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ES of perivascular nerve fibers but not submucosal neurons elicits dilation of the lumen of Brunner's gland acini. A, top: representative trace of an acinar lumen dilating after ES of perivascular nerve fibers (40 V, 5-ms pulse duration, 10 Hz) (left) and showing maximum measurable dilation after superfusion of carbachol (10 M) (right). Bottom: the effect of blockade of sodium-dependent neural transmission by TTX in a different preparation. Pretreatment of the preparation for 3 min with TTX completely prevented dilations elicited by ES of perivascular nerve fibers (left). Responses were restored after washout of the drug (right). B: a representative trace showing that ES of submucosal neurons (20 V, 0.7-ms pulse duration, 20 Hz) did not elicit dilation of the Brunner's gland acinus lumen (left). Stimulation of submucosal vasodilator neurons was studied in the duodenal Brunner's gland preparations to demonstrate that the stimulus parameters used to test for Brunner's gland dilation were sufficient to activate submucosal motoneurons and evoke an effector response. The representative trace on right shows submucosal arterioles preconstricted with PGF 2 (400 nM) superfused continuously commencing at arrowhead. Stimulation of an adjacent submucosal ganglia (20 V, 0.7-ms pulse duration, 20 Hz for 30 s) evoked a large dilation. Bars above traces indicate duration of treatment.
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This study examined the neural pathways innervating Brunner's glands using a novel in vitro model of acinar secretion from Brunner's glands in submucosal preparations from the guinea pig duodenum. Neural pathways were activated by focal electrical stimulation and excitatory agonists, and videomicroscopy was used to monitor dilation of acinar lumen....
Contexts in source publication
Context 1
... parent arterioles (Fig. 1). Extrinsic nerve fibers enter the submucosa within the perivascular connective tissue of submucosal arterioles (9). In preliminary studies, optimum stimulus parameters were studied by examining frequency (1-20 Hz), pulse dura- tion (1-10 ms), and train durations up to 30 s. Maximal dilations, which recovered to baseline (Fig. 2), were obtained with 20-40 V, 10 Hz, 5-ms pulse, and 30-s train duration, and these parameters were used in all subsequent studies. Our (18) previous studies demonstrated histologically and by electron microscopy that the dilations evoked by exogenous application of the cholinergic agonist carbachol result from mucin secretion from ...
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... nerves. Stimulation of perivascular nerve fibers elicited large dilations ( Fig. 2A; n 6) that averaged 47 6% of the maximum response to super- fusion of 10 M carbachol. These dilations typically returned to baseline within 30-60 s after the stimulus train. After a 10-min waiting period, reproducible re- sponses could be obtained two to three times with repeated stimulation. After pretreatment of the prep- aration for ...
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... ganglia. Submucosal neurons were stimulated (20 V, 20 Hz, 0.7-ms pulse duration for 30s) with electrodes placed on ganglia located adjacent to the Brunner's gland selected for videomicroscopy mon- itoring. Stimulation failed to elicit any dilation of Brunner's gland acini (Fig. 2B) in 70% of the submu- cosal neurons (5 of 7 neurons) and only very small dilations (10% of maximum) in the other 30% (2 of 7 neurons). Previous studies (21) (Fig. 1) were examined to directly demon- strate that the stimulus parameters were adequate to activate submucosal motoneurons and evoke an effec- tor response. Stimulation of ...
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... demon- strate that the stimulus parameters were adequate to activate submucosal motoneurons and evoke an effec- tor response. Stimulation of submucosal ganglia in the duodenum, using the same parameters examined for Brunner's gland secretion (20 V, 20 Hz, 0.7-ms pulse duration for 30 s) evoked large dilations of adjacent submucosal arterioles ( Fig. 2B; n ...
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... for 4 preparations. * P 0.001. B, top: representative traces comparing the lack of effect of DMPP on luminal diameter of a Brunner's gland acinus (left) with the maximum dilation obtained in response to superfusion of carba- chol (right). Dilation of submucosal arterioles was also studied to test for the adequacy of the stimulus, as described in Fig. 2. The vessel was preconstricted with PGF 2 (400 nM) from a resting outside diameter of 58 m (not shown). Bottom: the traces show that superfusion of DMPP (100 M) evoked a large dilation of the submucosal arteriole (left). After a 10-min washout period, TTX (1 M) was superfused for 3 min, the vessel was preconstricted again, and DMPP was ...
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... the lack of effect of DMPP and the small size of the dilations, these responses most likely represent activation of vagal fibers passing "en passe" or in close proximity to the ganglia. How- ever, both DMPP stimulation and electrical stimula- tion appear to be adequate to activate submucosal motoneurons (see Figs. 2 and 4), because we were able to demonstrate in the same preparation that they evoke large dilations of submucosal arterioles. In ad- dition, the vagally evoked Brunner's gland dilations were also hexamethonium insensitive, providing fur- ther evidence that submucosal neurons did not partic- ipate in these actions. ...
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... P (right) elicited dilations of the lumen of Brunner's gland acini. Capsaicin- evoked vasodilations were studied in the Brunner's gland duodenal preparation to establish that the stimulus was adequate to activate these nerves and evoke an effector response. Arterioles were precon- stricted with PGF 2 (400 nM) (not shown), as described in Fig. 2, from a resting outside diameter of 66 m. Bottom: representative traces show that superfusion of capsaicin (600 nM; left) and, after a 10-min washout, substance P (30 nM; right) evoked large dilations of the arteriole. Bars indicate duration of superfusions. B: summary of results in A. Bars are means SE for 4 trials. Maximal dilations ...
Citations
... The glands of Brunner, an exocrine structure confined to the duodenal submucosa, primarily consist of mucus-producing cells, and have been traditionally believed to function as buffers against gastric acidity [20][21][22] . Critically, the glands of Brunner are distinctively targeted by nerve terminals, with neural stimulation being necessary for mucus secretion 20,23,24 . Of note, a significant proportion of these terminals are of vagal origin 23 . ...
... Critically, the glands of Brunner are distinctively targeted by nerve terminals, with neural stimulation being necessary for mucus secretion 20,23,24 . Of note, a significant proportion of these terminals are of vagal origin 23 . We thus hypothesized that the vagal innervation of the mucosal glands of Brunner mediates the influence of brain activity on the microbiome. ...
... We first aimed to establish the influence of the vagus nerve on BG activity in vivo. BG is known to respond to the pro-digestive, vagus-mediated gut hormone cholecystokinin ("CCK") 23,24 . We confirmed that intraperitoneal CCK administration acts on BG to induce both mucus secretion and vesicle trafficking to the apical membrane ( Figures S1B-F). ...
Psychological states can regulate intestinal mucosal immunity by altering the gut microbiome. However, the link between the brain and microbiome composition remains elusive. We show that Brunner's glands in the duodenal submucosa couple brain activity to intestinal bacterial homeostasis. Brunner's glands mediated the enrichment of gut probiotic species in response to stimulation of abdominal vagal fibers. Cell-specific ablation of the glands triggered a transmissible dysbiosis associated with an immunodeficiency syndrome that led to mortality upon gut infection with pathogens. The syndrome could be largely prevented by oral or intra-intestinal administration of probiotics. In the forebrain, we identified a vagally-mediated, polysynaptic circuit connecting the glands of Brunner to the central nucleus of the amygdala. Intra-vital imaging revealed that excitation of central amygdala neurons activated Brunner's glands and promoted the growth of probiotic populations. Our findings unveil a vagal-glandular neuroimmune circuitry that may be targeted for the modulation of the gut microbiome.
... They are simple tubular glands in most mammals , extending from the muscularis mucosa through the thickness of the lamina propria and they open into the intestinal lumen at the villi base , in the lining epithelium of these glands are found stem cells, absorptive cells, goblet cells, paneth cells , and some enteroendocrine cells (9)(10)(11).Most studies on histology of the duodenum regard Brunner glands, these glands were discovered by John Jacob Wepter and named after the swiss anatomist Conard Brunner who first described these glands in 1687, Brunner's glands are specific to mammals (13) ,they are as mucous glands and some time serous glands ,their lies in submucosa of the duodenum (12)(13)(14)(15)(16). Brunner glands are produce an alkaline secretion that is capable to neutralizing the chymo acid of the stomach, and supporting favorable pH conditions for adequate action by pancreatic juice enzymes (17)(18)(19). ...
... The Brunner's glands of guinea pig were composed of only mucous acini,the secretion produced is a mixture of both acid and neutral mucins (18) The ducts of these glands penetrate the muscularis mucosae and usually pierce the base of the crypts of lieberkuhn to deliver their secretory product into the lumen of the duodenum (30),main secretory product of these glands is mucin which protects the duodenal mucosa by neutralizing acidic chyme from stomach, Mucins have been referred to as mucopolysaccharide and glycosaminoglycans (29)and possibly by the buffering capacity of its bicarbonate content ,also provides optimal conditions for enzyme action on pancreatic juices (32). These secretions are respond to parasympathetic vagal stimuli (14). ...
... These glands contain equal amounts of neutral and sialomucins ,intense staining of guinea pig Brunner's glands with PAS indicating the presence of substantial amount of neutral mucin,When AB pH 2.5 -PAS technique was employed Brunner's glands stained variably with blue and purple indicating presence of mixture of acid and neutral mucins. More intensity of blue indicates higher amount of acid mucin and moderate neutral mucin (14).Conclusion: The present study showed reversed relation between number of the crypts, goblet cells and the Brunner's glands for neutralize of the ingesta and available the mucosal immunity to protect of the duodenal lumen against the erosive effects of the gastric juice by virtue of the mucoid nature of its secretion. ...
purpose of this study was to describe, comparison the histological structures,
histochemical features and distribution of the goblet cells and Brunner's glands in the duodenum
of the rabbits and rats .The study was carried out on Ten samples of duodenum of each of rabbits
and rats , immediately after slaughtering. The specimens were divided into cranial ,descending
and ascending parts .five specimens was taken from each part of duodenum of each of the rabbits
and rats and fixed in 10% formalin for 24 hours and treating by routine histological technique.
Sections were stained by Hematoxylin & Eosin ,Picric acid stain and Alcian blue PH 2.5 stains.
Mean length of crypts of Lieberkuhn and number of each crypts, goblet cells and alveoli of
Brunner's glands in duodenum of rabbits were more than that in the duodenum of rats . The mean
length and number of crypts of Lieberkuhn was increase toward the last parts of the duodenum in
each of the rabbits and rats. Goblet cells were globular cells between the columnar cells in the
epithelium lined each of the villi and crypts of Lieberkuhn in the tunica mucosa of the duodenum
in rabbits and rats and take positive reaction each of PAS and Alcian blue pH 2.5 stains. The
mean number of goblet cells in crypts of Lieberkuhn in duodenum each rabbits and rats were
increased toward the jejunum. Brunner’s glands were branched tubuloalveolar glands in the
submucosa of each duodenal parts in rabbits , while absent in ascending part of rats duodenum,
and these glands in rabbits duodenum were composed of two types of the cells (serous and
mucous),while in rats duodenum only mucous cells, and stained with PAS stain only in
duodenum of each of the rabbits and rats. The mean number of the alveoli of the Brunner's
glands in the cranial part were more than that in other parts and decreased toward ascending part
in rabbits duodenum ,while absent in ascending part of rats duodenum..
... They are simple tubular glands in most mammals , extending from the muscularis mucosa through the thickness of the lamina propria and they open into the intestinal lumen at the villi base , in the lining epithelium of these glands are found stem cells, absorptive cells, goblet cells, paneth cells , and some enteroendocrine cells (9)(10)(11).Most studies on histology of the duodenum regard Brunner glands, these glands were discovered by John Jacob Wepter and named after the swiss anatomist Conard Brunner who first described these glands in 1687, Brunner's glands are specific to mammals (13) ,they are as mucous glands and some time serous glands ,their lies in submucosa of the duodenum (12)(13)(14)(15)(16). Brunner glands are produce an alkaline secretion that is capable to neutralizing the chymo acid of the stomach, and supporting favorable pH conditions for adequate action by pancreatic juice enzymes (17)(18)(19). ...
... The Brunner's glands of guinea pig were composed of only mucous acini,the secretion produced is a mixture of both acid and neutral mucins (18) The ducts of these glands penetrate the muscularis mucosae and usually pierce the base of the crypts of lieberkuhn to deliver their secretory product into the lumen of the duodenum (30),main secretory product of these glands is mucin which protects the duodenal mucosa by neutralizing acidic chyme from stomach, Mucins have been referred to as mucopolysaccharide and glycosaminoglycans (29)and possibly by the buffering capacity of its bicarbonate content ,also provides optimal conditions for enzyme action on pancreatic juices (32). These secretions are respond to parasympathetic vagal stimuli (14). ...
... These glands contain equal amounts of neutral and sialomucins ,intense staining of guinea pig Brunner's glands with PAS indicating the presence of substantial amount of neutral mucin,When AB pH 2.5 -PAS technique was employed Brunner's glands stained variably with blue and purple indicating presence of mixture of acid and neutral mucins. More intensity of blue indicates higher amount of acid mucin and moderate neutral mucin (14).Conclusion: The present study showed reversed relation between number of the crypts, goblet cells and the Brunner's glands for neutralize of the ingesta and available the mucosal immunity to protect of the duodenal lumen against the erosive effects of the gastric juice by virtue of the mucoid nature of its secretion. ...
... They are simple tubular glands in most mammals , extending from the muscularis mucosa through the thickness of the lamina propria and they open into the intestinal lumen at the villi base , in the lining epithelium of these glands are found stem cells, absorptive cells, goblet cells, paneth cells , and some enteroendocrine cells (9)(10)(11).Most studies on histology of the duodenum regard Brunner glands, these glands were discovered by John Jacob Wepter and named after the swiss anatomist Conard Brunner who first described these glands in 1687, Brunner's glands are specific to mammals (13) ,they are as mucous glands and some time serous glands ,their lies in submucosa of the duodenum (12)(13)(14)(15)(16). Brunner glands are produce an alkaline secretion that is capable to neutralizing the chymo acid of the stomach, and supporting favorable pH conditions for adequate action by pancreatic juice enzymes (17)(18)(19). ...
... The Brunner's glands of guinea pig were composed of only mucous acini,the secretion produced is a mixture of both acid and neutral mucins (18) The ducts of these glands penetrate the muscularis mucosae and usually pierce the base of the crypts of lieberkuhn to deliver their secretory product into the lumen of the duodenum (30),main secretory product of these glands is mucin which protects the duodenal mucosa by neutralizing acidic chyme from stomach, Mucins have been referred to as mucopolysaccharide and glycosaminoglycans (29)and possibly by the buffering capacity of its bicarbonate content ,also provides optimal conditions for enzyme action on pancreatic juices (32). These secretions are respond to parasympathetic vagal stimuli (14). ...
... These glands contain equal amounts of neutral and sialomucins ,intense staining of guinea pig Brunner's glands with PAS indicating the presence of substantial amount of neutral mucin,When AB pH 2.5 -PAS technique was employed Brunner's glands stained variably with blue and purple indicating presence of mixture of acid and neutral mucins. More intensity of blue indicates higher amount of acid mucin and moderate neutral mucin (14).Conclusion: The present study showed reversed relation between number of the crypts, goblet cells and the Brunner's glands for neutralize of the ingesta and available the mucosal immunity to protect of the duodenal lumen against the erosive effects of the gastric juice by virtue of the mucoid nature of its secretion. ...
... In the present study, the immunoreaction to the SP was strong in the Brunner's glands of the CAP treated group, whereas SP immunoreactivity was weak in the control groups. Moore et al. (34) demonstrated that multiple hormonal (such as gastrin, vasoactive intestinal polypeptide and secretin) inflammatory, and neuroendocrine agents activate Brunner's glands. In our previous study, VR1 immunoreaction was observed in the Brunner's glands of the CAP treated groups (52). ...
The aim of the present study was to investigate effects of low dose capsaicin (CAP) on substance P (SP) expression and histomorphometric properties of duodenum. In this study, 21-day-old rats were divided into three groups as control, CAP-treated and vehicle. The control group remained without any treatment. 0.5 mg/kg CAP prepared in a solvent and injected subcutaneously to CAP-treated group and vehicle group was injected with only solvent for 20 days. All rats were weighed daily. At the end of the experiment, tissue samples were collected and Crossman’s triple staining was used for histomorphometric examinations and labelled streptavidin-biotin immunohistochemical technique was used for SP expression. The body weight gain was lower in the CAP treated group but no significant differences between the groups. Low dose CAP did not alter the depth of crypt in the duodenum but the height of the villus was higher than the other group (p<0.05). In the CAP treated group, SP immunoreaction was stronger than the other groups in the surface epithelium, Lieberkühn crypts, in the Brunner’s glands, smooth muscles layer, and the neurons of the myenteric plexus of the duodenum. Finally, low dose CAP, markedly stimulated expression of SP and also induced positively histomorphometric changes in the duodenum. As a result of low dose CAP treatment may play important role in epithelial cell functions and in the regulation of digestive system physiology. © 2017, Chartered Inst. of Building Services Engineers. All rights reserved.
... For example, acid is secreted in the stomach for digestion, but also to sterilize food. Specialized glands in the duodenum (Brunner's glands) are able to sustain high levels of bicarbonate secretion to protect it from gastric acid and pepsin (Moore et al., 2000). Similarly, along the intestine, bursts of secretion, regulated largely by enteric cholinergic and VIP expressing nerves, protect the mucosa from physical damage in response to mechanical stimulation and the fluid itself serves to dilute potential cytotoxins (Barrett and Keely, 2000;Chu and Schubert, 2013). ...
Host defense is a vital role played by the gastrointestinal tract. As host to an enormous and diverse microbiome, the gut has evolved an elaborate array of chemical and physicals barriers that allow the digestion and absorption of nutrients without compromising the mammalian host. The control of such barrier functions requires the integration of neural, humoral, paracrine and immune signaling, involving redundant and overlapping mechanisms to ensure, under most circumstances, the integrity of the gastrointestinal epithelial barrier. Here we focus on selected recent developments in the autonomic neural control of host defense functions used in the protection of the gut from luminal agents, and discuss how the microbiota may potentially play a role in enteric neurotransmission. Key recent findings include: the important role played by subepithelial enteric glia in modulating intestinal barrier function, identification of stress-induced mechanisms evoking barrier breakdown, neural regulation of epithelial cell proliferation, the role of afferent and efferent vagal pathways in regulating barrier function, direct evidence for bacterial communication to the enteric nervous system, and microbial sources of enteric neurotransmitters. We discuss these new and interesting developments in our understanding of the role of the autonomic nervous system in gastrointestinal host defense.
... ion transporters; Brunner's glands; regulated traffic DUODENAL BRUNNER'S GLANDS are distinct structures consisting of clusters of serous cells and branching tubules that are located in the submucosal layer of the proximal duodenum in mammals. Brunner's glands are innervated by cholinergic vagal and polypeptidergic nerves that release vasoactive intestinal peptide (VIP) (42,54,68). The glands were thought to be either an extension of the pyloric glands or an accessory pancreas because they first appear at the pyloro-duodenum junction and extend along the proximal-distal duodenal axis in decreasing abundance up to the entry site of the biliary/ pancreatic duct. ...
... cAMP and gastrointestinal hormones including VIP, secretin, gastric inhibitory peptide, and CCK have been shown to stimulate bicarbonate secretion in the proximal duodenum but not specifically from the Brunner's glands (22,45,114). Secretion was reported in isolated Brunner's glands following prostaglandin E2, and hormone stimulation, but without direct confirmation that bicarbonate emanated from the glands (68). Indirect approaches using species lacking Brunner's glands have provided some functional insights into transport functions of the gland. ...
The Brunner's glands of the proximal duodenum exert barrier functions through secretion of glycoproteins and antimicrobial peptides. However, ion transporter localization, function, and regulation in the glands are less clear. Mapping the subcellular distribution of transporters is an important step towards elucidating trafficking mechanisms of fluid transport in the gland. The current study examined (1) changes in the distribution of intestinal anion transporters and the Aquaporin 5 (AQP5) water channel in rat Brunner's glands following second messenger activation; and (2) anion transporter distribution in Brunner's glands from healthy and disease affected human tissues. Cystic fibrosis transmembrane conductance regulator (CFTR), Aquaporin 5 (AQP5), sodium-potassium-coupled chloride co-transporter 1 (NKCC1), sodium-bicarbonate co-transporter (NBCe1), and the proton pump vacuolar ATPase (V-ATPase) were localized to distinct membrane domains and in endosomes at steady state. Carbachol and cAMP redistributed CFTR to the apical membrane. cAMP-dependent recruitment of CFTR to the apical membrane was accompanied by recruitment of AQP5 that was reversed by a PKA inhibitor. cAMP also induced apical trafficking of V-ATPase and redistribution of NKCC1 and NBCe1 to the basolateral membranes. The steady state distribution of AQP5, CFTR, NBCe1, NKCC1, and V-ATPase in human Brunner's glands from healthy controls, cystic fibrosis and celiac disease resembled that of rat; however, the distribution profiles were markedly attenuated in the disease-affected duodenum. These data support functional transport of chloride, bicarbonate, water and protons by second messenger-regulated traffic in mammalian Brunner's glands under physiologic and pathophysiologic conditions.
... TKs were, as reported earlier (13), expressed in neuronal tissue. Slender cells surrounding the Brunner's glands showed TK-IR possibly explained by the fact that these glands are innervated by TK signaling neurons (27). TK-IR cells were rarely seen in mucosa from the distal duodenum but were abundant the jejunal/ileal mucosa. ...
A new antibody, active against the common tachykinin (TK) C-terminal, was used to study TK expression in patients with endocrine tumors and a possible association between plasma-TK levels and symptoms of diarrhea and flush in patients with metastasizing ileocecal serotonin-producing carcinoid tumors (MSPCs).
TK, serotonin and chromogranin A (CgA) immunoreactivity (IR) was studied by immunohistochemistry in tissue samples from 33 midgut carcinoids and 72 other endocrine tumors. Circulating TK (P-TK) and urinary-5 hydroxyindoleacetic acid (U-5HIAA) concentrations were measured in 42 patients with MSPCs before treatment and related to symptoms in patients with the carcinoid syndrome. Circulating CgA concentrations were also measured in 39 out of the 42 patients.
All MSPCs displayed serotonin and strong TK expression. TK-IR was also seen in all serotonin-producing lung and appendix carcinoids. None of the other tumors examined contained TK-IR cells. Concentrations of P-TK, P-CgA, and U-5HIAA were elevated in patients experiencing daily episodes of either flush or diarrhea, when compared with patients experiencing occasional or none of these symptoms. In a Spearman partial rank test, the correlation of P-TK with daily diarrhea was independent of both U-5HIAA and CgA levels.
We found that TK synthesis occurs in serotonin-IR tumors and that P-TK levels are significantly correlated with symptoms of flush and diarrhea in patients with MSPCs. This is, to our knowledge, the first report demonstrating an independent correlation of P-TKs with carcinoid diarrhea, a symptom that is customarily regarded as serotonin mediated. Further investigations may present opportunities for new therapeutic possibilities.
... To better understand Br unner's physiolog y, we previously reported the development of an in vitro model that permitted the examination of Brunner's gland secretion by video microscopy, which recorded real time changes in diameter of the dilating lumen of Brunner's gland acini that corresponded to the extent of mucin exocytotic emptying [6,7] . Using this model, we demonstrated cholinergic stimulation of compound exocytosis of mucin into the ductal lumen, which was confirmed by electron microscopy and histology [6] . ...
... To better understand Br unner's physiolog y, we previously reported the development of an in vitro model that permitted the examination of Brunner's gland secretion by video microscopy, which recorded real time changes in diameter of the dilating lumen of Brunner's gland acini that corresponded to the extent of mucin exocytotic emptying [6,7] . Using this model, we demonstrated cholinergic stimulation of compound exocytosis of mucin into the ductal lumen, which was confirmed by electron microscopy and histology [6] . We then went on to examine vagal neural cholinergic innervation [6] , and its coupling to potassium channel current, which regulated the acinar cell membrane excitability leading to secretion [7] . ...
... Using this model, we demonstrated cholinergic stimulation of compound exocytosis of mucin into the ductal lumen, which was confirmed by electron microscopy and histology [6] . We then went on to examine vagal neural cholinergic innervation [6] , and its coupling to potassium channel current, which regulated the acinar cell membrane excitability leading to secretion [7] . ...
To examine the molecular mechanism of exocytosis in the Brunner's gland acinar cell.
We used a submucosal preparation of guinea pig duodenal Brunner's gland acini to visualize the dilation of the ductal lumen in response to cholinergic stimulus. We correlated this to electron microscopy to determine the extent of exocytosis of the mucin-filled vesicles. We then examined the behavior of SNARE and interacting Munc18 proteins by confocal microscopy.
One and 6 micromol/L carbachol evoked a dose-dependent dilation of Brunner's gland acini lumen, which correlated to the massive exocytosis of mucin. Munc18c and its cognate SNARE proteins Syntaxin-4 and SNAP-23 were localized to the apical plasma membrane, and upon cholinergic stimulation, Munc18c was displaced into the cytosol leaving Syntaxin-4 and SNAP-23 intact.
Physiologic cholinergic stimulation induces Munc18c displacement from the Brunner's gland acinar apical plasma membrane, which enables apical membrane Syntaxin-4 and SNAP-23 to form a SNARE complex with mucin-filled vesicle SNARE proteins to affect exocytosis.
... From this point, the secretion is discharged into the duodenal lumen. BG secretions are alkaline and fluid, and respond to parasympathetic vagal stimuli (Moore et al., 2000). Their alkalinity helps neutralize the chymo acid that originates in the stomach, and also provides optimal conditions for enzyme action on pancreatic juices (Morikawa et al.;Olsen et al., 1994). ...
The existence of Brunner's glands (BGs) in the duodenal submucosa is uncontestable, but their exact distribution along the full extent of the duodenal wall is unknown. Objective: To verify the BGs distribution along the human duodenum. Material and method: Twenty normal duodenums were examined. Two samples were removed from each of the four anatomical portions of the duodenum using a scalpel, in such a way that the whole circumference of each portion was excised. Sections were prepared and stained with hematoxylin-eosin. Twelve microscope fields were examined on each duodenal section. The mean numbers of glandular points per field were computed and compared, for the 12 microscope fields of each duodenal section examined. Results: The first duodenal portion presented large quantities of BGs in all of the fields examined. The second duodenal portion also showed the presence of BGs in all the fields examined, albeit in smaller quantities than in the first portion. In the third duodenal portion, BGs were present in six of the duodenums examined. In the fourth duodenal portion, there was a minimal quantity of glands, all located in only ten of the duodenums studied. Conclusions: BGs are present in the submucosa of all duodenal portions, with the greatest concentration in the first portion. Their concentration decreases significantly in the second portion of the duodenum. Furthermore, they become even fewer in number in the third portion and are minimally present in the fourth portion
