Post inflammatory damage to the enteric nervous system in diverticular disease and its relationship to symptoms.

Some patients with colonic diverticula suffer recurrent abdominal pain and exhibit visceral hypersensitivity, though the mechanism is unclear. Prior diverticulitis increases the risk of being symptomatic while experimental colitis in animals increases expression of neuropeptides within the enteric nervous system (ENS) which may mediate visceral hypersensitivity. Our aim was to determine the expression of neuropeptides within the ENS in diverticulitis (study 1) and in patients with symptomatic disease (study 2). Study 1 - Nerves in colonic resection specimens with either acute diverticulitis (AD, n = 16) or chronic diverticulitis (CD, n = 16) were assessed for neuropeptide expression recording % area staining with protein gene product (PGP9.5), substance P (SP), neuropeptide K (NPK), pituitary adenylate cyclase activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP) and galanin. Study 2 - Seventeen symptomatic and 15 asymptomatic patients with colonic diverticula underwent flexible sigmoidoscopy and multiple peridiverticular mucosal biopsies. Study 1- Neural tissue, as assessed by PGP staining was increased to a similar degree in circular muscle in both AD and CD. The CD specimens showed significant increases in the immunoreactivity of SP, NPK and galanin in both mucosal and circular muscle layer compared with controls. Study 2 - Mucosal histology was normal and PGP9.5 staining was similar between groups however patients with symptomatic diverticular disease demonstrated significantly higher levels of SP, NPK, VIP, PACAP and galanin within the mucosal plexus. Patients with symptomatic diverticular disease exhibit increased neuropeptides in mucosal biopsies which may reflect resolved prior inflammation, as it parallels the changes seen in acute and chronic diverticulitis.

A beta cell-specific knockout of hormone-sensitive lipase in mice results in hyperglycaemia and disruption of exocytosis.

AIMS/HYPOTHESIS: The enzyme hormone-sensitive lipase (HSL) is produced and is active in pancreatic beta cells. Because lipids are known to play a crucial role in normal control of insulin release and in the deterioration of beta cell function, as observed in type 2 diabetes, actions of HSL in beta cells may be critical. This notion has been addressed in different lines of HSL knockout mice with contradictory results. METHODS: To resolve this, we created a transgenic mouse lacking HSL specifically in beta cells, and characterised this model with regard to glucose metabolism and insulin secretion, using both in vivo and in vitro methods. RESULTS: We found that fasting basal plasma glucose levels were significantly elevated in mice lacking HSL in beta cells. An IVGTT at 12 weeks revealed a blunting of the initial insulin response to glucose with delayed elimination of the sugar. Additionally, arginine-stimulated insulin secretion was markedly diminished in vivo. Investigation of the exocytotic response in single HSL-deficient beta cells showed an impaired response to depolarisation of the plasma membrane. Beta cell mass and islet insulin content were increased, suggesting a compensatory mechanism, by which beta cells lacking HSL strive to maintain normoglycaemia. CONCLUSIONS/INTERPRETATION: Based on these results, we suggest that HSL, which is located in close proximity of the secretory granules, may serve as provider of a lipid-derived signal essential for normal insulin secretion.

Human islet amyloid polypeptide transgenic mice: in vivo and ex vivo models for the role of hIAPP in type 2 diabetes mellitus.

Human islet amyloid polypeptide (hIAPP), a pancreatic islet protein of 37 amino acids, is the main component of islet amyloid, seen at autopsy in patients with type 2 diabetes mellitus (DM2). To investigate the roles of hIAPP and islet amyloid in DM2, we generated transgenic mice expressing hIAPP in their islet beta cells. In this study, we found that after a long-term, high-fat diet challenge islet amyloid was observed in only 4 of 19 hIAPP transgenic mice. hIAPP transgenic females exhibited severe glucose intolerance, which was associated with a downregulation of GLUT-2 mRNA expression. In isolated islets from hIAPP males cultured for 3 weeks on high-glucose medium, the percentage of amyloid containing islets increased from 5.5% to 70%. This ex vivo system will allow a more rapid, convenient, and specific study of factors influencing islet amyloidosis as well as of therapeutic strategies to interfere with this pathological process.

Reconstructing the pancreas: restoration of normoglycemia, exocrine function, and islet innervation by islet transplantation to the pancreas.

Impaired function in transplanted islets may be ascribed in part to disturbed reinnervation. The objectives of this study were to determine whether islet transplantation to the pancreas in the presence of nerve growth factor (NGF) would restore islet innervation and endocrine and exocrine pancreatic function. Streptozotocin-diabetic Lewis rats received 800 syngeneic islets beneath the pancreatic capsule in the presence or absence of NGF (20 ng/d for 14 days). Fasting blood glucose was measured for 3 months. The pancreata were isolated and perfused in situ. Pancreatic juice was collected for amylase determination. The sympathetic trunks were isolated and stimulated electrically. The tissues were immunostained for nerve markers. All islet recipients remained euglycemic (4.2 +/- 0.6 mmol/L glucose). Ductal amylase concentrations were restored to near normal levels in contrast to diabetic controls (normal rat 98 +/- 8 U/L, islet transplant 78.4 +/- 9 U/L, diabetic control 14.5 +/- 8 U/L). NGF enhanced the innervation of transplanted islets in contrast to control islet transplants. Sympathetic adrenergic innervation was significantly increased by NGF (tyrosine hydroxylase [P < .001] and neuropeptide Y [P < .05]). No differences in parasympathetic innervation were observed (vesicular acetylcholine transporter). Electrical stimulation of the sympathetic trunks in the presence of 4 micromol/L phentolamine and 5 micromol/L atropine resulted in increased insulin secretion in NGF-treated islet transplants (164%) compared with control transplants (30%). The combination of growth factors and the pancreatic site may allow the use of fewer islets than conventional islet transplant sites and promote more normal transplanted islet function by the enhancement of islet reinnervation.

Prolonged elevation of galanin and tachykinin expression in mucosal and myenteric enteric nerves in trinitrobenzene sulphonic acid colitis.

Diverticulitis causes recurrent abdominal pain associated with increased mucosal expression of mucosal galanin and substance P (SP). We studied changes in mucosal and myenteric plexus neuropeptides in adult rats using a model of colonic inflammation, trinitrobenzenesulphonic acid colitis. We assessed the effects on the pan-neuronal markers protein gene product 9.5 (PGP9.5) and neurofilament protein, as well as specific neuropeptides at 1, 2, 3, 4, 6, 8, 10 and 14 weeks. Following the acute injury there was macroscopic resolution of inflammation but minor microscopic abnormalities persisted. Percent area stained of mucosal PGP9.5 fell initially but average levels on days 21 and 28 levels were significantly elevated (P < 0.001), returning to normal by day 42. Percent area staining of PGP9.5 in the muscle rose immediately and remained significantly elevated at 70 days (P < 0.001). SP, neuropeptide K and galanin followed a similar overall pattern. SP to PGP9.5 ratio was significantly increased in the muscle both acutely (days 1-28) and in the long term (days 70 and 98), whereas the galanin to PGP9.5 ratio was significantly increased in the mucosa throughout the study. Low-grade chronic inflammation after an acute initial insult causes a persistent increase in the expression of galanin in the mucosa and SP in muscle layer.

Ghrelin and insulin gene expression changes in streptozotocin-induced diabetic rats after rosiglitazone pretreatment.

The aim of the study was to evaluate the effect of rosiglitazone treatment on islet ghrelin and insulin gene expressions in streptozotocin (STZ)-induced diabetic rats. Animals were divided into four groups. 1. Intact controls. 2. Rosiglitazone-treated controls. 3. STZ-induced diabetes. 4. Rosiglitazone-treated diabetes. Rosiglitazone was given for 7 days at a dose of 20 mg/kg body weight. Ghrelin and insulin gene expressions were investigated by immunohistochemistry and in situ hybridization. There was no statistically significant difference in body weight between STZ-induced diabetic rats and rosiglitazone-treated diabetic rats during the experimental period. Furthermore, there were no significant differences in blood glucose levels and insulin immunoreactive cell numbers between STZ-induced diabetic rats and rosiglitazone-treated diabetic rats. There was a tendency towards a reduction of ghrelin gene expression in diabetic animals compared with intact controls. We found, in addition, that ghrelin immunoreactive and ghrelin mRNA expressing cells were frequent in the epithelial lining of the ducts suggesting ductal epithelium might be the source of the regenerating islet ghrelin cells, as is known for other islet cells. The results show that short-term rosiglitazone pretreatment had no significant effect on ghrelin and insulin gene expressions.

Glucagon receptor antagonism improves islet function in mice with insulin resistance induced by a high-fat diet.

AIMS/HYPOTHESIS: Increased glucagon secretion predicts deterioration of glucose tolerance, and high glucagon levels contribute to hyperglycaemia in type 2 diabetes. Inhibition of glucagon action may therefore be a potential novel target to reduce hyperglycaemia. Here, we investigated whether chronic treatment with a glucagon receptor antagonist (GRA) improves islet dysfunction in female mice on a high-fat diet (HFD). MATERIALS AND METHODS: After 8 weeks of HFD, mice were treated with a small molecule GRA (300 mg/kg, gavage once daily) for up to 30 days. Insulin secretion was studied after oral and intravenous administration of glucose and glucagon secretion after intravenous arginine. Islet morphology was examined and insulin secretion and glucose oxidation were measured in isolated islets. RESULTS: Fasting plasma glucose levels were reduced by GRA (6.0 +/- 0.2 vs 7.4 +/- 0.5 mmol/l; p = 0.017). The acute insulin response to intravenous glucose was augmented (1,300 +/- 110 vs 790 +/- 64 pmol/l; p < 0.001). The early insulin response to oral glucose was reduced in mice on HFD + GRA (1,890 +/- 160 vs 3,040 +/- 420 pmol/l; p = 0.012), but glucose excursions were improved. Intravenous arginine significantly increased the acute glucagon response (129 +/- 12 vs 36 +/- 6 ng/l in controls; p < 0.01), notably without affecting plasma glucose. GRA caused a modest increase in alpha cell mass, while beta cell mass was similar to that in mice on HFD + vehicle. Isolated islets displayed improved glucose-stimulated insulin secretion after GRA treatment (0.061 +/- 0.007 vs 0.030 +/- 0.004 pmol islet(-1) h(-1) at 16.7 mmol/l glucose; p < 0.001), without affecting islet glucose oxidation. CONCLUSIONS/INTERPRETATION: Chronic glucagon receptor antagonism in HFD-fed mice improves islet sensitivity to glucose and increases insulin secretion, suggesting improvement of key defects underlying impaired glucose tolerance and type 2 diabetes.

Enhanced mitochondrial metabolism may account for the adaptation to insulin resistance in islets from C57BL/6J mice fed a high-fat diet.

AIM/HYPOTHESIS: Hyperinsulinaemia maintains euglycaemia in insulin-resistant states. The precise cellular mechanisms by which the beta cells adapt are still unresolved. A peripherally derived cue, such as increased circulating fatty acids, may instruct the beta cell to initiate an adaptive programme to maintain glucose homeostasis. When this fails, type 2 diabetes ensues. Because mitochondria play a key role in beta cell pathophysiology, we tested the hypothesis that mitochondrial metabolism is critical for beta cell adaptation to insulin resistance. METHODS: C57BL/6J mice were given high-fat (HF) diet for 12 weeks. We then analysed islet hormone secretion, metabolism in vivo and in vitro, and beta cell morphology. RESULTS: HF diet resulted in insulin resistance and glucose intolerance but not frank diabetes. Basal insulin secretion was elevated in isolated islets from HF mice with almost no additional response provoked by high glucose. In contrast, a strong secretory response was seen when islets from HF mice were stimulated with fuels that require mitochondrial metabolism, such as glutamate, glutamine, alpha-ketoisocaproic acid and succinate. Moreover, while glucose oxidation was impaired in islets from HF mice, oxidation of glutamine and palmitate was enhanced. Ultrastructural analysis of islets in HF mice revealed an accumulation of lipid droplets in beta cells and a twofold increase in mitochondrial area. CONCLUSIONS/INTERPRETATION: We propose that beta cells exposed to increased lipid flux in insulin resistance respond by increasing mitochondrial volume. This expansion is associated with enhanced mitochondrial metabolism as a means of beta cell compensation.

Cutaneous innervation before and after one treatment period of acupuncture.

BACKGROUND: The effect of acupuncture on nociceptive pain is well documented, but effects on nociceptive itch have been contradictory. OBJECTIVES: To evaluate possible effects of acupuncture on the occurrence, distribution and function of sensory nerve fibres in human skin. METHODS: Ten subjects were treated by inserting 10 acupuncture needles subcutaneously at the upper lateral aspect of one buttock. The subjects were recruited from an acupuncture clinic and were undergoing specific acupuncture treatment for their disorders. The needles were stimulated (rotated to and fro) twice during the twice-weekly 25-min sessions over 5 weeks. Skin biopsies, diameter 3 mm, were taken before and 3-6 days after local acupuncture. Antibodies to the pan-neuronal marker protein gene product 9.5 (PGP 9.5), calcitonin gene-related peptide (CGRP), vanilloid receptor 1 (VR1) and mu- and delta-opioid receptors were employed to study sensory unmyelinated nerve fibres that transmit nociceptive pain and itch. A histamine prick test using planimetry was used to record experimental itch after acupuncture on the treated area and on the corresponding control skin, and a visual analogue scale was used to evaluate itch. RESULTS: The mean +/- SEM number of CGRP-immunoreactive nerve fibres per biopsy section was reduced from 36.0 +/- 3.3 to 21.3 +/- 4.0 (P = 0.05) after the treatment. PGP 9.5-immunoreactive nerve fibres were found both in the epidermis and in the subpapillary dermis. The mean +/- SEM total number of PGP 9.5-immunoreactive nerve fibres decreased from 249.8 +/- 16.7 to 211.8 +/- 12.0 (P = 0.03). The PGP 9.5-immunoreactive nerve fibres occurring in the dermis appeared more fragmented after the acupuncture compared with pretreatment. VR1 immunoreactivity was found both in the free nerve fibres and in kite-like formations, possibly mast cells, throughout the dermis, sometimes occurring around hair follicles. The mean +/- SEM number of VR1-immunoreactive elements was not significantly influenced by acupuncture, at 33.5 +/- 4.6 vs. 43.0 +/- 4.4 (P = 0.09). No immunoreactivity was found in the skin against mu- and delta-opioid receptors with the antibodies used in this study. Neither histamine-induced itch nor cutaneous responses were influenced by acupuncture. CONCLUSIONS: The present data indicate an effect of acupuncture on neuropathic itch but not histamine-mediated itch. Our findings support the opinion that the pain-relieving effects of acupuncture partly depend on its effect on the peripheral innervation.

CART knock out mice have impaired insulin secretion and glucose intolerance, altered beta cell morphology and increased body weight.

CART peptides are anorexigenic and are widely expressed in the central and peripheral nervous systems, as well as in endocrine cells in the pituitary, adrenal medulla and the pancreatic islets. To study the role of CART in islet function, we used CART null mutant mice (CART KO mice) and examined insulin secretion in vivo and in vitro, and expression of islet hormones and markers of beta-cell function using immunocytochemistry. We also studied CART expression in the normal pancreas. In addition, body weight development and food intake were documented. We found that in the normal mouse pancreas, CART was expressed in numerous pancreatic nerve fibers, both in the exocrine and endocrine portion of the gland. CART was also expressed in nerve cell bodies in the ganglia. Double immunostaining revealed expression in parasympathetic (vasoactive intestinal polypeptide (VIP)-containing) and in fewer sensory fibers (calcitonin gene-related peptide (CGRP)-containing). Although the expression of islet hormones appeared normal, CART KO islets displayed age dependent reduction of pancreatic duodenal homeobox 1 (PDX-1) and glucose transporter-2 (GLUT-2) immunoreactivity, indicating beta-cell dysfunction. Consistent with this, CART KO mice displayed impaired glucose-stimulated insulin secretion both in vivo after an intravenous glucose challenge and in vitro following incubation of isolated islets in the presence of glucose. The impaired insulin secretion in vivo was associated with impaired glucose elimination, and was apparent already in young mice with no difference in body weight. In addition, CART KO mice displayed increased body weight at the age of 40 weeks, without any difference in food intake. We conclude that CART is required for maintaining normal islet function in mice.

Secretoneurin is released into human airways by topical histamine but not capsaicin.

BACKGROUND: The neuropeptide secretoneurin, with potential relevance to leukocyte trafficking, is present in nerves of the nasal mucosa in allergic rhinitis and may be released in response to allergen and histamine exposure. There is no information on the occurrence and mechanisms of release of secretoneurin in healthy human airways. METHODS: The presence of secretoneurin in nasal biopsies and its release in response to nasal capsaicin and histamine challenges were examined. Symptoms and lavage fluid levels of fucose were recorded as markers of effects in part produced by neural activity. Bronchial histamine challenges followed by sputum induction and analysis of secretoneurin were also carried out. RESULTS: Nerves displaying secretoneurin immunoreactivity abounded in the nasal mucosa. Nasal capsaicin challenge produced local pain (P <0.05) and increased the levels of fucose (P <0.05), but failed to affect the levels of secretoneurin. Nasal histamine challenge produced symptoms (P <0.05) and increased the mucosal output of secretoneurin (P <0.05) and fucose (P <0.05). Bronchial histamine challenge increased the sputum levels of secretoneurin (P <0.05). CONCLUSIONS: We conclude that secretoneurin is present in healthy human airways and that histamine evokes its release in both nasal and bronchial mucosae. The present observations support the possibility that secretoneurin is involved in histamine-dependent responses of the human airway mucosa.

Ghrelin is expressed in a novel endocrine cell type in developing rat islets and inhibits insulin secretion from INS-1 (832/13) cells.

Ghrelin is produced mainly by endocrine cells in the stomach and is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R). It also influences feeding behavior, metabolic regulation, and energy balance. It affects islet hormone secretion, and expression of ghrelin and GHS-R in the pancreas has been reported. In human islets, ghrelin expression is highest pre- and neonatally. We examined ghrelin and GHS-R in rat islets during development with immunocytochemistry and in situ hybridization. We also studied the effect of ghrelin on insulin secretion from INS-1 (832/13) cells and the expression of GHS-R in these cells. We found ghrelin expression in rat islet endocrine cells from mid-gestation to 1 month postnatally. Islet expression of GHS-R mRNA was detected from late fetal stages to adult. The onset of islet ghrelin expression preceded that of gastric ghrelin. Islet ghrelin cells constitute a separate and novel islet cell population throughout development. However, during a short perinatal period a minor subpopulation of the ghrelin cells co-expressed glucagon or pancreatic polypeptide. Markers for cell lineage, proliferation, and duct cells revealed that the ghrelin cells proliferate, originate from duct cells, and share lineage with glucagon cells. Ghrelin dose-dependently inhibited glucose-stimulated insulin secretion from INS-1 (832/13) cells, and GHS-R was detected in the cells. We conclude that ghrelin is expressed in a novel developmentally regulated endocrine islet cell type in the rat pancreas and that ghrelin inhibits glucose-stimulated insulin secretion via a direct effect on the beta-cell.

Cocaine- and amphetamine-regulated transcript (CART) is expressed in several islet cell types during rat development.

Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic peptide widely expressed in the central and peripheral, including the enteric, nervous systems. CART is also expressed in pituitary endocrine cells, adrenomedullary cells, islet somatostatin cells, and in rat antral gastrin cells. We used immunocytochemistry (IHC) and in situ hybridization (ISH) to study CART expression in developing rat pancreas. We also examined co-expression of CART and islet hormones and developmental markers and the effect of CART on proliferation using clonal insulin cells (INS-1 832/13). A major portion of each of the islet cell types, except the ghrelin cells, expressed CART during a period before and around birth. Two weeks postnatally, CART expression was restricted to somatostatin cells. Pre- and early postnatally, many of the CART-expressing cells co-expressed cytokeratin 20 (CK20), a marker of duct cells and islet precursor cells, the trophic hormone gastrin, and a smaller subpopulation also harbored the proliferation marker Ki67. CART was also expressed in pancreatic nerve fibers, both sensory and autonomic, and in ganglion nerve cell bodies. Although highly expressed in the developing islets, CART did not affect proliferation of INS-1 cells. We have demonstrated that CART is expressed in several islet cell types during rat development but is restricted to somatostatin cells and neurons in the adult rat.

Cocaine- and amphetamine-regulated transcript: distribution and function in rat gastrointestinal tract.

Cocaine- and amphetamine-regulated transcript (CART) peptide, originally isolated from brain, is also expressed in the peripheral nervous system. The distribution, origin and projections of CART-expressing enteric neurones by immunocytochemistry and in situ hybridization in rat gastrointestinal (GI) tract were studied. Possible motor functions of CART were studied in vitro using longitudinal muscle strips from stomach, ileum and colon. Cocaine- and amphetamine-regulated transcript peptide was found in numerous myenteric neurones throughout the GI tract while CART-expressing submucous neurones were scarce. Cocaine- and amphetamine-regulated transcript was also expressed in the antral gastrin cells. Myenteric CART-expressing neurones in both small and large intestine issued short descending projections. In atrophic ileum, CART mRNA-expressing neurones increased in number while neurones containing CART peptide decreased. In hypertrophied ileum, no change in CART peptide or CART mRNA containing myenteric neurones was detected. Cocaine- and amphetamine-regulated transcript 55-102 (10(-9)-10(-7) mol L-1) did not induce any contractile or relaxatory responses in the muscle strips, neither did it affect responses induced by vasoactive intestinal peptide, pituitary adenylate cyclase-activating peptide or neuronal stimulation. In colonic, but not in ileal, strips addition of CART attenuated nitric oxide (NO) donor-induced relaxations. Although CART does not seem to play a pivotal role in classic neurotransmission to the longitudinal muscle, it may serve a modulatory role in NO transmission. It may, moreover, be involved in intestinal adaptation, and an additional hormonal role is also possible.

Postnatally disturbed pancreatic islet cell distribution in human islet amyloid polypeptide transgenic mice.

OBJECTIVE: Islet amyloid polypeptide (IAPP)/amylin is produced by the pancreatic islet beta-cells, which also produce insulin. To study potential functions of IAPP, we have generated transgenic mice overexpressing human IAPP (hIAPP) in the beta-cells. These mice show a diabetic phenotype when challenged with an oral glucose load. In this study, we examined the islet cytoarchitecture in the hIAPP mice by examining islet cell distribution in the neonatal period, as well as 1, 3 and 6 months after birth. RESULTS: Neonatal transgenic mice exhibited normal islet cell distribution with beta-cells constituting the central islet portion, whereas glucagon and somatostatin-producing cells constituted the peripheral zone. In contrast, in hIAPP transgenic mice at the age of 1 month, the glucagon-immunoreactive (IR) cells were dispersed throughout the islets. Furthermore, at the age of 3 and 6 months, the islet organisation was similarly severely disturbed as at 1 month. Expression of both endogenous mouse IAPP and transgenic hIAPP was clearly higher in 6-month-old mice as compared to newborns, as revealed by mRNA in situ hybridisation. CONCLUSIONS: Mice transgenic for hIAPP have islets with disrupted islet cytoarchitecture in the postnatal period, particularly affecting the distribution of glucagon-IR cells. This islet cellular phenotype of hIAPP transgenic mice is similar to that of other mouse models of experimental diabetes and might contribute to the impaired glucose homeostasis.

Immunolocalization of cholecystokinin-2 receptors in rat gastric mucosa.

BACKGROUND: Gastrin exerts trophic effects on the gastric mucosa by mechanisms not yet completely elucidated. Our aim was to localize the cholecystokinin-2 (CCK2) receptor in epithelial cells of foetal and adult rat stomachs in order to determine the cell types that are directly affected by gastrin. METHODS: Gastric tissue was subjected to indirect double immunofluorescence staining with antiserum against the C-terminal decapeptide of the CCK2 receptor and antibodies against 5' bromo-2-deoxyuridine, which had been injected into the rats I h before they were killed, the acid pump H,K-ATPase, the membrane-cytoskeletal linker ezrin, pepsin/pepsinogen or histidine decarboxylase. RESULTS: Undifferentiated foetal gastric epithelial cells expressed CCK2 receptors, whereas stem cells of adult gastric glands did not exhibit immunoreactivity. However, other epithelial cells in the progenitor zone of adult gastric glands did express CCK2 receptors. Some of these cells were faintly stained for H,K-ATPase; pepsin/pepsinogen was also detected in this region. Parietal cells in the isthmus/pit region of the glands contained ezrin, and some showed weak immunoreactivity for the CCK2 receptor. As expected, enterochromaffin-like cells also expressed CCK2 receptors. CONCLUSION: Our findings are consistent with the hypothesis that a CCK2 receptor mediates direct effects of gastrin on gastric epithelial cells during both stomach organogenesis and adult life.

The ghrelin cell: a novel developmentally regulated islet cell in the human pancreas.

OBJECTIVES: Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), was recently identified in the stomach. Ghrelin is produced in a population of endocrine cells in the gastric mucosa, but expression in intestine, hypothalamus and testis has also been reported. Recent data indicate that ghrelin affects insulin secretion and plays a direct role in metabolic regulation and energy balance. On the basis of these findings, we decided to examine whether ghrelin is expressed in human pancreas. Specimens from fetal to adult human pancreas and stomach were studied by immunocytochemistry, for ghrelin and islet hormones, and in situ hybridisation, for ghrelin mRNA. RESULTS: We identified ghrelin expression in a separate population of islet cells in human fetal, neonatal, and adult pancreas. Pancreatic ghrelin cells were numerous from midgestation to early postnatally (10% of all endocrine cells). The cells were few, but regularly seen in adults as single cells at the islet periphery, in exocrine tissue, in ducts, and in pancreatic ganglia. Ghrelin cells did not express any of the known islet hormones. In fetuses, at midgestation, ghrelin cells in the pancreas clearly outnumbered those in the stomach. CONCLUSIONS: Ghrelin is expressed in a quite prominent endocrine cell population in human fetal pancreas, and ghrelin expression in the pancreas precedes by far that in the stomach. Pancreatic ghrelin cells remain in adult islets at lower numbers. Ghrelin is not co-expressed with any known islet hormone, and the ghrelin cells may therefore constitute a new islet cell type.

Neuropeptide expression in the human trigeminal nucleus caudalis and in the cervical spinal cord C1 and C2.

In migraine and other primary headaches there is a strong vascular component. Besides the trigeminovascular components some of the associated symptoms point to the involvement of brain stem regions. The central limb of the trigeminal vascular pathway is its projection to the trigeminal nucleus caudalis (TNC) and to the C1-C2 levels of the spinal cord. The aim of the present study was to demonstrate the occurrence of some neurotransmitters in these regions in man. In both the TNC and in the Rexed's laminae I and II of the dorsal horns at the C1 and C2 levels there were numerous substance P immunoreactive fibres. Fibres containing calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide (PACAP) were moderately dense in number. Fibres containing vasoactive intestinal peptide (VIP) or nitric oxide synthase (NOS) were not seen in the TNC or at the C1 and C2 levels of the spinal cord.

The effect of the vasoactive intestinal polypeptide agonist Ro 25-1553 on induced tone in isolated human airways and pulmonary artery.

Ro 25-1553 is a metabolically stable analogue of endogenous vasoactive intestinal polypeptide (VIP). This compound is a potent bronchodilator in vitro as well as in vivo. Moreover, Ro 25-1553 has been shown to be highly selective of the VPAC2 receptor. We assessed the effect of Ro 25-1553 on isolated human bronchi and pulmonary arteries in vitro. Macroscopically normal human airways and pulmonary arteries were obtained from patients undergoing surgery for lung cancer. The relaxing capability of Ro 25-1553 on bronchial and pulmonary artery tone was measured using standard techniques. Bronchial rings were pre-contracted with 0.1 mM histamine, and tone in pulmonary artery rings was induced with 10 microM PGF2alpha. Increasing concentrations of Ro 25-1553 within a range of 1 pM to 10 microM were added and isometric tension changes were recorded. Ro 25-1553 caused a concentration-dependent relaxation of airway and pulmonary artery preparations, with an EC50 of approximately 10 nM and a maximal relaxation of 70%-75% of the induced tone. The presence of VPAC2 receptors in the two tissues, though low in density, was confirmed by in situ hybridization, immunocytochemistry and ligand binding. These findings indicate that the VIP analogue Ro 25-1553 may be useful in the treatment of asthma and/or chronic obstructive pulmonary diseases.