STORE-gastrointestinal functions and gastrointestinal hormones in patients with liver failure

This study aims to investigate the gastrointestinal functions of patients with liver failure (LF) based on gastrointestinal dysfunction (GD) scores and serum gastrointestinal hormone levels.The GD in LF patients was scored using the gastrointestinal dysfunction scoring criteria. Serum gastrin (GAS), cholecystokinin (CCK), and motilin (MTL) levels were determined in LF patients. In addition, liver function and prothrombin activity were detected, and ultrasonography was performed.The GD score was significantly higher in the LF groups than in the control group. Compared with the control group, serum GAS, CCK, and MTL levels significantly increased in the LF groups, and was positively correlated with the severity of LF. Furthermore, in the LF groups, GD was positively correlated with the severity of LF. However, the GD score and serum GAS, CCK, and MTL levels in the acute LF group were not statistically different, when compared with those in the subacute LF group, acute-on-chronic LF group and chronic LF group.LF plays a key role in the development of GD, and may be the main cause of obvious gastrointestinal symptoms, such as abdominal distension, nausea, vomiting and anorexia, in LF patients. The severity of GD is not associated with LF type, but is positively correlated with the severity of LF, suggesting that GD in LF patients may have complicated mechanisms.

Guanylin and uroguanylin mRNA expression is increased following Roux-en-Y gastric bypass, but guanylins do not play a significant role in body weight regulation and glycemic control

AIM

To determine whether intestinal expression of guanylate cyclase activator 2A (GUCA2A) and guanylate cyclase activator 2B (GUCA2B) genes is regulated in obese humans following Roux-en-Y gastric bypass (RYGB), and to evaluate the corresponding guanylin (GN) and uroguanylin (UGN) peptides for potentially contributing to the beneficial metabolic effects of RYGB.

METHODS

Enteroendocrine cells were harvested peri- and post-RYGB, and GUCA2A/GUCA2B mRNA expression was compared. GN, UGN and their prohormones (proGN, proUGN) were administered subcutaneously in normal-weight mice to evaluate effects on food intake and glucose regulation. The effect of pro-UGN or UGN overexpression, using adeno-associated virus (AAV) vectors, was assessed in diet-induced obese (DIO) mice. Intracerebroventricular administration of GN and UGN was performed in rats for assessment of putative centrally mediated effects on food intake. GN and UGN, as well as their prohormones, were evaluated for effects on glucose-stimulated insulin secretion (GSIS) in rat pancreatic islets and perfused rat pancreas.

RESULTS

GUCA2A and GUCA2B mRNA expression was significantly upregulated in enteroendocrine cells after RYGB. Peripheral administration of guanylins or prohormones did not influence food intake, oral glucose tolerance, and GSIS. Central administration of GN and UGN did not affect food intake in rats. Chronic AVV-mediated overexpression of UGN and proUGN had no effect on body weight or glucose homeostasis in DIO mice.

CONCLUSION

GN and UGN, as well as their prohormones, do not seem to play a significant role in body weight regulation and glycemic control, suggesting that guanylin-family peptides do not show promise as targets for the treatment of obesity or diabetes.

Interleukin-15 derived from Guanylin-GC-C-expressing macrophages inhibits fatty acid synthase in adipocytes

Recently we found that guanylin (Gn) and its receptor, guanylyl cyclase C (GC-C), are uniquely expressed in the mesenteric macrophages of some diet-resistant rats and that double-transgenic (dTg) rats overexpressing Gn and GC-C in macrophages demonstrate reduced fatty acid synthase and fat accumulation in fat tissue even when fed a high-fat diet (HFD). Lipid accumulation and fatty acid synthase mRNA levels in cocultured dTg rat adipocytes and macrophages were reduced compared with those in adipocytes cultured with WT rat macrophages. Here, we investigated whether Interleukin-15 (IL-15) derived from Gn-GC-C-expressing macrophages regulates lipid accumulation in adipocytes. IL-15 inhibited fatty acid synthase and lipid accumulation via STAT5 in cultured adipocytes. IL-15 mRNA and protein levels in the mesenteric fat of HFD-fed dTg rats were significantly higher than those of HFD-fed WT rats. Phosphorylated STAT5 levels in the mesenteric fat of HFD-fed dTg rats were increased compared with those of HFD-fed WT rats. In addition, the mRNA level of fatty acid synthase in the mesenteric fat was lower in HFD-fed dTg rats than in HFD-fed WT rats. These results support the hypothesis that IL-15 secreted from Gn-GC-C-expressing macrophages contributes to the inhibition of fatty acid synthase and lipid accumulation in adipocytes, leading to obesity resistance.

Transcriptomic Analysis and Meta-Analysis of Human Granulosa and Cumulus Cells

Specific gene expression in oocytes and its surrounding cumulus (CC) and granulosa (GC) cells is needed for successful folliculogenesis and oocyte maturation. The aim of the present study was to compare genome-wide gene expression and biological functions of human GC and CC. Individual GC and CC were derived from 37 women undergoing IVF procedures. Gene expression analysis was performed using microarrays, followed by a meta-analysis. Results were validated using quantitative real-time PCR. There were 6029 differentially expressed genes (q < 10⁻⁴); of which 650 genes had a log2 FC ≥ 2. After the meta-analysis there were 3156 genes differentially expressed. Among these there were genes that have previously not been reported in human somatic follicular cells, like prokineticin 2 (PROK2), higher expressed in GC, and pregnancy up-regulated nonubiquitous CaM kinase (PNCK), higher expressed in CC. Pathways like inflammatory response and angiogenesis were enriched in GC, whereas in CC, cell differentiation and multicellular organismal development were among enriched pathways. In conclusion, transcriptomes of GC and CC as well as biological functions, are distinctive for each cell subpopulation. By describing novel genes like PROK2 and PNCK, expressed in GC and CC, we upgraded the existing data on human follicular biology.

Postnatal weight gain induced by overfeeding pups and maternal high-fat diet during the lactation period modulates glucose metabolism and the production of pancreatic and gastrointestinal peptides

The impact of rapid weight gain on glucose metabolism during the early postnatal period remains unclear. We investigated the influence of rapid weight gain under different nutritional conditions on glucose metabolism, focusing on the production of pancreatic and gastric peptides. On postnatal day (PND) 2, C57BL/6N pups were divided into three groups: control (C) pups whose dams were fed a control diet (10%kcal fat) and nursed 10 pups each; maternal high-fat diet (HFD) pups whose dams were fed an HFD (45%kcal fat) and nursed 10 pups each; and overfeeding (OF) pups whose dams were fed the control diet and nursed 4 pups each. Data were collected on PND 7, 14 and 21. The body weight gains of the HFD and OF pups were 1.2 times higher than that of the C pups. On PND 14, the HFD pups had higher blood glucose levels, but there were no significant differences in serum insulin levels between the HFD and C pups. The OF pups had higher blood glucose and serum insulin levels than that of the C pups. Insulin resistance was found in the HFD and OF pups. On PND 14, the content of incretins in the jejunum was increased in the OF pups, and acyl ghrelin in the stomach was upregulated in the HFD and OF pups. These results suggest that neonatal weight gain induced by overfeeding pups and maternal high-fat diet during the early postnatal period modulates the insulin sensitivity and the production of pancreatic and gastrointestinal peptides.

Cross-species comparison of genes related to nutrient sensing mechanisms expressed along the intestine

INTRODUCTION

Intestinal chemosensory receptors and transporters are able to detect food-derived molecules and are involved in the modulation of gut hormone release. Gut hormones play an important role in the regulation of food intake and the control of gastrointestinal functioning. This mechanism is often referred to as "nutrient sensing". Knowledge of the distribution of chemosensors along the intestinal tract is important to gain insight in nutrient detection and sensing, both pivotal processes for the regulation of food intake. However, most knowledge is derived from rodents, whereas studies in man and pig are limited, and cross-species comparisons are lacking.

AIM

To characterize and compare intestinal expression patterns of genes related to nutrient sensing in mice, pigs and humans.

METHODS

Mucosal biopsy samples taken at six locations in human intestine (n = 40) were analyzed by qPCR. Intestinal scrapings from 14 locations in pigs (n = 6) and from 10 locations in mice (n = 4) were analyzed by qPCR and microarray, respectively. The gene expression of glucagon, cholecystokinin, peptide YY, glucagon-like peptide-1 receptor, taste receptor T1R3, sodium/glucose cotransporter, peptide transporter-1, GPR120, taste receptor T1R1, GPR119 and GPR93 was investigated. Partial least squares (PLS) modeling was used to compare the intestinal expression pattern between the three species.

RESULTS AND CONCLUSION

The studied genes were found to display specific expression patterns along the intestinal tract. PLS analysis showed a high similarity between human, pig and mouse in the expression of genes related to nutrient sensing in the distal ileum, and between human and pig in the colon. The gene expression pattern was most deviating between the species in the proximal intestine. Our results give new insights in interspecies similarities and provide new leads for translational research and models aiming to modulate food intake processes in man.

Guanylin and functional coupling proteins in the hepatobiliary system of rat and guinea pig

Guanylin, a bioactive intestinal peptide, is involved in the cystic fibrosis transmembrane conductance (CFTR)-regulated electrolyte/water secretion in various epithelia. In the present work we report on the expression and cellular localization of guanylin and its affiliated signaling and effector proteins, including guanylate cyclase C (Gucy2c), Proteinkinase GII (Pkrg2), CFTR and the solute carrier family 4, anion exchanger, member 2 (Slc4a2) in the hepatobiliary system of rat and guinea pig. Localization studies in the liver and the gallbladder revealed that guanylin is located in the secretory epithelial cells of bile ducts of the liver and of the gallbladder, while Gucy2c, Pkrg2, CFTR, and Slc4a2 are confined exclusively to the apical membrane of the same epithelial cells. Based on these findings, we assume that guanylin is synthesized as an intrinsic peptide in epithelial cells of the hepatobiliary system and released luminally into the hepatic and cystic bile to regulate electrolyte secretion by a paracrine/luminocrine signaling pathway.

Upregulation of endocrine gland-derived vascular endothelial growth factor in papillary thyroid cancers displaying infiltrative patterns, lymph node metastases, and BRAF mutation

BACKGROUND

Endocrine gland-derived vascular endothelial growth factor (Prok1) and prokineticin 2 (Prok2) are involved in the organ-specific regulation of angiogenesis, which is a crucial step toward cancer progression in most tumors, including those of thyroid gland. The oncogene BRAF V600E mutation is associated with poor clinical outcome of papillary thyroid cancer (PTC) and can independently predict its recurrence.

DESIGN

Our hypothesis was that Prok1 and Prok2 expression levels associated with BRAF mutations can be prognostic factors for PTC outcome. Prok1 and Prok2 were examined in PTC, a cell line derived from a human PTC (designated FB-2), euthyroid multinodular goiter (MNG), Graves' disease (GD), and contralateral normal thyroid (NT) tissues from PTC cases. We evaluated BRAF mutation and its relationship with Prok1 expression pattern in PTC.

METHODS

We studied Prok1 and Prok2 mRNAs by real-time polymerase chain reaction and BRAF mutation by mutant allele-specific polymerase chain reaction amplification. Formalin-fixed, paraffin-embedded blocks of PTC and NT were used for the immunohistochemical determination of Prok1 using anti-endocrine gland vascular endothelial growth factor primary antibody.

RESULTS

Prok1 and Prok2 transcripts were both present in thyroid tissues, and Prok1 was differentially expressed in PTC compared to MNG, GD, and NT. Prok1 mRNA levels were very low in NT and MNG and significantly higher in PTC, FB-2, and GD (p<0.05). Prok1 protein was almost undetectable in NT but was highly expressed in all PTC samples having an infiltrative pattern of growth and lymph node metastases ( p<0.05). Further, the expression of Prok1 in PTC was associated with 60% of the samples being positive for the BRAF mutation ( p<0.05).

CONCLUSIONS

We found that Prok1 is significantly increased in PTC, and its expression in PTC is related to BRAF mutation. These results suggest that Prok1 could be a new useful marker for thyroid cancer progression. Prok1 therefore could also be a potential target for novel therapeutic strategies, although the lack of functional data suggests caution against generalization of this assumption

Efferent projections of prokineticin 2 expressing neurons in the mouse suprachiasmatic nucleus

The suprachiasmatic nucleus (SCN) in the hypothalamus is the predominant circadian clock in mammals. To function as a pacemaker, the intrinsic timing signal from the SCN must be transmitted to different brain regions. Prokineticin 2 (PK2) is one of the candidate output molecules from the SCN. In this study, we investigated the efferent projections of PK2-expressing neurons in the SCN through a transgenic reporter approach. Using a bacterial artificial chromosome (BAC) transgenic mouse line, in which the enhanced green fluorescence protein (EGFP) reporter gene expression was driven by the PK2 promoter, we were able to obtain an efferent projections map from the EGFP-expressing neurons in the SCN. Our data revealed that EGFP-expressing neurons in the SCN, hence representing some of the PK2-expressing neurons, projected to many known SCN target areas, including the ventral lateral septum, medial preoptic area, subparaventricular zone, paraventricular nucleus, dorsomedial hypothalamic nucleus, lateral hypothalamic area and paraventricular thalamic nucleus. The efferent projections of PK2-expressing neurons supported the role of PK2 as an output molecule of the SCN.

Immunoelectron study of pancreatic carcinomas using antibodies to gastrointestinal hormones

The aim of this study was to investigate the ultrastructural appearance of pancreatic adenocarcinoma combined with glucagon and gastrin/cholecystokinin (CCK) expression. The authors investigated the ultrastructure and the immunocytochemistry of 12 human pancreatic cancer specimens and used 3 chronic pancreatitis samples and 6 adjacent histological normal pancreatic tissues (away from the tumor) as controls. The ultrastructural study revealed that chronic pancreatitis tissues were characterized by alterations of the secretory cells. The enzymic and secretory changes were confirmed by electron immunogold results. Glucagon appeared to be located not only in islet alpha cells but also in intermediate alpha acinar cells. The changes were more significant in adenocarcinoma cases. Abnormality in the immunoreaction of the peptides was indicated not only in the tumor area but also in the islets near the cancer. Cells immunoreactive with antibodies were found in all 12 adenocarcinoma cases. Abnormal co-location of both hormones in the same type of endocrine cell was also found. Moderately to poorly differentiated adenocarcinomas were poorly granulated compared with differentiated tumors. Increased and ectopic gastrin/CCK expression was correlated with pancreatic adenocarcinomas exhibiting poor histological grade and neoplastic endocrine cells, providing a potential marker for pancreatic adenocarcinomas with aggressive behavior.

Placental expression of EG-VEGF and its receptors PKR1 (prokineticin receptor-1) and PKR2 throughout mouse gestation

Compelling evidence indicates that vascular endothelial growth factor (VEGF) is an important mediator of placental angiogenesis and appears to be disregulated in pre-eclampsia (PE). Recently, we characterised the expression of EG-VEGF (endocrine gland-derived vascular endothelial growth factor), also known as prokineticin 1 (PK1) in human placenta during the first trimester of pregnancy and showed that this factor is likely to play an important role in human placentation. However, because it is impossible to prospectively study placentation in humans, it has been impossible to further characterise EG-VEGF expression throughout complete gestation and especially at critical gestational ages for PE development. In the present study, we used mouse placenta to further characterise EG-VEGF expression throughout gestation. We investigated the pattern of expression of EG-VEGF and its receptors, PKR1 and PKR2 at the mRNA and protein levels. Our results show that EG-VEGF and VEGF exhibit different patterns of expression and different localisations in the mouse placenta. EG-VEGF was mainly localised in the labyrinth whereas VEGF was mainly present in glycogen and giant cells. EG-VEGF mRNA and protein levels were highest before 10.5days post coitus (dpc) whereas those of VEGF showed stable expression throughout gestation. PKR1 protein was localised to the labyrinth layer and showed the same pattern of expression as EG-VEGF whereas PKR2 expression was maintained over 10.5dpc with both trophoblastic and endothelial cell localisations. Altogether these findings suggest that EG-VEGF may have a direct effect on both endothelial and trophoblastic cells and is likely to play an important role in mouse placentation.

Bv8, the amphibian homologue of the mammalian prokineticins, induces a proinflammatory phenotype of mouse macrophages

1.--The small protein Bv8, isolated from the amphibian skin, belongs to a novel family of secreted proteins linked to several biological effects. We describe the expression of Bv8/prokineticins and their receptors in mouse macrophages, and characterize their proinflammatory activities. 2.--The rodent analogue of Bv8, prokineticin-2, is expressed by macrophages, as well as its G-protein-coupled receptor prokineticin receptor (PKR-1 and PKR-2). PKR-1 is expressed more abundantly. 3.-- Bv8 induces potent chemotaxis of macrophages at concentrations as low as 10(-12) M. 4.-- It stimulates lipopolysaccharide-induced production of the proinflammatory cytokines IL-1 and IL-12, reducing that of the anti-inflammatory cytokine IL-10. The effects are observed starting at the very low concentration of 10(-11) M. 5.--Effects on chemotaxis and cytokine are not pertussis-toxin sensitive, but are completely prevented by addition of the phospholipase inhibitor U73122, suggesting a G(q) protein is involved in the Bv8-induced effects. 6.--Studies in PKR-1 knockout mice indicate that all the activities exerted by Bv8 on macrophages are mediated by the PKR-1 receptor. 7.--In conclusion, Bv8 appears to be able to induce the macrophage to migrate and to acquire a proinflammatory phenotype.

Expression of prokineticins and their receptors in the adult mouse brain

Prokineticins are a pair of regulatory peptides that have been shown to play important roles in gastrointestinal motility, angiogenesis, circadian rhythms, and, recently, olfactory bulb neurogenesis. Prokineticins exert their functions via activation of two closely related G-protein-coupled receptors. Here we report a comprehensive mRNA distribution for both prokineticins (PK1 and PK2) and their receptors (PKR1 and PKR2) in the adult mouse brain with the use of in situ hybridization. PK2 mRNA is expressed in discrete regions of the brain, including suprachiasmatic nucleus, islands of Calleja and medial preoptic area, olfactory bulb, nucleus accumbens shell, hypothalamic arcuate nucleus, and amygdala. PK1 mRNA is expressed exclusively in the brainstem, with high abundance in the nucleus tractus solitarius. PKR2 mRNA is detected throughout the brain, with prominent expression in olfactory regions, cortex, thalamus and hypothalamus, septum and hippocampus, habenula, amygdala, nucleus tractus solitarius, and circumventricular organs such as subfornical organ, median eminence, and area postrema. PKR2 mRNA is also detected in mammillary nuclei, periaqueductal gray, and dorsal raphe. In contrast, PKR1 mRNA is found in fewer brain regions, with moderate expression in the olfactory regions, dentate gyrus, zona incerta, and dorsal motor vagal nucleus. Both PKR1 and PKR2 are also detected in olfactory ventricle and subventricular zone of the lateral ventricle, both of which are rich sources of neuronal precursors. These extensive expression patterns suggest that prokineticins may have a broad array of functions in the central nervous system, including circadian rhythm, neurogenesis, ingestive behavior, reproduction, and autonomic function.

Cloning and Expression of Guanylin-like Peptides in Teleost Fish

Homologues of the guanylin peptide family are expressed in teleost fish. Using the eel as a model euryhaline species, cDNAs for three peptides, guanylin, uroguanylin, and renoguanylin, were cloned and found to be expressed within both renal and intestinal epithelia. Seawater (SW) acclimation resulted in upregulation of uroguanylin mRNA expression in the intestinal epithelia of both immature "yellow" and sexually mature "silver" eels. SW acclimation also resulted in an increase in guanylin mRNA in silver eel intestine, whereas there was no change in renoguanylin mRNA expression under any condition. No changes in expression were found in the kidney following SW acclimation.

Weight loss through ileal transposition is accompanied by increased ileal hormone secretion and synthesis in rats

Bariatric surgeries, such as gastric bypass, result in dramatic and sustained weight loss that is usually attributed to a combination of gastric volume restriction and intestinal malabsorption. However, studies parceling out the contribution of enhanced intestinal stimulation in the absence of these two mechanisms have received little attention. Previous studies have demonstrated that patients who received intestinal bypass or Roux-en-Y surgery have increased release of gastrointestinal hormones. One possible mechanism for this increase is the rapid transit of nutrients into the intestine after eating. To determine whether there is increased secretion of anorectic peptides produced in the distal small intestine when this portion of the gut is given greater exposure to nutrients, we preformed ileal transpositions (IT) in rats. In this procedure, an isolated segment of ileum is transposed to the jejunum, resulting in an intestinal tract of normal length but an alteration in the normal distribution of endocrine cells along the gut. Rats with IT lost more weight (P < 0.05) and consumed less food (P < 0.05) than control rats with intestinal transections and reanastomosis without transposition. Weight loss in the IT rats was not due to malabsorption of nutrients. However, transposition of distal gut to a proximal location caused increased synthesis and release of the anorectic ileal hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY; P < 0.01). The association of weight loss with increased release of GLP-1 and PYY suggests that procedures that promote gastrointestinal endocrine function can reduce energy intake. These findings support the importance of evaluating the contribution of gastrointestinal hormones to the weight loss seen with bariatric surgery.

Clinical endocrinology and metabolism. Development of gut endocrine cells

During development, the definitive endoderm differentiates into several gastrointestinal epithelial lineages, including enteroendocrine cells. The enteroendocrine lineage consists of at least 15 different cell types that are categorized based on their morphology, location and peptide hormone expression. The mechanisms regulating enteroendocrine cell differentiation are likely to be critical not only in embryonic development, but also during the constant renewal of gut epithelia in the adult. The identification of transcription factors and regulatory DNA elements required for cell type-specific gene expression in various endocrine cell types has broadened our understanding of the regulatory networks controlling the spatial and temporal activation of enteroendocrine differentiation programs. This chapter will review recent studies of transcription factors during enteroendocrine cell differentiation, with a focus on the central role for the Notch signaling pathway in enteroendocrine cell fate decisions.

EG-VEGF and Bv8: a novel family of tissue-restricted angiogenic factors

A novel family of angiogenic mitogens have been recently characterized. Endocrine gland-derived vascular endothelial growth factor (EG-VEGF), and the mammalian homologue of Bombina variegata peptide 8 (Bv8), are two highly related endothelial cell mitogens and chemotactic factors with restricted expression profiles and selective endothelial cell activity. These peptides share two cognate G-protein coupled receptors. The expression of human EG-VEGF occurs predominantly in steroidogenic glands. Consistent with such an expression pattern, the human EG-VEGF gene promoter has a potential binding site for steroidogenic factor (SF)-1, a pivotal element for steroidogenic-specific transcription. In the human ovary, the expression of EG-VEGF is temporally and spatially complementary to the expression of VEGF-A, both in the follicular and in the luteal phase, suggesting complementary and coordinated roles of these molecules in ovarian angiogenesis. Also, EG-VEGF expression correlates with vascularity in the polycystic ovary syndrome, a leading cause of infertility. Bv8 expression is mainly restricted to the testis. The identification of these tissue-selective angiogenic factors raises the possibility that other secreted molecules with selectivity for the endothelium of other organs exist.

Bv8, the amphibian homologue of the mammalian prokineticins, modulates ingestive behaviour in rats

1. The small protein Bv8, secreted by the skin of the frog Bombina variegata, belongs to a novel family of secreted proteins whose mammalian orthologues have been identified and named prokineticins (PK-1 and PK-2). 2. Bv8 (from 2.5 to 60 pmol) injected into the lateral ventricles of rat brain suppressed diurnal, nocturnal, deprivation-induced and neuropeptide Y-stimulated feeding and stimulated diurnal drinking. Nocturnal drinking was increased only in fasted rats. 3. PK-2 mRNA is expressed in discrete areas of the rat brain, including the suprachiasmatic nucleus (SCN), medial preoptic area (MPA) and nucleus of the solitary tract (NTS). In the SCN neurons, PK-2 mRNA is highest during the light phase of the circadian cycle and undetectable during the dark phase. 4. The G-protein-coupled receptor prokineticin receptor 2 (PKR-2), which binds Bv8 and PK-2 with high affinity, is mainly expressed in the piriform cortex, paraventricular thalamic nucleus, parataenial nucleus (PT), SCN, hypothalamic paraventricular (PVH) and dorsomedial (DMH) nuclei, arcuate nucleus (ARC) and subfornical organ (SFO) of the rat brain. 5. Bv8 microinjected into the ARC, at doses from 0.02 to 2.0 pmol during night-time or from 0.2 to 5 pmol in 24-h-fasted rats, selectively suppressed feeding without affecting drinking. When injected into the SFO, Bv8 (from 0.2 to 2 pmol) stimulated drinking but did not affect feeding. Bv8 injections into other brain areas left rat ingestive behaviours unchanged. 6. We hypothesize that PK-2-rich projections from SCN neurons to PKR-expressing ARC neurons could transmit the circadian rhythm of feeding, whereas inputs from the PK-2-expressing NTS neurons to the PKR-2-expressing SFO neurons could transmit visceral information on the water-electrolyte balance and osmotic regulation.

Elevated serum progastrin-releasing peptide (31-98) level is a predictor of short response duration after hormonal therapy in metastatic prostate cancer

BACKGROUND

The neuroendocrine (NE) pathway has been attracting attention as a mechanism for the androgen-independent progression because the neuropeptide provokes tumor growth and inhibits apoptosis under androgen-deprived milieu in prostate cancer cells. On the basis that serum progastrin-releasing peptide (ProGRP) is elevated in patients with advanced disease stage, we examined the prognostic value of the neuropeptide.

METHODS

Serum ProGRP status was determined with an enzyme-linked immunosorbent assay (ELISA) in 460 men with benign and malignant prostatic diseases, chronic renal failure, and healthy controls. Seventy patients with metastatic prostate cancer including four patients (5.7%) with NE carcinoma who underwent hormonal therapy were enrolled in the prognostic analyses by Cox proportional hazards model.

RESULTS

The serum status steadily shifted toward predominant expression of ProGRP with the progression of prostate cancer into metastatic and androgen-independent stages. Univariate analysis revealed that the deteriorated performance status (PS) and extent of bony disease (EOD), and high serum alkaline phosphatase (ALP), serum ProGRP, and nadir prostate-specific antigen (PSA) levels were associated with a lower progression-free survival (PFS) rate (P < 0.005). Multivariate analysis demonstrated that PS, serum ProGRP, and nadir PSA held an independent predictive value for PFS (P < 0.05), and all correlated with bone-related factors. Serum ProGRP was the most significant predictor among pre-treatment factors in this model (P = 0.0094).

CONCLUSIONS

The neuropeptide precursor ProGRP is a distinct serum marker that is useful to know the NE milieu and provides prognostic information in patients with advanced prostate cancer. Standard therapy for metastatic prostate cancer may make progress when further studies will clarify the causative link between serum ProGRP level and androgen-independent disease progression.

Presence and regulation of endocrine gland vascular endothelial growth factor/prokineticin-1 and its receptors in ovarian cells

Endocrine gland vascular endothelial growth factor (EG-VEGF) is a novel angiogenic mitogen selective for endothelial cells (EC) in endocrine glands. EG-VEGF is identical to a protein previously cloned and termed prokineticin (PK)-1. The present study examined the expression of EG-VEGF/PK-1 and its receptors in ovarian steroidogenic cells and EC and compared the regulation of EG-VEGF/PK-1 and VEGF expression in SV40 transformed luteinized human granulosa cell line (SVOG). Normal granulosa or SVOG cells expressed EG-VEGF/PK-1 mRNA. Incubation of SVOG cells with forskolin augmented EG-VEGF/PK-1 expression in a dose-dependent manner. Chemical hypoxia induced by CoCl(2) and desferrioxamine mesylate (100 micro M each) markedly reduced EG-VEGF/PK-1. In contrast, hypoxia significantly elevated VEGF mRNA (VEGF165, 189) and protein secretion. Thrombin, like hypoxia, also induced an opposite effect on VEGF and EG-VEGF/PK-1. Whereas EG-VEGF/PK-1 and VEGF were inversely regulated, steroidogenesis and EG-VEGF/PK-1 were positively correlated in SVOG cells. A distinct pattern of ovarian PK receptor (PK-R) expression was observed in which steroidogenic cells predominantly express PK-R1 receptors, whereas corpus luteum-derived EC express high levels of both PK-R1 and PK-R2. Therefore, acting via either PK-R2 or PK-R1, EG-VEGF/PK-1 may have angiogenic as well as nonangiogenic functions in the ovary.

[Phase III additional clinical study of 111In-pentetreotide (MP-1727): diagnosis of gastrointestinal hormone producing tumors based on the presence of somatostatin receptors]

Additional phase III multicenter clinical study was performed to investigate the efficacy, safety, and usefulness of somatostatin receptor scintigraphy using 111In-pentetreotide (MP-1727), which binds to somatostatin receptors. Forty patients were included in the study; Group A: 18 patients, gastrointestinal hormone producing tumors had been detected with conventional imaging modalities, Group B: 22 patients, no tumors had been detected with conventional imaging modalities in spite of high serum hormone levels. By comparing the results of the octreotide suppression test, 12/16 cases (75.0%) of Group A and 11/19 cases (57.9%) of Group B were assessed as "effective." By comparing the results of immunohistological examination, 5/9 cases (55.6%) of Group A and 2/4 cases (50.0%) of Group B were assessed as "effective." Severe adverse events were not observed in any of the evaluable 35 cases. MP-1727 was judged as clinically useful in 11/16 cases (68.8%) of Group A and 5/19 cases (26.3%) of group B. These results suggest that MP-1727 scintigraphy is very useful for the diagnosis and decision of the therapeutic strategy of gastrointestinal hormone producing tumors.

Expression of endocrine gland-derived vascular endothelial growth factor in ovarian carcinoma

The first tissue-specific angiogenic molecule, endocrine gland-derived vascular endothelial growth factor (EG-VEGF), was identified recently in human ovary, raising hopes of developing tumor type-specific angiogenesis inhibitors. In the present study, we analyzed the expression of EG-VEGF mRNA in normal human tissues and ovarian neoplasms by quantitative real-time reverse transcription-PCR. EG-VEGF mRNA was expressed in all ovarian neoplasms examined. No significant difference was identified among benign, low malignant potential neoplasms or stage I ovarian cancer, all of which exhibited 2-fold lower mRNA levels compared with normal premenopausal ovaries. EG-VEGF mRNA levels further decreased in late stage compared with early stage carcinomas (P < 0.05) and were consistently lower in laser capture microdissected tumor islets compared with surrounding stroma. EG-VEGF was undetectable by reverse transcription-PCR in 17 established epithelial ovarian cancer cell lines or in cultured human ovarian surface epithelial cells, whereas it was detected in peripheral blood as well as tumor-infiltrating T lymphocytes. Finally, in contrast to VEGF, EG-VEGF mRNA levels did not correlate with clinical outcome in advanced ovarian carcinoma. These results suggest that EG-VEGF is most likely derived from nonepithelial components of ovarian carcinomas and may play a marginal role in promoting angiogenesis in advanced ovarian carcinoma. We postulate that EG-VEGF-targeted antiangiogenic therapy may prove useful in early stage but not in advanced stage ovarian carcinoma.

Molecular cloning and characterization of prokineticin receptors

Recent studies have identified two novel biofunctional proteins, termed prokineticin 1/EG-VEGF and prokineticin 2, which were mammalian homologues of mamba MIT1 and frog Bv8. Prokineticins have been demonstrated to exert their physiological functions through G-protein coupled receptors (GPCRs). In this study, we report the molecular identification of two endogenous prokineticin receptors, designated PK-R1 and PK-R2, through a search of the human genomic DNA database. PK-R1, locating in chromosome 2, and PK-R2, locating in chromosome 20p13, shared 87% homology, which was an extremely high value among known GPCRs. In functional assays, mammalian cells expressing PK-Rs responded to prokineticins in a concentration-dependent manner. Tissue distribution analysis revealed that expression of PK-R1 was observed in the testis, medulla oblongata, skeletal muscle and skin, while that of PK-R2 showed preferential expression in the central nervous system. The tissue distribution of PK-Rs reported in this paper suggests that the prokineticins play multifunctional roles in vivo.

Site-specific effects of dietary salt intake on guanylin and uroguanylin mRNA expression in rat intestine

Guanylin and uroguanylin are newly discovered intestinal peptides that have been shown to affect NaCl transport in both the intestine and kidney. The present study tests the hypothesis that guanylin and uroguanylin mRNA expression in each major region of the intestine is regulated by NaCl intake. Semiquantitative multiplex RT-PCR analysis was used to determine the molecular expression of guanylin and uroguanylin in the duodenum, jejunum, ileum, and colon in rats maintained on low (LS), normal (NS), or high (HS) NaCl intake for 4 days. LS intake reduced the expression of uroguanylin, and to a lesser degree, guanylin mRNA in all intestinal segments compared to NS intake. The duodenum was the site of the greatest decrease for both. In contrast, HS intake significantly increased the expression of guanylin mRNA only in the duodenum and jejunum and had minimal effect on uroguanylin mRNA. The minimum time required for altered gene expression was determined by delivering an oral NaCl challenge directly to the gastrointestinal tract by oro-gastric administration to LS or NS animals. In LS rats, NaCl oro-gastric administration significantly increased mRNA expression of both peptides in all intestinal segments. Furthermore, the increases in guanylin and uroguanylin mRNA were detected within 4 h and plateaued by 8 h. Conversely, acute oro-gastric administration of the same NaCl solution to NS rats caused elevations of guanylin mRNA only in the duodenum and jejunum, and of uroguanylin mRNA only in the ileum and colon. In conclusion, the data demonstrate that variations in NaCl intake lead to intestinal segment-specific changes in guanylin and uroguanylin mRNA expression.

Identification of two prokineticin cDNAs: recombinant proteins potently contract gastrointestinal smooth muscle

The motility of gastrointestinal tract is regulated by classical neurotransmitters, neuropeptides, and humoral agents. Two novel human cDNAs have been cloned based on their sequence similarity to a frog skin secretion protein, Bv8, and a nontoxic protein of mamba snake venom. These human cDNAs encode two secreted proteins of 86 and 81 amino acids. Northern blot hybridization has revealed that these cDNAs are expressed in gastrointestinal tract, particularly the stomach. Recombinant proteins with authentic N-terminal sequences have been produced in Escherichia coli and refolded into functional proteins by careful control of protein aggregation. Mass spectrometry has confirmed the formation of five pairs of disulfide bonds. The refolded recombinant proteins potently contract gastrointestinal smooth muscle with EC(50) values in the subnanomolar range. The contractile effects of the recombinant proteins are specific for gastrointestinal smooth muscle, because they have no effect on vascular or respiratory smooth muscle. To reflect their potent and specific effects on gastrointestinal smooth muscle cells, we have named these recombinant proteins prokineticins. Ligand binding studies with iodinated prokineticin revealed the presence of a high-affinity site in ileal smooth muscle. The displacement of specific binding by GTP gamma S suggests that the prokineticin receptor may belong to the family of G protein-coupled receptors. Experiments with verapamil and nifedipine revealed that calcium influx is essential for the contractile activity of prokineticins on gastrointestinal smooth muscle. In summary, we have identified two novel endogenous regulators of gastrointestinal motility. The availability of recombinant prokineticins should provide novel therapeutic agents for disorders involving impaired gastrointestinal motility.

Frontiers of pancreas regeneration

Recent advances in molecular biological techniques have made the search for the factors in pancreas regeneration more intensive. Many transcription factors and growth factors have been suggested to be involved in the proliferation, differentiation, and maintenance of endocrine and exocrine pancreas. Among the transcription factors, PDX-1 has been examined in a major pancreatectomy model and is suggested to play a role in beta-cell differentiation. Among the growth factors and related peptides, reg protein seems to be a promising candidate which can be applied to clinical practice. Our previous study showed that proton pump inhibitor-induced endogenous hypergastrinemia enhanced insulin secretion and pancreas regeneration. Our results and other studies have suggested that endogenous gastrin induces beta-cell differentiation. On the other hand, the role of classical gut hormones such as gastrin and cholecystokinin in pancreas regeneration has become less significant, as it has been shown that rodents deficient in the genes for these hormones form almost normal pancreas. Results in dogs have shown that pancreas regeneration occurs after major pancreatectomy. A preliminary experiment in primates also suggests latent developmental capacity in the adult primate pancreas. These results lead us to expect that regeneration of the remnant pancreas after subtotal pancreatectomy would be a good target of certain therapies to enhance pancreatic regeneration.

Exposure to ionizing radiation modifies circulating gastrin levels and gastrointestinal endocrine cell densities in the rat

PURPOSE

Gastrointestinal functions, controlled partly by gut peptides, are disturbed by ionizing radiation exposure. The effect of whole-body irradiation on circulating gastrin levels, densities of gastrointestinal endocrine cells and gastric acid secretion was investigated.

MATERIALS AND METHODS

Rats were exposed to 2 or 6 Gy gamma-radiation. They were killed 3 or 7 days later and compared with shams. Plasma gastrin and basal acid output were measured. Endocrine cells were identified by argyrophilia or immunohistochemistry and their densities estimated.

RESULTS

Radiation exposure significantly increased gastrinaemia and gastric acid output at the times studied (p<0.05-p<0.001). Endocrine cells displayed different sensitivities to irradiation. In the gastric mucosa, a 6 Gy dose induced a decrease in fundic argyrophil cell, antral gastrin and somatostatin cell densities, always accentuated 7 days after irradiation, while in the intestinal mucosa it induced an increase, with highest values often at 7 days post-irradiation (p<0.01-p<0.001). This was true for neurotensin cells in the jejunum and ileum, substance P cells in ileum and enteroglucagon cells in the descending colon.

CONCLUSIONS

Whole-body irradiation in rats significantly alters plasma gastrin levels, and several gut endocrine cell densities. This has repercussions on hormonal function, such as that exerted on acid secretion, and may explain gastrointestinal dysfunction observed following radiation exposure.

Intestinal growth is associated with elevated levels of glucagon-like peptide 2 in diabetic rats

Glucagon-like peptide 2 (GLP-2) has recently been identified as a novel intestinal growth factor. Because experimental diabetes is associated with bowel growth, we examined the relationship between GLP-2 and intestinal growth in rats made diabetic by streptozotocin (STZ) injection and treated with or without insulin for 3 wk. Ileal concentrations of the intestinal proglucagon-derived peptides, i.e., glicentin + oxyntomodulin, and GLPs 1 and 2, were increased by 57 +/- 20% above those of controls in untreated STZ diabetes (P < 0.05-0.001). Similar increases in plasma concentrations of glicentin + oxyntomodulin (77 +/- 15% above controls, P < 0.01) and GLP-2 (91 +/- 32% above controls, P < 0.05) were seen in untreated STZ diabetes. Both wet and dry small intestinal weight increased by 74 +/- 20% above controls (P < 0.01) in STZ diabetes, and macromolecular analysis indicated parallel increases in both protein (P < 0.001) and lipid (P < 0.05) content. Villus height (P < 0.001) and crypt depth (P < 0.01) were also increased in untreated diabetic rat intestine. Insulin therapy prevented the changes in plasma GLP-2 and intestinal mass seen in untreated STZ diabetes. Thus STZ diabetes is associated with both increased production of GLP-2 and enhanced bowel weight, thereby suggesting a role for GLP-2 in diabetes-associated bowel growth.

PYY in developing murine islet cells: comparisons to development of islet hormones, NPY, and BrdU incorporation

Exhaustive characterizations of antisera to the structurally related peptides pancreatic polypeptide (PP), neuropeptide Y (NPY), and peptide YY (PYY) enabled us to establish the developmental pattern of these peptides in rat and mouse pancreas. PYY was the earliest detectable peptide and was present in all early appearing endocrine cell types. NPY appeared later and occurred exclusively in a subpopulation of insulin cells, whereas PP cells arose latest. At the earliest stage studied, all endocrine cells stored PYY. Most of these cells also contained glucagon. Subsequently, the endocrine cells comprised glucagon+PYY cells and glucagon+PYY+insulin cells. Later, cells storing either only insulin or insulin+PYY appeared. Quantitations of the relative numbers of these cell populations during development were consistent with a precursor role of triple-positive (insulin+glucagon+PYY) cells. Moreover, bromodeoxyuridine (BrdU) injections at E15.5 showed that a large percentage of triple-positive cells were in S-phase and therefore were actively dividing, whereas almost no pure insulin cells or insulin+PYY cells synthesized DNA at this time. These results suggest that PYY-positive endocrine cells may represent precursors for mature islet cells.

Peptide YY expression is an early event in colonic endocrine cell differentiation: evidence from normal and transgenic mice

The hormone peptide YY is produced by endocrine cells in the pancreas, ileum and colon. We have previously shown that peptide YY is coexpressed in all four islet cell types in the murine pancreas when they first appear, suggesting a common peptide YY-producing progenitor. In the colon, peptide YY has been frequently identified in glucagon-expressing L-type endocrine cells. Characterization of colonic endocrine tumors in transgenic mice expressing simian virus 40 large T antigen under the control of the peptide YY gene 5′ flanking region revealed tumor cells producing not only peptide YY and glucagon, but also neurotensin, cholecystokinin, substance P, serotonin, secretin, and gastrin. This suggested that multiple enteroendocrine lineages were related to peptide YY-producing cells. Subsequent examination of the ontogeny of colonic endocrine differentiation in nontransgenic mice revealed that peptide YY was the first hormone to appear during development, at embryonic day 15.5. Between embryonic days 16.5 and 18.5, cells expressing glucagon, cholecystokinin, substance P, serotonin, secretin, neurotensin, gastrin and somatostatin first appeared and peptide YY was coexpressed in each cell type at this time. Peptide YY coexpression continued in a significant fraction of most enteroendocrine cell types throughout fetal and postnatal development and into adulthood, with the exception of serotonin-producing cells. This latter population of cells expanded dramatically after birth with rare coexpression of peptide YY. These studies indicate that expression of peptide YY is an early event in colonic endocrine differentiation and support the existence of a common progenitor for all endocrine cells in the colon.

A rat gastrin-human gastrin chimeric transgene directs antral G cell-specific expression in transgenic mice

Gastrin gene expression in the gastrointestinal tract is under both developmental and spatial regulation. In the mature animal, gastrin, an important regulator of parietal acid secretion, is expressed primarily in G cells of the antrum. To determine whether specific promoter elements can direct expression to the gastric antrum in vivo, 450 nucleotides of the proximal rat gastrin promoter were cloned and used to construct a rat gastrin-human gastrin reporter chimeric transgene, which was injected into the mouse germ line. Northern blot analysis, in situ hybridization, and double-label immunocytochemistry studies demonstrated expression of the transgene specifically in antral G cells. Low levels of transgene expression were observed in the ileum and colon, where immunohistochemical studies demonstrated colocalization in enteroendocrine cells expressing peptide YY. The same 450-nucleotide rat gastrin promoter, when joined to the human growth hormone gene, did not result in antral expression. Similarly, a human gastrin-human gastrin reporter transgene also did not achieve antral expression, although it did express in the liver. These results suggest that cis-acting elements present in both the basal 450-nucleotide rat gastrin promoter and the intragenic sequences of the human gastrin gene are necessary to direct expression of a transgene specifically to antral G cells.

Early regional expression and secretion of peptide YY and enteroglucagon after massive resection of small bowel

BACKGROUND

Previous studies suggest that peptide YY (PYY) and enteroglucagon have an important role in intestinal adaptation after massive small bowel resection. This study was done to define the mechanisms, timing, and anatomic distribution of the PYY and enteroglucagon response.

STUDY DESIGN

Lewis rats underwent resection of 70 percent of the small bowel (leaving equal segments of jejunum and ileum), transection, or laparotomy alone. Jejunum, ileum, and colon were compared in resected, transected, and control bowel six hours, 24 hours, one week, and two weeks postoperatively.

RESULTS

Analysis of DNA, RNA, and protein per cm of bowel demonstrated hyperplastic changes. Radioimmunoassay revealed plasma PYY and enteroglucagon to be significantly elevated 24 hours after resection and they remained so through week two. In contrast, tissue PYY and enteroglucagon content decreased significantly in all tissues (p < 0.05) after resection. Reverse transcriptase polymerase chain reaction and Southern blot analysis demonstrated an immediate and sustained increase in PYY messenger RNA (mRNA) in both the ileum (fourfold) and in the colon (2.5-fold) at six hours (p < 0.05). A gradual increase in PYY mRNA was also demonstrated in the jejunum with significance at two weeks (p < 0.05). Proglucagon mRNA was significantly higher in the jejunum, compared with the ileum and colon, at 24 hours, one week, and two weeks postresection.

CONCLUSIONS

Alterations in PYY and enteroglucagon synthesis occur early in the ileum and colon after massive small bowel resection. The residual jejunum, however, is primarily responsible for the adaptive hyperenteroglucagonemia. These findings suggest that although PYY and enteroglucagon are colocalized to the same cell type, there is a gene-specific response for these two peptides after resection.

Ovarian carcinoid with severe constipation due to peptide YY production

We report a patient with primary trabecular carcinoid of the ovary with severe constipation probably due to peptide YY production by the tumor. A 43-year-old female had complained of severe constipation for several months and was found to have a left ovarian tumor. The surgically resected tumor was diagnosed as trabecular carcinoid by light microscopic examination. The carcinoid tumor cells were intensely and uniformly stained by the Grimelius technique. Immunohistochemically, the tumor cells were strongly positive for peptide YY, which has a strong inhibitory action on intestinal motility. The patient has been free from constipation since the removal of the tumor. The present case supports previously reported findings that not typical carcinoid syndrome but rather severe constipation accompanies primary trabecular carcinoid of the ovary, and that peptide YY is presumably the cause of the constipation.

Distribution, formation, and molecular forms of the peptide xenin in various mammals

In the present investigation we isolated the recently discovered pentacosapeptide xenin from gastric mucosa of man, dog, pig, guinea pig, rat, and rabbit. HPLC, mass spectrometry, and amino acid sequence analysis showed xenin-25 in concentrations of 54-144 pmol/g tissue in gastric mucosa of each species. Extraction with 2% TFA followed by analytical C18 HPLC revealed 0.02-84 pmol/g xenin-25 also in hypothalamus, lung, liver, heart, kidney, adrenal gland, pancreas, testicle, skin, and duodenal, jejunal, ileal, and colonic mucosa of dog and man, respectively. Digestion of these acid extracts with pepsin liberated xenin-25 in concentrations from 2 up to 166 pmol/g tissue. Gel chromatography revealed a large molecular weight precursor of xenin-25 and evidence for an endogenous acid protease coeluting with pepsinogen capable of releasing xenin-25 from its precursor. Maximal concentrations of xenin-25 were obtained when canine gastric mucosa was incubated with 2% TFA at room temperature for 2 h. Longer incubation times led to a decline of xenin-25 concentration and to formation of xenin-16 and xenin-9, both C-terminal fragments of xenin-25. We conclude that xenin-25 is present not only in human gastric mucosa but also in the stomach of various other mammals. Xenin-25 is further present in low concentrations in many other organs where a pepsin-like protease generates xenin-25 from a large precursor and processes it to smaller fragments.

Gastrin-releasing peptide is produced in the pregnant ovine uterus

Our previous finding of appreciable quantities of a gastrin-releasing peptide (GRP)-like immunoreactive (GRPLI) entity in ovine fetal and maternal plasma led us to examine the ovine pregnant uterus as a possible source of this material. At term, intense immunohistochemical staining for GRPLI occurred in the endometrial epithelial cells, and the term ovine uterus also contained abundant GRP messenger RNA (mRNA). In contrast, GRP mRNA was not detected in fetal membranes. GRP mRNA was present in the uterus on gestational day 63; a significant increase in GRP mRNA had occurred by day 100. Thereafter, levels remained elevated until term, but 3 months postpartum, GRP mRNA levels were greatly reduced. As previous studies suggested the GRPLI entity to be of greater molecular size than GRP-(1-27), we deduced the primary structure of ovine uterus GRP by sequencing a complementary DNA clone isolated from a complementary DNA library constructed from term ovine uterus polyadenylated RNA. Ovine uterine GRP is composed of 27 amino acid residues and has a conserved C-terminal region, similar to GRP structures in other species. We conclude that during pregnancy, the ovine uterus produces considerable quantities of GRP, which may play an important but hitherto unrecognized role in utero-placental development and possibly in fetal development after transfer to the fetus.

Immunohistochemical studies indicate multiple enteroendocrine cell differentiation pathways in the mouse proximal small intestine

The enteroendocrine cell system of the mammalian gastrointestinal tract is comprised of at least 16 different subpopulations. Each subpopulation shows a characteristic distribution along both the crypt-villus and cephalo-caudal axes. In both the small intestine and colon of adult mice, multilabel immunohistochemistry has demonstrated that two or more neuroendocrine products can be coexpressed in various combinations in single cells along the crypt-villus axis, suggesting that enteroendocrine phenotypes may be actively regulated. Using bromodeoxyuridine (BrdU) incorporation and multilabel immunohistochemistry, we have previously demonstrated an enteroendocrine cell differentiation pathway consisting of two subpopulations of cells in the mouse proximal small intestine--one involving the sequential expression of substance P, serotonin, and secretin in cells migrating out of the crypts into the villi, and a second involving the expression of substance P and serotonin in cells which remain in the crypts. In this report, we use double label immunohistochemistry and BrdU incorporation to define the temporal and spatial interrelationships between gastrin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and gastric inhibitory peptide (GIP) immunoreactive cells in the mouse proximal small intestine. The expression of these products was compared with that of substance P, serotonin, and secretin. Minimal overlap of expression was found in cells immunoreactive for substance P or serotonin with gastrin, CCK, GLP-1, or GIP; however, secretin was found colocalized in villus-associated gastrin, CCK, and GLP-1 containing cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Sepsis increases production of total secreted proteins, vasoactive intestinal peptide, and peptide YY in isolated rat enterocytes

The effect of sepsis on the synthesis of endogenous and secretory proteins, including vasoactive intestinal peptide (VIP) and peptide YY (PYY), was determined in enterocytes from jejunum of rats. Sepsis was induced by cecal ligation and puncture (CLP). Control rats were sham-operated. Total endogenous and secreted protein synthesis was assessed in incubated jejunal enterocytes by measuring incorporation of 3H-phenylalanine into protein. Release of VIP and PYY into the medium of incubated enterocytes and cellular levels of the gut peptides were measured by radioimmunoassay. Sixteen hours after CLP, synthesis rates of both endogenous and secreted proteins were increased, and this effect of sepsis was most pronounced in cells from the lower parts of the villi and crypts. Enterocytes from septic rats released more VIP and PYY into the incubation medium, and approximately half of the peptides they released were newly synthesized VIP and PYY. Intracellular levels of VIP and PYY were increased as early as 4 hours after induction of sepsis. Our results suggest that sepsis stimulates the synthesis of endogenous and secretory proteins, including certain gut peptides, in small intestine mucosa. This is consistent with previous observations of increased circulating levels of VIP, PYY and other gastrointestinal hormones during sepsis. The biological significance of increased synthesis of gut peptides and other intestinal proteins during sepsis remains to be determined.

Effect of intraduodenal infusion of tocamphyl on pancreatic exocrine secretion and gastrointestinal hormone release in rats

Tocamphyl is a synthetic choleretic that is derived from a root extract of Curcuma longa, L. We investigated the effect of tocamphyl on pancreatic exocrine secretion and bile flow, and on the release of some gastrointestinal hormones, by administering it intraduodenally using anesthetized rats. Tocamphyl stimulated pancreatic exocrine secretion in terms of volume and amylase output in a dose-related manner. Neither a CCK-receptor antagonist, CR1505 (loxiglumide), nor atropine sulfate infused intravenously suppressed the stimulatory effects of tocamphyl on pancreatic exocrine secretion and bile flow. The stimulatory effect on bile flow was stronger than that on pancreatic exocrine secretion. Plasma secretin levels were augmented with the increasing doses of tocamphyl, but CCK levels were not. These results indicate that intraduodenally administered tocamphyl stimulates pancreatic exocrine secretion and bile flow, and suggest that the stimulatory action is, at least in part, mediated by secretin, but not by either CCK or the cholinergic pathway.

Production of gastrin-releasing peptide by a non-small cell lung carcinoma cell line adapted to serum-free and growth factor-free conditions

Gastrin-releasing peptide is an important growth-modulating factor in developing lung epithelium. It is known to be produced by small cell carcinomas of the lung, and an autocrine loop involving gastrin-releasing peptide and its receptor has been demonstrated in many small cell lung tumors. We investigated whether such an autocrine loop could also be demonstrated in non-small cell lung carcinoma, since gastrin-releasing peptide is known to stimulate human bronchial epithelial cells, from which non-small cell tumors should emerge. We report here that gastrin-releasing peptide is produced by a bronchiolo-alveolar carcinoma cell line (A549) adapted to serum-free and growth factor-free conditions. A549 cells adapted to these conditions, termed A549-R0 cells, display extensive membrane interdigitations, Golgi apparatus, and secretory-like granules, and grow as a mixture of attached colonies and floating cells. Gastrin-releasing peptide is present in the conditioned medium produced by A549-R0 cells. Colony formation of cells derived from a squamous cell carcinoma of the lung, 239T, was stimulated 9-fold by A549-R0 conditioned medium or by authentic gastrin-releasing peptide, measured in serum-free conditions. The growth stimulatory activity was inhibited by a monoclonal antibody to gastrin-releasing peptide. Transcripts for receptors for the bombesin family of peptides were also demonstrated in A549-R0 cells and 239T cells. These results demonstrate that non-small cell lung carcinomas can secrete gastrin-releasing peptide and can also respond to the peptide.

Measurement of gut hormone gene expression: mRNA and peptides

During the past decade numerous methods for measurement of mRNA and peptides have been developed. Since the expression cascade from DNA to protein is regulated at all levels, the methods should be carefully designed to accomplish the purpose of the analysis. Regulation of the nuclear processing, the translational activity and the decay of a particular mRNA changes the proportionality between transcriptional activity and production of prepropeptide. Moreover, the post-translational maturation of the pro-hormones may be attenuated. Detection of mRNA is valuable and feasible because it is easy to generate cDNA probes for most hormones, and because mRNA demonstration unequivocally indicates the cellular site of gene expression. The deduction of preprohormone structures has also made it possible to improve the versatility of radioimmunoassays (RIA). Monospecific antibodies and pure tracers have allowed the development of sequence-specific RIA libraries for bioactive peptides and their precursors. Recently we have introduced a simple processing-independent analysis (PIA) for clinical use, since the post-translational maturation of gut peptides may be changed in gastrointestinal diseases. So far PIA has improved the diagnostic sensitivity for gut hormone tumours.

Expression of peptide YY and mRNA for the NPY/PYY receptor of the Y1 subtype in dorsal root ganglia during rat embryogenesis

We have used in situ hybridization to study the distribution of mRNA for neuropeptide Y (NPY), peptide YY (PYY) and the NPY/PYY receptor of the Y1 subtype during ontogenesis in the rat and immunohistochemistry to analyse peptide immunoreactivity for NPY and PYY. We found that mRNA and immunoreactivity for NYY are transiently expressed in dorsal root ganglia (DRG) at embryonic day 16 (E16). In contrast, neither NPY mRNA nor NPY-like immunoreactivity were found in DRG at any developmental stage. The Y1 receptor mRNA is not expressed in DRG at E16 but it appears in these ganglia later in development (E20) and it is present in DRG of adult rats. In sagittal sections of whole embryos at very early stages of development we found that the onset of PYY mRNA expression is around day 11, when mRNA for PYY is found in the foregut. NPY and Y1-receptor mRNA are not detected in whole embryo sections until around day 14. Therefore, PYY mRNA expression precedes by 2-3 days the expression of mRNA for both NPY and the Y1 receptor. At E14, PYY mRNA is present in trigeminal ganglia and stomach. Our results suggest that PYY is not only a gut hormone but may also act as a neuropeptide with roles in the development of sensory neurons.

Isolation, characterization, and developmental expression of the rat peptide-YY gene

In the present study we describe the isolation, structural characterization, and developmental expression of the gene encoding the intestinal hormone peptide-YY. Examination of the nucleotide sequence of the peptide-YY gene reveals that each of the four exons encodes a functional domain of its mRNA that is analogous to the corresponding exons of the genes encoding two closely related peptides neuropeptide-Y and pancreatic polypeptide. The highly conserved structural organization of the genes encoding this family of three peptides suggests that each gene arose from the duplication of a common ancestral gene. Developmental studies reveal that the peptide-YY gene exhibits a complex pattern of tissue-specific expression in the gastrointestinal tract. Unlike many gastrointestinal hormones, peptide-YY mRNA levels are highest before birth. The pancreas appears to be the major site of peptide-YY gene expression in the fetus, exceeding colonic expression by 7-fold. The abundance of peptide-YY mRNA in the pancreas declines rapidly after birth, in contrast to the colon, where mRNA levels are maintained throughout development into adulthood. Expression of the peptide-YY gene before birth antedates the presence of known enteral secretagogues for this hormone, suggesting alternate mechanisms that control its biosynthesis during development.

Immunoreactivity to peptides belonging to the pancreatic polypeptide family (NPY, aPY, PP, PYY) and to glucagon-like peptide in the endocrine pancreas and anterior intestine of adult lampreys, Petromyzon marinus: an immunohistochemical study

Immunoreactivity of antisera directed against human neuropeptide Y (NPY), anglerfish polypeptide YG (aPY), bovine pancreatic polypeptide (bPP), salmon pancreatic polypeptide (sPP), porcine peptide tyrosine tyrosine (PYY), and salmon glucagon-like peptide (GLP) was investigated in the endocrine pancreas and anterior intestine of adult lampreys, Petromyzon marinus, by immunohistochemical analysis. There was no immunoreactivity to anti-sPP and anti-bPP in any tissue and anti-GLP immunostaining was only present in the anterior intestine. The immunoreactivity to antisera raised against NPY, aPY, and PYY was colocalized within the same small number of cells in the caudal and cranial pancreas of juveniles and the caudal pancreas of upstream migrant adults. These antibodies did not immunostain B- or D-cells and thus, NPY, aPY, and PYY were likely localized in a third cell type (3a) in the lamprey pancreas. Immunostaining of a few cells with only anti-aPY suggested the possibility of a fourth cell type (3b). Immunoreactivity was similar in the cranial and caudal pancreas of male upstream migrants; however, in the female cranial pancreas, a few cells demonstrated intense immunoreaction to anti-aPY, while weaker immunostaining with this antiserum was observed in B-cells. In the intestine of juvenile and upstream migrant lampreys, positive immunostaining to GLP, NPY, aPY, and PYY antibodies was colocalized within the same cell. We believe that this cell may contain PYY/glucagon family peptides. Other intestinal cells immunostained with either GLP or somatostatin-34 antiserum.

[Detection of gut hormone mRNAs by synthetic DNA probes in gut hormone producing tissues]

Synthetic DNA probes were tested as hybridization probes for detecting gut hormone mRNAs. When 4 gut hormones, including gastrin, somatostatin, gastrin-releasing peptide and calcitonin were examined, these probes were shown to be useful for mRNA detection in the tissues producing respective hormones. It was also revealed that there was a good correlation between the concentration of peptides determined by radioimmunoassay and the amounts of mRNAs. This methodology was applied for multiple gut hormone producing tumor with the aim to elucidate the mechanisms responsible for this phenomenon, and demonstrated that the tumor expressed a large amount of mature mRNAs encoding respective hormones. These results indicate that increase of mRNA production is one of the mechanism responsible for multiple gut hormones production by tumor.

Is helodermin produced by medullary thyroid carcinoma cells and normal C-cells? Immunocytochemical evidence

Helodermin is a VIP/secretin-like 35-amino acid peptide originally isolated from the venom of the lizard Gila monster. Recently, helodermin-immunoreactive material was demonstrated in mammalian salivary glands, brain and gut. In the present study 8 human medullary thyroid carcinomas as well as 4 normal thyroid glands were examined immunocytochemically for the presence of helodermin using an antiserum raised against helodermin-(5-35) that does not cross-react with VIP or secretin. Cells displaying helodermin-like immunoreactivity were found in all tumours examined except one. On the whole the helodermin-immunoreactive cells had the same distribution as those storing calcitonin, suggesting coexistence of the two peptides in most of the tumour cells. Also normal human C-cells displayed helodermin immunoreactivity. The results suggest that a peptide chemically related to helodermin is a constituent of human medullary thyroid carcinoma cells as well as of normal C-cells.

A possible high molecular weight precursor to vasoactive intestinal polypeptide sequestered into pheochromocytoma chromaffin granules

Chromaffin granules, the catecholamine storage granules of pheochromocytoma were isolated from five human pheochromocytoma tumors. Vasoactive intestinal polypeptide (VIP) immunoreactivity was detected in all chromaffin granule preparations, paralleling the synthetic VIP antibody binding curve over a range of serial dilutions. In addition, gel filtration revealed an immunoreactive peptide peak coeluting with VIP. However, high molecular weight immunoreactive material was also detected on the column. This high molecular weight material was further characterized by sodium dodecyl sulfate gel electrophoresis, followed by electroblotting onto nitrocellulose paper and detection by anti-VIP antibodies with a secondary antibody conjugated to horseradish peroxidase. A 70 000 dalton immunoreactive band was identified, in which reactivity with anti-VIP antibody was inhibited by VIP; this band did not cross react with non-related antibodies. This 70 000 dalton protein may be an intermediate molecule in the biosynthesis and processing of VIP.

Ontogeny of vasoactive intestinal peptide in the human fetal digestive tract

Immunocytochemistry and radioimmunoassay were used to assess the appearance time and tissue distribution of vasoactive intestinal peptide (VIP) in the digestive tract of the human fetus. By radioimmunoassay, VIP was measurable from 10 weeks of gestation. The peptide was abundantly distributed in the jejuno-ileum and colon, where the tissue peptide concentration rose from 9-14 weeks of gestation (18.4 +/- 4.4 and 22.0 +/- 5.0 pmol/g wet weight, respectively) to 15-21 weeks (83.0 +/- 21.1 and 98.6 +/- 36.4 pmol/g, respectively). Lower concentrations were recorded in pancreas from 9-14 weeks of gestation (4.3 +/- 0.8 pmol/g) to 15-21 weeks (13.9 +/- 3.7 pmol/g). The peptide concentration was 15.6 +/- 1.9 pmol/g in fundus and 25.5 +/- 3.2 pmol/g in antrum from 15 to 21 weeks of gestation. The highest concentration was recorded in duodenum from 15 to 21 weeks of gestation (118.4 +/- 40.8 pmol/g wet weight). Tissue VIP concentration and age were positively correlated in the jejuno-ileum. By immunofluorescence, immunoreactive VIP was localized in nervous fibers in the muscularis externa, in the submucosa and in the lamina propria. Scarce cell bodies were also found in the myenteric plexus. No immunofluorescent endocrine cells were observed. These results suggest: (1) the early appearance of immunoreactive VIP in gut, as early as 10 weeks of gestation; (2) the peptide, localized in nervous structures only, follows the same distribution pattern as that in adults; (3) the development of VIPergic structures is a continuous process, initiated during the 3rd month of pregnancy.