An immunohistochemical study on the distribution of endocrine cells in the chicken gastrointestinal tract

The distribution and the frequency of occurrence of nine types of gut endocrine cells were revealed using immunohistochemical methods in eight portions from the gastrointestinal tract of the chicken (Gallus gallus var domestica). In the proventriculus, somatostatin- and gastrin-releasing polypeptide (GRP)-immunoreactive cells were commonly found. Serotonin-, pancreatic glucagon-, and enteroglucagon-immunoreactive cells were uncommon. Avian pancreatic polypeptide (APP)-immunoreactive cells were rare. In the gizzard, numerous GRP-, and a small number of somatostatin-immunoreactive cells were observed. The pyloric region was characterized by the presence of abundant gastrin-, somatostatin-, and neurotensin-immunoreactive cells. Numerous serotonin-immunoreactive cells were detected in all portions of the intestine. Moderate numbers of neurotensin-immunoreactive cells were detected in all portions of the intestine except for the cecum. A few gastrin- and somatostatin-immunoreactive cells were detected in the duodenum and jejunum. A small number of pancreatic glucagon-immunoreactive cells were detected in the jejunum and ileum. Enteroglucagon-immunoreactive cells were detected in the small intestine in increasing numbers forwards the ileum. Motilin-immunoreactive cells were rare in the small intestine.     

Immunocytochemical study of gastro-entero-pancreatic (GEP) endocrine cells in the vampire bat (Desmodos rotundus)

The distribution and frequency of gastro-entero-pancreatic (GEP) endocrine cells were studied in vampire bats by immunocytochemistry. Moderate numbers of somatostatin- and a few 5-hydroxytryptamine (5-HT)- and glucagon-immunoreactive cells were seen in the fundic cecum of the stomach. Numerous gastrin- and moderate numbers of somatostatin- and 5-HT-immunoreactive cells were found in the pyloric region. Moderate numbers of 5-HT-, somatostatin-, and gastrin-immunoreactive cells also were found in BRUNNER's glands. In addition to the above-mentioned 4 immunoreactive cell types, cells immunoreactive for glicentin, secretin, cholecystokinin (CCK), gastric inhibitory peptide (GIP), and neurotensin were found in the intestine. Numerous insulin-, moderate numbers of somatostatin- and glucagon-, and a few 5-HT-immunoreactive cells were detected in the pancreatic islets with lesser numbers scattered within the exocrine pancreas. Motilin- and pancreatic polypeptide-immunoreactive cells were not observed in this study.     

An immunohistochemical survey of endocrine cells and nerves in the proximal small intestine of the platypus,Ornithorhynchus anatinus

The relative frequencies of endocrine cells and peptidergic nerve elements in the proximal small intestine of the adult platypus were studied by immunohistochemistry. Six kinds of endocrine cells - serotonin (5-HT)-, somatostatin-, gastrin-, motilin-, cholecystokinin (CCK)- and bovine pancreatic polypeptide (BPP)-immunoreactive cells - were identified in this study. These endocrine cells were found most frequently in the intestinal glands, in moderate numbers in the tubular ducts and were infrequent in the surface folds. 5-HT-immunoreactive cells were most numerous, somatostatin-, gastrin-, motilin- and BPP-immunoreactive cells were moderately numerous, whereas CCK-immunoreactive cells were rare. Five kinds of neuropeptides: substance P, vasoactive intestinal polypeptide (VIP), gastrin releasing peptide (GRP), somatostatin and leu-enkephalin, were detected in the intramural nerve elements. Substance P-, VIP- and GRP-immunoreactive nerve fibers were found most frequently in the lamina propria mucosae of the surface folds. The relationships between the possible functions of the peptides and amine detected in this study as well as the characteristic structure of the digestive tract of the adult platypus are discussed.     

Ontogenesis of endocrine cells in the chicken intestine: an immunohistochemical study

The authors report the time of appearance, morphology and topographic distribution of gastrin/cholecystochinin- (G/CCK-), somatostatin- (SRIF-), neurotensin- (NT-), motilin- (MO-) and substance P-like immunoreactive (SP-LI) elements during embryonic and postnatal development, in ileum, caeca and colon of chick embryos (from 8 days of incubation to hatching), newborn chicks (up to 15-days old) and adult chickens. In the ileum, G/CCK-LI and SP-LI cells appeared on day 11, the others on about day 13. In the caeca the first cells of all types were seen from about day 17. In the colon, NT-LI cells appeared early, on day 9, SP-LI and occasional SRIF-LI cells from day 13 on and MO-LI and G/CCK-LI only from day 17. In the ileum all the cells studied were present, in the caeca and colon they were extremely scarce, apart from NT-LI cells which were more numerous. In the prenatal stages, SP-LI was found only in epithelial cells; after hatching, it was also present in metasympathetic nerve elements.     

Immunohistochemical studies on the ontogenesis of some endocrine cells in the chicken antrum and duodenum

The time of appearance, morphology and topographic distribution of gastrin/CCK-, somatostatin-, 5HT-, and bombesin-like immunoreactive cells during embryonic and postnatal development were studied in chicken antrum and duodenum with immunohistochemical methods. Gastrin/CCK-like cells appeared on or about the 11th day in the antrum and duodenum, somatostatin-like cells around the 12th day in the antrum and the 11th day in the duodenum, bombesin-like cells appeared only in the antrum and only at hatching. In the early stages of development all the immunoreactive cells were localized in the surface epithelium, descending deeper into the glands as these form, although some cells could always be seen in the surface epithelium. Around the 17th day the number of gastrin/CCK-like cells and somatostatin-like cells in the antrum increases, while 5HT-like already become more numerous in the duodenum from the 13th day onwards. Two territories were recognized in the antrum of the adult: the first was near the duodenum where gastrin/CCK-like and somatostatin-like cells, often in close contact, were very numerous; the other territory was near the gizzard where bombesin-like cells were more numerous. Both regions contained 5HT-like cells in smaller number. In adult duodenum, 5HT-like cells were the most numerous, while somatostatin-like cells and gastrin/CCK-like cells, found in more superficial locations, were more scanty.     

An immunohistochemical study of the pancreatic endocrine cells of the nude mouse, Balb/c-nu/nu

The regional distribution and frequency of the pancreatic endocrine cells in the nude mouse, Balb/c-nu/nu were studied by immunohistochemical (peroxidase anti-peroxidase; PAP) methods using specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP). The pancreas of the mouse was divided into two lobes, the splenic and duodenal lobes, and each lobe was subdivided into three regions, the pancreatic islets (central and peripheral regions), the exocrine region and the pancreatic duct region (consisting of duct epithelium and surrounding connective tissue--sub-epithelial connective tissue). In the pancreatic islets, most of insulin-immunoreactive (IR) cells were located in the central region, and glucagon-, somatostatin and hPP-IR cells were located in the peripheral region regardless of the lobe. In the splenic part, glucagon-IR cells were also located in the central regions, and more numerous somatostatin-IR cells were detected in the central regions compared to those of the duodenal part. hPP-IR cells were restricted to the peripheral regions in both lobes but more numerous cells were detected in the duodenal portion as compared to those of the splenic portion. In the exocrine parenchyma of the splenic lobe, only insulin-, glucagon- and somatostatin-IR cells were detected.. Here, the insulin- and glucagon-IR cells formed cell clusters, while somatostatin-IR cells were present as solitary cells. In the exocrine region of the duodenal portion, only insulin-, somatostatin- and hPP-IR cells were observed, with the same distributional pattern as that found in the splenic lobe. However, clusters of cells consisting only of hPP-IR cells were distributed in the pancreas parenchyma as small islets. In the pancreatic duct region, only solitary hPP-IR cells were demonstrated in the sub-epithelial connective tissue regions of the splenic portion. In conclusion, some strain-dependent characteristic distributional patterns of pancreatic endocrine cells, especially of the hPP-IR cells, were found in the nude mouse. In addition, somewhat different distributional patterns were found between the two pancreatic lobes.     

Presence of somatostatin-28 like immunoreactivity in the human pancreas

Specific antisera against somatostatin-28 were prepared by absorption of somatostatin-28 antisera with sepharose 4B-somatostatin-14. Indirect immunofluorescence techniques using somatostatin-14 antisera and specific antisera against somatostatin-28 were carried out to elucidate the time of occurrence of somatostatin-28 in the fetal pancreatic islets and to ascertain whether somatostatin-28 was present in the adult pancreatic islets or not, and further to examine whether cells reacting with specific antisera against somatostatin-28 are identical to those reacting with somatostatin-14 antisera or not. Somatostatin-28 like immunoreactivity occurred in the fetal pancreatic islets at 11th week's gestation and was found in all fetal pancreatic islets examined in the present study. It was also found in the adult pancreatic islets. Furthermore, cells reacting with specific antisera against somatostatin-28 in the fetal and adult pancreatic islets were identical to those reacting with somatostatin-14 antisera. Thus, the present study elucidated the presence of somatostatin-28 like immunoreactivity in the human pancreas. However, it could not be decided whether cells reacting with somatostatin-28 antisera contain either only somatostatin-28 or both somatostatin-28 and somatostatin-14; in other words, whether somatostatin-14 is produced from somatostatin-28 or not, since somatostatin-14 antisera had a cross-reactivity to both somatostatin-14 and somatostatin-28.     

Distribution and frequency of endocrine cells in the pancreas of the ddY mouse: an immunohistochemical study

The regional distribution and frequency of pancreatic endocrine cells in ddY mice were studied by an immunohistochemical (peroxidase anti-peroxidase; PAP) method using four types of specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP). In the pancreatic islets, most of insulin-immunoreactive (IR) cells were located in the central portion. Most of glucagon- and somatostatin-IR cells were observed in peripheral regions although a somewhat smaller number of cells were also located in the central regions. HPP-IR cells were randomly distributed throughout the entire islets. In the exocrine pancreas, insulin-, glucagon-, somatostatin- and hPP-IR cells were detected; they occurred mainly among the exocrine parenchyma as solitary cells. Cell clusters consisted of only insulin- or only glucagon-IR cells and were distributed in the pancreas parenchyma as small islets. In addition, insulin- and glucagon-IR cells were also demonstrated in the pancreatic duct regions. Insulin-IR cells were located in the epithelium and sub-epithelial connective tissue regions as solitary cells and/or clusters (3-4 cells), and glucagon-IR cells were mainly located in the epithelium as solitary cells. Overall, there were 63.89+/-5.39% insulin-, 26.52+/-3.55% glucagon-, 7.25+/-2.83% somatostatin- and 1.90+/-0.58% hPP-IR cells. In conclusion, some strain-dependent characteristic distributional patterns of pancreatic endocrine cells were found in the ddY mouse.     

Immunocytochemical investigation of the gastro-entero-pancreatic (GEP) neurohormonal peptides in the pancreas and gastrointestinal tract of the dogfish Squalus acanthias

The pancreas and gastrointestinal tract (GIT) of adults and of an embryonic stage of 11 cm long (about half the length of newborn fish) of the spiny dogfish, Squalus acanthias, were investigated immunocytochemically for the occurrence of the gastro-entero-pancreatic (GEP) neurohormonal peptides. In the pancreas of adult forms 5 endocrine cell types were seen, namely insulin-, somatostatin-, glucagon-, pancreatic polypeptide (PP)- and gastric inhibitory peptide (GIP)-immunoreactive cells. These cell types form scattered islets and were seen sometimes to surround small ducts. GIP-immunoreactivity cells did not occur in glucagon-containing cells. In the mucosa of GIT of adults 18 endocrine cell types were observed, viz. insulin-, somatostatin-, glucagon-, glicentin, PP-, polypeptide YY (PYY)-, vasoactive intestinal polypeptide (VIP)-, GIP-, gastrin C-terminus, CCK-, neurotensin N-terminus-, bombesin/gastrin releasing peptide (GRP)-, substance P-, enkephalin-, alpha-endorphin, beta-endorphin-, serotonin- and calcitonin immunoreactive cells. These cells occurred mostly in the intestine. All these cell types were of the open type, except glucagon- and glicentin-immunoreactive cells in the stomach, which seemed to be of the closed type. In the muscle layers and the submucosa, VIP and substance P- immunoreactive nerves and neurons were observed. In the pancreas of the dogfish embryo only 3 endocrine cell types could be demonstrated, namely insulin-, somatostatin- and glucagon-immunoreactive cells. In the mucosa of the GIT of the embryos studied 12 endocrine cell types were detected, viz. insulin-, somatostatin-, glucagon-, PP-, PYY-, VIP, GIP, gastrin C-terminus-, CCK-, neurotensin N-terminus-, enkephalin- and serotonin immunoreactive cells. The number of these cells, except that of PYY-immunoreactive cells, was lower than that of adults and in some cases their distribution did not correspond with that of adults.     

An immunohistochemical study on the distribution of endocrine cells in the gastrointestinal tract of the musk shrew, Suncus murinus

The endocrine cells in the gastrointestinal tract of the musk shrew were studied immunohistochemically. Eleven kinds of endocrine cells, immunoreactive for serotonin, somatostatin, gastrin, cholecistokinin, gastric inhibitory polypeptide, motilin, secretin, neurotensin, pancreatic glucagon, enteroglucagon and bovine pancreatic polypeptide, were revealed. In the stomach, serotonin-, somatostatin-, gastrin-, pancreatic glucagon- and enteroglucagon-immunoreactive cells were detected. The first three types of cells predominated and were more abundant in the pyloric glands than in the other stomach regions. In the small intestine, all types of endocrine cells were found, each having different distributions and relative frequencies. In the large intestine, 10 types of endocrine cells except cholecystokinin-immunoreactive cells were detected. Serotonin- and bovine pancreatic polypeptide-immunoreactive cells were more numerous in the large intestine than in the small intestine.     

Immunocytochemical investigation of the gastro-enteropancreatic (GEP) neurohormonal peptides in the pancreas and gastrointestinal tract of the dogfishSqualus acanthias

Summary The pancreas and gastrointestinal tract (GIT) of adults and of an embryonic stage of 11 cm long (about half the length of newborn fish) of the spiny dogfish,Squalus acanthias, were investigated immunocytochemically for the occurrence of the gastro-entero-pancreatic (GEP) neurohormonal peptides. In the pancreas of adult forms 5 endocrine cell types were seen, namely insulin-, somatostatin-, glucagon-, pancreatic polypeptide (PP)- and gastric inhibitory peptide (GIP)-immunoreactive cells. These cell types form scatterd islets and were seen sometimes to surround small ducts. GIP-immunoreactivity cells did not occur in glucagon-containing cells. In the mucosa of GIT of adults 18 endocrine cell types were observed, viz. insulin-, somatostatin-, glucagon-, glicentin-, PP-, polypeptide YY (PYY)-, vasoactive intestinal polypeptide (VIP)-, GIP-, gastrin C-terminus, CCK-, neurotensin N-terminus-, bombesin/gastrin releasing peptide (GRP)-, substance P-, enkephalin-, -endorphin, -endorphin-, serotonin- and calcitonin immunoreactive cells. These cells occurred mostly in the intestine. All these cell types were of the open type, except glucagon- and glicentin-immunoreactive cells in the stomach, which seemed to be of the closed type. In the muscle layers and the submucosa, VIP and substance P-immunoreactive nerves and neurons were observed. In the pancreas of the dogfish embryo only 3 endocrine cell types could be demonstrated, namely insulin-, somatostatin- and glucagon-immunoreactive cells. In the mucosa of the GIT of the embryos studied 12 endocrine cell types were detected, viz. insulin-, somatostatin-, glucagon-, PP-, PYY-, VIP, GIP, gastrin C-terminus-, CCK-, neurotensin N-terminus-, enkephalin- and serotonin immunoreactive cells. The number of these cells, except that of PYY-immunoreactive cells, was lower than that of adults and in some cases their distribution did not correspond with that of adults.     

Effects of ammonia,chloroquine, and monensin on the vacuolar apparatus of an absorptive epithelium

Summary The distribution of two major immunoreactive forms of somatostatin, somatostatin-14 and somatostatin-34, within the brain, pancreas and intestine of adult lampreys, Petromyzon marinus, was identified using antisera raised against these peptides. Immunostaining of the brain is similar in juveniles and upstream migrants, and somatostatin-14 is the major somatostatin form demonstrated. A few somatostatin-34-containing cells are localized within the olfactory bulbs, thalamus and hypothalamus, but cells immunoreactive to anti-somatostatin-34 in the hypothalamus and thalamus do not co-localize somatostatin-14. Immunostaining of pinealocytes within the pineal pellucida with anti-somatostatin-14 may infer a novel function for this structure. Somatostatin-14 and somatostatin-34 are co-localized within D-cells of the cranial pancreas and caudal pancreas of juveniles and upstream migrants. Numerous somatostatin-34-immunoreactive cells are distributed within the epithelial mucosa of the anterior intestine but not all of these cells cross-react with anti-somatostatin-14. It appears that somatostatin-34 is the major somatostatin in the pancreo-gastrointestinal system of adult lampreys.     

An immunohistochemical study of pancreatic endocrine cells in SKH-1 hairless mice

The regional distribution and frequency of the pancreatic endocrine cells in the SKH-1 hairless mouse were studied by an immunohistochemical (peroxidase anti-peroxidase; PAP) method using four types of specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (PP). The pancreas of mice were divided into three portions; pancreatic islets, exocrine and pancreatic ducts. The pancreatic islets were further subdivided into three regions (central, mantle and peripheral region) according to their located types of immunoreactive cells. In the pancreatic islet portions, insulin-immunoreactive cells were located in the central and mantle regions with 84.60 +/- 7.65 and 33.00 +/- 12.45/100 cells frequencies, respectively, but most of somatostatin-, glucagon- and PP-immunoreactive cells were detected in the mantle and peripheral regions. In the mantle region, somatostatin-, glucagon- and PP-immunoreactive cells were demonstrated with 28.70 +/- 9.91, 52.00 +/- 14.05 and 2.60 +/- 1.51/100 cells frequencies, respectively, and showed 6.20 +/- 2.86, 15.30 +/- 5.31 and 21.50 +/- 10.28/100 cells frequencies, respectively in peripheral regions. However, glucagon-immunoreactive cells were also demonstrated in the central regions with 4.00 +/- 2.83/100 cells frequency. In the exocrine portions, insulin-, glucagon-, somatostatin- and PP-immunoreactive cells were demonstrated in the SKH-1 mouse with 0.90 +/- 0.74, 0.80 +/- 0.79,4.90 +/- 3.54 and 2.70 +/- 1.34/100 cells frequencies, respectively. In the pancreatic duct portions, insulin-, glucagon- and somatostatin-immunoreactive cells were demonstrated in the subepithelial connective tissues and showed islet-like appearances with 30.30 +/- 14.67, 2.70 +/- 3.13 and 5.90 +/- 4.23/100 cells frequencies, respectively. However, no PP-immunoreactive cells were demonstrated in these regions. In conclusion, some peculiar distributional patterns of pancreatic endocrine cells were found in the SKH-1 hairless mouse.     

Conversion of somatostatin-28 to somatostatin-14 during maturation of epithelial cells in the porcine jejunum

Fractions of isolated epithelial cells were harvested from a segment of porcine jejunum by ten successive incubations with a chelating buffer. The cell fractions showed a progressive decrease in the activity of the brush-border enzymes, alkaline phosphatase and sucrase, with increasing incubation number but a progressive increase in the ability to incorporate labelled thymidine into DNA. Fractions enriched in cells from the crypt region (fractions 9 and 10) contained higher concentrations per mg protein of somatostatin-like immunoreactivity (1.8-fold), glucagon-like immunoreactivity (5.3-fold) and serotonin (3.0-fold) than fractions enriched in cells from the villus tip (fractions 1 and 2). Analysis of extracts of the fractions by gel filtration/radioimmunoassay showed that somatostatin-28 represented the predominant molecular form of somatostatin-like immunoreactivity in all cell fractions but the relative proportion of somatostatin-14 (and related metabolites) to somatostatin-28 was significantly higher (P less than 0.05) in fractions enriched in villus cells (fraction 1 and 2) than in fractions enriched in crypt cells (fractions 5-10). This result suggests that metabolism of somatostatin-28 to somatostatin-14 takes place during migration of the D cell from the crypt base to the villus tip. Heterogeneity in the somatostatin-14 region of the chromatograms indicates that the peptide may be further metabolized by the action of aminopeptidases.     

Distribution and characterisation of immunoreactive somatostatin in human gastrointestinal tract

Immunoreactive somatostatin (IRS) was measured in acid extracts of human gastrointestinal tissue. The highest levels were found in the duodenum, pancreas, jejunum and stomach with lower levels in the ileum and colon. In the antrum, pylorus, duodenum and pancreas the main peak of IRS (1.6K IRS) coeluted with synthetic somatostatin-14 on both gel filtration chromatography and HPLC. In the body of stomach, jejunum, ileum and colon, a large peak coeluting with synthetic somatostatin-28 (3.5K IRS) on both chromatographic systems was also identified, while minor peaks of IRS assigned molecular weights of 6000 (6K) and greater than 15 000 (15K) were seen in some extracts. The total IRS content and pattern of molecular forms were similar in tissues obtained from adults at surgery or rapid post mortem, and in tissue taken from human fetuses after prostaglandin termination of pregnancy. When tissues were divided into mucosal and muscle layers, greater than 90% of the IRS was in the mucosa with less than 10% in the muscle layer. In the muscle layer the IRS was almost entirely the 1.6K form in all tissues. Immunohistochemical studies showed the IRS in the mucosa to be localised in endocrine-type cells, while in the muscle layer the IRS is present in nerve fibres and neurones of the myenteric plexus. It is suggested that (1) different mechanisms may control the biosynthesis of somatostatin-14 and somatostatin-28 in mucosal cells in different parts of the gut, (2) different biosynthetic controls may operate in endocrine-like and neuronal cells in the same region of the gut.     

Comparative morphology and biochemistry of pancreatic tissue fragments transplanted into the anterior eye chamber and subcutaneous regions of the rat

The present study was designed to compare the morphological changes occurring in pancreatic tissue fragments transplanted into the anterior eye chamber (AEC) and the subcutaneous (SC) regions of the rat. Pancreatic tissue segments were removed from the tail end of the pancreas of neonatal rats and transplanted into the AEC and SC region of the neck of homologous rats. Five weeks after transplantation, the grafts were removed and processed for light microscopy, immunohistochemistry and radioimmunoassay. In both pancreatic tissue grafts, the acinar cells degenerated completely after transplantation. In contrast to this, insulin-, glucagon-, somatostatin- and pancreatic polypeptide-positive cells and pancreatic ducts survived equally well in both the AEC and SC grafts. The pattern and percentage distribution of insulin-, glucagon-, somatostatin- and PP-producing cells in the AEC and SC grafts was similar to that observed in normal pancreas. However, the percentage distribution of glucagon- and PP-containing cells was significantly (p < 0.03) lower in SC grafts when compared to normal. Radioimmunoassay showed that the AEC and SC pancreatic tissue grafts contained large quantities of insulin and glucagon. However, the insulin content of AEC was slightly but not significantly higher than that of SC grafts. The protein content of pancreatic tissue grafts in these transplantation sites was still significantly (p < 0.05) lower compared to normal. Lymphatic infiltration was also more conspicuous in SC grafts compared to AEC grafts. This infiltration by lymphatic cells was confined only to the endocrine portion of the graft. In conclusion, pancreatic tissue grafts survived in both the AEC and SC regions of rats but the AEC appears to be more conducive to graft survival than the SC region.     

Changes in the thymus of peripubertal rats induced by centrally applied somatostatin-28

The aim of this study was to investigate the effects of centrally applied somatostatin-28 on morphometric characteristics of the thymus, the thymocyte subpopulations, as well as, on apoptosis and phases of cell cycle in thymocytes. For this purpose, peripubertal male rats were cannulated intracerebroventriculary and treated with repeated, nanomolar concentrations of somatostatin-28 (experimental group) or saline (control group). Animals were sacrificed and their thymuses were used for the analysis of thymocyte subpopulations, cell cycle and apoptosis by flow cytometry and for the evaluation of morphometric parameters by stereological analysis. Our results showed that somatostatin-28 caused decrease of the thymic mass and volume, as well as total thymocytes number. Stereological analysis revealed volume decrease of thymic cortex and medulla accompanied with cellularity decrease. Somatostatin in the deeper cortex decreased the number of thymocytes, per volume unit, while in outer cortex raised their number. A significant increase in the percentage of double-negative and both single-positive thymocyte subpopulations, in parallel with a diminished percentage of double-positive cells was found. The cellularity of double-positive and single-positive thymocyte subpopulations was decreased. Somatostatin-28 treatment augmented the percentage of apoptotic cells, while the percentage of the cells represented in phases of cell cycle was reduced. These results suggest that somatostatin-28 induce thymus hypotrophy as result of decreasing cortex and medulla volume and cellularity. Changes in the percentage and cellularity of thymocyte subpopulations and numerical density of thymocytes in outer and deeper cortex, indicate that somatostatin-28 evoked disturbance in transition of double-negative to double-positive thymocytes.     

Changes in the Thymus of Peripubertal Rats Induced by Centrally Applied Somatostatin-28

The aim of this study was to investigate the effects of centrally applied somatostatin-28 on morphometric characteristics of the thymus, the thymocyte subpopulations, as well as, on apoptosis and phases of cell cycle in thymocytes. For this purpose, peripubertal male rats were cannulated intracerebroventriculary and treated with repeated, nanomolar concentrations of somatostatin-28 (experimental group) or saline (control group). Animals were sacrificed and their thymuses were used for the analysis of thymocyte subpopulations, cell cycle and apoptosis by flow cytometry and for the evaluation of morphometric parameters by stereological analysis. Our results showed that somatostatin-28 caused decrease of the thymic mass and volume, as well as total thymocytes number. Stereological analysis revealed volume decrease of thymic cortex and medulla accompanied with cellularity decrease. Somatostatin in the deeper cortex decreased the number of thymocytes, per volume unit, while in outer cortex raised their number. A significant increase in the percentage of double-negative and both single-positive thymocyte subpopulations, in parallel with a diminished percentage of double-positive cells was found. The cellularity of double-positive and single-positive thymocyte subpopulations was decreased. Somatostatin-28 treatment augmented the percentage of apoptotic cells, while the percentage of the cells represented in phases of cell cycle was reduced. These results suggest that somatostatin-28 induce thymus hypotrophy as result of decreasing cortex and medulla volume and cellularity. Changes in the percentage and cellularity of thymocyte subpopulations and numerical density of thymocytes in outer and deeper cortex, indicate that somatostatin-28 evoked disturbance in transition of double-negative to double-positive thymocytes.     

Primary sensory neurons of the rat showing calcitonin gene-related peptide immunoreactivity and their relation to substance P-, somatostatin-, galanin-, vasoactive intestinal polypeptide- and cholecystokinin-immunoreactive ganglion cells

Summary By use of the indirect immunofluorescence technique the distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) has been analyzed in cervical and lumbar dorsal root ganglia of untreated and colchicine-treated rats. In addition, lumbar ganglia were examined 2 weeks after transection of the sciatic nerve. The occurrence of CGRP-positive cells in relation to ganglion cells containing substance P-, somatostatin-, galanin-, cholecystokinin (CCK)-, and vasoactive intestinal polypeptide (VIP)/peptide histidine isoleucin (PHI)-LI has been evaluated on consecutive sections as well as using elution-restaining and double-staining techniques.CGRP-LI was observed in many ganglion cells of all sizes ranging in diameter from 15 m to 65 m. Thus, this peptide occurs also in the large primary sensory neurons. In contrast to the sensory peptides described to date, CGRP-positive cells constituted up to 50% of all and 70% of the medium-sized neurons, thus being the most frequently occurring peptide in sensory neurons so far encountered. Subpulations of CGRP-positive neurons were shown to contain substance P-, somatostatin-, or galanin-LI and some CGRP-positive neurons contained both substance P- and galanin-LI. In fact, most substance P-, somatostatin- and galanin-positive cell bodies were CGRP-immunoreactive. The coexistence analysis further revealed that galanin and substance P often coexisted and that some cells contained both substance P- and somatostatin-LI, whereas no coexistence between galanin and somatostatin has as yet been seen. VIP/PHI-LI was only shown in a few cells in untreated or colchicine-treated rats. However, after transcetion of the sciatic nerve numerous VIP/PHI-positive cells were observed, some of which also contained CGRP-LI.The present results indicate that a CGRP-like peptide is present in a wide range of primary sensory neurons probably not related to specific sensory modalities. Often this peptide coexists with other biologically active peptides. Taken together these findings suggest that CGRP may have a generalized function.     

Depolarizing influences regulate somatostatin synthesis and processing in cultured cerebral cortical cells

There is increasing evidence that persistent depolarization plays a critical role not only in excitation-secretion coupling, but also in the mechanisms linking excitation of neuronal cells to long-term adaptative changes in biosynthesis of neuropeptides. Somatostatin (SRIF) release and synthesis are affected by numerous agents, such as high concentrations of potassium that cause depolarization of cellular membrane. In the present work, we tried to determine whether prolonged exposure to veratridine (VTD) regulates SRIF synthesis. We found that exposure to VTD (100 microM) resulted in the stimulation of total (cell content + media) immunoreactive SRIF (IR-SRIF). This effect was calcium- and sodium-dependent, since it was prevented when verapamil (VPM) 20 microM or tetrodotoxin (TTX) 1 microM were added simultaneously with VTD. Cerebral cortical cells were exposed to high potassium concentrations, and the nature of the IR-SRIF was characterized by high-pressure liquid chromatography (HPLC) or gel filtration. It was evident that chronic exposure to high potassium concentrations modified the elution profile of medium IR-SRIF on HPLC and gel filtration, causing an increase in somatostatin-28 (S-28) and a decrease in somatostatin-14 (S-14). The results indicate that chronic exposure to VTD or high potassium concentration increases immunoreactive somatostatin and augments synthesis of its high-molecular-weight forms. This suggests that chronic membrane depolarization activating sodium and calcium channels initiates the entry of calcium ions, which triggers somatostatin release and causes a depletion of its intracellular stores. The stimulation of somatostatin secretion could be coupled to synthesis of the peptide.