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Neuroprotective effects of novel anorexigenic analogs of prolactin-releasing peptide (PrRP) in models of neurodegeneration in vitro and in vivo
Mengr, Anna ; Maletínská, Lenka (advisor) ; Sumová, Alena (referee) ; Hampl, Aleš (referee)
Alzheimer's disease (AD) is a progressive brain disorder characterized by extracellular beta amyloid (Aβ) plaques, intracellular neurofibrillary tangles formed by hyperphosphorylated Tau protein and neuroinflammation. Since obesity and type 2 diabetes mellitus (T2DM) have been established as risk factors for the development of neurological disorders, anorexigenic and antidiabetic peptides, such as prolactin-releasing peptide (PrRP) seem to be potential neuroprotective agents. In the first part of the study, the molecular mechanisms of action of natural PrRP31 and its lipidized analog palm11 -PrRP31 was studied in the human neuroblastoma cell line SH-SY5Y. Both compounds significantly activated the signaling pathways typical for insulin promoting cell survival and growth. Moreover, PrRP31 and palm11 -PrRP31 increased cell viability and suppressed apoptosis in methylglyoxal-stressed SH-SY5Y cells. The second part of the thesis was focused on the neuroprotective and anti-inflammatory effects of 2-month-long subcutaneous administration of palm11 -PrRP31 in the brains of APP/PS1 mice, model of Aβ pathology. Palm11 -PrRP31 significantly reduced the Aβ plaque load and microgliosis in the hippocampi, cortices, and cerebella. Furthermore, palm11 -PrRP31 increased the synaptogenesis and attenuated...
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Effects of stable analogs of anorexigenic neuropeptides in models of metabolic syndrome
Mráziková, Lucia ; Maletínská, Lenka (advisor) ; Kříž, Jan (referee) ; Bardová, Kristina (referee)
Obesity is a worldwide health problem and an effective treatment is still scarce. Anorexigenic neuropeptides, such as prolactin-releasing peptide (PrRP), have a potential for the treatment of obesity and its complications, but in their natural form they have several limitations such as poor bioavailability, low stability and inability to cross the blood-brain barrier after peripheral administration. Recently we have designed lipidized analogs of PrRP. Lipidization makes this peptide more stable and able to act centrally after peripheral administration. The aim of this study was to investigate the chronic effect of PrRP palmitoylated at position 11 (palm11 -PrRP31) on obesity and obesity-related metabolic parameters and to clarify mechanisms of its action. We used three rodent models of obesity: Wistar Kyoto (WKY) rats with high-fat diet-induced obesity (DIO) having intact leptin and leptin receptor as well as rodents with disrupted leptin function: leptin deficient ob/ob mice and fa/fa rats with a disturbed leptin signaling. Consumption of a high-fat diet in DIO WKY rats increased their body weight, caused strong glucose intolerance and increased liver mRNA expression of enzymes of de novo lipogenesis. Palm11 -PrRP31 treatment significantly decreased cumulative food intake, body weight, plasma...
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Effects of PrRP (prolactin-releasing peptide) and NPFF (neuropeptide FF) analogs in vitro and in vivo
Tichá, Anežka ; Ryšlavá, Helena (advisor) ; Železná, Blanka (referee)
Prolactin-releasing peptide (PrRP) and neuropeptide FF (NPFF) belong to the RF-amide family. These peptides have identical C-terminal amino acid sequence (R-F-NH2) and similar biological activities. PrRP was identified as an endogenous ligand of an orphan receptor GPR10 able to stimulate PRL-secretion in vitro and in vivo, but soon it was discoverd that this is not the primary function of this peptide. PrRP is thought to be an anorexigenic peptide as PrRP and GPR10 are found in several parts of the brain responsible for food intake regulation and because both GPR10 and PrRP deficient mice suffer from hyperphagia and late-onset obesity. In this study, relationship between PrRP and NPFF was studied using both in vitro binding and sell signaling and in vivo food intake and analgesia test in mice. In vitro experiments showed that PrRP bound to rat pituitary RC-4B/C cells containing GPR10 receptor with high affinity and NPFF, its stable analog 1DMe and its antagonist RF9 up to 10-5 M concentration did not bind to GPR10. NPFF, 1DMe and PrRP were bound to cell membranes with transfected NPFF2 receptor with high affinity, but RF9 with low affinity in a range of 10-7 M, in contrast to published literature. In vivo experiments with fasted mice confirmed that centrally injected PrRP and NPFF significantly...
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New analogues of prolactin-releasing peptide with prolonged effect on food intake
Tichá, Anežka ; Ryšlavá, Helena (advisor) ; Konvalinka, Jan (referee)
Prolactin-releasing peptide (PrRP) is a member of the family of RF-amide peptides. These peptides have typical C-terminal sequence -Arg-Phe-NH2 and similar biological effects. PrRP was discovered as an endogenous ligand of an orphan receptor GPR10 while searching for a factor responsible for a prolactin secretion. This effect was not later confirmed and nowadays, PrRP is mainly considered as an anorexigenic peptide. This is supported by a fact that PrRP and GPR10 deficient mice suffer from hyperphagia and late-onset obesity. Besides GPR10, PrRP is bound to NPFF2 receptor whose endogenous ligand is neuropeptide FF (NPFF). In this study, the PrRP's analogues modified at the N-terminus with fatty acids of different lenghts were tested in vitro on binding and activation MAPK/ERK1/2 signalling pathway. In in vivo experiments on food intake, the central anorexigenic effects of lipidized PrRP-analogues were tested provided their crossing blood brain barrier. Binding studies showed that all analogues bound to rat pituitary RC-4B/C cells with high affinity, analogues containing fatty acid with Ki of one order of magnitude lower than native PrRP. High affinity was also confirmed for binding to cells overexpressing GPR10 receptor and cell membranes with overexpressed NPFF2 receptor. All tested analogues...
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The role of stable analogs of prolactin-releasing peptide in obesity and hypertension.
Neprašová, Barbora ; Maletínská, Lenka (advisor) ; Poledne, Rudolf (referee) ; Rossmeisl, Martin (referee)
Anorexigenic neuropeptides have the potential to decrease food intake and ameliorate obesity and its complications such as high blood glucose or high blood pressure. However, they are not able to cross the blood-brain barrier after peripheral application. Recently, we have designed and synthesized lipidized analogs of prolactin-releasing peptide (PrRP), which resulted in stabilization of the molecule and allowed us to apply the peptide to the periphery to achieve its central biological effect, as it was demonstrated by increased neuronal activity shown by c-Fos in particular hypothalamus nuclei. The aim of this study was to choose the effective dose in acute food intake experiments and then to characterize the subchronic effect of palmitoylated PrRP analogs in mouse and rat models of obesity and diabetes. Several animal models were used: diet-induced obese (DIO) mice (C57Bl/6J), DIO Sprague-Dawley rats, and two rat models with leptin receptor-deficiency: Zucker diabetic (ZDF) rats and spontaneously hypertensive (SHROB) rats. Consumption of a high-fat diet in DIO mice and rats increased their body weight and blood pressure. Two-week intraperitoneal treatment with palmitoylated PrRP31 lowered the food intake, body weight, and returned the blood pressure to normal levels. This treatment also improved...
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New analogues of prolactin-releasing peptide with prolonged effect on food intake
Tichá, Anežka ; Ryšlavá, Helena (advisor) ; Konvalinka, Jan (referee)
Prolactin-releasing peptide (PrRP) is a member of the family of RF-amide peptides. These peptides have typical C-terminal sequence -Arg-Phe-NH2 and similar biological effects. PrRP was discovered as an endogenous ligand of an orphan receptor GPR10 while searching for a factor responsible for a prolactin secretion. This effect was not later confirmed and nowadays, PrRP is mainly considered as an anorexigenic peptide. This is supported by a fact that PrRP and GPR10 deficient mice suffer from hyperphagia and late-onset obesity. Besides GPR10, PrRP is bound to NPFF2 receptor whose endogenous ligand is neuropeptide FF (NPFF). In this study, the PrRP's analogues modified at the N-terminus with fatty acids of different lenghts were tested in vitro on binding and activation MAPK/ERK1/2 signalling pathway. In in vivo experiments on food intake, the central anorexigenic effects of lipidized PrRP-analogues were tested provided their crossing blood brain barrier. Binding studies showed that all analogues bound to rat pituitary RC-4B/C cells with high affinity, analogues containing fatty acid with Ki of one order of magnitude lower than native PrRP. High affinity was also confirmed for binding to cells overexpressing GPR10 receptor and cell membranes with overexpressed NPFF2 receptor. All tested analogues...
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Effects of PrRP (prolactin-releasing peptide) and NPFF (neuropeptide FF) analogs in vitro and in vivo
Tichá, Anežka ; Ryšlavá, Helena (advisor) ; Železná, Blanka (referee)
Prolactin-releasing peptide (PrRP) and neuropeptide FF (NPFF) belong to the RF-amide family. These peptides have identical C-terminal amino acid sequence (R-F-NH2) and similar biological activities. PrRP was identified as an endogenous ligand of an orphan receptor GPR10 able to stimulate PRL-secretion in vitro and in vivo, but soon it was discoverd that this is not the primary function of this peptide. PrRP is thought to be an anorexigenic peptide as PrRP and GPR10 are found in several parts of the brain responsible for food intake regulation and because both GPR10 and PrRP deficient mice suffer from hyperphagia and late-onset obesity. In this study, relationship between PrRP and NPFF was studied using both in vitro binding and sell signaling and in vivo food intake and analgesia test in mice. In vitro experiments showed that PrRP bound to rat pituitary RC-4B/C cells containing GPR10 receptor with high affinity and NPFF, its stable analog 1DMe and its antagonist RF9 up to 10-5 M concentration did not bind to GPR10. NPFF, 1DMe and PrRP were bound to cell membranes with transfected NPFF2 receptor with high affinity, but RF9 with low affinity in a range of 10-7 M, in contrast to published literature. In vivo experiments with fasted mice confirmed that centrally injected PrRP and NPFF significantly...
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