Immunohistochemical study on the distribution of endocrine cells in the gastrointestinal tract of the babirusa, Babyrousa babyrussa (Suidae)

The distribution and relative frequency of endocrine cells in the gastrointestinal tract of the babirusa were studied immunohistochemically using the avidin-biotin-peroxidase complex method. Thirteen types of gut endocrine cells were detected; they were immunoreactive for chromogranin, serotonin, somatostatin, gastrin, bovine pancreatic polypeptide (BPP), glucagon, secretin, cholecystokinin (CCK), methionine-enkephalin-Arg6-Gly7-Leu8 (MENK8), motilin, gastric inhibitory polypeptide (GIP) and peptide tyrosine tyrosine (PYY). Cells that were immunoreactive for chromogranin, serotonin, somatostatin and glucagon were found in all portions of the gastrointestinal tract. MENK8-immunoreactive cells were observed in the stomach and small intestine. Gastrin-immunoreactive cells were detected in the pyloric region and duodenum. PYY-immunoreactive cells were found in the small and large intestine. Cells immunoreactive for motilin, CCK, GIP, and secretin were observed in the proximal small intestine and those immunoreactive for neurotensin were found only in the ileum. Although the distribution pattern of endocrine cells in the gastrointestinal tract of babirusa was similar to those reported for pig, restricted distribution of several endocrine cells, gastrin, BPP, MENK8, motilin, CCK, GIP, secretin and neurotensin and wider distribution of glucagon and PYY were observed in the babirusa. The unexpected presence of MENK8 in all glandular regions of the stomach and PYY in the small intestine was also noted. The distribution of gut endocrine cells might be related to the regulatory characteristics of the babirusa digestive tract.     

Immunolocalization of ghrelin in the stomach of Sprague-Dawley rat

To investigate the distribution of ghrelin in different regions of stomach in Sprague-Dawley rat, and attempt to compare with those of humans and other mammalian species in this study, the stomach of rats was divided into five sections, cardia, fundus, greater curvature, lesser curvature and pylorus. Immunohistochemistry and Western blotting were performed to investigate the ghrelin-producing cells. The immunolocalization and protein levels of ghrelin differed significantly in different regions of stomach in rats. It was present at a high level in the greater curvature of the pars glandularis, and the lesser curvature. In the fundus and pylorus, no ghrelin immunoreactive cells were detected. In this study, we elucidated the distribution of ghrelin-producing cells in different regions of rat stomach in detail for the first time. It is further considered that the differences of ghrelin distribution in stomach of different species may induce different stimulatory effects on fat accumulation and metabolism.     

An immunohistochemical study of the gastro-entero-pancreatic endocrine cells in the alimentary tract of the Korean tree squirrel, Sciurus vulgaris corea.

The regional distribution and relative frequencies of gastrointestinal endocrine cells were studied immunohistochemically in the gastrointestinal mucosa of Korean tree squirrels. Seven kinds of endocrine cells were identified in this study. Although a large number of 5-hydroxytryptamine-immunoreactive cells were seen throughout the gastrointestinal tract, they were most predominant in the duodenum. A moderate number of glucagon-immunoreactive cells which were restricted to the cardia and fundus of the stomach was also observed. Bovine chromogranin-immunoreactive cells were numerous in the cardia and pylorus of the stomach, found in moderate numbers in the fundus, duodenum and large intestine, but rare in the jejunum. Porcine chromogranin-immunoreactive cells were found in moderate numbers in the stomach but were rare in the duodenum. Gastrin/cholecystokinin-immunoreactive cells were abundant in the pyloric gland region but scarce in the duodenum. Bovine pancreatic polypeptide-immunoreactive cells were observed to be rare and found only in the pyloric gland region. Somatostatin-immunoreactive cells were distributed moderately in the stomach but were few in number in the intestine. No insulin-immunoreactive cells were found in the gastrointestinal tract of Korean tree squirrels. These results suggest that although the Korean tree squirrel is a herbivorous rodent, the distribution pattern of its gastro-entero-endocrine cells is rather similar to that reported for omnivorous animals.     

An immunohistochemical study of gastrointestinal endocrine cells in the BALB/c mouse

The distributions and frequencies of some endocrine cells in the eight portions of the gastrointestinal tract (GIT) of BALB/c mouse were studied. Endocrine cells were stained using immunohistochemical method with seven types of antisera against bovine chromogranin (BCG), serotonin, gastrin, cholecystokinin (CCK)-8, somatostatin, glucagon and human pancreatic polypeptide (HPP), and the regional distributions and their relative frequencies were observed in the eight portions of the GIT of BALB/c mice. All seven types of immunoreactive (IR) cells were identified. Most of the IR cells in the intestinal portion were generally spherical or spindle in shape (open type cell) while round-shaped cells (closed type cell) were found in the intestinal gland and stomach regions occasionally. Their relative frequencies varied according to each portion of the GIT. BCG-IR cells were observed throughout the whole GIT except for the rectum and they were most predominant in the pylorus. Serotonin-IR cells were detected throughout the whole GIT and they showed the highest frequency in the fundus. Gastrin- and CCK-IR cells were restricted to the pylorus and duodenum with a majority in the pylorus and rare or a few frequencies in the duodenum. Compared with other mammals, somatostatin-IR cells were restricted to the fundus and pylorus with a few frequencies, respectively. In addition, glucagon- and HPP-IR cells were restricted to the fundus and duodenum, respectively, with relative low frequencies. Some species-dependent unique distributions and frequencies of endocrine cells were observed in the GIT of BALB/c mouse compared with other rodents.     

Immunohistochemical Study of Endocrine Cells in the Gastrointestinal Tract of the Philippine Carabao (Bubalus bubalis)

The distribution and frequency of occurrence of endocrine cells in the gastrointestinal tract of the Philippine carabao (Bubalus bubalis) were studied by immunohistochemistry. Fourteen types of immunoreactive (IR) endocrine cells were revealed. Among the cell types, only chromogranin, serotonin, and bovine pancreatic polypeptide (BPP) were present in the entire gut, while the others showed restricted distribution: somatostatin, gastrin, and cholecystokinin in the abomasum and small intestine; methionine-enkephalin-Arg⁶-Gly⁷-Leu⁸, motilin, neurotensin, secretin, gastric inhibitory peptide, and substance P in the small intestine; peptide tyrosine tyrosine (PYY) in the large intestine: and glucagon in the whole intestinal tract. Most of the cell types showed peak density in the pyloric, duodenal, or rectal region. The highest cell type heterogeneity was observed in the duodenum. The distribution profile of the gut endocrine cells in the carabao is closely related to that in the Holstein cattle. Important findings include the occurrence of BPP-IR cells in the entire gut and the high frequency of PYY-IR cells in the large intestine.     

Digestive enzymes along digestive tract of a carnivorous fish Glyptosternum maculatum (Sisoridae,Siluriformes)

This study attempted to determine the presence, distribution and levels of digestive proteases, pepsin, amylase and lipase in the homogenates of digestive tract of a freshwater, cold‐adapted, carnivorous teleost of Tibet, Glyptosternum maculatum (n = 10, mean weight: 129.6 ± 28.9 g, mean length: 195.1 ± 16.6 mm, approximately 6 years old), at different temperatures and pH levels. The descending order of protease activity was as follows: stomach (pepsin, 16.16 ± 0.96 U/mg protein), anterior intestine (3.18 ± 0.25 U/mg protein), posterior intestine (1.76 ± 0.21 U/mg protein) and middle intestine (1.52 ± 0.23 U/mg protein). Amylase activity levels in descending order were as follows: anterior intestine (0.0062 ± 0.0007 U/mg protein), stomach (0.0032 ± 0.0009 U/mg protein), middle intestine (0.0023 ± 0.0005 U/mg protein) and posterior intestine (0.0023 ± 0.0004 U/mg protein). The highest lipase activity was found in the anterior intestine (0.83 ± 0.25 U/mg protein), followed by posterior intestine (0.51 ± 0.19 U/mg protein), middle intestine (0.48 ± 0.09 U/mg protein) and stomach (0.39 ± 0.10 U/mg protein). The optimal temperature and pH level for protease were 50 °C and 9.0–10.0, respectively, along the intestine. The pepsin optima in the stomach were 30 °C and 2.0 respectively. The optimal temperature for amylase was found to be 30 °C along the digestive tract and the optimal pH was 7.0 in the intestine and 6.0 in the stomach. The optimal temperature and pH levels of lipase were 30 °C, pH 6.0 for the stomach and 40–50 °C, pH 8.0 for the intestine, respectively. Hepato‐somatic index was 1.35 ± 0.2% and relative intestine length was 0.90 ± 0.19. The weight ratio of the stomach and intestine to body weight was 1.63 ± 0.43% and 1.57 ± 0.24% respectively.     

Distribution and Activity of Fatty Acid Amide Hydralase (FAAH) in the Gastrointestinal Neurons of Mouse

The endocannabinoid anandamide may regulate intestinal motility through activation of CB1 receptors. Anandamide is then inactivated by fatty acid amide hydrolase (FAAH), a membrane bound enzyme. Under pathological conditions, inactivation of such enzymatic activity may lead to inhibition of the intestinal motility. Here, preliminary reports on the distribution of Fatty Acid Amide Hydrolase (FAAH) immunoreactivity in the mouse gastrointestinal neurons, and the pharmacological effects of N‐arachidonoylserotonin (AA‐5HT), a selective inhibitor of FAAH, are reported. FAAH was revealed by an indirect immunofluorescence. Laminar preparations containing the myenteric or the submucous plexus adhered, were peeled off after the whole gut wall had been stretched out and fixed in 4% paraformaldehyde. They were subsequently incubated with a polyclonal anti‐serum directed against a region near the N‐terminus of the human FAAH and revealed by a FITC‐conjugated goat anti‐rabbit secondary anti‐serum. FAAH‐immunoreactive neurons were observed within the myenteric ganglia throughout the GIT. The positive nerve cells varied in size and density of immunoreactivity. Stomach and large intestine showed the highest neuronal density. AA‐5HT significantly reduced both gastric emptying and gastrointestinal tract transit. Such inhibitory effect was reduced by the C1 receptor antagonist SR141716A. Both morphological and pharmacological results suggest that FAAH may play a critical role in controlling gut anandamide levels.     

Postnatal changes in bacterial populations in the gastrointestinal tract of dogs

OBJECTIVE: To describe postnatal changes in the populations of bacteria in the gastrointestinal tract (GIT) of dogs. ANIMALS: 110 Beagles ranging from neonatal to adult dogs. PROCEDURE: Contents of the stomach and proximal and distal portions of the colon and contents and mucosa of the mid region of the small intestine were collected from puppies at 1 day after birth and subsequent suckling; puppies at 21, 42, and 63 days after birth; and adult female dogs (ie, dams of the puppies) for enumeration of bacterial populations. RESULTS: The entire GIT was colonized at day 1 by all groups of bacteria studied; aerotolerant forms were dominant. During subsequent postnatal development, there were changes in the relative proportions of the various groups of bacteria with anaerobic groups increasing in absolute and relative numbers. CONCLUSIONS AND CLINICAL RELEVANCE: Establishment of bacterial populations in the GIT of dogs is a gradual process that begins immediately after birth. Age-related changes in the relative proportions of bacterial groups coincided with changes in diet and physiologic processes of the host and can influence nutritional state and disease resistance of developing dogs. Differences among regions of the GIT suggest that fecal samples may have limited use for understanding the populations of bacteria and the age and diet-related changes in various regions of the GIT.     

Immunohistochemical survey of the gut endocrine cells in the common tree shrew (Tupaia belangeri).

Regional distribution and relative frequency of endocrine cells in the gastrointestinal tract of the common tree shrew (Tupaia belangeri) were studied immunohistochemically. Ten types of immunoreactive endocrine cells were localized in the gastric mucosa, i.e., chromogranin-, serotonin-, gastrin-, somatostatin-, bovine pancreatic polypeptide (BPP)-, enteroglucagon-, pancreatic glucagon-, peptide tyrosine tyrosine (PYY)-, motilin-, and substance P (SP)-immunoreactive (IR) cells. In the intestine, 13 types of immunoreactive cells were observed, i.e., chromogranin-, serotonin-, somatostatin-, gastrin-, BPP-, enteroglucagon-, PYY-, secretin-, cholecystokinin (CCK)-, gastric inhibitory peptide (GIP)-, motilin-, neurotensin-, and SP-IR cells. The regional distribution and relative frequency of the cell types varied along the gastrointestinal tract. Basically, the types, distribution, and relative frequency of the gut endocrine cells were similar to those reported in other mammalian species. However, some characteristic findings were noted in the present study: (1) the considerably large number of gastrin-IR cells in the pyloric region; (2) numerous serotonin-IR cells in the stomach; (3) appreciable number of BPP-IR cells in the transitional region of the stomach; and (4) wide distribution of PYY- and motilin-IR cells in the gut.     

The Influence of Restricted Feeding on Glucagon‐Like Peptide‐1 (GLP‐1)‐Containing Cells in the Chicken Small Intestine

The influence of restricted feeding on the distribution of glucagon‐like peptide‐1 (GLP‐1)‐containing endocrine cells in the chicken small intestine was investigated using immunohistochemical and morphometrical techniques. This study demonstrated that the restricted feeding had an influence on the activity of GLP‐1‐immunoreactive cells in the chicken small intestine. There were differences in the localization and the frequency of occurrence of GLP‐1‐immunoreactive cells in the small intestine between control and restricted groups, especially 25% feed supply group provided with 25% of the intake during the adapting period. GLP‐1‐immunoreactive cells in the control chickens were mainly located in epithelium from crypts to the lower part of intestinal villi. Those in restricted groups, however, tended to be located from crypts to the middle part of intestinal villi. The frequency of occurrence of GLP‐1‐immunoreactive cells was lowest in the control group, medium in 50% feed supply group and highest in 25% feed supply group at each intestinal region examined in this study, that is, increased with the advancement of restricting the amount of feed supply. These data show that the quantity of food intake is one of signals that have an influence on the secretion of GLP‐1 from L cells in the chicken small intestine.     

Immunohistochemical study on the distribution and relative frequency of endocrine cells in the stomach of the Malayan Pangolin, Manis javanica

The distribution and relative frequency of six kinds of endocrine cells in the stomach of the Malayan pangolin, Manis javanica were studied immunohistochemically using the avidin-biotin-peroxidase complex method. The stomach of the pangolin has three regions of mucous gland, one oxyntic gland and one pyloric gland. Cells immunoreactive for chromogranin, serotonin, somatostatin, BPP and glucagon were detected in all of the gastric glands, while gastrin-immunoreactive cells were found in the entire gastric gland except for the oxyntic gland. The distribution pattern of endocrine cells in the mucous gland and pyloric gland was mainly from the middle to apical portions of the glands. The endocrine cells were rare or not detected in the basal portion of all of the mucous glands and pyloric gland, but they were also found in the basal portion of the oxyntic gland. The distribution pattern of the endocrine cells in the mucous and pyloric glands suggested that this position facilitates a quick response to the luminal ingesta. The wide distribution of gastrin-immunoreactive cells in all of the mucous glands and pyloric gland was the most remarkable finding. This distribution suggests a major function of gastrin-immunoreactive cells for the digestive process in the Malayan pangolin stomach.     

Serotonin-containing cells in the gastrointestinal tract of newborn foals and adult horses

Serotonin (5-hydroxytryptamine, 5-HT), a regulatory amine of mucosal enterochromaffin cells plays an important role in the control of gastrointestinal smooth muscle contraction and epithelial secretion. Serotonin has also been associated with gastric ulcers, diarrhoea and abdominal pain. In spite of the high incidence of these gastrointestinal disorders in newborn foals and adult horses, no data are available regarding 5-HT immunoreactive cells (i.c.) in the gastrointestinal tract (GIT) of foals, and for adult horses, data are incomplete and contradictory. In this study, the distribution and relative frequency of 5-HT i.c. in the GIT of newborn foals and adult horses were determined immunohistochemically. In foals as in adults, a relatively large number of 5-HT i.c. were detected in all portions of the GIT. In foals, a significantly higher amount of cells was found in the pyloric region and margo plicatus of the stomach, as well as in the caecum and colon ascendens compared with adults. Our results provided rationale for further research concerning the role of 5-HT i.c. during the milk diet or in the regulation of gastrointestinal growth/cell proliferation, and in the pathogenesis of gastric ulcers, especially in newborn foals.     

Localization of amylin‐like immunoreactivity in the striped velvet gecko pancreas

Immunohistochemical techniques were employed to investigate the distribution of amylin‐like immunoreactive cells in the pancreas of gecko Homopholis fasciata. Four types of endocrine cells were distinguished: insulin immunoreactive (B cells), pancreatic polypeptide immunoreactive (PP cells), glucagon and pancreatic polypeptide immunoreactive (A/PP cells) and somatostatin immunoreactive cells (D cells). Pancreatic islets contained B, A/PP and D cells, whereas extrainsular regions contained B, D and PP cells. In the pancreatic islets, amylin‐like immunoreactive cells corresponded to B cells, but not to A/PP or D cells. In the extrainsular regions, amylin‐like immunoreactive cells corresponded to either B or PP cells. Amylin secreted from intrainsular B cells may regulate pancreatic hormone secretion in an autocrine and/or a paracrine fashion. On the other hand, amylin secreted from extrainsular PP and B cells, and/or intrainsular B cells may participate in the modulation of calcium homoeostasis in an endocrine fashion.     

Immunocytochemical distribution of endocrine cells in the gastrointestinal tract of the horse

Endocrine cells immunoreactive for somatostatin, gastrin, glicentin, glucagon, secretin, cholecystokinin, motilin and neurotensin were identified immunocytochemically in the gastrointestinal mucosa of the horse. Somatostatin-, glicentin- and glucagon-immunoreactive cells were very numerous in the cardiac and fundic regions of the stomach, whereas most gastrin-immunoreactive cells were confined to the pyloric region. Somatostatin-immunoreactive cells also were detected in all portions of the small intestine while gastrin-immunoreactive cells were confined exclusively to the upper portion and glicentin-immunoreactive cells were limited to the lower portions of the small intestine. Secretin-, cholecystokinin- and motilin-immunoreactive cells were observed only in the duodenum, while neurotensin-immunoreactive cells were confined primarily to the ileum. In the large intestine, somatostatin- and glicentin-immunoreactive cells were detected in the colon and rectum. The preferential location of endocrine cells provides additional information for future studies on the physiological roles of gastrointestinal peptides in the gastrointestinal tract of the horse.     

Fatal Gastrointestinal Infection with ‘Flexispira rappini’‐Like Organisms in a Cat

A 4‐month‐old male British Blue cat with catarrhal to haemorrhagic enteritis showed massive colonization of the stomach, small intestine and caecum with spiral‐shaped bacilli. In the stomach, organisms were located in foveolae and gland lumina and within unaltered and degenerate epithelial cells. Inflammatory infiltration was moderate and T cell dominated. In the intestine, bacilli were found in the gut lumen, between villi, in crypt lumina and within epithelial cells. Degeneration of crypt epithelial cells as well as crypt dilation and moderate to massive macrophage‐dominated infiltration of the mucosa and submucosa were observed. Immunohistochemically, bacilli were positive with an antibody against Helicobacter. Ultrastructurally, the organisms strongly resembled ‘Flexispira rappini’, a spiral‐shaped Helicobacter species known as a normal intestinal colonizer in dogs and mice.     

An immunohistochemical study of endocrine cells in the alimentary tract of the red-bellied frog, Bombina orientalis

The regional distribution and relative frequency of endocrine cells was studied immunohistochemically (PAP method) in the alimentary tract of the red-bellied frog, Bombina orientalis, using antisera against serotonin, somatostatin, chromogranin (CG), cholecystokinin (CCK)-8, bombesin, secretin, glucagon and pancreatic polypeptide (PP). Eight kinds of endocrine cells were identified in this study. These immunoreactive cells were located in the gastric glands of the stomach regions and in the intestinal or esophageal epithelium with variable frequencies. They were spherical or spindle-shaped. Serotonin- and somatostatin-immunoreactive cells were demonstrated in the whole alimentary tract including esophagus. CG-immunoreactive cells were restricted to the stomach. CCK-8-immunoreactive cells were observed from the antrum to the ileum. Bombesin-immunoreactive cells were restricted to the stomach. Secretin-immunoreactive cells were demonstrated in the pylorus, duodenum and ileum. Glucagon-immunoreactive cells were found in the antrum and duodenum. PP-immunoreactive cells were detected from the antrum to the rectum. In conclusion, throughout the alimentary tract of the red-bellied frog, the different regional distribution and relative frequency of endocrine cells were demonstrated. The regional distributions and relative frequencies of the endocrine cells in the alimentary tract of the red-bellied frog were resembled to those of the other anuran species except for esophagus.     

Influences of protein ingestion on glucagon‐like peptide (GLP)‐1‐immunoreactive endocrine cells in the chicken ileum

Influences of a specific dietary nutrient on glucagon‐like peptide (GLP)‐1‐containing cells in the chicken intestine are not yet clear. Significance of dietary protein level on GLP‐1‐containing cells in the chicken ileum was investigated. Chickens fed control or experimental diets of varying protein levels were examined using immunohistochemical and morphometrical techniques. We show that the protein ingestion had an impact on the activities of GLP‐1‐immunoreactive cells in the chicken ileum. Weight gains declined with decreasing dietary crude protein (CP) levels, but no significant differences were detected in the daily feed intake and villous height. GLP‐1‐immunoreactive cells with a round or oval shape were frequently observed in the lower CP level groups (4.5% and 0%). Frequencies of occurrence of GLP‐1‐immunoreactive cells were 41.1 ± 4.1, 38.5 ± 4, 34.8 ± 3.1 and 34.3 ± 3.7 (cells/mm², mean ± SD) for dietary CP level of 18%, 9%, 4.5% and 0% groups, respectively and significant differences were recognized between the control and lower CP level groups (P < 0.05). Multiple regression analysis indicated a significant correlation between the daily protein intake and frequencies of occurrence of GLP‐1‐immunoreactive cells. The protein ingestion is one of the signals that influence GLP‐1‐containing cells in the chicken small intestine.     

Immunohistochemical study of endocrine cells in the gastrointestinal tract of the barking deer, Muntiacus muntjak

The morphology, distribution and relative frequencies of endocrine cells in the gastrointestinal tract of the barking deer (Muntiacus muntjak) were investigated. The immunohistochemical method employed used seven types of antisera against chromogranin, serotonin, gastrin, cholecystokinin, somatostatin, glucagon and insulin. Chromogranin and serotonin immunoreactive (IR) cells were found throughout the gastrointestinal tract. Conversely, gastrin-IR cells were only found in the oxyntic gland, pyloric gland and duodenum, while cholecystokinin-IR and somatostatin-IR cells were detected in the oxyntic gland, pyloric gland and small intestines. Somatostatin-IR cells were also seen in the caecum. Glucagon-IR cells were found in all parts of the gastrointestinal tract apart from the colon and rectum. No insulin-IR cells were found in the gastrointestinal tract of this species. The cells in the small intestine were generally spindle shaped with long cytoplasmic processes ending in the lumen (open type), while in the stomach and large intestine, they were occasionally round or spherical in shape (closed type). An uncommon distribution pattern of endocrine cells in the gastrointestinal tract of the barking deer was noted for cholecystokinin- and glucagon-IR cells.