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

An immunohistochemical study of endocrine cells in the digestive tract of Varanus salvator (Reptile: Varanidae)

Aim:

The aim of the study was to identify the distribution pattern and frequency of endocrine cell types in the digestive tract of Varanus salvator.

Materials and Methods:

The presence of endocrine cells (glucagon, somatostatin, and serotonin) in the digestive tract (esophagus, stomach, and intestine) was detected using the avidin-biotin complex (ABC) method.

Results:

Three types of endocrine cells immunoreactive to antisera glucagon, serotonin, and somatostatin were found in the caudal portion of the small and large intestines but were not observed in the esophagus, stomach, and caput and medial sections of the small intestine. Endocrine cells distributed in the digestive tract of V. salvator vary in color intensity, from weak to sharp, in response to the primer antibody.

Conclusion:

Endocrine cells in the digestive tract that is immunoreactive to glucagon, somatostatin, and serotonin are those found in the caudal portion of the small and large intestines. They are varied in distribution pattern, frequency, and color intensity.

The tree shrew as a model for infectious diseases research

Despite major advances in medicine, infectious diseases still pose a significant threat to humanity. Mammalian models of disease have proved extremely useful in adding to the understanding of infectious diseases and the development of prophylactic and/or therapeutic interventions. Arguably the most important considerations of any animal model are (I) the similarity of the model to humans with respect to anatomy, physiology, immunology and disease progression, and (II) the expense of conducting experiments using the model organism. Often the choice of a model represents a compromise between these factors. Here we review the Northern Tree shrew (Tupaia belangeri), or tupaia, as a useful model for the study of infectious diseases. Tupaias are non-human primates similar in size to squirrels that are indigenous to Asia. Their genome has been sequenced and, overall, shows relatively high similarity to humans. There is also a close homology of many aspects of tupaia biology with human biology. Importantly, from an infectious diseases viewpoint, tupaias are susceptible to infection with unadapted human pathogens and manifest clinical signs akin to human infections. Overall, the relatively small size of the tupaia, their homology to humans and their susceptibility to human pathogens make them a useful model for the study of infectious diseases.

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.

An immunocytochemical study of the endocrine cells in the stomach and duodenum of Zonotrichia capensis subtorquata (Passeriformes, Emberizidae)

The main purpose of this study was to evaluate the regional distribution pattern and relative frequency of some endocrine cells in the three portions of the gastrointestinal tract (GIT)--the proventriculus, gizzard and duodenum- of the rufous-collared sparrow (Zonotrichia capensis subtorquata), by immunohistochemical methods using six types of polyclonal antisera, specific for serotonin (5-HT), somatostatin (D cells), glucagon, motilin, polypeptide YY (PYY) and insulin. In the proventriculus, endocrine cells immunoreactive for all of these markers were observed. The somatostatin-immunoreactive cells were found with greater frequency, with the presence of cytoplasmic processes. In the gizzard, endocrine cells secreting somatostatin, 5-HT and PYY were detected, while those secreting glucagon and insulin were not. In the final part of the gizzard, endocrine cells secreting 5-HT were more frequent, and cells secreting somatostatin and insulin were not detected. All of the cell types studied were observed in the duodenum in different frequencies, except for cells immunoreactive for glucagon and insulin. The somatostatin-positive (D cells) were the most numerous, being more prevalent in the intestinal glands. The other endocrine cells were identified in smaller numbers, some of them located in the intestinal villi and Lieberkuhn glands. The finding of these cell types in the duodenum confirms their preferential location in the final portions of the principal segments of the digestive system and suggests control by feedback of its functions. In conclusion, some interesting distributional patterns of gastrointestinal endocrine cells were found in this species of sparrow.

The regional distribution and relative frequency of gastrointestinal endocrine cells in the nude mice, Balb/c-nu/nu: an immunohistochemical study

The distributions and frequencies of some endocrine cells in the eight portions of the gastrointestinal (GI) tract - fundus, pylorus, duodenum, jejunum, ileum, cecum, colon and rectum of the nude mouse, Balb/c-nu/nu were studied with immunohistochemical method using six types of anti-sera against serotonin, gastrin, cholecystokinin (CCK)-8, somatostatin, glucagon and human pancreatic polypeptide (hPP). All of six types of immunoreactive (IR) cells were identified. Most of IR cells in the intestinal portion were generally spherical or spindle in shape (open type cell) while cells showing round in shape (close type cell) were found in the intestinal gland and stomach regions occasionally. Their relative frequencies were varied according to each portion of GI tract. Serotonin-IR cells were detected throughout the whole GI tract and they showed the highest frequency in the pylorus. Gastrin-IR cells were restricted to the pylorus and duodenum with numerous and a few frequencies, respectively. CCK-8-IR cells were also restricted to the pylorus, duodenum and jejunum with numerous, a few and rare frequencies, respectively. Somatostatin-IR cells were demonstrated throughout the whole GI tract except for the colon and rectum, and they showed the highest frequency in the fundus. In addition, glucagon- and hPP-IR cells were restricted to the fundus and rectum, respectively with a few frequencies. In conclusion, the general distribution patterns and relative frequency of GI endocrine cells of the nude mouse, Balb/c-nu/nu was similar to that of other strains of mice. However, some strain and/or species-dependent unique distributions and frequencies of endocrine cells were also observed especially for somatostatin- and hPP-IR cells.

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.

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.

An immunohistochemical study of the gastrointestinal endocrine cells in the C57BL/6 mice

The regional distributions and relative frequencies of some gastrointestinal endocrine cells in the eight portions (fundus, pylorus, duodenum, jejunum, ileum, cecum, colon and rectum) of the gastrointestinal tract of C57BL/6 mouse was studied with immunohistochemical method using seven types of specific anti-sera against chromogranin A (CGA), serotonin, somatostatin, human pancreatic polypeptide (HPP), glucagon, gastrin and cholecystokinin (CCK)-8. In this study, all these seven types of immunoreactive (IR) cells were identified. Most of these IR cells in the intestinal portion were generally spherical or spindle in shape (open-type cell) while cells showing round in shape (closed-type cell) were found in the intestinal gland and stomach regions occasionally. Their relative frequencies were varied according to each portion of gastrointestinal tract. CGA-IR cells were demonstrated throughout the whole gastrointestinal tract and they showed most predominant in the pylorus and duodenum. Serotonin-IR cells were detected throughout whole gastrointestinal tract and they showed highest frequency in the stomach and colon. Somatostatin-IR cells were demonstrated throughout whole gastrointestinal tract except for large intestine and showed highest frequency in the fundus. HPP-IR cells were found in the fundus with rare frequency. Peculiarly, glucagon-IR cells were restricted to the fundus, ileum and colon with a few frequencies. Gastrin-IR cells were restricted to the pylorus with numerous frequency and CCK-8-IR cells were observed in the pylorus, duodenum and jejunum with numerous and/or a few frequencies, respectively. In conclusion, some peculiar distributional patterns of gastrointestinal endocrine cells were found in C57BL/6 mouse.

Histological study on intestinal diverticulum of tree shrew (Tupaia javanica)

Tree shrews possess an intestinal diverticulum. We investigated this diverticulum with histological and immunohistochemical methods to determine whether this diverticulum was cecum or not. The ratio of the length of diverticulum/small intestine was apparently shorter than that of several primates. In the histological study, mucous membrane of the small intestine was shifted to that of the large intestine at the junction of the diverticulum. Histological features of the diverticulum were similar to those of the large intestine, but the shape of mucousal surface was rather simpler than that of the large intestine. Immunohistochemical study revealed 5-HT positive cells in the bottom of crypts and CD3- and CD 8-positive lymphocytes in lymphoid nodules. These findings suggest that the tree shrew has a cecum with primitive characteristics.

The regional distribution and relative frequency of gastrointestinal endocrine cells in SHK-1 hairless mice: an immunohistochemical study

The regional distributions and relative frequencies of some gastrointestinal endocrine cells in the eight portions (fundus, pylorus, duodenum, jejunum, ileum, caecum, colon and rectum) of the gastrointestinal tract of SKH-1 hairless mice were investigated using immunohistochemical methods and seven types of specific antisera against somatostatin, serotonin, glucagon, cholecystokinin (CCK)-8, secretin, pancreatic polypeptide (PP) and gastrin. In this study, somatostatin-, serotonin-, glucagon-, CCK-8-, secretin- and gastrin-immunoreactive (IR) cells were identified. Most of these IR cells in the intestinal portion were generally spherical or spindle-shaped (open-type cell) while cells that were round in shape (close-type cell) were occasionally found in the stomach regions. Their relative frequencies were varied according to each portion of gastrointestinal tract. Somatostatin-IR cells were found throughout the gastrointestinal tract except for the large intestine. Serotonin-IR cells were detected throughout the whole gastrointestinal tract and were the most predominant endocrine cell types in this species of mouse. Glucagon-IR cells were restricted to the fundus, occurring rarely. CCK-8-IR cells were observed in the pylorus, duodenum and jejunum with frequencies that were numerous, moderate and few, respectively. Peculiarly, secretin-IR cells were demonstrated in the whole intestinal tract with either few or rare frequencies. Gastrin-IR cells were restricted to the pylorus and were numerous. However, no PP-IR cells were found in this study. In conclusion, some peculiar distributional patterns of gastrointestinal endocrine cells were found in SKH-1 hairless mouse.