Wei-Guang Ding

Light and electron microscopy of neuropeptide Y-containing nerves in human liver, gallbladder, and pancreas.

Neuropeptide Y-containing nerve fibers were identified by light and electron microscopic immunocytochemistry in the human liver, gallbladder, and pancreas. In the liver, neuropeptide Y-containing nerve fibers were distributed richly in Glissons sheath and were prominent around the walls of the interlobular vein, interlobular hepatic artery, and hepatic bile duct. The fibers also formed a dense network surrounding the hepatocytes. The nerve terminals were found close to the endothelial cells of blood vessels, as well as being distributed in Disses space, where they appeared to terminate. Occasionally these terminals contacted directly the membrane of a hepatocyte. In the gallbladder, neuropeptide Y fibers were found in each layer, with an especially dense network in the lamina propria. The fibers also ran close to the epithelium and parallel to the muscle bundles. Blood vessels throughout the gallbladder were well supplied with such nerve fibers. In the pancreas, neuropeptide Y fibers were found mainly near blood vessels and partly in gaps between exocrine glands, seeming to terminate on certain endocrine cells. Nerve terminals were located in the vascular walls and adjacent to the surface of exocrine acinar cells. These studies provide a basis for correlating the neuropeptide Y distribution with pharmacological and physiological studies in humans.

Neuropeptide Y and peptide YY immunoreactivities in the pancreas of various vertebrates

NPY-like immunoreactivity was observed in nerve fibers and endocrine cells in pancreas of all species examined except the eel, which showed no NPY innervation. The density of NPY-positive nerve fibers was higher in mammals than in the lower vertebrates. These nerve fibers were distributed throughout the parenchyma, and were particularly associated with the pancreatic duct and vascular walls. In addition, the density of NPY-positive endocrine cells was found to be higher in lower vertebrates than mammals; in descending order: eel = turtle = chicken > bullfrog > mouse = rat = human > guinea pig = dog. These NPY-positive cells in the cel and certain mammals tended to be localized throughout the islet region, whereas in the turtle and chicken they were mainly scattered in the exocrine region. PYY-immunoreactivity was only present in the pancreatic endocrine cells of all species studied, and localized similarly to NPY. Thus these two peptides may play endocrine or paracrine roles in the regulation of islet hormone secretion in various vertebrate species.

Development of neuropeptide Y innervation in the liver

Hepatic neuropeptide Y (NPY) innervation was studied by immunohistochemistry in various mature vertebrates including the eel, carp, bullfrog, turtle, chicken, mouse, rat, guinea pig, dog, monkey, and human. In addition, an ontogenetic study on hepatic NPY was made in developing mice and guinea pigs. In all species examined except the eel, NPY‐like immunoreactivity was detected in nerve fibers. In the carp, bullfrog, turtle, chicken, mouse, and rat, NPY‐positive fibers were distributed around the wall of hepatic vessels and the bile duct of the Glissons sheath. The density of NPY‐positive fibers increased with evolution. However, in the guinea pig, dog, monkey, and human, numerous NPY‐positive fibers were observed not only in the Glissons sheath but also in the liver parenchyma. Positive fibers formed a dense network that surrounded the hepatocytes. The present immunoelectron microscopic study has confirmed that NPY‐positive terminals are closely apposed to hepatocytes. Ontogenically, NPY‐positive fibers were first found in the embryonic liver of 19‐day‐old mice. Positive fibers increased with age, and the highest peak was seen 1 week after birth. However, NPY‐positive nerve fibers were present abundantly in Glissons sheath and in the hepatic parenchyma of neonatal (3 and 7 days old) guinea pigs in a distribution similar to that in mature animals. This ontogenetic pattern suggests that NPY plays a certain role in the developing liver. Microsc. Res. Tech. 39:365–371, 1997.

Phylogenetic and ontogenetic study of neuropeptide Y-containing nerves in the liver.

SummaryThe distribution of neuropeptide Y was investigated by light and electron microscopic immunohistochemistry in the liver of various vertebrates including the eel, carp, bullfrog, turtle, chicken, mouse, rat, guinea-pig, dog, monkey and human. The ontogenetic development of neuropeptide Y was also studied in the mouse liver. In all species examined except the eel, neuropeptide Y-like immunoreactivity was detected in nerve fibres. In the carp, bullfrog, turtle, chicken, mouse and rat, positive fibres were distributed around the wall of hepatic vessels and the bile duct of the Glissons sheath. The density of the positive fibres increased with evolution. On the other hand, in the guinea-pig, dog, monkey and human, numerous neuropeptide Y-positive fibres were observed not only in the Glissons sheath but also in the liver parenchyma. Positive fibres formed a dense network to surround hepatocytes. The present immunoelectron microscopic study has confirmed that neuropeptide Y-positive terminals are closely apposing to hepatocytes. Ontogenetically, neuropeptide Y-positive fibres were first found in embryonic liver of 19-day-old mice. Positive fibres increased with age and the highest peak was seen one week after birth. This ontogenetic pattern has suggested that neuropeptide Y plays a certain role in developing liver.

Distribution of taurine-like immunoreactivity in the mouse liver during ontogeny and after carbon tetrachloride or phenobarbital intoxication

SummaryThe ontogenic pattern of development of taurine-like immunoreactivity (TLI) was studied in the mouse liver. The effect on adult mice of carbon tetrachloride or phenobarbital treatment was also examined. Light-microscopically, granules of TLI were first found in the liver from 17-day-old embryos, diffusely distributed throughout the lobules. These positive granules increased with age, were most numerous in the two-week-old mouse, and were notably decreased in the central region of some lobules in the three-week-old mouse. In mature mice, hepatocytes containing TLI-positive granules were distributed unevenly in each liver lobule, and were located predominantly in the peripheral region. Electron-microscopically, TLI was observed in small vesicles in the cytoplasm of hepatocytes and was found mainly in the cisternal lumen of smooth-surfaced endoplasmic reticulum. Some taurine-positive vesicles surrounding the reticulum seemed to associate with the protoplasm. Similar positive vesicles were often located near the bile canaliculi. In carbon tetrachloride-intoxicated mature mice, TLI was no longer limited to the peripheral region of lobules; hepatocytes situated in the central region of lobules also contained intense TLI. In mice injected with a small and repeated dose of phenobarbital, the distribution pattern of TLI was similar to that in the untreated group. However, in mice injected with a large dose of phenobarbital, TLI was markedly increased, especially in the central region of lobules. The results demonstrate that the distribution pattern of TLI in mouse liver changes during development, and that the pattern in mature mice is affected by intoxication with carbon tetrachloride or a toxic dose of phenobarbital.

Phylogenetic study of serotonin-immunoreactive structures in the pancreas of various vertebrates

SummaryThe distribution pattern of serotonin (5HT) in the pancreas was studied immunohistochemically by using a 5HT monoclonal antibody in various vertebrates including the eel, bullfrog, South African clawed toad, turtle, chicken, mouse, rat, guinea-pig, cat, dog and human. In all species examined, except the bullfrog, 5HT-like immunoreactivity was observed in nerve fibers, in endocrine cells, or in both. Positive nerve fibers were found in the eel, turtle, mouse, rat and guinea-pig. These fibers ran mainly along the blood vessels and partly through the gap between the exocrine glands. In the eel and guinea-pig, positive fibers invaded the pancreatic islet. Occasionally, these positive fibers were found adjacent to the surface of both exocrine and endocrine cells, suggesting a regulatory role of 5HT in pancreatic function. 5HT-positive endocrine cells were observed in the pancreas of all species except for the bullfrog and rat. In the eel and in mammals such as the mouse, guinea-pig, cat, dog and human, 5HT-positive cells were mainly observed within the pancreatic islet. In the South African clawed toad, turtle and chicken, the positive cells were mainly in the exocrine region. The present study indicates that the distribution patterns of 5HT in the pancreas varies considerably among different species.

Phylogenic study of calcitonin gene-related peptide-immunoreactive structures in the pancreas.

Abstractu2002The immunohistochemical localization of calcitonin gene-related peptide was examined, at both light and electron microscopic levels, in the pancreas of various vertebrates, including the eel, bullfrog, turtle, chicken, mouse, rat, guinea pig, dog, monkey, and human. Immunoreactive staining was observed in nerve fibers in every animal species examined, but positive endocrine cells were limited to the rat, monkey, and human. The density of the positive endocrine cells varied considerably among the three species (monkey > rat > human). Positive nerve fibers were distributed throughout the parenchyma, being particularly rich around pancreatic ducts, and near large or small blood vessels. In four species (eel, mouse, rat, and dog), positive nerve fibers formed a dense network in the islet region. There were positive varicose nerve fibers around exocrine cells. These fibers, varying in density in different species (relatively high in the eel, bullfrog, and rat), were sometimes adjacent to acinar cells. At the electron microscopic level, positive nerve terminals were often demonstrated in close apposition to the outer membrane of acinar cells. The eel pancreas revealed an exceptional pattern of staining in neuronal cell bodies that were scattered in the interlobular connective tissue. Despite these anatomical differences, the omnipresence of this peptide suggests its essential role(s) in the pancreas.

Immunohistochemical Localization of Taurine-Conjugated Bile Acids in the Liver of Mouse, Rat, Monkey and Human

The liver and brain are organs rich in taurine (14,17). Taurine is present at high concentrations in liver and brain of developing mammals, and, may be important in normal fetal and neonatal development (11,29). In the brain, a role of taurine as an inhibitory neurotransmitter or neuromodulator has been proposed (13,20). A number of immunohistochemical studies have clarified the localization of taurine (3,31) or its synthesizing enzyme, cysteine sulfinic acid decarboxylase (4). However, the localization of taurine in the liver has not been well settled. In our previous immunohistochemical studies using antiserum to taurine, we have found that the antiserum recognizes not only taurine in the brain but also bile acids conjugated with taurine in the liver (15,7,30).