Peptides (v.86, #C)

Influence of glucagon-like peptide 2 on energy homeostasis by Sara Baldassano; Antonella Amato; Flavia Mulè (1-5).
Glucagon like peptide-2 (GLP-2) is a gastrointestinal hormone released from enteroendocrine L-type cells together with glucagon like peptide-1 in response to dietary nutrients. GLP-2 acts through a specific receptor, the GLP-2 receptor, mainly located in the gut and in the brain. Classically, GLP-2 is considered a trophic hormone involved in the maintenance of intestinal epithelial morphology and function. This role has been targeted for therapies promoting repair and adaptive growth of the intestinal mucosa. Recently, GLP-2 has been shown to exert beneficial effects on glucose metabolism specially in conditions related to increased uptake of energy, such as obesity. Several actions of GLP-2 are related to a positive energy balance: GLP-2 increases not only the absorptive surface, but also expression and activity of epithelial brush-border nutrient transporters and digestive enzymes, intestinal blood flow, postprandial chylomicron secretion and it inhibits gastrointestinal motility, providing the opportunity to increase absorption of nutrients. Other actions, including anorexigenic effects, appear in opposition to the energy intake. In this review, we discuss the GLP-2 functions related to energy homeostasis. GLP-2 could be considered an hormone causing positive energy balance, which, however has the role to mitigate the metabolic dysfunctions associated with hyper-adiposity.
Keywords: GLP-2; L-type enteroendocrine cells; Food intake; Obesity; Insulin resistance;

Association between nesfatin-1 levels and metabolic improvements in severely obese patients who underwent biliopancreatic derivation with duodenal switch by David H. St-Pierre; Julie Martin; Hiroyuki Shimizu; Yuko Tagaya; Takahumi Tsuchiya; Simon Marceau; Laurent Biertho; Marjorie Bastien; Sarah-Maude Caron-Cantin; Serge Simard; Denis Richard; Katherine Cianflone; Paul Poirier (6-12).
Nesfatin-1 is a neuroendocrine peptide with potent anorexigenic activity in rodents. The potential role of nesfatin-1 on the regulation of energy balance, metabolic functions and inflammation is currently debated in obese humans. In the present study, nesfatin-1 fluctuations and their associations with metabolic factors were investigated in severely obese patients who underwent biliopancreatic diversion with duodenal switch (BPD/DS) and severely obese controls (SOC).Sixty severely obese patients who underwent BPD/DS and 15 SOC (matched for BMI and age) were included in the study. Associations between nesfatin-1 levels and body composition, glucose metabolism, lipid profile as well as inflammatory markers were evaluated at baseline and over a post-surgery12-month (12 M) period.Body weight was reduced at 6 M and at 12 M in BPD/DS patients (P  < 0.001). Nesfatin-1 levels were reduced at 6 M (women: P  < 0.05) and at 12 M (men and women; P  < 0.001) in BPD/DS patients. At baseline, nesfatin-1 levels negatively correlated with weight, fat (FM) and fat-free mass (FFM) in the whole population (combined BPD/DS and SOC patients). At 12 M, nesfatin-1 concentrations positively correlated with weight, FM, fasting insulin, insulin resistance, total cholesterol, LDL-cholesterol, triglyceride and apoB values. At 12 M, % changes in nesfatin-1 were positively associated with% changes in weight, FM, FFM, fasting insulin, insulin resistance, total cholesterol, LDL-cholesterol, apoB and C-reactive protein.Nesfatin-1 levels decrease following BPD/DS-induced weight loss and are significantly associated with parameters of metabolic health.
Keywords: Nesfatin-1; Biliopancreatic diversion with duodenal switch; Type 2 diabetes; Cardiometabolic health;

Display OmittedPrevious studies have indicated that most trypsin inhibitor-like cysteine-rich domain (TIL)-type protease inhibitors, which contain a single TIL domain with ten conserved cysteines, inhibit cathepsin, trypsin, chymotrypsin, or elastase. Our recent findings suggest that Cys2nd and Cys6th were lost from the TIL domain of the fungal-resistance factors in Bombyx mori, BmSPI38 and BmSPI39, which inhibit microbial proteases and the germination of Beauveria bassiana conidia. To reveal the significance of these two missing cysteines in relation to the structure and function of TIL-type protease inhibitors in B. mori, cysteines were introduced at these two positions (D36 and L56 in BmSPI38, D38 and L58 in BmSPI39) by site-directed mutagenesis. The homology structure model of TIL domain of the wild-type and mutated form of BmSPI39 showed that two cysteine mutations may cause incorrect disulfide bond formation of B. mori TIL-type protease inhibitors. The results of Far-UV circular dichroism (CD) spectra indicated that both the wild-type and mutated form of BmSPI39 harbored predominantly random coil structures, and had slightly different secondary structure compositions. SDS-PAGE and Western blotting analysis showed that cysteine mutations affected the multimerization states and electrophoretic mobility of BmSPI38 and BmSPI39. Activity staining and protease inhibition assays showed that the introduction of cysteine mutations dramaticly reduced the activity of inhibitors against microbial proteases, such as subtilisin A from Bacillus licheniformis, protease K from Engyodontium album, protease from Aspergillus melleus. We also systematically analyzed the key residue sites, which may greatly influence the specificity and potency of TIL-type protease inhibitors. We found that the two missing cysteines in B. mori TIL-type protease inhibitors might be crucial for their inhibitory activities against microbial proteases. The genetic engineering of TIL-type protease inhibitors may be applied in both health care and agricultural industries, and could lead to new methods for breeding fungus-resistant transgenic crops and antifungal transgenic silkworm strains.
Keywords: TIL-type protease inhibitors; Missing cysteines; Inhibitory activities; Microbial proteases; Bombyx mori;

Activation of NPFF2 receptor stimulates neurite outgrowth in Neuro 2A cells through activation of ERK signaling pathway by Hong-ping Yu; Nan Zhang; Ting Zhang; Zi-long Wang; Ning Li; Hong-hai Tang; Run Zhang; Meng-na Zhang; Biao Xu; Quan Fang; Rui Wang (24-32).
Neurite outgrowth is an important process in neural regeneration and plasticity, especially after neural injury, and recent evidence indicates that several Gαi/o protein-coupled receptors play an important role in neurite outgrowth. The neuropeptide (NP)FF system contains two Gαi/o protein-coupled receptors, NPFF1 and NPFF2 receptors, which are mainly distributed in the central nervous system. The aim of the present study was to determine whether the NPFF system is involved in neurite outgrowth in Neuro 2A cells. We showed that Neuro 2A cells endogenously expressed NPFF2 receptor, and the NPFF2 receptor agonist dNPA inhibited cyclic adenosine monophosphate (cAMP) production stimulated by forskolin in Neuro 2A cells. We also demonstrated that NPFF and dNPA dose-dependently induced neurite outgrowth in Neuro 2A cells, which was completely abolished by the NPFF receptor antagonist RF9. Pretreatment with mitogen-activated protein kinase inhibitors PD98059 and U0126 decreased dNPA-induced neurite outgrowth. In addition, dNPA increased phosphorylation of extracellular signal-regulated kinase (ERK) in Neuro 2A cells, which was completely antagonized by pretreatment with U0126. Our results suggest that activation of NPFF2 receptor stimulates neurite outgrowth in Neuro 2A cells through activation of the ERK signaling pathway. Moreover, NPFF2 receptor may be a potential therapeutic target for neural injury and degeneration in the future.
Keywords: NPFF2 receptor; Neurite outgrowth; Neuro 2A cells; MEK/ERK signaling pathway;

Angiotensin-(1-5), an active mediator of renin-angiotensin system, stimulates ANP secretion via Mas receptor by Lamei Yu; Kuichang Yuan; Hoang Thi Ai Phuong; Byung Mun Park; Suhn Hee Kim (33-41).
Angiotensin-(1-5) [Ang-(1-5)], which is a metabolite of Angiotensin-(1-7) [Ang-(1-7)] catalyzed by angiotensin-converting enzyme (ACE), is a pentapeptide of the renin-angiotensin system (RAS). It has been reported that Ang-(1-7) and Ang-(1-9) stimulate the secretion of atrial natriuretic peptide (ANP) via Mas receptor (Mas R) and Ang II type 2 receptor (AT2R), respectively. However, it still remains unknown whether Ang-(1-5) has a similar function to Ang-(1-7). We investigated the effect of Ang-(1-5) on ANP secretion and to define its signaling pathway using isolated perfused beating rat atria. Ang-(1-5) (0.3, 3, 10 μM) stimulated high pacing frequency-induced ANP secretion in a dose-dependent manner. Ang-(1-5)-induced ANP secretion (3 μM) was attenuated by the pretreatment with an antagonist of Mas R (A-779) but not by an antagonist of AT1R (losartan) or AT2R (PD123,319). An inhibitor for phosphatidylinositol 3-kinase (PI3K; wortmannin), protein kinase B (Akt; API-2), or nitric oxide synthase (NOS; L-NAME) also attenuated the augmentation of ANP secretion induced by Ang-(1-5). Ang-(1-5)-induced ANP secretion was markedly attenuated in isoproterenol-treated hypertrophied atria. The secretagogue effect of Ang-(1-5) on ANP secretion was similar to those induced by Ang-(1-9) and Ang-(1-7). These results suggest that Ang-(1-5) is an active mediator of renin-angiotensin system to stimulate ANP secretion via Mas R and PI3K-Akt-NOS pathway.
Keywords: Atrial natriuretic peptide; Angiotensin-(1-5); Angiotensin-(1-7); Receptor; Isoproterenol; Hypertrophy;

Identification and functional characterization of a pyrokinin neuropeptide receptor in the Lyme disease vector, Ixodes scapularis by Kinsi Gondalia; Anam Qudrat; Brigida Bruno; Janet Fleites Medina; Jean-Paul V. Paluzzi (42-54).
Pyrokinin-related peptides are pleiotropic factors that are defined by their conserved C-terminal sequence FXPRL-NH2. The pyrokinin nomenclature derives from their originally identified myotropic actions and, as seen in some family members, a blocked amino terminus with pyroglutamate. The black-legged tick, Ixodes scapularis, is well known as a vector of Lyme disease and various other illnesses; however, in comparison to blood-feeding insects, knowledge on its physiology (along with other Ixodid ticks) is rather limited. In this study, we have isolated, examined the expression profile, and functionally deorphanized the pyrokinin peptide receptor in the medically important tick, I. scapularis. Phylogenetic analysis supports that the cloned receptor is indeed a bona fide member of the pyrokinin-related peptide receptor family. The tick pyrokinin receptor transcript expression is most abundant in the central nervous system (i.e. synganglion), but is also detected in trachea, female reproductive tissues, and in a pooled sample comprised of Malpighian (renal) tubules and the hindgut. Finally, functional characterization of the identified receptor confirmed it as a pyrokinin peptide receptor as it was activated equally by four endogenous pyrokinin-related peptides. The receptor was slightly promiscuous as it was also activated by a peptide sharing some structural similarity, namely the CAPA-periviserokinin (CAPA-PVK) peptide. Nonetheless, the I. scapularis pyrokinin receptor required a CAPA-PVK peptide concentration of well over three orders of magnitude to achieve a comparable receptor activation response, which indicates it is quite selective for its native pyrokinin peptide ligands. This study sets the stage for future research to examine the prospective tissue targets identified in order to resolve the physiological roles of this family of peptides in Ixodid ticks.
Keywords: Lyme disease; Ixodes scapularis; Pyrokinin peptide; G protein coupled receptor (GPCR); Pheromone biosynthesis activating neuropepitde (PBAN); Diapause hormone (DH); Neuropeptide; Periviscerokinin; Capability gene;

RISK pathway is involved in oxytocin postconditioning in isolated rat heart by Mirali Polshekan; Kadijeh Jamialahmadi; Vahid Khori; Ali Mohammad Alizadeh; Mohsen Saeidi; Majid Ghayour-Mobarhan; Yahya Jand; Mohammad Hossein Ghahremani; Yaghoub Yazdani (55-62).
The reperfusion injury salvage kinase (RISK) pathway is a fundamental signal transduction cascade in the cardioprotective mechanism of ischemic postconditioning. In the present study, we examined the cardioprotective role of oxytocin as a postconditioning agent via activation of the RISK pathway (PI3K/Akt and ERK1/2).Animals were randomly divided into 6 groups. The hearts were subjected under 30 minutes (min) ischemia and 100 min reperfusion. OT was perfused 15 min at the early phase of reperfusion. RISK pathway inhibitors (Wortmannin; an Akt inhibitor, PD98059; an ERK1/2 inhibitor) and Atosiban (an OT receptor antagonist) were applied either alone 10 min before the onset of the ischemia or in the combination with OT during early reperfusion phase. Myocardial infarct size, hemodynamic factors, ventricular arrhythmia, coronary flow and cardiac biochemical marker were measured at the end of reperfusion.OT postconditioning (OTpost), significantly decreased the infarct size, arrhythmia score, incidence of ventricular fibrillation, Lactate dehydrogenase and it increased coronary flow. The cardioprotective effect of OTpos was abrogated by PI3K/Akt, ERK1/2 inhibitors and Atosiban.Our data have shown that OTpost can activate RISK pathway mostly via the PI3K/Akt and ERK1/2 signaling cascades during the early phase of reperfusion.
Keywords: Isolated heart preparation; Myocardial reperfusion injury; Myocardial ischemia; Oxytocin;

Blockage of neonatal leptin signaling induces changes in the hypothalamus associated with delayed pubertal onset and modifications in neuropeptide expression during adulthood in male rats by Virginia Mela; Sara Jimenez; Alejandra Freire-Regatillo; Vicente Barrios; Eva-María Marco; Ana-Belén Lopez-Rodriguez; Jesús Argente; María-Paz Viveros; Julie A. Chowen (63-71).
The neonatal leptin surge, occurring from postnatal day (PND) 5 to 13 and peaking at PND9 in rodents, is important for the development of neuroendocrine circuits involved in metabolic control and reproductive function. We previously demonstrated that treatment with a leptin antagonist from PND 5 to 9, coincident with peak leptin levels in the neonatal surge, modified trophic factors and markers of cell turnover and neuronal maturation in the hypothalamus of peri-pubertal rats. The kisspeptin system and metabolic neuropeptide and hormone levels were also modified. Here our aim was to investigate if the timing of pubertal onset is altered by neonatal leptin antagonism and if the previously observed peripubertal modifications in hormones and neuropeptides persist into adulthood and affect male sexual behavior. To this end, male Wistar rats were treated with a pegylated super leptin antagonist (5 mg/kg, s.c.) from PND 5 to 9 and killed at PND102–103. The appearance of external signs of pubertal onset was delayed. Hypothalamic kiss1 mRNA levels were decreased in adult animals, but sexual behavior was not significantly modified. Although there was no effect on body weight or food intake, circulating leptin, insulin and triglyceride levels were increased, while hypothalamic leptin receptor, POMC and AgRP mRNA levels were decreased. In conclusion, alteration of the neonatal leptin surge can modify the timing of pubertal onset and have long-term effects on hypothalamic expression of reproductive and metabolic neuropeptides.
Keywords: Leptin antagonist; Kisspeptin; Puberty; Sexual behavior;

The PLC/PKC/Ras/MEK/Kv channel pathway is involved in uncarboxylated osteocalcin-regulated insulin secretion in rats by Jingying Gao; Tao Bai; Lele Ren; Yaqin Ding; Xiangqin Zhong; Hui Wang; Yangyan Guo; Jie Li; Yunfeng Liu; Yi Zhang (72-79).
Uncarboxylated osteocalcin, a bone matrix protein, has been proposed to regulate glucose metabolism by increasing insulin secretion, improving insulin sensitivity and stimulating β cell proliferation. Our previous study also indicated that uncarboxylated osteocalcin stimulates insulin secretion by inhibiting voltage-gated potassium (KV) channels. The goal of this study is to further investigate the underlying mechanisms for the regulation of Kv channels and insulin secretion by uncarboxylated osteocalcin. Insulin secretion and Kv channel currents were examined by radioimmunoassay and patch-clamp technique, respectively. Calcium imaging system was applied to measure intracellular Ca2+ concentration ([Ca2+]i). The protein levels were detected by western blot. The results showed that uncarboxylated osteocalcin potentiated insulin secretion, inhibited Kv channels and increased [Ca2+]i compared to control. These effects were suppressed by phospholipase-C (PLC)/protein kinase C (PKC)/Ras/MAPK-ERK kinase (MEK) signaling pathway, indicating that this signaling pathway plays an important role in uncarboxylated osteocalcin-regulated insulinotropic effect. In addition, the results also showed that adenylyl cyclase (AC) did not influence the effect of uncarboxylated osteocalcin on insulin secretion and Kv channels, suggesting that AC is not involved in uncarboxylated osteocalcin-stimulated insulin secretion. These findings provide new insight into the mechanism of uncarboxylated osteocalcin-regulated insulin secretion.
Keywords: Uncarboxylated osteocalcin; Voltage-gated potassium channel; Phospholipase-C; Insulin secretion;

The plasma levels of CST and BCKDK in patients with sepsis by Bo Zhang; Gui-Zhi Sun; Min-Ling Zhu; Yue Li; Dian-jun Sun; Bo Zhang; Xiu-Ping Bai (80-84).
CST has been recently identified as a mediator of various beneficial effects in animal models of sepsis. At present, no data are available concerning the levels of CST in sepsis patients. In sepsis the plasma amino acid pattern is characterized by decreased branced chain amino acids (BCAAs). We investigated the levels of plasma CST or branched-chain α-ketoacid dehydrogenase kinase (BCKDK) and their relationship to component traits in patients with sepsis.We studied 228 patients and divided them into two groups based on severity of infection. Blood samples were taken at study entry, and CST, BCKDK were measured.CST and BCKDK levels were significantly higher in patients with sepsis than in controls: the median plasma CST concentration was 103.1 ng/ml (range, <83.13–189.7 ng/ml) in patients with sepsis and 49.69 ng/ml (range, <19.38–100.8 ng/ml) in controls (p  = 0.0022); the median plasma BCKDK concentration was 801.7 ng/ml in sepsis group and 745 ng/ml in controls (p  = 0.0292). Additionally, there was correlation between the plasma concentrations of CST and BCKDK in sepsis patients (r2  = 0.6357, p  < 0.01).We conclude that the plasma levels of CST in sepsis patients were higher than in controls, and there is a relationship between CST and BCKDK in sepsis patients. Future experimental and clinical studies are needed to evaluate CST as a novel prognostic tool in sepsis patients and its potential therapeutic use in sepsis.
Keywords: Sepsis; Cortistatin; BCKDK;

Ascending aortic adventitial remodeling and fibrosis are ameliorated with Apelin-13 in rats after TAC via suppression of the miRNA-122 and LGR4-β-catenin signaling by Ran Xu; Zhen-Zhou Zhang; Lai-Jiang Chen; Hui-Min Yu; Shu-Jie Guo; Ying-Le Xu; Gavin Y. Oudit; Yan Zhang; Qing Chang; Bei Song; Dong-Rui Chen; Ding-Liang Zhu; Jiu-Chang Zhong (85-94).
Apelin has been proved to be a critical mediator of vascular function and homeostasis. Here, we investigated roles of Apelin in aortic remodeling and fibrosis in rats with transverse aortic constriction (TAC). Male Sprague-Dawley rats were subjected to TAC and then randomized to daily deliver Apelin-13 (50 μg/kg) or angiotensin type 1 receptor (AT1) blocker Irbesartan (50 mg/kg) for 4 weeks. Pressure overload resulted in myocardial hypertrophy, systolic dysfunction, aortic remodeling and adventitial fibrosis with reduced levels of Apelin in ascending aortas of rat after TAC compared with sham-operated group. These changes were associated with marked increases in levels of miRNA-122, TGFβ1, CTGF, NFAT5, LGR4, and β-catenin. More importantly, Apelin and Irbesartan treatment strikingly prevented TAC-mediated aortic remodeling and adventitial fibrosis in pressure overloaded rats by blocking AT1 receptor and miRNA-122 levels and repressing activation of the CTGF-NFAT5 and LGR4-β-catenin signaling. In cultured primary rat adventitial fibroblasts, exposure to angiotensin II (100 nmol L−1) led to significant increases in cellular migration and levels of TGFβ1, CTGF, NFAT5, LGR4 and β-catenin, which were effectively reversed by pre-treatment with Apelin (100 nmol L−1) and miRNA-122 inhibitor (50 nmol L−1). In conclusion, Apelin counterregulated against TAC-mediated ascending aortic remodeling and angiotensin II-induced promotion of cellular migration by blocking AT1 receptor and miRNA-122 levels and preventing activation of the TGFβ1-CTGF-NFAT5 and LGR4-β-catenin signaling, ultimately contributing to attenuation of aortic adventitial fibrosis. Our data point to Apelin as an important regulator of aortic remodeling and adventitial fibrosis and a promising target for vasoprotective therapies.
Keywords: Apelin; Aortic remodeling; Angiotensin II; LGR4; Adventitial fibrosis; Pressure overload;

Glucagon-like peptide-1 (GLP-1) and its analogues have a beneficial role in cardiovascular system. Here, we aimed to investigate whether liraglutide, a GLP-1 analogue, modulated angiogenesis impaired by palmitic acid (PA) in cultured human umbilical vein endothelial cells (HUVECs). Cells were incubated with liraglutide (3–100 nmol/L) in the presence of PA (0.5 mmol/L), and endothelial tube formation was observed and quantified. The protein levels of signaling molecules were analyzed and the specific inhibitors were used to identify the signaling pathways through which liraglutide affected angiogenesis. Results showed that liraglutide ameliorated endothelial tube formation impaired by PA in HUVECs in a dose-dependent manner. Meanwhile, liraglutide increased the phosphorylation of Akt and forkhead box O1 (Foxo1), and upregulated the levels of guanosine 5′-triphosphate cyclohydrolase 1 (GTPCH1) and endothelial nitric oxide synthase (eNOS) in PA-impaired HUVECs. Notably, addition of the PI3K inhibitor LY294002, Foxo1 nuclear export inhibitor trifluoperazine dihydrochloride (TFP), GTPCH1 inhibitor 2,4-diamino-6-hydroxypyrimidine (DAHP) or NOS inhibitor N-nitro-l-arginine-methyl ester (L-NAME) eliminated the angiogenic effect of liraglutide. Moreover, either LY294002 or TFP abolished the liraglutide-induced upregulation of GTPCH1 and eNOS protein levels. In conclusion, liraglutide restores angiogenesis in PA-impaired HUVECs. The effect is mediated via upregulation of GTPCH1 and eNOS levels in a PI3K/Akt-Foxo1-dependent mechanism.
Keywords: Liraglutide; Angiogenesis; Foxo1; GTPCH1;

Carnosine ameliorates cognitive deficits in streptozotocin-induced diabetic rats: Possible involved mechanisms by Siamak Ahshin-Majd; Samira Zamani; Taktom Kiamari; Zahra Kiasalari; Tourandokht Baluchnejadmojarad; Mehrdad Roghani (102-111).
Diabetic patients are at increased risk to develop cognitive deficit and senile dementia. This study was planned to assess the benefits of chronic carnosine administration on prevention of learning and memory deterioration in streptozotocin (STZ)-diabetic rats and to explore some of the involved mechanisms. Rats were divided into 5 groups: i.e., control, carnosine100-treated control, diabetic, and carnosine-treated diabetics (50 and 100 mg/kg). Carnosine was injected i.p. at doses of 50 or 100 mg/kg for 7 weeks, started 1 week after induction of diabetes using streptozotocin. Treatment of diabetic rats with carnosine at a dose of 100 mg/kg at the end of the study lowered serum glucose, improved spatial recognition memory in Y maze, improved retention and recall in elevated plus maze, and prevented reduction of step-through latency in passive avoidance task. Furthermore, carnosine at a dose of 100 mg/kg reduced hippocampal acetylcholinesterase (AChE) activity, lowered lipid peroxidation, and improved superoxide dismutase (SOD) activity and non-enzymatic antioxidant defense element glutathione (GSH), but not activity of catalase. Meanwhile, hippocampal level of nuclear factor-kappaB (NF-κB), tumor necrosis factor α (TNF-α), and glial fibrillary acidic protein (GFAP) decreased and level of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase 1 (HO-1) increased upon treatment of diabetic group with carnosine at a dose of 100 mg/kg. Taken together, chronic carnosine treatment could ameliorate learning and memory disturbances in STZ-diabetic rats through intonation of NF-κB/Nrf2/HO-1 signaling cascade, attenuation of astrogliosis, possible improvement of cholinergic function, and amelioration of oxidative stress and neuroinflammation.
Keywords: Diabetes mellitus; Streptozotocin; Carnosine; Learning and memory; Cognition;

The predictive value of plasma catestatin for all-cause and cardiac deaths in chronic heart failure patients by Fen Peng; Songyun Chu; Wenhui Ding; Lin Liu; Jing Zhao; Xiaojing Cui; Renxu Li; Jie Wang (112-117).
In the present study, we found:Catestatin (CST) is a proteolytic fragment of Chromogranin A with a broad spectrum of activities in the cardiovascular system. The level of plasma CST increases in chronic heart failure patients, but its potential relationship to patient prognosis is unknown. In this study, we measured plasma CST levels in 202 chronic heart failure patients and followed them for a median of 52.5 months. The plasma CST level was higher in patients with all-cause death and cardiac death than in survivors. According to univariate COX regression, higher plasma CST levels predicted increased risk of all-cause and cardiac death. After adjustment for other confounding factors, plasma CST was an independent risk factor for both outcomes, and the hazard ratios (HRs) were 1.84 (95% CI: 1.02–3.32, p = 0.042) and 2.41 (95% CI: 1.26–4.62, p = 0.008) for all-cause death and cardiac death, respectively. The new risk-predictive model considering CST was superior to the previous model for both outcomes by ANOVA and likelihood ratio tests (p = 0.040 and p = 0.008, respectively). Concurrent increases in plasma BNP (B-type natriuretic peptide) and CST levels predicted the highest risk for both all-cause and cardiac deaths [HR = 5.18 (95% CI: 1.94–13.87, p = 0.001) and HR = 9.19 (95% CI: 2.75–30.78, p < 0.001), respectively]. Large-scale studies are needed to further assess the value of plasma CST in predicting heart failure prognosis.
Keywords: Catestatin; Heart failure; Prognosis; All-cause death; Cardiac death;

Metformin, α-glucosidase inhibitors (α-GIs), and dipeptidyl peptidase 4 inhibitors (DPP-4Is) reduce hyperglycemia without excessive insulin secretion, and enhance postprandial plasma concentration of glucagon-like peptide-1 (GLP-1) in type-2 diabetes mellitus (T2DM) patients. We assessed add-on therapeutic effects of DPP-4I anagliptin in Japanese T2DM patients treated with metformin, an α-GI miglitol, or both drugs on postprandial responses of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), and on plasma concentration of the appetite-suppressing hormone leptin. Forty-two Japanese T2DM patients with inadequately controlled disease (HbA1c: 6.5%–8.0%) treated with metformin (n = 14), miglitol (n = 14) or a combination of the two drugs (n = 14) received additional treatment with anagliptin (100 mg, p.o., b.i.d.) for 52 weeks. We assessed glycemic control, postprandial responses of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), and on plasma concentration of leptin in those patients. Add-on therapy with anagliptin for 52 weeks improved glycemic control and increased the area under the curve of biologically active GLP-1 concentration without altering obesity indicators. Total GIP concentration at 52 weeks was reduced by add-on therapy in groups treated with miglitol compared with those treated with metformin. Add-on therapy reduced leptin concentrations. Add-on therapy with anagliptin in Japanese T2DM patients treated with metformin and miglitol for 52 weeks improved glycemic control and enhanced postprandial concentrations of active GLP-1/total GIP, and reduce the leptin concentration.
Keywords: Type-2 diabetes mellitus; DPP-4I; GLP-1; &alpha; Metformin;

Regional specificity of the gut-incretin response to small intestinal glucose infusion in healthy older subjects by Rachael S. Rigda; Laurence G. Trahair; Tanya J. Little; Tongzhi Wu; Scott Standfield; Christine Feinle-Bisset; Christopher K. Rayner; Michael Horowitz; Karen L. Jones (126-132).
The importance of the region, as opposed to the length, of small intestine exposed to glucose in determining the secretion of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) remains unclear. We sought to compare the glycemic, insulinemic and incretin responses to glucose administered to the proximal (12–60 cm beyond the pylorus), or more distal ( > 70 cm beyond the pylorus) small intestine, or both. 10 healthy subjects (9M,1F; aged 70.3 ± 1.4 years) underwent infusion of glucose via a catheter into the proximal (glucose proximally; GP), or distal (glucose distally; GD) small intestine, or both (GPD), on three separate days in a randomised fashion. Blood glucose, serum insulin and plasma GLP-1, GIP and CCK responses were assessed. The iAUC for blood glucose was greater in response to GPD than GP (P < 0.05), with no difference between GD and GP. GP was associated with minimal GLP-1 response (P = 0.05), but substantial increases in GIP, CCK and insulin (P < 0.001 for all). GPD and GD both stimulated GLP-1, GIP, CCK and insulin (P < 0.001 for all). Compared to GP, GPD induced greater GLP-1, GIP and CCK responses (P < 0.05 for all). Compared with GPD, GD was associated with greater GLP-1 (P < 0.05), but reduced GIP and CCK (P < 0.05 for both), responses. We conclude that exposure of glucose to the distal small intestine appears necessary for substantial GLP-1 secretion, while exposure of both the proximal and distal small intestine result in substantial secretion of GIP.
Keywords: Glucagon-like peptide-1; Glucose-dependent insulinotropic polypeptide; Incretin; Glucose; Older subjects;

Accruing evidence have confirmed that the fetal programming in response to adverse environmental in utero factors plays essential roles in the pathogenesis of hypertension in later life. High sugar intake has been accepted worldwide in everyday life diet and becomes the critical public health issue. Our previous studies indicated that intake of high sucrose (HS) during pregnancy could change the vascular reactivity and dipsogenic behavior closely associated with abnormal renin-angiotensin system (RAS), to increase the risk of hypertension in adult offspring. In the present study, we tested the hypothesis that maternal HS intake in pregnancy may further deteriorate the Ang II-induced cardiovascular responses in the aged offspring. HS intake was provided to pregnant rats throughout the gestation. Blood pressure (BP) in conscious state and vascular contractility in vitro were measured in 22-month-old aged offspring rats. In addition, mRNA and protein expressions and epigenetic changes of Ang II type 1 receptor (AT1R) gene in blood vessels were determined with the methods of real-time RT-PCR, Western blotting, and Chromatin Immunoprecipitation Assay (CHIP). Results showed that, in the aged offspring, maternal HS intake during gestation would cause the elevation of basal BP which could be diminished by losartan. Although the circulatory Ang II was not changed, levels of local Ang II were significantly increased in blood vessels. In addition, prenatal HS exposure would significantly enhance the AT1R-mediated vasoconstrictions in both aorta and mesenteric arteries of the aged offspring. Moreover, in the aged offspring of prenatal HS exposure, mRNA and protein expressions of AT1R gene in both large and small blood vessels were significantly increased, which should be closely associated with the changes of epigenetic mechanisms such as histone modifications. Collectively, we proposed that maternal HS intake during gestation would cause abnormal BP responses mediated via the enhancement of vascular RAS, together with the increased expression of AT1R gene related to the its epigenetic changes, which would actually lead to the overt phenotype of hypertension in the aged offspring.
Keywords: High sucrose; Angiotensin; Aged offspring; Hypertension; Epigenetics;

Reduced intake of carbohydrate prevents the development of obesity and impaired glucose metabolism in ghrelin O-acyltransferase knockout mice by Tetsuya Kouno; Nobuteru Akiyama; Kumiko Fujieda; Isamu Nanchi; Tomohiko Okuda; Takanori Iwasaki; Shogo Oka; Hideo Yukioka (145-152).
A close relationship between acylated-ghrelin and sucrose intake has been reported. However, little has been examined about the physiological action of ghrelin on preference for different types of carbohydrate such as glucose, fructose, and starch. The current study was aimed to investigate the role of acylated-ghrelin in the determinants of the choice of carbohydrates, and pathogenesis of chronic disorders, including obesity and insulin resistance. In a two-bottle-drinking test, ghrelin O-acyltransferase (GOAT) knockout (KO) mice consumed a less amount of glucose and maltodextrin, and almost the same amount of fructose and saccharin solution compared to WT littermates. The increased consumption of glucose and maltodextrin was observed when acylated-ghrelin, but not unacylated-ghrelin, was exogeneously administered in normal C57BL/6J mice, suggesting an association of acylated-ghrelin with glucose-containing carbohydrate intake. When fed a diet rich in maltodextrin, starch and fat for 12 weeks, GOAT KO mice showed less food intake and weight gain, as well as improved glucose tolerance and insulin sensitivity than WT mice. Our data suggests that blockade of GOAT activity may offer a therapeutic option for treatment of obesity and its associated metabolic syndrome by preventing from overconsumption of carbohydrate-rich food.
Keywords: Ghrelin; Carbohydrate; Body weight; Food intake;

Growth hormone-releasing hormone induced transactivation of epidermal growth factor receptor in human triple-negative breast cancer cells by Eva Vacas; Laura Muñoz-Moreno; Pedro L. Valenzuela; Juan C. Prieto; Andrew V. Schally; María J. Carmena; Ana M. Bajo (153-161).
Triple-negative breast cancer (TNBC) is a subset of breast cancers which is negative for expression of estrogen and progesterone receptors and human epidermal growth factor receptor-2 (HER2). Chemotherapy is currently the only form of treatment for women with TNBC. Growth hormone-releasing hormone (GHRH) and epidermal growth factor (EGF) are autocrine/paracrine growth factors in breast cancer and a substantial proportion of TNBC expresses receptors for GHRH and EGF. The aim of this study was to evaluate the interrelationship between both these signaling pathways in MDA-MB-468 human TNBC cells. We evaluated by Western blot assays the effect of GHRH on transactivation of EGF receptor (EGFR) as well as the elements implicated. We assessed the effect of GHRH on migration capability of MDA-MB-468 cells as well as the involvement of EGFR in this process by means of wound-healing assays. Our findings demonstrate that in MDA-MB-468 cells the stimulatory activity of GHRH on tyrosine phosphorylation of EGFR is exerted by two different molecular mechanisms: i) through GHRH receptors, GHRH stimulates a ligand-independent activation of EGFR involving at least cAMP/PKA and Src family signaling pathways; ii) GHRH also stimulates a ligand-dependent activation of EGFR implicating an extracellular pathway with an important role for metalloproteinases. The cross-talk between EGFR and GHRHR may be impeded by combining drugs acting upon GHRH receptors and EGFR family members. This combination of GHRH receptors antagonists with inhibitors of EGFR signalling could enhance the efficacy of both types of agents as well as reduce their doses increasing therapeutic benefits in management of human breast cancer.
Keywords: GHRH; Triple-negative breast cancer; EGFR; Transactivation; Cell migration; GHRH antagonist;

Knowledge about neuroendocrine mechanisms regulating appetite in fish, including the role of leptin, is inconclusive. We investigated leptin mRNA abundance in various tissues, plasma leptin levels and the hypothalamic gene expression of putative orexigenic (neuropeptide Y and agouti-regulated peptide) and anorexigenic (melanocortin receptor, proopiomelanocortins (POMCs), cocaine- and amphetamine-regulated transcript and corticotropin-releasing factor) neuropeptides in relation to feeding status in rainbow trout (Oncorhynchus mykiss). Blood and tissues were first (Day 1) sampled from trout that had been fed or fasted for 4 months and the day after (Day 2) from fasted fish after they had been given a large meal, and their continuously fed counterparts. The fasted fish ate vigorously when they were presented a meal. There were no differences between fed, fasted and re-fed fish in hypothalamic neuropeptide transcript levels, except for pomca1 and pomcb, which were higher in fasted fish than in fed fish at Day 1, and which, for pomcb, decreased to the level in fed fish after the meal at Day 2. Plasma leptin levels did not differ between fasted, re-fed and fed fish. A higher leptina1 transcript level was seen in the belly flap of fasted fish than in fed fish, even after re-feeding on Day 2. The data do not reveal causative roles of the investigated brain neuropeptides, or leptin, in appetite regulation. It is suggested that the elevated pomc transcript levels provide a satiety signal that reduces energy expenditure during prolonged fasting. The increase in belly flap leptin transcript with fasting, which did not decrease upon re-feeding, indicates a tissue-specific role of leptin in long-term regulation of energy homeostasis.
Keywords: Appetite; Hypothalamus; Neuropeptides; Leptin; Fish; Fasting;