 78, No. 1, pp. 141-152.