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peptide science.

Metabolic regulation of ghrelin O-acyl transferase (GOAT) expression in the mouse hypothalamus, pituitary, and stomach.

Mol Cell Endocrinol

Manuel D Gahete, Jose Córdoba-Chacón, Roberto Salvatori +3 more

Ghrelin acts as an endocrine link connecting physiological processes regulating food intake, body composition, growth, and energy balance. Ghrelin is the only peptide known to undergo octanoylation. The enzyme mediating this process, ghrelin O-acyltransferase (GOAT), is expressed in the gastrointestinal tract (GI; primary source of circulating ghrelin) as well as other tissues. The present study demonstrates that stomach GOAT mRNA levels correlate with circulating acylated-ghrelin levels in fasted and diet-induced obese mice. In addition, GOAT was found to be expressed in both the pituitary and hypothalamus (two target tissues of ghrelin's actions), and regulated in response to metabolic status. Using primary pituitary cell cultures as a model system to study the regulation of GOAT expression, we found that acylated-ghrelin, but not desacyl-ghrelin, increased GOAT expression. In addition, growth-hormone-releasing hormone (GHRH) and leptin increased, while somatostatin (SST) decreased GOAT expression. The physiologic relevance of these later results is supported by the observation that pituitary GOAT expression in mice lacking GHRH, SST and leptin showed opposite changes to those observed after in vitro treatment with the corresponding peptides. Therefore, it seems plausible that these hormones directly contribute to the regulation of pituitary GOAT. Interestingly, in all the models studied, pituitary GOAT expression paralleled changes in the expression of a dominant spliced-variant of ghrelin (In2-ghrelin) and therefore this transcript may be a primary substrate for pituitary GOAT. Collectively, these observations support the notion that the GI tract is not the only source of acylated-ghrelin, but in fact locally produced des-acylated-ghrelin could be converted to acylated-ghrelin within target tissues by locally active GOAT, to mediate its tissue-specific effects.

Minireview: Mechano-growth factor: a putative product of IGF-I gene expression involved in tissue repair and regeneration.

Endocrinology

Ronald W Matheny, Bradley C Nindl, Martin L Adamo

The discovery that IGF-I mRNAs encoding isoforms of the pro-IGF-I molecule are differentially regulated in response to mechanical stress in skeletal muscle has been the impetus for a number of studies designed to demonstrate that alternative splicing of IGF-I pre-mRNA involving exons 4, 5, and 6 gives rise to a unique peptide derived from pro-IGF-I that plays a novel role in myoblast proliferation. Research suggests that after injury to skeletal muscle, the IGF-IEb mRNA splice variant is up-regulated initially, followed by up-regulation of the IGF-IEa splice variant at later time points. Up-regulation of IGF-IEb mRNA correlates with markers of satellite cell and myoblast proliferation, whereas up-regulation of IGF-IEa mRNA is correlated with differentiation to mature myofibers. Due to the apparent role of IGF-IEb up-regulation in muscle remodeling, IGF-IEb mRNA was also named mechano-growth factor (MGF). A synthetically manufactured peptide (also termed MGF) corresponding to the 24 most C-terminal residues of IGF-IEb has been shown to promote cellular proliferation and survival. However, no analogous peptide product of the Igf1 gene has been identified in or isolated from cultured cells, their conditioned medium, or in vivo animal tissues or biological fluids. This review will discuss the relationship of the Igf1 gene to MGF and will differentiate actions of synthetic MGF from any known product of Igf1. Additionally, the role of MGF in satellite cell activation, aging, neuroprotection, and signaling will be discussed. A survey of outstanding questions relating to MGF will also be provided.

Drug-loaded nanoparticles targeted to the colon with polysaccharide hydrogel reduce colitis in a mouse model.

Gastroenterology

Hamed Laroui, Guillaume Dalmasso, Hang Thi Thu Nguyen +3 more

One of the challenges to treating inflammatory bowel disease (IBD) is to target the site of inflammation. We engineered nanoparticles (NPs) to deliver an anti-inflammatory tripeptide Lys-Pro-Val (KPV) to the colon and assessed its therapeutic efficacy in a mouse model of colitis.

[Effect of the novel nootropic and neuroprotective dipeptide noopept on the streptozotocin-induced model of sporadic Alzheimer disease in rats].

Eksp Klin Farmakol

R U Ostrovskaia, A P Tsaplina, Iu V Vakhitova +2 more

Streptozotocin-intracerebroventricularly treated rats are proposed as an experimental model of sporadic Alzheimer disease (AD). Diabetogenic toxin streptozotocin (STZ) administered in both cerebral ventricles in a dose of 3 mg/kg decreases the expression of NGF and BDNF mainly in the hippocampus and increases the content of malonic dialdehyde (MDA)--a product of lipid peroxidation--in the brain tissues. These metabolic changes are accompanied by a pronounced cognitive deficiency, which is manifested by long-term memory deterioration in the passive avoidance test. These manifestations of pathology are not accompanied by hyperglycemia in the case of intraventricular STZ administration, in contrast to the systemic (in particular, intraperitoneal) route of introduction that causes a pronounced increase in the blood glucose level. These results are consistent with the existing notions that (i) STZ administered intraventricularly provokes a complex of changes imitating the sporadic AD and (ii) this disease can be considered as a manifestation of type-III diabetes. The new original cognition enhancing and neuroprotective dipeptide noopept decreases the aforementioned metabolic changes and the accompanying long-term deterioration of the memory. Previously, this systemically active dipeptide was shown to be capable of increasing expression of NGF and BDNF in the hippocampus, stimulating the antibody production to beta-amyloid, inhibiting the lipid peroxidation, activating the endogenous antioxidant systems, and decreasing the rate of glutamate release (cholinopositive effect). Taken together, these data indicate that noopept can be considered as a multipotent substance acting upon several important pathogenic chainsof the sporadic AD.

Effects of different intensities of resistance exercise on regulators of myogenesis.

J Strength Cond Res

Colin D Wilborn, Lemuel W Taylor, Michael Greenwood +2 more

A single bout of high-intensity resistance exercise is capable of activating the expression of various genes in skeletal muscle involved in hypertrophy such as myosin heavy chain (MHC) isoforms, myogenic regulatory factors (MRFs), and growth factors. However, the specific role exercise intensity plays on the expression of these genes is not well defined. The purpose of this study was to investigate the effects of exercise intensity on MHC (type I, IIA, IIX), MRF (Myo-D, myogenin, MRF-4, myf5), and growth factor (insulin-like growth factor [IGF]-1, IGF-1 receptor [IGF-R1], mechano-growth factor [MGF]) mRNA expression. Thirteen male participants (21.5 +/- 2.9 years, 86.1 +/- 19.5 kg, 69.7 +/- 2.7 in.) completed bouts of resistance exercise involving 4 sets of 18-20 repetitions with 60-65% 1 repetition maximum (1RM) and 4 sets of 8-10 repetitions with 80-85% 1RM. Vastus lateralis biopsies were obtained immediately before exercise, and at 30 minutes, 2 hours, and 6 hours after each bout. The levels of mRNA expression were determined using real-time polymerase chain reaction. Data were analyzed using 2 x 4 multivariate analysis of variance (p <or= 0.05). For both intensities, MHC type IIX, IGF-1, IGF-R1, MGF, Myo-D, myogenin, MRF-4, and myf5 mRNA were all significantly increased in response to resistance exercise by 2 hours after exercise, whereas myostatin and the cyclin-dependent kinase inhibitor p27(kip) were decreased at 2 hours after exercise (p < 0.05). Resistance exercise between 60-85% 1RM upregulates the mRNA expression of MHC and factors involved in myogenic activation of satellite cells while concomitantly decreasing expression of myogenic inhibitors.

[The original nootropic and neuroprotective drug noopept potentiates the anticonvulsant activity of valproate in mice].

Eksp Klin Farmakol

E V Kravchenko, I V Ponteleeva, S S Trofimov +3 more

The influence of the original dipeptide drug noopept, known to possess nootrope, neuroprotector, and anxiolytic properties, on the anticonvulsant activity of the antiepileptic drug valproate has been studied on the model of corazole-induced convulsions in mice. Neither a single administration of noopept (0.5 mg/kg, i.p.) nor its repeated introduction in 10 or 35 days enhanced the convulsant effect of corazole, which is evidence that noopept alone does not possess anticonvulsant properties. Prolonged (five weeks) preliminary administration of noopept enhanced the anticonvulsant activity of valproate. This result justifies the joint chronic administration of noopept in combination with valproate in order to potentiate the anticonvulsant effect of the latter drug. In addition, the administration of noopept favorably influences the cognitive functions and suppresses the development of neurodegenerative processes.

Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects.

Growth Horm IGF Res

Lucila Sackmann-Sala, Juan Ding, Lawrence A Frohman +1 more

To identify biomarkers of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) action in human serum.

Growth hormone and growth hormone secretagogue effects on nitrogen balance and urea synthesis in steroid treated rats.

Growth Horm IGF Res

Niels Kristian Aagaard, Thorbjørn Grøfte, Jacob Greisen +6 more

Growth hormone (GH) reduces the catabolic side effects of steroid treatment via effects on the amino-nitrogen metabolism. Ipamorelin is a synthetic peptide with GH releasing properties. We wished to study the metabolic effects of Ipamorelin and GH on selected hepatic measures of alpha-amino-nitrogen conversion during steroid-induced catabolism.

Efficacy of anti-aging products for periorbital wrinkles as measured by 3-D imaging.

J Cosmet Dermatol

Joseph R Kaczvinsky, Christopher E M Griffiths, Marcia S Schnicker +1 more

The periorbital area is a key wrinkle-prone region, where the first signs of aging usually appear.

Prolylcarboxypeptidase regulates food intake by inactivating alpha-MSH in rodents.

J Clin Invest

Nicholas Wallingford, Bertrand Perroud, Qian Gao +12 more

The anorexigenic neuromodulator alpha-melanocyte-stimulating hormone (alpha-MSH; referred to here as alpha-MSH1-13) undergoes extensive posttranslational processing, and its in vivo activity is short lived due to rapid inactivation. The enzymatic control of alpha-MSH1-13 maturation and inactivation is incompletely understood. Here we have provided insight into alpha-MSH1-13 inactivation through the generation and analysis of a subcongenic mouse strain with reduced body fat compared with controls. Using positional cloning, we identified a maximum of 6 coding genes, including that encoding prolylcarboxypeptidase (PRCP), in the donor region. Real-time PCR revealed a marked genotype effect on Prcp mRNA expression in brain tissue. Biochemical studies using recombinant PRCP demonstrated that PRCP removes the C-terminal amino acid of alpha-MSH1-13, producing alpha-MSH1-12, which is not neuroactive. We found that Prcp was expressed in the hypothalamus in neuronal populations that send efferents to areas where alpha-MSH1-13 is released from axon terminals. The inhibition of PRCP activity by small molecule protease inhibitors administered peripherally or centrally decreased food intake in both wild-type and obese mice. Furthermore, Prcp-null mice had elevated levels of alpha-MSH1-13 in the hypothalamus and were leaner and shorter than the wild-type controls on a regular chow diet; they were also resistant to high-fat diet-induced obesity. Our results suggest that PRCP is an important component of melanocortin signaling and weight maintenance via control of active alpha-MSH1-13 levels.

Follistatin induces muscle hypertrophy through satellite cell proliferation and inhibition of both myostatin and activin.

Am J Physiol Endocrinol Metab

Hélène Gilson, Olivier Schakman, Stéphanie Kalista +3 more

Follistatin (FS) inhibits several members of the TGF-beta superfamily, including myostatin (Mstn), a negative regulator of muscle growth. Mstn inhibition by FS represents a potential therapeutic approach of muscle atrophy. The aim of our study was to investigate the mechanisms of the FS-induced muscle hypertrophy. To test the role of satellite cells in the FS effect, we used irradiation to destroy their proliferative capacity. FS overexpression increased the muscle weight by about 37% in control animals, but the increase reached only 20% in irradiated muscle, supporting the role of cell proliferation in the FS-induced hypertrophy. Surprisingly, the muscle hypertrophy caused by FS reached the same magnitude in Mstn-KO as in WT mice, suggesting that Mstn might not be the only ligand of FS involved in the regulation of muscle mass. To assess the role of activin (Act), another FS ligand, in the FS-induced hypertrophy, we electroporated FSI-I, a FS mutant that does not bind Act with high affinity. Whereas FS electroporation increased muscle weight by 32%, the muscle weight gain induced by FSI-I reached only 14%. Furthermore, in Mstn-KO mice, FSI-I overexpression failed to induce hypertrophy, in contrast to FS. Therefore, these results suggest that Act inhibition may contribute to FS-induced hypertrophy. Finally, the role of Act as a regulator of muscle mass was supported by the observation that ActA overexpression induced muscle weight loss (-15%). In conclusion, our results show that satellite cell proliferation and both Mstn and Act inhibition are involved in the FS-induced muscle hypertrophy.

Melanoma imaging using (111)In-, (86)Y- and (68)Ga-labeled CHX-A''-Re(Arg11)CCMSH.

Nucl Med Biol

Lihui Wei, Xiuli Zhang, Fabio Gallazzi +8 more

A novel alpha-melanocyte-stimulating hormone peptide analog CHX-A''-Re(Arg(11))CCMSH, which targeted the melanocortin-1 receptor (MC1-R) overexpressed on melanoma cells, was investigated for its biodistribution and tumor imaging properties.

Growth hormone stimulates mechano growth factor expression and activates myoblast transformation in C2C12 cells.

Kobe J Med Sci

Mari Imanaka, Keiji Iida, Ayumi Murawaki +7 more

Mechano growth factor (MGF) is an alternatively spliced variant of insulin-like growth factor-I (IGF-I). Previous reports have revealed that the MGF in skeletal muscles is induced by mechanical overload or muscle injury. In the present study, we examined the effect of growth hormone (GH) on MGF expression in C2C12 mouse muscle cell lines since GH is the principal regulator of IGF-I. The MGF mRNA increased 1 h following GH stimulation whereas IGF-IEa mRNA, which encodes a systemic type of IGF-I, increased 4 h following GH stimulation. The diverse expression of MGF and IGF-IEa was also observed in the case of muscle injury by using bupivacaine in the same cell line. Furthermore, GH induced the increase of MyoD as well as M-cadherin expression, the peak of which was parallel to that of MGF. These results indicate that GH directly and preferentially increased MGF prior to the IGF-IEa expression in C2C12 cells, which may lead to the activation of muscle satellite cells.

Myostatin reduces Akt/TORC1/p70S6K signaling, inhibiting myoblast differentiation and myotube size.

Am J Physiol Cell Physiol

Anne Ulrike Trendelenburg, Angelika Meyer, Daisy Rohner +3 more

Myostatin is a negative regulator of skeletal muscle size, previously shown to inhibit muscle cell differentiation. Myostatin requires both Smad2 and Smad3 downstream of the activin receptor II (ActRII)/activin receptor-like kinase (ALK) receptor complex. Other transforming growth factor-beta (TGF-beta)-like molecules can also block differentiation, including TGF-beta(1), growth differentiation factor 11 (GDF-11), activins, bone morphogenetic protein 2 (BMP-2) and BMP-7. Myostatin inhibits activation of the Akt/mammalian target of rapamycin (mTOR)/p70S6 protein synthesis pathway, which mediates both differentiation in myoblasts and hypertrophy in myotubes. Blockade of the Akt/mTOR pathway, using small interfering RNA to regulatory-associated protein of mTOR (RAPTOR), a component of TOR signaling complex 1 (TORC1), increases myostatin-induced phosphorylation of Smad2, establishing a myostatin signaling-amplification role for blockade of Akt. Blockade of RAPTOR also facilitates myostatin's inhibition of muscle differentiation. Inhibition of TORC2, via rapamycin-insensitive companion of mTOR (RICTOR), is sufficient to inhibit differentiation on its own. Furthermore, myostatin decreases the diameter of postdifferentiated myotubes. However, rather than causing upregulation of the E3 ubiquitin ligases muscle RING-finger 1 (MuRF1) and muscle atrophy F-box (MAFbx), previously shown to mediate skeletal muscle atrophy, myostatin decreases expression of these atrophy markers in differentiated myotubes, as well as other genes normally upregulated during differentiation. These findings demonstrate that myostatin signaling acts by blocking genes induced during differentiation, even in a myotube, as opposed to activating the distinct "atrophy program." In vivo, inhibition of myostatin increases muscle creatine kinase activity, coincident with an increase in muscle size, demonstrating that this in vitro differentiation measure is also upregulated in vivo.

Development of a LC-MS/MS method to monitor palmitoyl peptides content in anti-wrinkle cosmetics.

Anal Chim Acta

Raluca-Ioana Chirita, Patrick Chaimbault, Jean-Christophe Archambault +2 more

Palmitoyl peptides are anti-aging agents widely used in cosmetics. This article describes the development of a LC-MS/MS analytical procedure that allows, after a liquid-liquid extraction procedure, their unambiguous detection in cosmetic formulation. MS/MS detection is shown to be specific regarding placebo formulations. Limits of quantification, linearity, accuracy and precision of the method were estimated. The results presented show that palmitoyl peptides can be thus reliably assayed. The palmitoylated pentapeptide palmitoyl-lysyl-threonyl-threonyl-lysyl-serine (pal-KTTKS) was assayed in anti-wrinkle creams using palmitoyl-glycyl-histidyl-lysine (pal-GHK) as internal standard. From the results obtained, the influence of the formulation on pal-KTTKS availability is evidenced.

Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus.

J Pharmacol Exp Ther

Kalina Venkova, William Mann, Richard Nelson +1 more

Ghrelin and ghrelin mimetics stimulate appetite and enhance gastric motility. The present study investigates whether ipamorelin, a selective growth hormone secretagogue and agonist of the ghrelin receptor, would accelerate gastrointestinal transit and ameliorate the symptoms in a rodent model of postoperative ileus (POI). Fasted male rats were subjected to laparotomy and intestinal manipulation. At the end of surgery, a dye marker was infused in the proximal colon to evaluate postsurgical colonic transit time, which was the time to the first bowel movement. In addition, fecal pellet output, food intake, and body weight were monitored regularly for 48 h. Ipamorelin (0.01-1 mg/kg), growth hormone-releasing peptide (GHRP)-6 (20 microg/kg), or vehicle (saline) were administered via intravenous bolus infusion after a single dosing or a 2-day repetitive dosing regimen (four doses a day at 3-h intervals). Compared with the vehicle, a single dose of ipamorelin (1 mg/kg) or GHRP-6 (20 microg/kg) decreased the time to the first bowel movement but had no effect on cumulative fecal output, food intake, or body weight gain measured 48 h after the surgery. In contrast, repetitive dosing of ipamorelin (0.1 or 1 mg/kg) significantly increased the cumulative fecal pellet output, food intake, and body weight gain. The results suggest that postsurgical intravenous infusions of ipamorelin may ameliorate the symptoms in patients with POI.

Neuronal M3 muscarinic acetylcholine receptors are essential for somatotroph proliferation and normal somatic growth.

Proc Natl Acad Sci U S A

Dinesh Gautam, Jongrye Jeon, Matthew F Starost +8 more

The molecular pathways that promote the proliferation and maintenance of pituitary somatotrophs and other cell types of the anterior pituitary gland are not well understood at present. However, such knowledge is likely to lead to the development of novel drugs useful for the treatment of various human growth disorders. Although muscarinic cholinergic pathways have been implicated in regulating somatotroph function, the physiological relevance of this effect and the localization and nature of the receptor subtypes involved in this activity remain unclear. We report the surprising observation that mutant mice that selectively lack the M(3) muscarinic acetylcholine receptor subtype in the brain (neurons and glial cells; Br-M3-KO mice) showed a dwarf phenotype associated with a pronounced hypoplasia of the anterior pituitary gland and a marked decrease in pituitary and serum growth hormone (GH) and prolactin. Remarkably, treatment of Br-M3-KO mice with CJC-1295, a synthetic GH-releasing hormone (GHRH) analog, rescued the growth deficit displayed by Br-M3-KO mice by restoring normal pituitary size and normal serum GH and IGF-1 levels. These findings, together with results from M(3) receptor/GHRH colocalization studies and hypothalamic hormone measurements, support a model in which central (hypothalamic) M(3) receptors are required for the proper function of hypothalamic GHRH neurons. Our data reveal an unexpected and critical role for central M(3) receptors in regulating longitudinal growth by promoting the proliferation of pituitary somatotroph cells.

Comparative studies of Noopept and piracetam in the treatment of patients with mild cognitive disorders in organic brain diseases of vascular and traumatic origin.

Neurosci Behav Physiol

G G Neznamov, E S Teleshova

Noopept stimulates the expression of NGF and BDNF in rat hippocampus.

Bull Exp Biol Med

R U Ostrovskaya, T A Gudasheva, A P Zaplina +4 more

We studied the effect of original dipeptide preparation Noopept (N-phenylacetyl-L-prolylglycine ethyl ester, GVS-111) with nootropic and neuroprotective properties on the expression of mRNA for neurotropic factors NGF and BDNF in rat hippocampus. Expression of NGF and BDNF mRNA in the cerebral cortex and hippocampus was studied by Northern blot analysis. Taking into account the fact that pharmacological activity of Noopept is realized after both acute and chronic treatment, we studied the effect of single and long-term treatment (28 days) with this drug. Expression of the studied neurotropic factors in the cerebral cortex was below the control after single administration of Noopept, while chronic administration caused a slight increase in BDNF expression. In the hippocampus, expression of mRNA for both neurotrophins increased after acute administration of Noopept. Chronic treatment with Noopept was not followed by the development of tolerance, but even potentiated the neurotrophic effect. These changes probably play a role in neuronal restoration. We showed that the nootropic drug increases expression of neurotrophic factors in the hippocampus. Our results are consistent with the hypothesis that neurotrophin synthesis in the hippocampus determines cognitive function, particularly in consolidation and delayed memory retrieval. Published data show that neurotrophic factor deficiency in the hippocampus is observed not only in advanced Alzheimer's disease, but also at the stage of mild cognitive impairment (pre-disease state). In light of this our findings suggest that Noopept holds much promise to prevent the development of Alzheimer's disease in patients with mild cognitive impairment. Moreover, therapeutic effectiveness of Noopept should be evaluated at the initial stage of Alzheimer's disease.

The thymus-neuroendocrine axis: physiology, molecular biology, and therapeutic potential of the thymic peptide thymulin.

Ann N Y Acad Sci

Paula C Reggiani, Gustavo R Morel, Gloria M Cónsole +7 more

Thymulin is a thymic hormone exclusively produced by the thymic epithelial cells. It consists of a nonapeptide component coupled to the ion zinc, which confers biological activity to the molecule. After its discovery in the early 1970s, thymulin was characterized as a thymic hormone involved in several aspects of intrathymic and extrathymic T cell differentiation. Subsequently, it was demonstrated that thymulin production and secretion is strongly influenced by the neuroendocrine system. Conversely, a growing core of information, to be reviewed here, points to thymulin as a hypophysotropic peptide. In recent years, interest has arisen in the potential use of thymulin as a therapeutic agent. Thymulin was shown to possess anti-inflammatory and analgesic properties in the brain. Furthermore, an adenoviral vector harboring a synthetic gene for thymulin, stereotaxically injected in the rat brain, achieved a much longer expression than the adenovirally mediated expression in the brain of other genes, thus suggesting that an anti-inflammatory activity of thymulin prevents the immune system from destroying virus-transduced brain cells. Other studies suggest that thymulin gene therapy may also be a suitable therapeutic strategy to prevent some of the endocrine and metabolic alterations that typically appear in thymus-deficient animal models. The present article briefly reviews the literature on the physiology, molecular biology, and therapeutic potential of thymulin.