Effect of vagotomy on expression of neuropeptides and histamine in rat oxyntic mucosa

The effect of vagotomy and pyloroplasty on the density of nerve fibers containing bombesin/gastrin-releasing peptide (GRP), calcitonin gene-related peptide (CGRP), and galanin as well as histamine-, 5-hydroxytryptamine (5-HT)-, and somatostatin-containing cells in the oxyntic mucosa of the rat stomach was studied. Ten days after vagotomy and pyloroplasty the density of histamine-containing cells in the oxyntic mucosa was increased by 70% (P<0.05), and these cells were larger and showed more extensive cell processes than in control animals. The density of 5-HT-immunoreactive (IR) cells and somatostatin-IR cells were not affected. A marked decrease in the density of CGRP-IR nerve fibers and a slighter decrease in the density of GRP-IR nerve fibers was observed in the mucosal layer, while only a minor reduction of CGRP-IR fibers, and no reduction of GRP-IR fibers was seen in the muscular layer. The density of galanin-IR nerve fibers was not affected. The height of the oxyntic mucosa was reduced by about 25% (P<0.05). Thus, a striking effect on the histamine-IR cells was seen, supporting the view that these cells are regulated by the vagus nerve. The study also indicates that a major portion of the CGRP-IR nerve fibers, and part of the GRP-IR nerve fibers, in the mucosal layer of the fundic region are of vagal origin or regulated by normal vagus nerve activity.This study was supported by the Medical Research Council of the Academy of Finland.     

降钙素基因相关肽免疫反应纤维在大鼠心肌内的分布和密度

目的 观察降钙素基因相关肽免疫反应(CGRP-IR)纤维在大鼠心肌内的分布和密度，为心肌病的研究奠定形态学基础。方法 用免疫组织化学法显示大鼠心肌内的CGRP-IR纤维，计算其分布密度。结果在心房肌内和心室肌内均可见CGRP-IR纤维分布于心肌纤维之间，心房肌内CGRP-IR纤维的面积密度和数量密度均高于心室肌。结论 CGRP-IR纤维在大鼠心肌内分布广泛，其分布密度存在部位差异。     

Peptide-containing nerve fibers in the stomach wall of rat and mouse

Peptide-containing nerve fibers were found to be numerous in the glandular stomach of the rat and mouse. The immunoreactive neuropeptides demonstrated included vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), gastrin-releasing peptide (GRP), substance P (SP), enkephalin, somatostatin, cholecystokinin, and neuropeptide Y (NPY). The density and distribution of the various peptide-containing fibers did not differ overtly between the pyloric and oxyntic gland areas except for the GRP fibers, which were fewer in the pyloric than in the oxyntic mucosa. The entire VIP nerve fiber population was found to also contain PHI. Immunoreactive NPY was found to occur in the VIP/PHI fibers (VIP/PHI/NPY fibers) in the smooth muscle and intramural ganglia of both rat and mouse and in the mucosa of the mouse. Mucosal VIP/PHI fibers in the rat did not contain any NPY-like material. Perivascular NPY fibers in both species and mucosal NPY fibers in the rat did not contain VIP or PHI. The mucosa harbored numerous GRP fibers and VIP/PHI (rat) or VIP/PHI/NPY (mouse) fibers, and a modest number of NPY (rat) and SP fibers. In the submucosa the peptide-containing nerve fibers were found mainly in the ganglia and around blood vessels. Blood vessels received a rich supply of NPY fibers; the number of perivascular VIP/PHI, GRP, and SP fibers was much lower by comparison. The smooth muscle and myenteric ganglia harbored not only VIP/PHI/NPY, GRP, and SP fibers but also enkephalin, somatostatin, and cholecystokinin fibers. Gastrin-releasing peptide, VIP/PHI/NPY, SP, and enkephalin nerve cell bodies occurred in the myenteric ganglia. As studied in the rat, vagal denervation did not affect the density and distribution of the various peptide-containing nerve fibers. After sympathectomy, mucosal and perivascular NPY fibers disappeared. The other types of peptide-containing nerve fibers were not affected.     

Inhibitory effect of GLP-1 on gastric motility persists after vagal deafferentation in pigs

BACKGROUND: Glucagon-like peptide 1 (GLP-1) is an intestinal hormone that is secreted in response to meal ingestion. GLP-1 inhibits gastric emptying and reduces postprandial gastric secretion and may play a physiological regulatory role in controlling appetite and energy intake in humans. The GLP-1 receptors have been identified in several organs including the stomach, brain and pancreas. The GLP-1 mechanism of action on insulin secretion is at least partly mediated via receptors on the pancreatic islet, but the mechanism by which GLP-1 retards gastric emptying is not known and may involve neural interactions, although GLP-1 has no effect on vagally stimulated motor activity of the isolated porcine antrum. MATERIAL AND METHODS: Previously, an experimental model was developed with centrally (insulin hypoglycaemia) induced vagally mediated stimulation of antral motility, recorded by force transducers, in anaesthetized pigs. This model has now been developed further to include vagal deafferentation to determine the role of the afferent vagus in mediating the inhibitory effect of GLP-1 on gastric motility. RESULTS: Intravenous infusion of GLP-1 resulting in slightly supraphysiological plasma levels inhibited the antral contractile force, with the amplitude falling from 29.9+/-5.7 mm to 14.6+/-3.5 mm (p<0.001). After vagal deafferentation GLP-1 still inhibited antral motility (from 36.6+/-6.4 mm to 25+/-4.4 mm (p<0.019). The decrease in amplitude was the same before and after deafferentation. CONCLUSIONS: GLP-1 significantly inhibited centrally induced antral motility and the inhibitory effect of GLP-1 on gastric motility persisted after vagal deafferentation, supporting the hypothesis that the inhibitory effect results from direct interaction of GLP with receptors in the CNS, which in turn reduce vagal efferent output.     

支气管哮喘大鼠肺内非肾上腺素能非胆碱能神经分布及其神经肽含量的相关性研究

目的 探讨支气管哮喘(简称哮喘)大鼠肺内非肾上腺素能非胆碱能(non-adrenergic non-cholinergic,NANC)神经分布及其神经肽含量的变化并分析两者的相关性.方法 20只Wister大鼠随机分成正常组和哮喘组.采用免疫组织化学和计算机图象分析观察大鼠肺内降钙素基因相关肽(calcitonin gene-related peptide,CGRP)和血管活性肠肽(vasoactive intestinal peptide,VIP)免疫反应阳性纤维的变化,并且用酶联免疫吸附试验法测定肺泡灌洗液中CGRP和VIP的浓度.结果 ①哮喘大鼠肺内CGRP和VIP阳性纤维的分布和密度均发生了显著的变化,CGRP阳性纤维显著增多,染色加深,相对阳性染色面积和光密度值,与对照组相比,差异有统计学意义(P＜0.01);VIP阳性纤维明显缺乏,相对阳性染色面积和光密度值,与对照组相比,差异有统计学意义(P＜0.05或P＜0.01).②哮喘大鼠肺泡灌洗液中CGRP的浓度与正常对照组相比显著增高(P＜0.01),与CGRP阳性纤维的相对染色面积(r=0.903)和光密度值(r=0.880)呈正相关;VIP的浓度显著降低(P＜0.01),与VIP阳性纤维的相对染色面积(r=0.899)和光密度值(r=0.878)呈正相关.结论 哮喘大鼠肺内NANC神经分布异常,这可能是导致相应的神经肽含量变化的直接原因.     

Substance P-containing nerve fibers are numerous in human but not in feline intestinal mucosa

The regional and topographic distribution of substance P-containing nerve fibers in the human and feline intestinal wall was studied by immunocytochemistry and radioimmunoassay. The concentration of substance P was measured in the different layers of the duodenum, jejunum, ileum, and colon. In both humans and cat, substance P fibers were fairly numerous, and the substance P concentration was comparatively high in the smooth muscle layer, including the myenteric ganglia. In humans, but not in cat, substance P fibers were numerous, and the substance P concentration was also high in the mucosa. Substance P-containing nerve cell bodies were observed in the myenteric ganglia of both species. In the submucous ganglia, such nerve cell bodies were seen in the human intestine only, suggesting that they represent the origin of the numerous mucosal substance P fibers in this species. Previous studies have revealed a relative paucity of substance P fibers in the intestinal mucosa of several mammals, such as mouse, rat, and pig. The cat can now be added to those having few mucosal substance P fibers, whereas humans seem to be notably rich in such fibers, suggesting that substance P may play a role in the regulation of mucosal functions in the human intestine.     

The vagus exerts trophic control of the stomach in the rat

Bilateral subdiaphragmatic truncal vagotomy results in great functional changes in the stomach although the changes in the gastric mucosal architecture are small. A trophic effect of the vagus on the stomach is revealed after unilateral vagal sectioning, taking advantage of the fact that, in the rat, each vagal trunk innervates only one side of the stomach, and that denervation of one side does not impair the functional capacity of the other. The denervated side of the stomach displayed atrophy that was reflected in reduced weight and height of the oxyntic mucosa and a reduced density of argyrophil cells. The lack of atrophy after bilateral vagotomy can be explained by counteracting forces, in that the subsequent rise in gastrin secretion (due to lack of acid feedback inhibition of gastrin release) probably masks antitrophic effects of the vagotomy per se. Interestingly, the number of somatostatin cells in the oxyntic mucosa was not reduced after unilateral vagotomy, nor was the weight of the antral mucosa or the density of enterochromaffin and gastrin cells in the antrum on the denervated side.     

支气管哮喘大鼠肺内非肾上腺素能非胆碱能神经分布及神经肽含量的相关性研究

目的探讨支气管哮喘（简称哮喘）大鼠肺内非肾上腺素能非胆碱能（non—adrenergicnon—cholinergic,NANC）神经分布及其神经肽含量的变化并分析两者的相关性。方法20只Wister大鼠随机分成正常组和哮喘组。采用免疫组织化学和计算机图象分析观察大鼠肺内降钙素基因相关肽（calcitoningene-relatedpeptide,CGRP）和血管活性肠肽（vasoactiveintestinalpeptide,VIP）免疫反应阳性纤维的变化,并且用酶联免疫吸附试验法测定肺泡灌洗液中CGRP和VIP的浓度。结果①哮喘大鼠肺内CGRP和VIP阳性纤维的分布和密度均发生了显著的变化,CGRP阳性纤维显著增多,染色加深,相对阳性染色面积和光密度值,与对照组相比,差异有统计学意义（P〈0．01）;VIP阳性纤维明显缺乏,相对阳性染色面积和光密度值,与对照组相比,差异有统计学意义（P〈0．05或P〈0．01）。②哮喘大鼠肺泡灌洗液中CGRP的浓度与正常对照组相比显著增高（P〈0．01）,与CGRP阳性纤维的相对染色面积（r=0．903）和光密度值（r=0．880）呈正相关;VIP的浓度显著降低（P〈0.01）,与VIP阳性纤维的相对染色面积（r=0．899）和光密度值（r=0．878）呈正相关。结论哮喘大鼠肺内NANC神经分布异常,这可能是导致相应的神经肽含量变化的直接原因。     

Role of Capsaicin-Sensitive Nerves in Gastric and Hepatic Injury Induced by Cold-Restraint Stress

The role of capsaicin-sensitive afferent fibers on cold-restraint stress-induced gastric and hepatic injury was examined at the macroscopic and ultrastructural levels. Wistar albino rats were treated with capsaicin either locally (intragastric, perivagal, and periceliac) or systemically (neonatal, intraperitoneal). Perineural and neonatal treatment with capsaicin was used to denervate afferent fibers, while intragastric capsaicin treatment would have activated mucosal afferent fibers just before the stress exposure. Capsaicin decreased significantly the formation of macroscopic gastric lesions caused by stress in all treatment groups. At the electron microscopic level, however, denervation of vagal afferent fibers with capsaicin was most effective in prevention of cellular injury in gastric mucosa. In the liver, systemic denervation of afferent fibers completely inhibited stress-induced cellular damage, while denervation of afferent fibers in vagus and splanchnic nerve was partially effective. Central neural pathways sensitive to capsaicin may mediate formation of both gastric and hepatic injury resulting from stress.     

In vivo microscopy of the gastric microcirculation

A method for observing the gastric microcirculation directly in the living animal and the results of its application to the study of the rat gastric microcirculation are described. The exteriorized stomach of an anesthetized rat was transilluminated by a cool light transmitted from a high intensity light source by means of a quartz rod. Illumination was adequate for direct microscopic visualization of blood flow through the muscle layer. After a portion of muscle and serosa had been dissected carefully, blood flow could be traced through the rich submucosal network of arterioarterial anastamoses down to the mucosa and back through collecting veins, emerging from the mucosa to the submucosal venovenous anastamotic network. By everting and transilluminating the exteriorized stomach, the superficial mucosa was visualized and blood flow could be traced through the hexagonally distributed capillaries surrounding the gastric glands to the collecting veins. The distribution of vessels in each of these layers is described in detail. Despite a careful search, no arteriovenous anastamoses were found, either in the submucosa or in the superficial mucosa.Supported by Veterans Administration research funds and a grant from the Orange County Heart Association.     

Relation of intragastric pH with the response of gastrin and somatostatin secretion to electrical vagal stimulation]

The association of gastrin and somatostatin secretion with intragastric pH was investigated in the in vitro experimental system that provides concurrent isolated rat stomach perfusion and vagal stimulation. As a result, it was found that the gastric cavity must be neutral or alkaline for gastrin secretion to respond to electrical vagal stimulation. For somatostatin secretion to respond to the same stimulus the gastric cavity must be acidic. It was further suggested that gastrin secretion may be regulated by non-cholinergic neurons which are in turn regulated by non-nicotinic preganglionic fibers, while somatostatin secretion may be regulated by non-cholinergic excitatory neurons as well as by cholinergic inhibitory neurons which are regulated by nicotinic preganglionic fibers.     

Development and distribution of mast cells and neuropeptides in human fetus duodenum

AIM: To study the developmental regularities and heterogeneity of mast cells (MC) in human fetus duodenum and the distribution and developmental regularities of substance P(SP), calcitonin gene-related peptide (CGRP)-immunoreactive (IR) peptidergic nerves in fetus duodenum, as well as the relationship between MC, SP and CGRP- IR peptidergic nerves. METHODS: Duodena from 21 cases of human fetus and one term infant were stained by hematoxylin-eosin (HE), toluidine blue (TB) and immunohistochemical avidin-biotinylated peroxidase complex (ABC) method. RESULTS: Lobe-shape intestinal villi in duodenum were already developed at the twelfth week. At the 21st wk, muscular mucosa appeared gradually, and four layers were observed in the wall of duodenum. TB staining showed that the granules in the immature MC were pale violet, while the mature MC were strong violet in color by TB staining. Connective tissue MC (CTMC) appeared occasionally in submucosa and muscular layer of duodenum at the 16th wk. While the mucosa MC (MMC) appeared at the 18th wk. At the 22nd wk, both CTMC and MMC were activated, and distributed in the surrounding blood vessels and ganglions. The verge of some MC were unclear, and showed degranular phenomena. At the 14th wk, SP and CGRP-IR nerve fibers and cells appeared in the myenteric and submucous plexuses in small intestine, and the responses were turn strongly. Neurons were light to deep brown, and nerve fibers were present as varicose and liner profiles. On the corresponding site of serial sections, SP and CGRP immunohistochemical reactions were coexisted in one nerve fiber or cell. Some of MC showed SP and CGRP-IR positive staining. CONCLUSION: There are two heterogeneous kinds of MC in duodenum, MMC and CTMC. MC might play an important role in regulating blood circulation and sensation.     

Site-specific formation of gastric ulcers by the electric stimulation of the left or right gastric branch of the vagus nerve in the rat

The present study was conducted to investigate the role of the parasympathetic nervous system innervating the stomach in gastric ulcer formation, with special reference to its neuroanatomic characteristics in rats. First, the effects of electric vagal stimulation on the gastric mucosa were examined. The electric stimulation of the left or right gastric branch of the vagus nerve caused gastric mucosal lesions to develop. Interestingly, however, gastric lesions were found on the anterior wall in the rats that had received electric stimulation to the left gastric branch of the vagus nerve and on the posterior wall in the rats that had received stimulation to the right gastric branch. Next, the cells of origin projecting to the left or right gastric branch of the vagus nerve were identified by means of a horseradish peroxidase retrograde tracer method. The left and right gastric branches were found to be innervated by the left and right dorsal motor nuclei of the vagus nerve in the medulla oblongata, respectively. It has been reported that the left and right dorsal motor nuclei of the vagus nerve separately innervate the anterior or posterior gastric wall. The present results, therefore, suggest that the long-lasting excitation of neurons in the dorsal motor nucleus facilitates the site-specific formation of gastric ulcers through the left or right gastric branch of the vagus nerve.     

Site-Specific Formation of Thyrotropin-Releasing Hormone-Induced Gastric Ulcers through the Vagal System

Okumura T, Uehara A, Watanabe Y, Taniguchi Y, Kitamori S, Namiki M. Site-specific formation of thyrotropin-releasing hormone-induced gastric ulcers through the vagal system. Scand J Gastroenterol 1994;29:226-231.

The left and right dorsal motor nuclei (DMN) separately innervate the anterior and posterior gastric walls through the left and right gastric branches of the vagus nerve (GBVN) in rats. The present study was carried out to investigate the effects of selective centrally originated excitation of the unilateral vagal system on the gastric area in which vagus-induced gastric ulcers developed. Since intracisternally injected thyrotropin-releasing hormone (TRH) stimulates neurons in the bilateral DMNs to produce gastric ulcers, selective stimulation of the unilateral vagal system was produced by contralateral gastric branch vagotomy before intracisternal injection of TRH. Intracisternal injection of TRH (2 ng/rat) into left gastric branch-vagotomized rats resulted in lesion formation only on the posterior gastric wall and not on the anterior wall. In contrast, in right gastric branch-vagotomized rats TRH-induced gastric lesions were observed only on the anterior gastric wall and not on the posterior wall. These results suggest that selective stimulation of the left or right DMN induces site-specific ulcer formation through the left or right GBVN. Next, gastric acid secretion was determined in pylorus-ligated rats to examine a role of acid hypersecretion in site-specific ulcer formation caused by TRH. Of interest was that gastric acid secretion in unilaterally vagotomized rats given TRH intracisternally was significantly smaller than that in sham-operated rats given intracisternal saline, although the former rats developed gastric ulcers, whereas the latter did not. It is therefore speculated that gastric hyperacidity plays a less important role in the peripheral mechanisms of TRH-induced site-specific gastric ulceration.     

Localization of ANP-synthesizing cells in rat stomach

INTRODUCTION Since antrial natriuretic peptide (ANP) was isolated from atrium by de Bold et al in 1981[1-3], brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), dendroaspis (DNP), micrurus natriuretic peptide (MNP), and ventricular natriuretic peptide (VNP) have been found in succession. They distribute not only in the heart but all over the body[4-10]. ANP regulates a variety of physiological functions, including natriuresis, diuresis and vasodilation. Three types…     

Reproductive failure due to experimentally induced constant estrus does not alter the LH-RH fiber density in the median eminence of the rat

The effects of anterior hypothalamic deafferentation on luteinizing hormone releasing hormone (LH-RH) fiber density in the mediobasal hypothalamus (MBH) were compared to those of a number of nonsurgical treatments which give rise to anovulatory sterility (injections of estradiol valerate, exposure to constant light, or neonatal androgen administration) in the female rat. All of the treatments used (surgical and nonsurgical) disrupted the normal 4-day pattern of estrous cyclicity. Bilateral anterior hypothalamic deafferentation markedly reduced the packing density of LH-RH fibers in the MBH. Unilateral deafferentation reduced the number of fibers on the ipsilateral side of the MBH by 31-64% and on the contralateral side by 15-40%. In contrast, none of the three nonsurgical treatments had any significant effect on the LH-RH fiber density. Electron microscopic examination revealed no morphologic, or distribution differences in MBH LH-RH fibers between control females and animals rendered anovulatory by the nonsurgical experimental procedures. These results demonstrate that estrogen, androgen, and constant light induced anovulatory sterility are not associated with any overt change in the number or morphology of LH-RH immunoreactive fibers in the MBH, suggesting that the primary lesion responsible for the failure of normal estrous cyclicity in such animals resides in the systems responsible for regulating the activity of the LH-RH neurons rather than in the LH-RH neurons themselves.     

The mechanism of vagotomy-induced acute gastric mucosal injury in the rat

The present study investigated the integrity of the rat gastric mucosa after 6 hours of vagotomy without drainage. Transection vagotomy was employed to ensure complete gastric vagal denervation. Vagotomy without drainage produced gastric distension and mucosal injury confined to the glandular part. Anterior truncal vagotomy produced injury in 70% of rats, whereas truncal or transection vagotomy produced injury in all rats. The injury score with transection vagotomy was significantly higher than that with anterior truncal (21.2 mm2 +/- 1.6 vs. 8 mm2 +/- 2.7, mean +/- SEM, n = 10, p less than .01) or truncal vagotomy (21.2 mm2 +/- 1.6 vs. 15.6 mm2 +/- 1.4, mean +/- SEM, n = 10, p less than .05). Histologic examination of the mucosal injury revealed necrosis involving the epithelium and lamina propria. Cholestyramine, pyloroplasty, or gastric diversion protected the stomach against the vagotomy-induced mucosal injury. The results demonstrate in the rat that vagotomy without drainage produces within 6 hours injury of the gastric mucosa, which increases as vagal denervation is rendered more complete. Because cholestyramine protects the rat stomach against vagotomy-induced acute gastric mucosal injury, reflux of duodenal contents appears to be the principal factor behind this injury. Pyloroplasty prevents gastric distension but probably not duodenal contents refluxing, suggesting that this distention also may have a role in the mechanism of the said injury.     

Evaluation of acetic acid-induced gastric ulcers in rats by scanning acoustic microscopy.

To clarify the mechanism of gastric ulcer recurrence, we studied acetic acid-induced gastric ulcers. The healing of these gastric ulcers was then studied for 4-21 weeks after the injection. Forty-eight ulcers were examined by macroscopic observation and scanning acoustic microscopy (SAM) and by histologic study of the ulcers. SAM has a higher radio frequency and provides more detailed information about the gastric wall than endoscopic ultrasonography (EUS). Thirteen healed and 35 non-healed gastric ulcers were observed by macroscopic observation over 4-21 weeks. SAM enabled us to observe the normal gastric wall of the rat in five different layers. The SAM echo patterns of the healed ulcers were all one pattern. On the other hand, we were able to classify the echo patterns of the non-healed ulcers into two different patterns; one pattern consisted of a high-echogenic region in the first and second layers with an underlying relatively high echogenic region in a horizontal pattern. The other pattern showed a poorly defined and spotted low-echogenic region in the first and second layers which fanned out toward the fifth layer. However, these two different ulcers could not be distinguished macroscopically. Histologic findings supported the results of the SAM study which showed one pattern in healed ulcers and two patterns in non-healed ulcers. In the non-healed ulcers the two different patterns may be ascribed to the proliferation of collagen fibers. SAM makes it possible to image the proliferation of collagen fibers and identify the two different types with an accuracy of 97%.(ABSTRACT TRUNCATED AT 250 WORDS)     

A separating method for quantifying mucus glycoprotein localized in the different layer of rat gastric mucosa.

A method was devised for separating rat gastric mucosa into three layers each containing a different mucin species. The mucus gel (first layer) was removed by stirring the gastric mucosa in a solution of phosphate-buffered saline containing 2% N-acetylcysteine. The surface mucosa (second layer), rich in surface mucus cells, was then separated from the deep mucosa (third layer) containing mucus neck cells, by scraping with forceps. The effectiveness of this method was confirmed by light microscopical observation after GOCTS-PCS (dual staining by the galactose oxidase-cold thionin Schiff method and paradoxical concanavalin A method) and AB-PAS staining (dual staining with alcian blue and the periodic acid Schiff method). The fixed specimen of scraped mucus and cell debris was rich in AB-PAS and GOCTS positive mucus, but was hardly stained by PCS, indicating mucus derived from surface mucus cells to have been efficiently recovered from this preparation. The residual mucosa could be stained by PCS but hardly at all by AB-PAS or GOCTS. The lyophilized powder specimens obtained from the three different layers of rat gastric mucosa were used to extract and quantify mucus glycoprotein (mucin). This was done to examine changes in mucin content in the three layers of gastric mucosa one hour following the oral administration of 20% ethanol or 0.35 N hydrochloric acid, both mild irritants. Mucin content was noted to significantly increase in the first layer but hardly at all in the second layer. In the third layer, it decreased significantly by 0.35 N hydrochloric acid, but changed only slightly by 20% ethanol administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of tetragastrin on mucus glycoprotein in rat gastric mucosal protection

The effects of tetragastrin on mucus glycoprotein (mucin) metabolism and mucosal protection in rat gastric mucosa were investigated. Rats were administered with various doses of tetragastrin (12, 120, or 400 [μg/kg body weight; s.c), followed by 50% ethanol-induced gastric injury. Tetragastrin caused a significant increase in mucin content in the corpus mucosa and prevented 50% ethanol-induced gastric mucosal damage in a dose-dependent manner. For assessment of the effects of tetragastrin on the metabolism of gastric mucin in detail, changes in mucin distribution in the three different layers of rat gastric mucosa were examined one hour after single administration of tetragastrin. A significant increase in the mucin content was noted in the mucus gel and surface mucosal layer. Mucin content in the deep mucosa corresponding mainly to the mucus neck cell mucin underwent virtually no change by this treatment. An increase in mucin in the mucus gel and surface mucosa would thus appear due to the administration of tetragastrin and may possibly be related to the protective action of the gastric mucosa against injury. The data demonstrate a possibility that gastrin may have potential for enhancing gastric mucosal protection associated with mucus secretion and/or mucus synthesis on the surface mucosa of rat gastric mucosa.