Cytokeratin, lectin, and acidic mucin modulation in differentiating colonic epithelial cells of mice after feeding Western-style diets

Several studies have recently reported the development of colonic epithelial cell hyperproliferation in rodents following the ingestion of Western-style diets. In this study, additional measurements related to differentiation and maturation of the colonic epithelial cells were made after feeding this type of diet. Two Western-style diets high in fat and phosphate content and low in calcium and vitamin D were fed to C57BL/6J mice for 12, 24, and 52 weeks. Diet A contained American Blend fat as a source of lipids, diet B contained corn oil, and control diet C was a standard AIN-76A semisynthetic diet which is lower in fat content and higher in calcium and vitamin D. Colonic epithelial cells were studied for three biomarkers: cytokeratin catalogue no. 18 (clone LE64) expression, soybean agglutinin carbohydrate lectin binding, and acidic mucins including sialo- and sulfomucins. Feeding of diets A and B revealed that colonic epithelial cells had increased expression of cytokeratin catalogue 18 and SBA carbohydrate lectin binding compared to controls (P = 0.0001 for diet A versus C and diet B versus C). Significant differences were found between diets B and C (P = 0.0001) and diets A and C (P = 0.0001) in total acidic mucins and in the ratio of sialomucin:sulfomucin (P = 0.0001). These findings demonstrate that both functional and structural modifications occurred in colonic epithelial cells under these dietary conditions, and further defined this rodent model for preclinical evaluation of nutritional and chemopreventive interventions.     

Three-dimensional structure of the rat pancreatic duct in normal and inflammated pancreas

We observed the corrosion casts of the Wistar rats' pancreatic ducts with scanning electron microscopy (SEM), and their conventionally fixed pancreatic tissue with SEM and transmission electron microscopy (TEM). These findings revealed the following facts about the three-dimensional structure of pancreatic duct. (1) The interlobular and intralobular ducts branch like a tree, and the intercalated ducts wind and fork into two branches, although parts of the intercalated ducts anastomose with each other. The intercellular secretory canaliculi extend from the central lumina, which run straight through the center of the acini, finally approaching close to the basement membranes of acini. (2) The lumina of pancreatic ducts (i.e., the interlobular up to the intercalated ducts) are cylindric and have smooth surfaces. The luminal surface of each epithelial cell, however, is decorated by numerous microvilli and a single cilium. The length of the latter tends to be short in proportion to the diameter of pancreatic duct. Moreover the epithelial cell surfaces, which border each central lumen, have various densities of microvilli. (3) The intraductal cilium core is provided with nine microtubules, which is different from the number of microtubules encountered within the cilium core of uterine tube or bronchial epithelium. The number of microtubules in the cross-sectioned intraductal cilia decreases toward the distal portion of cilia. SEM and TEM observations on WBN/Kob rats' pancreatic ducts suggest that increased pancreatic ductal pressure causes the helical shape of the pancreatic ductal lumen. Such a helical form might also be caused by the protrusion of epithelial cell boundaries into their lumen and the hypertrophy and hyperplasia of epithelial cells, thus leading to the formation of numerous depressions equipped with elongated cilia.     

The pancreas in cystic fibrosis: chemical composition and comparative morphology

Sections of pancreas from 16 individuals who died with cystic fibrosis (CF) were classified by morphometric criteria into four categories in increasing order of pancreatic involvement. The concentration of acini, islets, main ducts, lobular ducts, connective tissue, and fat was compared with control levels. The results show that in the least involved pancreases, from neonates who died under 5 months of age, acini were reduced to 33% of control levels and the following were increased: islets, to 410%, lobular ducts, to 250%; and main ducts, to 1700% of controls. With increasing severity of the pancreatic disease the acini were further reduced to 5% and lobular ducts to 37% of control levels, respectively. Main ducts increased by 19-fold, and fatty infiltration accounted for more than 25% of the fresh weight of the pancreas in 9 of the 16 specimens. Comparative biochemical studies of 35 fibrocystic pancreases were quantitatively related to the severity of the pancreatic involvement as follows. Water and volatile matter, normally accounting for 80 +/-% of the weight of the fresh pancreas, was reduced to less than 30% in the most affected organs. The concentration of zinc diminished from near normal mean levels of 193 mugZn/g dry pancreas to 10% of this amount in the severely involved pancreas. Elevated concentrations of calcium, amounting to over 10 times control level, were found in obstructed ductal structures. Calcium was depleted from pancreatic sections adjacent to the obstructions. The following biochemical indicators were significantly different in their mean levels in the 35 fibrocystic pancreases when compared with the 17 controls: (P less than or equal to 0.001) fat, water, zinc, calcium, copper, magnesium, potassium, and sodium (P less than or equal to 0.01).     

Immunocytochemical localization of the NPY/PYY Y1 receptor in the developing pancreas

Neuropeptide Y, peptide YY, and pancreatic polypeptide are structurally related peptides that are considered to play a role in the regulation of pancreatic secretion and blood flow. Several receptor subtypes for these peptides have been identified, and the Y1, Y2, Y4/PP1, Y5, and Y5/PP2/Y2b receptors are cloned. We have prepared polyclonal peptide antibodies that recognize the Y1 receptor and now report on its localization in the adult and developing rat pancreas. In the adult pancreas, Y1 receptors were detected both in some centroacinar and intralobular duct cells and in endothelial cells. In the developing pancreas (E12.5-E16.5), Y1 receptor immunoreactivity was observed in numerous nonendocrine epithelial cells. These cells occurred in the immediate vicinity of peptide YY-positive endocrine cells. At E16.5, a fraction of these Y1 receptor-containing cells co-stored amylase. One day later, Y1 receptor immunoreactivity became restricted to pancreatic duct-like cells that occurred in close proximity to peptide YY cells. In fetal rats, intense Y1 receptor staining was also observed in endothelial cells. These observations, together with the finding of early pancreatic peptide YY expression, suggest that peptide YY produced by fetal endocrine cells may exert an action on exocrine cells, duct cells and endothelial cells during development.     

Women''s opinion on abortion legalization in a middle size county in southern Brazil

To study pancreas enzyme content regulation when the diet was modified in suckling goats, a comparison was made between kids fed a milk replacer and ones fed maternal milk. A total of 25 preruminant Granadina breed goats were bottle-fed a milk replacer ad libitum from postnatal days 3 to 28 (until the age of 3 days kids had been fed colostrum). Body weight, pancreas weight, total protein concentration, and enzyme activities in pancreatic tissue were determined at 3, 7, 14, 21 and 28 days of age, and the results were compared to those previously obtained in kids fed maternal milk for the same period. Lipase activity was significantly lower in the group fed milk replacer, which was poorer in fat. Amylase activity was higher in this group, perhaps due to the starch products present in the milk substitute. However, the postnatal evolution of chymotrypsin activity followed a similar pattern regardless of diet. Our results seem to confirm that in preruminant kids there is a nutritional regulation of pancreatic amylase and lipase activities, depending on the amounts of their respective substrates in the diet, similar to that described in nonruminants.     

Effects of high fat diet and cholecystokinin receptor blockade on pancreatic growth and tumor initiation in the hamster

The mechanism by which high-fat diet potentiates pancreatic cancer is not known, but trophic hormones may be involved. In preliminary growth studies, hamsters fed a high fat diet (17.5% lard, 17.5% corn oil) for 14 days showed a 16.3% increase (P < 0.01) in pancreatic weight compared to controls on low fat diet (2.5% lard, 2.5% corn oil). A significant increase was also seen at 28 days. Similar increases were seen in pancreatic DNA (29%, P < 0.01) and pancreatic RNA (22%, P < 0.05) at 14 days. Plasma cholecystokinin (CCK) levels at 14 days were 2.5 fold higher in the animals fed high fat (P < 0.01). Infusion of the CCK antagonist MK329 (25 nmol/kg/h) completely abolished the increase in pancreatic weight, pancreatic DNA and pancreatic RNA. The effect of CCK receptor blockade during the initiation period of carcinogenesis was investigated in hamsters fed the same diets used in the growth studies. One hundred animals received a single injection of N-nitrosobis(2-oxopropyl)amine, (BOP, 20 mg/kg). Half of the hamsters in each diet group received a 2 week infusion of MK329 (25 nmol/kg/h), beginning 8 days before carcinogen administration. At the time of death, 55 weeks after carcinogen administration, non-fasting plasma CCK levels were 31% higher in the high fat fed hamsters than in the low fat fed animals (P < 0.01). The high-fat diet group had a 3-fold increase in total cancer incidence and a 5-fold increase in advanced lesions (adenocarcinomas). Tumor incidence and yield were not changed in either diet group by CCK-receptor blockade during the initiation period. Cholecystokinin appears to mediate the short-term trophic effect that high-fat feeding has on the pancreas. However, potentiation of pancreatic cancer by high-fat diet in the hamster cancer model does not appear to be influenced by endogenous cholecystokinin at the time of tumor induction.     

Inhibition of stimulated amylase secretion by adrenomedullin in rat pancreatic acini

Adrenomedullin is a novel hypotensive peptide originally isolated from human pheochromocytoma and recently localized to PP cells of the pancreatic islets of Langerhans. Based on the pancreatic islet-acinar axis model, we investigated the effect of adrenomedullin on regulated exocytosis of exocrine pancreas. Using rat [125I]-adrenomedullin, specific binding sites were localized to rat pancreatic acini. We next examined the effect of adrenomedullin on 100 pM cholecystokinin (CCK)-stimulated amylase release from pancreatic acini. Adrenomedullin inhibited amylase secretion in a dose-dependent manner by approximately 50% at maximum, and the IC50 was 1.1 pM. However, adrenomedullin did not affect rat [125I]CCK binding to isolated acini or reduce the intracellular free Ca2+ concentration increased by CCK. Adrenomedullin also inhibited amylase secretion induced by 1 microM calcium ionophore A23187, suggesting that adrenomedullin inhibits stimulated amylase secretion by functioning at a step(s) distal to the ligand-receptor binding system and intracellular calcium mobilizing mechanism. In streptolysin-O permeabilized acini, 10 nM adrenomedullin shifted the calcium dose-response curve to the right, indicating that adrenomedullin inhibits calcium-induced amylase secretion by reducing calcium sensitivity of the pancreatic exocytotic machinery. In addition, pretreatment of pancreatic acini with pertussis toxin abolished the inhibitory effect of adrenomedullin on CCK-stimulated amylase secretion. These results indicate that adrenomedullin inhibits stimulated amylase secretion by reducing the calcium sensitivity of the exocytotic machinery of the pancreatic acini. A pertussis toxin-sensitive GTP-binding protein(s) is also involved in this mechanism.     

Impact of protein deprivation on protein and DNA synthesis in the developing rat pancreas

The metabolic effects of protein malnutrition on growth and development of the exocrine pancreas are largely unknown. The aim of the present study was to evaluate the effects of protein malnutrition on pancreatic protein and DNA synthesis during postnatal development. Rat dams and their offspring were fed a protein-deficient diet (6% casein) or a control diet (25% casein) during gestation, lactation and after weaning. Pancreatic protein and DNA synthesis were measured in vitro at postnatal ages 1, 3, 10, 23, 36 and 60 days, by assessing [3H]leucine and [3H]thymidine incorporation in freshly isolated acini. Different patterns of protein synthesis were seen in the two groups. At birth, pancreatic protein synthesis was low in both control and malnourished animals. At day 3, protein synthesis in the control acini increased 10-fold while synthesis in acini of the malnourished animal group was only 50% of age-matched control values. No differences in protein synthesis were detected between the control and malnourished groups between 10 and 36 days of age. At 60 days (adulthood), acinar protein synthesis declined in the control-fed rats, but a significant increase was observed in the malnourished animals (p < 0. 0005). At birth, DNA synthesis was high in the acini from both control and malnourished animals. The low-protein diet induced a slight reduction in DNA synthesis at day 3, without altering the general pattern during later stages of development. In conclusion, protein deprivation has variable effects on pancreatic protein and DNA synthesis at different stages of postnatal development. Furthermore, the mechanisms of control within acini appear to be intrinsically regulated.     

The insulo-acinar portal and insulo-venous drainage systems in the pancreas of the mouse, dog, monkey and certain other animals: a scanning electron microscopic study of corrosion casts

Scanning electron microscopy of vascular casts of the pancreas from monkies, cattle, pigs, dogs, cats, rabbits, guinea pigs and mice showed certain species differences in the occurrence of intralobular and interlobular islets and in the microcirculatory pattern of these islets. Interlobularly located islets were frequently found in the mouse and guinea pig, as has been previously established in the rat (Murakami and Fujita, 1992); they emitted insulo-venous efferent vessels directly draining into veins. In contrast, the intralobular islets in the guinea pig usually issued insulo-acinar portal vessels continuous with the lobular capillary network. In the mouse, they usually emitted both the insulo-acinar portal and insulo-venous efferent vessels. The insulo-venous efferent vessels, including those of the interlobular islets, could partly be portal in nature since they occasionally issued portal branches directed to the lobular capillary network. In rabbits, cats, dogs, pigs, cattle and monkies, as in men (Murakami et al., 1992), essentially all islets in the pancreas were intralobular in location and usually emitted the portal vessels only. In the mouse and rabbit, as in the rat (Murakami and Fujita, 1992), the islet received afferent vessels in its superficial aspect and issued efferent vessels from its deep aspect. In the Formosan monkey, as previously reported in the rhesus monkey (Fujita and murakami, 1973), the afferent vessels usually ran deep into the islet which emitted vessels from its superficial aspect. In other animals examined in this study, as in humans (Murakami et al., 1992), no consistent rule concerning the microcirculatory pattern within the islet could be determined.     

Dietary fat type and energy restriction interactively influence plasma leptin concentration in rats

To investigate whether dietary fat source and energy restriction interactively influence plasma leptin levels and its association of leptin with insulin action, rats were fed diets containing either fish, safflower oil, or beef tallow (20% wt/wt) for 10 weeks. Groups of rats consumed each diet ad libitum or at 85% or 70% of ad libitum energy intake in a design that held fat intake constant. Graded levels of energy restriction caused body weight to decrease (P < 0.001) differently according to the dietary fat provided. Plasma leptin concentrations were 60% higher (P < 0.05) in the groups fed fish oil and safflower oil ad libitum compared with those in the beef tallow group, despite smaller perirenal fat mass and fat cell size in the fish oil-fed animals. Energy restriction resulted in a 62% decrease (P < 0.05) in leptin levels in fish oil- and safflower oil-fed rats, whereas no changes were observed in beef tallow-fed animals. Plasma insulin levels were lower (P < 0.05) in the fish oil group fed ad libitum compared with those in the two other diet groups. These data demonstrate a hyperleptinemic effect in animals consuming diets rich in polyunsaturated fatty acid, which can be normalized to the level of saturated fat consumption by mild energy restriction. Thus, dietary fatty acid composition, independent of adipose tissue mass, is an important determinant of circulating leptin level in diet-induced obesity.     

Characterization of Borrelia spp. isolated from the tick, Ixodes tanuki and small rodents in Japan

Rat pancreatic periacinar fibroblastoid cells (PFCs) appear to be involved in intralobular fibrosis and acinar cell regeneration. We isolated pancreatic acini of the rat, cultured the fibroblastoid cells, and characterized the cells morphologically and immunohistochemically. Isolated acini were seeded on culture dishes, and spindle-shaped cells migrated and proliferated. On Electronmicroscopic examination, microfilament bundles were seen, and the intracellular localization of vimentin, alpha-smooth muscle actin, and non-muscle myosin was identified immunohistochemically. These findings strongly suggest that the cells were myofibroblast-like. The PFCs were also demonstrated, immunohistochemically, to contain prolyl hydroxylase, type-I procollagen, type-III procollagen, type-IV collagen, fibronectin, and laminin. Stimulation by transforming growth factor beta 1 (TGF beta 1) increased intracellular immunoreactive prolyl hydroxylase and collagen synthesis in the PFCs. These findings indicate that PFCs proliferate in culture as myofibroblast-like cells and synthesize extracellular matrix components. It is possible that PFCs are involved in intralobular fibrosis in response to stimulation with TGF beta 1.     

Iron overload in the rat pancreas following portacaval shunting and dietary iron supplementation

Reproduction of pancreatic iron overload in an animal model has been difficult to achieve primarily because of the first-pass extraction of iron by the liver. We hypothesized that portacaval shunting would avoid this hepatic phenomenon and increase pancreatic iron deposition. An end-to-side portacaval shunt was surgically created in male Sprague-Dawley rats, and they were subsequently fed a carbonyl iron-supplemented diet for 17 weeks. This resulted in marked iron accumulation in the pancreas (1621 +/- 188 micrograms/g) compared to minimal deposition in sham-operated rats fed the same diet (138 +/- 53 micrograms/g). Iron deposition in the acinar and centroacinar cells was confirmed histologically by Gomori staining, as well as by ultrastructural examination. Iron overloading was associated with enhanced oxidative stress evidenced by a twofold increase in the levels of glutathione disulfide and thiobarbituric acid-reactive substances. Also, adducts of proteins with malondialdehyde and 4-hydroxynonenal were demonstrated in acinar and ductal cells. Other apparent consequences of iron overload were a 50% reduction in pancreatic amylase content and a decrease in pancreatic protein concentration. These hypotrophic changes were associated with a reduced mass of zymogen granules in the acinar cells noted histologically. Our results show that a combination of portacaval shunting and carbonyl iron feeding achieve pancreatic iron overload and support the role of oxidative stress in the pathogenesis of iron-induced damage in the pancreas.     

Uptake of the food-derived heterocyclic amine carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and its N-hydroxy metabolite into rat pancreatic acini and hepatocytes in vitro

Sinc DNA adducts of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) are formed at relatively high levels in the rat pancreas but not liver, we examined the uptake of PhIP and its N-hydroxy metabolite (N-OH-PhIP) into pancreatic acini and hepatocytes to determine if differential tissue uptake was a factor modulating the formation of PhIP-DNA adducts. In addition, since the precursors of PhIP formation are two amino acids and since various amino acid transporters have been identified in the pancreas, the possible involvement of these transporters in the uptake of PhIP and N-OH-PhIP was investigated. The uptake both heterocyclic compounds into both tissue preparations was rapid, with maximal uptake occurring with 1-2 min. However, PhIP uptake into pancreatic acini was significantly (2-way ANOVA, P < 0.05) greater than uptake of N-OH-PhIP into pancreatic acini and the uptake of both PhIP and N-OH-PhIP into hepatocytes. Although uptake was rapid, efflux of both compounds from both tissue preparations was also rapid. However, the efflux rate constant (1.86 +/- 0.6/min, mean +/- SEM) for PhIP) was significantly lower (Student's t-test, P < 0.05) than that for N-OH-PhIP (4.14 +/- 0.04/min) from pancreatic acini. This, combined with the increased uptake of PhIP into pancreatic acini , suggests that there is substantial but reversible binding of PhIP in the pancreas. The uptake of both PhIP and N-OH-PhIP into pancreatic acini and hepatocytes was not affected by the presence of various amino acids in the incubation buffer, indicating that amino acid transporters are not involved in uptake of these compounds. Furthermore, uptake of both compounds did not appear to be dependent on metabolic energy supply. The above data, together with the high octanol:buffer partition coefficients (logP = 1.322 and 1.301 for PhiP and N-OH-PhIP respectively) suggest that both uptake and efflux of PhIP and N-OH-PhIP are consistent with a process of passive diffusion. The tissue binding characteristics for PhIP in the pancreas may create conditions whereby pancreatic cytochrome P450 1A1 can catalyse the formation of N-OH-PhIP. While N-OH-PhIP is not the ultimate reactive DNA binding species, it has been shown to directly bind to and form DNA adducts. Therefore, it is possible that the apparent selective accumulation of PhIP may contribute to the high level of PhIP-DNA adducts formed in the rat pancreas.     

Overexpression of Rab3D enhances regulated amylase secretion from pancreatic acini of transgenic mice

Rab3D, a member of the ras-related GTP-binding protein Rab family, is localized to secretory granules of various exocrine tissues such as acinar cells of the pancreas, chief cells of the stomach, and parotid and lacrimal secretory cells. To elucidate the function of Rab3D in exocytosis, we have generated transgenic mice that over-express Rab3D specifically in pancreatic acinar cells. Hemagglutinin-tagged Rab3D was localized to zymogen granules by immunohistochemistry, and was shown to be present on zymogen granule membranes by Western blotting; both results are similar to previous studies of endogenous Rab3D. Secretion measurements in isolated acinar preparations showed that overexpression of Rab3D enhanced amylase release. Amylase secretion from intact acini of transgenic mice 5 min after 10 pM cholecystokinin octapeptide (CCK) stimulation was enhanced by 160% of control. In streptolysin-O-permeabilized acini of transgenic mice, amylase secretion induced by 100 microM GTP-gamma-S was enhanced by 150%, and 10 microM Ca2+-stimulated amylase secretion was augmented by 206% of that of the control. To further elucidate Rab3D involvement in stimulus-secretion coupling, we examined the effect of CCK on the rate of GTP binding to Rab3D. Stimulation of permeabilized acini with 10 pM CCK increased the incorporation of radiolabeled GTP into HA-tagged Rab3D. These results indicate that overexpression of Rab3D enhances secretagogue-stimulated amylase secretion through both calcium and GTP pathways. We conclude that Rab3D protein on zymogen granules plays a stimulatory role in regulated amylase secretion from pancreatic acini.     

A pancreatic extract-enriched diet corrects ileal mucosa atrophy in endotoxemic aged rats

An altered adaptive response of the pancreas and small intestine to nutritional stress has an adverse impact upon nutritional status in elderly humans or senescent rats. We evaluated the effects of a pancreatic extract nutritional supplement on intestinal mucosa adaptation in LPS-treated aged rats. Endotoxemic rats were starved for 48 hr and then refed ad libitum for four days with a standard diet. Afterwards they received, over one week, the standard diet enriched with either pancreatic extract (PE) (2.4 g/day) or casein (isonitrogenous to PE supplement). Healthy aged rats fed ad libitum with a standard diet were studied in parallel. Whereas no changes occurred in the jejunal segment, an adaptive villus hyperplasia was observed in the proximal ileum of rats receiving PE without an increase in the brush border hydrolase activities. Our results indicate that oral PE supplementation exerts a trophic effect on the ileal mucosa of aged rats in response to nutritional stress.     

Primary prevention of diabetes mellitus by prevention of obesity in monkeys

Many, but not all, adult rhesus monkeys spontaneously develop significant increases in body fat mass, and many, but not all, progress to develop overt adult-onset type II diabetes. The purpose of this study was to determine whether both an increase in body fat and onset of diabetes could be simultaneously prevented through long-term maintenance of stable normal adult body weight by caloric titration. Eight adult male monkeys were provided a complete normal chow diet, but with daily amounts restricted and titrated on a weekly basis to maintain a constant body weight (weight-stabilized group). This regimen has been continued for 5-9 yr (mean +/- SD of 7 +/- 0.5 yr) with monkeys attaining the age of 17.9 +/- 0.6 yr and with maintenance of normal body fat (17.7 +/- 1.8%). The age-matched ad libitum fed group (18.1 +/- 0.2 yr of age) consisted of 19 monkeys maintained under identical laboratory conditions and diet, but with food available ad libitum. Results showed weight-stabilized monkeys weighed significantly less than ad libitum fed monkeys (10.4 +/- 0.2 vs. 16.1 +/- 0.7 kg, respectively, P < 0.05) and had significantly better glucose tolerance as measured by Kglucose (glucose disappearance rate) (3.9 +/- 0.3 vs. 2.4 +/- 0.2, P +/- 0.05). Of the 19 ad libitum fed age-matched monkeys, 4 were overtly diabetic, and 6 others had significantly reduced glucose tolerance. Hyperinsulinemia did not develop in the weight-stabilized group, and beta-cell response to glucose remained normal; both were significantly different from the exaggerated levels of the ad libitum fed group (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Morphology and histochemistry of the rabbit pancreatic innervation

Stimulation of extrinsic nerves markedly alters pancreatic endocrine and exocrine secretion, yet little is known of the neurochemical organization and physiologic roles of specific neural pathways within the pancreas. Here we report histochemical staining for acetylcholinesterase (AChE), NADPH-diaphorase (NADPH-d), nitric oxide synthase (NOS), and several neuropeptides to identify the neurotransmitter content of rabbit pancreatic nerves. An extensive network of AChE-positive nerve fibers was found throughout the islets, acini, ducts, ganglia, and blood vessels. All pancreatic neurons were AChE positive, two thirds were NADPH-d positive, and many were NOS positive. Ganglia in the head/neck region were connected to the duodenal myenteric plexus by AChE- and NADPH-d-positive fibers, and NADPH-d-positive pancreatic neurons appeared to send processes toward both the duodenum and pancreas. Many pancreatic neurons were vasoactive intestinal peptide (VIP) positive, and VIP nerve terminals were abundant in ganglia, acini, islets, and ducts. Pituitary adenylate cyclase-activating peptide (PACAP-38)-positive fibers also were observed within acini and passing through ganglia. Substance P (SP)-, calcitonin gene-related peptide (CGRP)-, and dopamine beta-hydroxylase (DBH)-positive fibers were abundant along blood vessels and ducts, and varicose fibers were observed in pancreatic ganglia. Fine galanin-positive fibers were also occasionally observed running with blood vessels and through ganglia. Thus the rabbit pancreas receives a dense, diverse innervation by cholinergic, adrenergic, and peptidergic nerves and cholinergic pancreatic neurons, most also containing VIP or NOS or both, appear to innervate both endocrine and exocrine tissue, and may mediate local communication between the duodenum and pancreas.     

Pancreatic exocrine secretion during the first days after weaning in pigs

Feed replacement at weaning plays an important role in the induction of pancreatic maturation. To understand the changes in the exocrine pancreas at weaning and the relation to postweaning problems, we studied the function of the exocrine pancreas and changes of intestinal hemolytic Escherichia coli in four pigs. The pigs were chronically fitted with pancreatic duct catheters and T-shaped cannula inserted into the duodenum for reintroduction of pancreatic juice. One day before weaning (at 30 d of age), pancreatic juice was collected for 1 h before and 1 h after a morning and an evening suckling. The pigs were not creep fed, but from weaning the pigs received a standard weaning diet ad libitum. On d 1, 2, 3, and 5 after weaning, pancreatic juice was collected continuously for the 24-h period. The total pancreatic secretion was measured at hourly intervals, 1.5-mL samples were taken for analysis, and the remaining juice was returned to the animal. On these days, samples from the duodenum, ileum, and rectum were also taken for analyses of hemolytic E. coli. From the day before to 5 d after weaning, a gradual increase in pancreatic secretion was observed concerning volume (P < .001) and protein (P < .01) and trypsin (P < .02) levels. An increase (P < .01) in hemolytic E. coli in the duodenal contents was also documented during this period. We assume that the gradual increase in the measured variables of pancreatic secretion is related to the increasing consumption of solid feed. However, the appearance of E. coli and disappearance of milk components from the gastrointestinal tract could be other factors stimulating the exocrine pancreas.     

Spontaneous weight loss in young subjects of normal weight after 11 weeks of unrestricted intake of a low-fat/high-fiber diet

The present study investigated the spontaneous, unintended body weight changes observed during the first 11 weeks of an eight months' ad libitum low-fat/high-fibre diet (25.5 energy-% fat, 58.5 energy-% carbohydrate, 3.9 g dietary fiber/MJ), primarily aimed at investigating changes in blood lipid concentrations. Subjects were normal-weight, young, healthy students, 24 in the intervention group, and 24 in the control group (no diet). After 11 weeks, an overall decrease in body weight (1.3 +/- 0.4 kg) (mean +/- SEM) (p < 0.01) and fat mass (1.6 +/- 0.2 kg, p < 0.001) was observed in the intervention group. Fat-free mass remained unchanged. Initial body weight and fat mass correlated significantly to changes in body weight and fat mass. No changes were observed in the control group. In conclusion, the ad libitum intake of a low-fat/high-fibre diet led to a spontaneous, small loss of body weight and fat mass in young, normal-weight subjects.     

Effects of islet hormones on nerve-mediated and acetylcholine-evoked secretory responses in the isolated pancreas of normal and diabetic rats

This study employs the pancreas of normal and diabetic rats to investigate the relationship between the endocrine and exocrine pancreas in the control of exocrine secretion employing enzyme and immunohistochemical and physiological techniques. Acetylcholine esterase (ACh-E) positive nerves were distributed in the interacinar regions of the pancreas lying close to the exocrine cells. There was no difference between the cholinergic innervation of the pancreas in normal and diabetic rat. Insulin (INS) immunopositive cells were observed in the peripheral and central portions of the Islet of Langerhans in the pancreas of normal rat. In the diabetic animals the number of INS-positive cells were decreased. In contrast, glucagon (GLU) and somatostatin (SOM)-immunopositive cells were identified mainly in the peripheral parts of the Islets of Langerhans and their numbers increased markedly in the diabetic pancreas. Insulin alone had no significant effect on amylase secretion in the normal pancreas whereas GLU and SOM evoked small increases in amylase out compared to basal. In contrast, the islet hormones have no detectable secretory effect on the diabetic pancreas compared to control. Both electrical field stimulation (EFS) of intrinsic secretomotor nerves and exogenous application of acetylcholine (ACh) resulted in marked increases in amylase secretion. In pancreatic acini and acinar cells ACh evoked dose-dependent increases in amylase release. In normal pancreatic segments a combination of either INS or GLU with EFS or ACh resulted in marked potentiation of amylase output. In contrast, SOM inhibited the EFS-evoked amylase output but enhanced the secretory response to ACh. In pancreatic acini and acinar cells from normal rat and in pancreatic segments from diabetic rats, the islet hormones had no potentiating effect on the ACh-evoked secretory response. Similarly, in the diabetic rat the islet hormone had no effect on EFS-evoked amylase output. In fura-2 loaded pancreatic acinar cells ACh-induced a marked increase in intracellular free calcium concentration [Ca2+]i compared to basal. Either INS or GLU, but not SOM, elicited a small increase in [Ca2+]i. Combining either INS or GLU with ACh resulted in a potentiation of [Ca2+]i compared with ACh alone. In contrast, SOM had no significant effect on the ACh-induced [Ca2+]i compared to the response obtained with ACh alone. In pancreatic acinar cells of diabetic rat ACh-elicited similar magnitude of [Ca2+]i compared to acinar cells of normal rat. However, when the islet hormones were combined with ACh there was no enhancement of [Ca2+]i compared to ACh alone. The results indicate that the potentiation of either EFS or ACh-evoked secretory responses by the islet hormones seem to occur only in pancreatic segments which have intact viable Islets of Langerhans and not in either acini and acinar cells or from the pancreas of diabetic rat. Moreover, it is apparent that cellular Ca2+ is involved with the interaction of ACh with either INS or GLU.