Intracerebroventricular injection of spexin stimulates the hypothalamic-pituitary-testicular axis and increases the secretion of male reproductive hormones in rats.

BACKGROUND: Male reproductive functions are regulated in the hypothalamic-pituitary-gonadal (HPG) axis. Any problem in this axis would lead to the deterioration of reproductive functions. The present study aimed to investigate the effects of intracerebroventricular (icv) Spexin (SPX) infusion on the HPG axis in detail. METHODS: 40 Wistar albino rats were divided into four groups: control, sham, SPX 30 nmol and SPX 100 nmol (n=10). 30 nmol/1 µl/hour SPX was administered icv to the rats in the SPX 30 nmol group for 7 days, while rats in the SPX 100 nmol group were administered 100 nmol/1 µl/hour SPX. On the 7th day, the rats were decapitated, blood and tissue samples were collected. Serum LH, FSH and testosterone levels were determined with the ELISA method, GnRH mRNA expression level was determined in hypothalamus with the RT-PCR method. Seminiferous tubule diameter and epithelial thickness were determined with the hematoxylin-eosin staining method. RESULTS: SPX infusion was increased GnRH mRNA expression in the hypothalamus tissue independent of the dose (p<0.05). Serum LH, FSH and testosterone levels in the SPX groups were increased when compared to the control and sham groups independent of the dose (p <0.05). Histological analysis revealed that SPX infusion did not lead to any changes in seminiferous epithelial thickness, while the tubule diameter increased in the SPX groups (p<0.05). CONCLUSION: The study findings demonstrated that icv SPX infusion stimulated the HPG axis and increased the secretion of male reproductive hormones.

Early erythroferrone levels can predict the long-term haemoglobin responses to erythropoiesis-stimulating agents.

BACKGROUND AND PURPOSE: Our previous study reported that erythroferrone (ERFE), a newly identified hormone produced by erythroblasts, responded to recombinant human erythropoietin (rHuEPO) sensitively but its dynamics was complicated by double peaks and circadian rhythm. This study intends to elucidate the underlying mechanisms for the double peaks of ERFE dynamics and further determine whether early ERFE measurements can predict haemoglobin responses to rHuEPO. EXPERIMENTAL APPROACH: By using the purified recombinant rat ERFE protein and investigating its deposition in rats, the production of ERFE was deconvoluted. To explore the role of iron in ERFE production, we monitored short-term changes of iron status after injection of rHuEPO or deferiprone. Pharmacokinetic/pharmacodynamic (PK/PD) modelling was used to confirm the mechanisms and examine the predictive ability of ERFE for long-term haemoglobin responses. KEY RESULTS: The rRatERFE protein was successfully purified. The production of ERFE was deconvoluted and showed two independent peaks (2 and 8 h). Transient iron decrease was observed at 4 h after rHuEPO injection and deferiprone induced significant increases of ERFE. Based on this mechanism, the PK/PD model could characterize the complex dynamics of ERFE. In addition, the model predictions further revealed a stronger correlation between ERFE and haemoglobin peak values than that for observed values. CONCLUSIONS AND IMPLICATIONS: The complex dynamics of ERFE should be composited by an immediate release and transient iron deficiency-mediated secondary production of ERFE. The early peak values of ERFE, which occur within a few hours, can predict haemoglobin responses several weeks after ESA treatment.

Asprosin, a novel therapeutic candidate for painful neuropathy: an experimental study in mice.

Recent studies indicate presence of a strong link between adipokines and neuropathic pain. However, the effects of asprosin, a novel adipokine, on neuropathic pain have not been studied in animal models.Mouse models were employed to investigate the antinociceptive effectiveness of asprosin in the treatment of three types of neuropathic pain, with metabolic (streptozocin/STZ), toxic (oxaliplatin/OXA), and traumatic (sciatic nerve ligation/CCI [chronic constriction nerve injury]) etiologies, respectively. Changes in nociceptive behaviors were assessed relative to controls using thermal (the hot plate and cold plate tests, at 50 °C and 4 °C respectively) and mechanical pain (von Frey test) tests after intraperitoneal (i.p.) administration of asprosin (10 µg/kg) and gabapentin (50 mg/kg) in several times intervals. Besides, possible effect of asprosin on the motor coordination of mice was assessed with a rotarod test. Serum level of asprosin was quantified by ELISA.In neuropathic pain models (STZ, OXA, and CCI), asprosin administration significantly reduced both mechanical and thermal hypersensitivity, indicating that it exhibits a clear-cut antihypersensitivity effect in the analyzed neuropathic pain models. The most effective time of asprosin on pain threshold was observed 60 min after its injection. Also, asprosin displayed no notable effect on the motor activity. Asprosin levels were significantly lower in neuropathic pain compared to healthy group (p < 0.05).The results yielded by the present study suggest that asprosin exhibits an analgesic effect in the neuropathic pain models and may have clinical utility in alleviating chronic pain associated with disease and injury originating from peripheral structures.

30-Day spexin treatment of mice with diet-induced obesity (DIO) and type 2 diabetes (T2DM) increases insulin sensitivity, improves liver functions and metabolic status.

Spexin (SPX) is a 14 aa peptide discovered in 2007 using bioinformatics methods. SPX inhibits food intake and regulates lipid, and carbohydrate metabolism. Here, we evaluate the ability of SPX at improving metabolic control and liver function in obese and type 2 diabetic animals. The effects of 30 days SPX treatment of mice with experimentally induced obesity (DIO) or type 2 diabetes (T2DM) on serum glucose and lipid levels, insulin sensitivity and hormonal profile (insulin, glucagon, adiponectin, leptin, TNF alpha, IL-6 and IL-1ß) are characterized. In addition, alterations of hepatic lipid and glycogen contents are evaluated. We report that SPX decreases body weight in healthy and DIO mice, and reduces lipid content in all three animal groups. SPX improves insulin sensitivity in DIO and T2DM animals. In addition, SPX modulates hormonal and metabolic profile by regulating the concentration of adiponectin (concentration increase) and leptin (concentration decrease) in the serum blood of DIO and T2DM mice. Lastly, SPX decreases lipid content as well as IL-6 and TNF-α protein levels in liver of DIO and T2DM mice, and reduces IL-6 and TNF-alpha concentrations in the serum derived from T2DM mice. Based on our results, we conclude that SPX could be involved in the development of obesity and type 2 diabetes mellitus and it can be further evaluated as a potential target for therapy of DIO and T2DM.

Short-term administration of spexin in rats reduces obesity by affecting lipolysis and lipogenesis: An in vivo and in vitro study.

The present study aimed to characterize the role of spexin (SPX) in maintaining glucose and lipid homeostasis in vivo in rats with diet-induced obesity. The in vitro effect of spexin on metabolic and endocrine functions of adipocytes isolated from obese rats was also investigated. The in vivo experiment was conducted on rats with diet-induced obesity and administered with SPX for 7 days. Lipid and carbohydrate parameters, liver markers, and hormonal profile were measured. In in vitro studies, adipocytes isolated from obese rats were used. The effect of SPX on lipolysis, lipogenesis, and leptin secretion from fat cells was assessed. The results showed that short-term administration of SPX causes weight loss, increases insulin sensitivity, and improves the metabolic state of obese rats. The in vitro experiments showed that spexin and its receptors, namely galanin receptor 2 (GALR2) and galanin receptor 3 (GALR3), were expressed in various fat depots and in adipocytes from obese rats. We also found that the addition of spexin increased the basal and isoproterenol-stimulated lipolysis and reduced the basal and insulin-stimulated lipogenesis in adipocytes isolated from obese rats. Molecular analysis showed that SPX activated hormone-sensitive lipase (HSL) phosphorylation and upregulated perilipin and HSL mRNA expression. These results suggest that SPX regulates metabolism of obese rats by affecting lipolysis and lipogenesis in adipocytes. Moreover, the present study for the first time demonstrates that SPX modulates leptin synthesis and secretion from isolated adipocytes.

ELABELA antagonizes intrarenal renin-angiotensin system to lower blood pressure and protects against renal injury.

Emerging evidence has demonstrated that (pro)renin receptor (PRR)-mediated activation of intrarenal renin-angiotensin system (RAS) plays an essential role in renal handling of Na+ and water balance and blood pressure. The present study tested the possibility that the intrarenal RAS served as a molecular target for the protective action of ELABELA (ELA), a novel endogenous ligand of apelin receptor, in the distal nephron. By RNAscope and immunofluorescence, mRNA and protein expression of endogenous ELA was consistently localized to the collecting duct (CD). Apelin was also found in the medullary CDs as assessed by immunofluorescence. In cultured CD-derived M1 cells, exogenous ELA induced parallel decreases of full-length PRR (fPRR), soluble PRR (sPRR), and prorenin/renin protein expression as assessed by immunoblotting and medium sPRR and prorenin/renin levels by ELISA, all of which were reversed by 8-bromoadenosine 3',5'-cyclic monophosphate. Conversely, deletion of PRR in the CD or nephron in mice elevated Apela and Apln mRNA levels as well as urinary ELA and apelin excretion, supporting the antagonistic relationship between the two systems. Administration of exogenous ELA-32 infusion (1.5 mg·kg-1·day-1, minipump) to high salt (HS)-loaded Dahl salt-sensitive (SS) rats significantly lowered mean arterial pressure, systolic blood pressure, diastolic blood pressure, and albuminuria, accompanied with a reduction of urinary sPRR, angiotensin II, and prorenin/renin excretion. HS upregulated renal medullary protein expression of fPRR, sPRR, prorenin, and renin in Dahl SS rats, all of which were significantly blunted by exogenous ELA-32 infusion. Additionally, HS-induced upregulation of inflammatory cytokines (IL-1ß, IL-2, IL-6, IL-17A, IFN-γ, VCAM-1, ICAM-1, and MCP-1), fibrosis markers (TGF-ß1, FN, Col1A1, PAI-1, and TIMP-1), and kidney injury markers (NGAL, Kim-1, albuminuria, and urinary NGAL excretion) were markedly blocked by exogenous ELA infusion. Together, these results support the antagonistic interaction between ELA and intrarenal RAS in the distal nephron that appears to exert a major impact on blood pressure regulation.

Development and in vitro characterization of polymeric nanoparticles containing recombinant adrenomedullin-2 intended for therapeutic angiogenesis.

Cardiovascular diseases (CVD) are the leading cause of death worldwide. Growth factor therapy has emerged as novel therapeutic strategy under investigation for CVD. In this sense, adrenomedullin-2 (ADM-2) has been recently identified as a new angiogenic factor able to regulate the regional blood flow and cardiovascular function. However, the therapeutic value of ADM-2 is limited by its short biological half-life and low plasma stability. Poly (lactic-co-glycolic acid) (PLGA) micro- and nanoparticles have been investigated as growth factor delivery systems for cardiac repair. In this study, we aimed to develop PLGA nanoparticles containing ADM-2 intended for therapeutic angiogenesis. PLGA nanoparticles containing ADM-2 were prepared by a double emulsion modified method, resulting in 300 nm-sized stable particles with zeta potential around - 30 mV. Electron microscopy analysis by SEM and TEM revealed spherical particles with a smooth surface. High encapsulation efficiency was reached (ca.70%), as quantified by ELISA. ADM-2 associated to polymer nanoparticles was also determined by EDS elemental composition analysis, SDS-PAGE and LC-MS/MS for peptide identification. In vitro release assays showed the sustained release of ADM-2 from polymer nanoparticles for 21 days. Cell viability experiments were performed in J774 macrophages and H9c2 cardiomyocyte cells, about which PLGA nanoparticles loaded with ADM-2 did not cause toxicity in the range 0.01-1 mg/ml. Of note, encapsulated ADM-2 significantly induced cell proliferation in EA.hy926 endothelial cells, indicating the ADM-2 bioactivity was preserved after the encapsulation process. Collectively, these results demonstrate the feasibility of using PLGA nanoparticles as delivery systems for the angiogenic peptide ADM-2, which could represent a novel approach for therapeutic angiogenesis in CVD using growth factor therapy.

Exacerbated pressor and sympathoexcitatory effects of central Elabela in spontaneously hypertensive rats.

Elabela (ELA) is a newly discovered peptide that acts as a novel endogenous ligand of angiotensin receptor-like 1 (APJ) receptor. This study was designed to evaluate the effects of ELA-21 in paraventricular nucleus (PVN) on blood pressure and sympathetic nerve activity in spontaneously hypertensive rats (SHR). Experiments were performed in male Wistar-Kyoto rats (WKY) and SHR. ELA expression was upregulated in PVN of SHR. PVN microinjection of ELA-21 increased renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), plasma norepinephrine, and arginine vasopressin (AVP) levels in SHR. Intravenous injection of ELA-21 significantly decreased MAP and HR in both WKY and SHR, but only induced a slight decrease in RSNA. APJ antagonist F13A in PVN abolished the effects of ELA-21 on RSNA, MAP and HR. Intravenous infusion of both ganglionic blocker hexamethonium and AVP V1a receptor antagonist SR49059 caused significant reduction in the effects of ELA-21 on RSNA, MAP and HR in SHR, while combined administration of hexamethonium and SR49059 abolished the effects of ELA-21. ELA-21 microinjection stimulated Akt and p85α subunit of phosphatidylinositol 3-kinase (PI3K) phosphorylation in PVN, whereas PI3K inhibitor LY294002 or Akt inhibitor MK-2206 almost abolished the effects of ELA-21 on RSNA, MAP, and HR. Chronic PVN infusion of ELA-21 induced sympathetic activation, hypertension, and AVP release accompanied with cardiovascular remodeling in normotensive WKY. In conclusion, ELA-21 in PVN induces exacerbated pressor and sympathoexcitatory effects in hypertensive rats via PI3K-Akt pathway.NEW & NOTEWORTHY We demonstrated that PVN microinjection of ELA-21 increases sympathetic nerve activity and blood pressure, which can be abolished by pretreatment of APJ antagonist. This is the first demonstration that central ELA can induce hypertension. The pressor effects in PVN are mediated by both sympathetic activation and vasopressin release via PI3K-Akt pathway. Our data confirm that ELA is upregulated in the PVN of SHR and so may be involved in the pressor and sympathoexcitatory effects in hypertension.

How Satiating Are the 'Satiety' Peptides: A Problem of Pharmacology versus Physiology in the Development of Novel Foods for Regulation of Food Intake.

Developing novel foods to suppress energy intake and promote negative energy balance and weight loss has been a long-term but commonly unsuccessful challenge. Targeting regulation of appetite is of interest to public health researchers and industry in the quest to develop 'functional' foods, but poor understanding of the underpinning mechanisms regulating food intake has hampered progress. The gastrointestinal (GI) or 'satiety' peptides including cholecystokinin (CCK), glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) secreted following a meal, have long been purported as predictive biomarkers of appetite response, including food intake. Whilst peptide infusion drives a clear change in hunger/fullness and eating behaviour, inducing GI-peptide secretion through diet may not, possibly due to modest effects of single meals on peptide levels. We conducted a review of 70 dietary preload (DIET) and peptide infusion (INFUSION) studies in lean healthy adults that reported outcomes of CCK, GLP-1 and PYY. DIET studies were acute preload interventions. INFUSION studies showed that minimum increase required to suppress ad libitum energy intake for CCK, GLP-1 and PYY was 3.6-, 4.0- and 3.1-fold, respectively, achieved through DIET in only 29%, 0% and 8% of interventions. Whether circulating 'thresholds' of peptide concentration likely required for behavioural change can be achieved through diet is questionable. As yet, no individual or group of peptides can be measured in blood to reliably predict feelings of hunger and food intake. Developing foods that successfully target enhanced secretion of GI-origin 'satiety' peptides for weight loss remains a significant challenge.

Recombinant Fc-Elabela fusion protein has extended plasma half-life andmitigates post-infarct heart dysfunction in rats.

Activation of the apelin receptor, or APJ, by apelin is considered a therapeutic avenue for cardiovascular disease, including heart failure. Recently, a novel endogenous ligand for APJ named Elabela (ELA) has been discovered and is known to possess anti-heart failure activity in animal models. However, the short in vivo half-life of ELA constrains its clinical potential. To extend its half-life in vivo, we attempted to make IgG-Fc-ELA fusion proteins. We found that Fc-ELA-32 fusion proteins are cleaved during protein production, whereas Fc-ELA-21 fusion proteins are expressed intact, so we focused our studies on the latter. The Fc-ELA-21 fusion protein retained its functionality in vitro and had a half-life of approximately 44 h in circulation in mice after subcutaneous injection. Daily injection of the fusion protein in MI rats for 4 weeks significantly mitigated heart dysfunction with respect to hemodynamics. At the cellular and tissue levels, treatment of Fc-ELA-21 fusion protein significantly increased angiogenesis, promoted cardiomyocyte proliferation and reduced apoptosis and heart fibrosis near the infarct area. In comparison, ELA-21 had a half-life of 13 min and showed no significant cardioprotective activities. These data suggest that Fc-ELA-21 may be a potential therapeutic for heart failure.

Spexin/NPQ Induces FBJ Osteosarcoma Oncogene (Fos) and Produces Antinociceptive Effect against Inflammatory Pain in the Mouse Model.

Spexin/NPQ is a novel highly conserved neuropeptide. It has a widespread expression in the periphery and central nervous system. However, the effects of central spexin on acute inflammatory pain are still unknown. This study explored the mechanisms and effects of supraspinal spexin on inflammatory pain. The results from the mouse formalin test show that i.c.v. administration of spexin decreased licking/biting time during the late and early phases. The nonamidated spexin had no effect on pain response. The antinociception of spexin was blocked by galanin receptor 3 antagonist SNAP 37889. The Galr3 and Adcy4 mRNA levels in the brain were increased after injection with spexin. The antinociceptive effects of spexin were completely reversed by opioid receptor antagonist naloxone and κ-opioid receptor antagonist nor-binaltorphimine dihydrochloride. Spexin up-regulated the dynorphin and κ-opioid receptor gene and protein expression. PCR array assay and real-time PCR analysis show that spexin up-regulated the mRNA level of the FBJ osteosarcoma oncogene (Fos). T-5224, the inhibitor of c FBJ osteosarcoma oncogene (c-Fos)/activator protein 1 (AP-1), blocked the increased mRNA level of Pdyn and Oprk1 induced by spexin. I.C.V. spexin (2.43 mg/kg) increased the number of c-Fos-positive neurons in most subsections of periaqueductal gray. In addition, in the acetic acid-induced writhing test, i.c.v. spexin produced an antinociceptive effect. Our results indicate that spexin might be a novel neuropeptide with an antinociceptive effect against acute inflammatory pain.

Obestatin improve spatial memory impairment in a rat model of fetal alcohol spectrum disorders via inhibiting apoptosis and neuroinflammation.

Clinical and experimental evidence have demonstrated that, use of alcohol during pregnancy can interrupt brain development. Alcohol-induced neurocognitive deficits in offspring's are involved with activation of oxidative-inflammatory cascade joined with extensive apoptotic neurodegeneration in different brain regions such as hippocampus. Obestatin is a newly discovered peptide with anti-inflammatory, antioxidant, activities in different animal models. In this study, we aimed to evaluate the protective effects of obestatin on alcohol-induced neuronal apoptosis and neuroinflammation in rat pups with postnatal ethanol exposure. Through intragastric intubation, ethanol (5/27 g/kg/day) was administered in male Wistar rat pups on postnatal days 2-10 (third trimester in humans). The animals received Obestatin (1 and 5 µg/kg, S.C.) on postnatal days 2-10. Thirty-six days after birth, the spatial memory test was performed using Morris water maze test, and then, antioxidant enzymes and TNF-α levels were measured by ELISA assay. The expression level of GFAP and caspase-3 proteins was determined via immunohistochemical staining after the behavioral test. Obestatin significantly improved spatial memory deficits (P < .01), and obestatin treatment could significantly increase glutathione and total superoxide dismutase activity (P < .05), reduce level of malondialdehyde (P < .05) and TNF-α in comparison with the ethanol group (P < .01). It's also reduced caspase-3 level, and decreased GFAP-positive cells in the hippocampus of ethanol-exposed rat pups (P < .01). The result of this study shows the potential involvement of oxidative-inflammatory cascade-mediated apoptotic signaling in cognitive deficits due to postnatal ethanol exposure, the results also indicated the neuroprotective effects of Obestatin on alcohol-related behavioral, biochemical and molecular deficits.

Phoenixin participated in regulation of food intake and growth in spotted scat, Scatophagus argus.

Phoenixin (Pnx) is an endogenous peptide known to be involved in reproduction and food intake in rats, with two active isoforms, phoenixin-14 (Pnx-14) and phoenixin-20 (Pnx-20). However, little is known about the functions of Pnx in teleost. Here, pnx was cloned and was detected in all tissues of both male and female in spotted scat (Scatophagus argus), including growth axis, hypothalamus, pituitary, and liver. Real-time PCR analysis showed that pnx in the hypothalamus increased significantly after 2 d and 7 d fasting, while reduced significantly after re-feeding (P < 0.05). When pituitary and liver fragments were cultured in vitro with Pnx-14 and Pnx-20 (10 nM and 100 nM) for 6 h, the expression of ghrhr (growth hormone-releasing hormone receptor) and gh (growth hormone) in the pituitary, and ghr1 (growth hormone receptor 1) in the liver increased significantly, except ghr2 (growth hormone receptor 2) incubated with 10 nM and 100 nM Pnx-20 and ghr1 incubated with 10 nM Pnx-20. Similarly, the expression of ghrhr and gh in the pituitary, as well as ghr1 and ghr2 in the liver, increased significantly after injecting S. argus with Pnx-14 and Pnx-20 (10 ng/g and 100 ng/g body weight). These results indicate that Pnx is likely to be involved in the regulation of food intake, and also regulates the growth of S. argus by increasing ghrhr and gh expression in the pituitary, ghr1 and ghr2 in the liver, and ghr1 directly in the liver.

Divergent responses to kisspeptin in children with delayed puberty.

BACKGROUND: The neuropeptide kisspeptin stimulates luteinizing hormone (LH) secretion in healthy adults but not in adults with idiopathic hypogonadotropic hypogonadism. We hypothesized that, in children presenting with delayed or stalled puberty, kisspeptin would elicit LH secretion in those children found on detailed nighttime neuroendocrine profiling to have evidence of emerging reproductive endocrine function. METHODS: Eleven boys and four girls were admitted overnight to assess LH secretion at baseline, after a single intravenous bolus of kisspeptin, and after a single intravenous bolus of gonadotropin-releasing hormone (GnRH). Subjects then received exogenous pulsatile GnRH for 6 days and returned for a second visit to measure responses to kisspeptin and GnRH after this pituitary "priming." Responses to kisspeptin and GnRH were also measured in 5 healthy men. RESULTS: Of the 15 children with delayed/stalled puberty, 6 exhibited at least one spontaneous LH pulse overnight; all of these subjects had clear responses to kisspeptin, as did one additional subject. Seven subjects had no response to kisspeptin, and one subject exhibited an intermediate response. In the children who responded to kisspeptin, the responses had features comparable to those of adult men. CONCLUSION: In this first report of kisspeptin administration to pediatric subjects to our knowledge, children with delayed/stalled puberty showed a wide range of responses, with some showing a robust response and others showing little to no response. Further follow-up will determine whether responses to kisspeptin predict future pubertal entry for children with delayed puberty. TRIAL REGISTRATION: ClinicalTrials.gov NCT01438034 and NCT01952782. FUNDING: NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01 HD043341, R01 HD090071, P50 HD028138), NIH National Center for Advancing Translational (UL1 TR001102), NIH National Institute of Diabetes and Digestive and Kidney Diseases (T32 DK007028), the Massachusetts General Hospital Executive Committee on Research Fund for Medical Discovery, Harvard Catalyst, Doris Duke Charitable Foundation (award 2013110), Charles H. Hood Foundation, Robert and Laura Reynolds MGH Research Scholar Program, and Harvard University. These funding sources had no role in the design of this study and did not have any role in conducting the study, analyses, interpretation of the data, or the decision to submit results.

Growth Hormone Secretagogue (A233) Improves Growth and Changes the Tissue Fatty Acid Profile in Juvenile Tilapia (Oreochromis niloticus).

Growth hormone (GH) release is a process that is well regulated by several factors, including GH secretagogues. GH can mediate the regulation of the fatty acid level and composition. The aim of this study was to determine the effect of a synthetic GH secretagogue peptide (A233) on the growth and fatty acid composition in tilapia (Oreochromis niloticus). To address this objective, we administrated a diet supplemented with A233 to juvenile tilapia for 60 days. The group fed with a diet supplemented with 600 µg of A233 per kg of feed increased in weight (4.81 ± 0.09 g) and specific growth rate (2.49 ± 0.03%/day) compared to the control diet group (3.63 ± 0.08 g, 2.07 ± 0.04%/day; respectively) (p < 0.001). In the muscle, the total lipids for the control diet group were higher than that in the group fed with 600 µg of A233 per kg feed; however, no differences were detected in the liver. In both tissues, the patterns of fatty acid composition and content were generally similar, with some exceptions. Tilapia fed with 600 µg of A233 per kg of feed showed, in liver and muscle, a significantly higher composition and content of n-3 polyunsaturated fatty acids (such as 20:5n-3, 22:5n-3, 22:6n-3) and n-3/n-6 PUFA than animals fed with the control diet. To our knowledge, this is the first report on the the effects of natural or synthetic GH secretagogues (GHS) on fatty acid composition, implying an increase in the nutritional quality of the tilapia.

Phoenixin: a novel brain-gut-skin peptide with multiple bioactivity.

In this brief review we summarize the current fndings relative to the discovery of a small peptide ligand, phoenixin (PNX). Using a bioinformatic approach, two novel peptides PNX-14 and PNX-20 containing 14 and 20 amino acids, respectively, were isolated from diverse tissues including the brain, heart, lung and stomach. Mass spectrometry analysis identified a major and minor peak corresponding to PNX-14 and PNX-20, in rat or mouse spinal cord extracts. With the use of a rabbit polyclonal antiserum, phoenixin immunoreactivity (irPNX) was detected in discrete areas of the rodent brain including several hypothalamic subnuclei and dorsal motor nucleus of the vagus. In addition, irPNX was detected in a population of sensory ganglion cells including dorsal root ganglion, nodose ganglion and trigeminal ganglion, and in cell processes densely distributed to the superficial layers of the dorsal horn, nucleus of the solitary tract and spinal trigeminal tract. irPNX cell processes were also detected in the skin and myenteric plexus, suggesting a brain-gut and/or brain-skin connection. Pharmacological studies show that PNX-14 injected subcutaneously to the nape of the neck of mice provoked dose-dependent repetitive scratching bouts directed to the back of the neck with the hindpaws. Our result suggests that the peptide PNX-14 and/or PNX-20, may serve as one of the endogenous signal molecules transducing itch sensation. Additionally, results from other laboratories show that exogenous PNX may affect a number of diverse behaviors such as memory formation, depression, reproduction, food-intake and anxiolytic-like behaviors.

Controlling the bioactivity of a peptide hormone in vivo by reversible self-assembly.

The use of peptides as therapeutic agents is undergoing a renaissance with the expectation of new drugs with enhanced levels of efficacy and safety. Their clinical potential will be only fully realised once their physicochemical and pharmacokinetic properties have been precisely controlled. Here we demonstrate a reversible peptide self-assembly strategy to control and prolong the bioactivity of a native peptide hormone in vivo. We show that oxyntomodulin, a peptide with potential to treat obesity and diabetes, self-assembles into a stable nanofibril formulation which subsequently dissociates to release active peptide and produces a pharmacological effect in vivo. The subcutaneous administration of the nanofibrils in rats results in greatly prolonged exposure, with a constant oxyntomodulin bioactivity detectable in serum for at least 5 days as compared to free oxyntomodulin which is undetectable after only 4 h. Such an approach is simple, cost-efficient and generic in addressing the limitations of peptide therapeutics.

ELABELA-APJ axis protects from pressure overload heart failure and angiotensin II-induced cardiac damage.

AIMS: Elabela/Toddler/Apela (ELA) has been identified as a novel endogenous peptide ligand for APJ/Apelin receptor/Aplnr. ELA plays a crucial role in early cardiac development of zebrafish as well as in maintenance of self-renewal of human embryonic stem cells. Apelin was the first identified APJ ligand, and exerts positive inotropic heart effects and regulates the renin-angiotensin system. The aim of this study was to investigate the biological effects of ELA in the cardiovascular system. METHODS AND RESULTS: Continuous infusion of ELA peptide significantly suppressed pressure overload-induced cardiac hypertrophy, fibrosis and impaired contractility in mice. ELA treatment reduced mRNA expression levels of genes associated with heart failure and fibrosis. The cardioprotective effects of ELA were diminished in APJ knockout mice, indicating that APJ is the key receptor for ELA in the adult heart. Mechanistically, ELA downregulated angiotensin-converting enzyme (ACE) expression in the stressed hearts, whereas it showed little effects on angiotensin-converting enzyme 2 (ACE2) expression, which are distinct from the effects of Apelin. FoxM1 transcription factor, which induces ACE expression in the stressed hearts, was downregulated by ELA but not by Apelin. ELA antagonized angiotensin II-induced hypertension, cardiac hypertrophy, and fibrosis in mice. CONCLUSION: The ELA-APJ axis protects from pressure overload-induced heart failure possibly via suppression of ACE expression and pathogenic angiotensin II signalling. The different effects of ELA and Apelin on the expression of ACE and ACE2 implicate fine-tuned mechanisms for a ligand-induced APJ activation and downstream signalling.

New Targets for Drug Treatment of Obesity.

Antiobesity medical management has shown unsatisfactory results to date in terms of efficacy, safety, and long-term maintenance of weight loss. This poor performance could be attributed to the complexity of appetite regulation mechanisms; the serious drug side effects; and, crucially, the lack of profile-matching treatment strategies and individualized, multidisciplinary follow-up. Nevertheless, antiobesity pharmacotherapy remains a challenging, exciting field of intensive scientific interest. According to the latest studies, the future of bariatric medicine lies in developing drugs acting at multiple levels of the brain-gut axis. Currently, research is focused on the generation of combination treatments based on gut hormones in a way that mimics changes underlying surgically induced weight loss, in addition to centrally acting agents; these aim to restore energy balance disruptions and enhance energy expenditure. Collectively, the pharmacological resolution of obesity could potentially be achieved with combination regimens targeting different molecules and levels of the energy homeostasis system, in parallel with matching patients' needs, resulting in a favorable metabolic profile.

Obestatin modulates ghrelin's effects on the basal and stimulated testosterone secretion by the testis of rat: an in vitro study.

The functional antagonism between obestatin and ghrelin in the testis is under investigation. We investigated the ability of obestatin to counteract the inhibitory effect of ghrelin on basal and stimulated testosterone (T) secretion in vitro. Testicular strips from adult rats were incubated with 10 ng/ml and 100 ng/ml of obestatin alone, ghrelin alone and obestatin + ghrelin. Obestatin modulation of stimulated T secretion was evaluated by incubation of testicular samples with 10 ng/ml and 100 ng/ml obestatin, ghrelin and obestatin + ghrelin in the absence and presence of 10 IU of human chorionic gonadotrophin (hCG). T concentrations in the hCG treated groups were significantly (P<0.0001) higher than those in the control groups. Obestatin caused a significant increase in basal T secretion in a dose-dependent manner; however, obestatin at the both 10 ng/ml and 100 ng/ml significantly (P<0.0001) increased hCG-stimulated T secretion. In contrast, ghrelin in a dose-dependent manner significantly (P<0.001) decreased both basal and hCG-induced T secretion by testicular slices. Obestatin opposed the inhibitory effect of ghrelin on T secretion under both basal and hCG-stimulated conditions at all doses tested. In conclusions, administration of obestatin was able to antagonize the inhibitory effect of ghrelin on testosterone secretion in vitro.