RESUMEN
This study investigated the neuroprotective effects of exendin-4 (EXE-4), an analog of the glucagon-like peptide 1 receptor (GLP-1R) on memory and on the neuronal populations that constitute the hippocampus of rats submitted to a sporadic dementia of Alzheimer's type (SDAT). Male Wistar rats received streptozotocin (STZ icv, 3 mg/kg diluted in aCFS, 5 µl/ventricle) and were treated for 21 days with EXE-4 (10 µg/kg, ip; saline as the vehicle). Four groups were formed: vehicle, EXE-4, STZ, and STZ + EXE-4. The groups were submitted to Y-Maze (YM), object recognition (ORT), and object displacement tasks (ODT) to assess learning and memory. The brains were used for immunohistochemical and immunofluorescent techniques with antibodies to NeuN, cleaved caspase-3 (CC3), PCNA, doublecortin (DCX), synaptophysin (SYP), and insulin receptor (IR). STZ worsened spatial memory in the YMT, as well as short-term (STM) and long-term (LTM) memories in the ORT and ODT, respectively. EXE-4 protected against memory impairment in STZ animals. STZ reduced mature neuron density (NeuN) and increased cell apoptosis (CC3) in the DG, CA1, and CA3. EXE-4 protected against neuronal death in all regions. EXE-4 increased PCNA+ cells in all regions of the hippocampus, and STZ attenuated this effect. STZ reduced neurogenesis in DG per se as well as synaptogenesis induced by EXE-4. EXE-4 increased immunoreactivity to IR in the CA1. From these findings, EXE-4 showed a beneficial effect on hippocampal pyramidal and granular neurons in the SDAT showing anti-apoptotic properties and promoting cell proliferation. In parallel, EXE-4 preserved the memory of SDAT rats. EXE-4 appears to enhance synapses at CA3 and DG. In conclusion, these data indicate that agonists to GLP-1R have a beneficial effect on hippocampal neurons in AD.
RESUMEN
PURPOSE: In the present study, we investigated whether intra-islet GLP-1 production and its modulation have a role in apoptosis, proliferation or neogenesis that is compromised by protein restriction during the foetal and suckling periods. METHODS: Exendin-4, a GLP-1 receptor agonist (treated groups), or saline (non-treated groups) was intraperitoneally administered for 15 days from 75 to 90 days of age in female adult rats consisting of offspring born to and suckled by mothers fed a control diet (control groups) and who had the same diet until 90 days of age or offspring born to and suckled by mothers fed a low-protein diet and who were fed the control diet after weaning until 90 days of age (protein-restricted group). RESULTS: The ß-cell mass was lower in the protein-restricted groups than in the control groups. Exendin-4 increased ß-cell mass, regardless of the mother's protein intake. The colocalization of GLP-1/glucagon was higher in the protein-restricted rats than in control rats in both the exendin-4-treated and non-treated groups. The frequency of cleaved caspase-3-labelled cells was higher in the non-treated protein-restricted group than in the non-treated control group and was similar in the treated protein-restricted and treated control groups. Regardless of treatment with exendin-4, Ki67-labelled cell frequency and ß-catenin/DAPI colocalization were elevated in the protein-restricted groups. Exendin-4 increased the area of endocrine cell clusters and ß-catenin/DAPI and FoxO1/DAPI colocalization regardless of the mother's protein intake. CONCLUSIONS: Protein restriction in early life increased intra-islet GLP-1 production and ß-cell proliferation, possibly mediated by the ß-catenin pathway.
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Péptido 1 Similar al Glucagón , Islotes Pancreáticos , Animales , Proliferación Celular , Dieta con Restricción de Proteínas , Femenino , Péptidos , Ratas , Ponzoñas , beta CateninaRESUMEN
Studies using mesenchymal stromal cells (MSCs) as a source of insulin-secreting cells (IPCs) are a promising path in the pursuit for diabetes therapy. Here, we investigate three short-term differentiation protocols in order to generate IPCs from autologous adipose-derived stromal cells (ADSCs) with an expressive insulin-secreting profile in vitro and in vivo, as well as the signaling pathways involved in the chosen differentiation protocols. We extracted and cultured ADSCs and differentiated them into IPCs, using three different protocols with different inductors. Afterwards, the secretory profile was analyzed and IPCs differentiated in exendin-4/activin A medium, which presented the best secretory profile, was implanted in the kidney subcapsular region of diabetic rats. All protocols induced the differentiation, but media supplemented with exendin-4/activin A or resveratrol induced the expression and secretion of insulin more efficiently, and only the exendin-4/activin-A-supplemented medium generated an insulin secretion profile more like ß-cells, in response to glucose. The PI3K/Akt pathway seems to play a negative role in IPC differentiation; however, the differentiation of ADSCs with exendin-4/activin A positively modulated the p38/MAPK pathway. Resveratrol medium activated the Jak/STAT3 pathway and generated IPCs apparently less sensitive to insulin and insulin-like receptors. Finally, the implant of IPCs with the best secretory behavior caused a decrease in hyperglycemia after one-week implantation in diabetic rats. Our data provide further information regarding the generation of IPCs from ADSCs and strengthen evidence to support the use of MSCs in regenerative medicine, specially the use of exendin-4/activin A to produce rapid and effectively IPCs with significant in vivo effects.
Asunto(s)
Adipocitos/metabolismo , Células Secretoras de Insulina/metabolismo , Tejido Adiposo/citología , Tejido Adiposo/metabolismo , Animales , Transporte Biológico , Biomarcadores , Diferenciación Celular , Células Cultivadas , Diabetes Mellitus Experimental , Expresión Génica , Glucosa/metabolismo , Inmunohistoquímica , Insulina/genética , Insulina/metabolismo , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/metabolismo , Fenotipo , Ratas , Transducción de SeñalRESUMEN
Organ transplantation is the gold standard therapy for the majority of patients with terminal organ failure. However, it is still a limited treatment especially due to the low number of brain death (BD) donors in relation to the number of waiting list recipients. Strategies to increase the quantity and quality of donor organs have been studied, and the administration of exendin-4 (Ex-4) to the donor may be a promising approach. Male Wistar rats were randomized into 3 groups: (1) control, without central nervous system injury; (2) BD induced experimentally, and (3) BD induced experimentally + Ex-4 administered immediately after BD induction. After BD induction, animals were monitored for 6 h before blood collection and kidney biopsy. Kidney function was assessed by biochemical quantification of plasma kidney markers. Gene and protein expressions of inflammation- and stress-related genes were evaluated by RT-qPCR and immunoblot analysis. Animals treated with Ex-4 had lower creatinine and urea levels compared with controls. BD induced oxidative stress in kidney tissue through increased expression of Ucp2, Sod2 and Inos, and Ex-4 administration reduced the expression of these genes. Ex-4 also induced increased expression of the anti-apoptotic Bcl2 gene. Nlrp3 and Tnf expressions were up-regulated in the BD group compared with controls, but Ex-4 treatment had no effect on these genes. Our findings suggest that Ex-4 administration in BD rats reduces BD-induced kidney damage by decreasing the expression of oxidative stress genes and increasing the expression of Bcl2.
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Exenatida/metabolismo , Exenatida/farmacología , Riñón/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Muerte Encefálica , Creatina/análisis , Citocinas/metabolismo , Modelos Animales de Enfermedad , Exenatida/fisiología , Genes bcl-2/efectos de los fármacos , Inflamación/metabolismo , Riñón/metabolismo , Trasplante de Riñón , Masculino , Proteína con Dominio Pirina 3 de la Familia NLR/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Ratas , Ratas Wistar , Donantes de Tejidos , Factor de Necrosis Tumoral alfa/efectos de los fármacos , Urea/análisisRESUMEN
Diabetes mellitus is a metabolic disorder that results in glucotoxicity and the formation of advanced glycated end products (AGEs), which mediate several systemic adverse effects, particularly in the brain tissue. Alterations in glutamatergic neurotransmission and cognitive impairment have been reported in DM. Exendin-4 (EX-4), an analogue of glucagon-like peptide-1 (GLP-1), appears to have beneficial effects on cognition in rats with chronic hyperglycemia. Herein, we investigated the ability of EX-4 to reverse changes in AGE content and glutamatergic transmission in an animal model of DM looking principally at glutamate uptake and GluN1 subunit content of the N-methyl-D-aspartate (NMDA) receptor. Additionally, we evaluated the effects of EX-4 on in vitro models and the signaling pathway involved in these effects. We found a decrease in glutamate uptake and GluN1 content in the hippocampus of diabetic rats; EX-4 was able to revert these parameters, but had no effect on the other parameters evaluated (glycemia, C-peptide, AGE levels, RAGE, and glyoxalase 1). EX-4 abrogated the decrease in glutamate uptake and GluN1 content caused by methylglyoxal (MG) in hippocampal slices, in addition to leading to an increase in glutamate uptake in astrocyte culture cells and hippocampal slices under basal conditions. The effect of EX-4 on glutamate uptake was mediated by the phosphatidylinositide 3-kinases (PI3K) signaling pathway, which could explain the protective effect of EX-4 in the brain tissue, since PI3K is involved in cell metabolism, inhibition of apoptosis, and reduces inflammatory responses. These results suggest that EX-4 could be used as an adjuvant treatment for brain impairment associated with excitotoxicity.
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Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Experimental/metabolismo , Exenatida/uso terapéutico , Ácido Glutámico/metabolismo , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Diabetes Mellitus Experimental/fisiopatología , Modelos Animales de Enfermedad , Exenatida/farmacología , Productos Finales de Glicación Avanzada/metabolismo , Glicosilación , Hipocampo/metabolismo , Masculino , Fosfatidilinositol 3-Quinasas/metabolismo , Piruvaldehído/metabolismo , Ratas Wistar , Receptor para Productos Finales de Glicación Avanzada/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Transducción de Señal/efectos de los fármacos , Estreptozocina , Transmisión Sináptica/efectos de los fármacosRESUMEN
The aim of this study was to evaluate Exendin-4 (EX-4) effects on islet volume and number in the mouse pancreas. Thirty-two healthy adult male NMRI mice were randomly divided into control and experimental groups. EX-4 was injected intraperitoneally (i. p.) at doses of 0.25 (E1 group), 0.5 (E2 group), and 1 µg/kg (E3 group), twice a day for 7 consecutive days. One day after the final injection, the mice were sacrificed, and the pancreas from each animal dissected out, weighed, and fixed in 10% formalin for measurement of pancreas and islet volume, and determination of islet number by stereological assessments. There was a significant increase in the weight of pancreases in the E3 group. Islet and pancreas volumes in E1 and E2 groups were unchanged compared to the control group. The E3 group showed a significant increase in islet and pancreas volume (P < 0.05). There were no significant changes in the total number of islets in all three experimental groups. The results revealed that EX-4 increased pancreas and islet volume in non-diabetic mice. The increased total islet mass is probably caused by islet hypertrophy without the formation of additional islets.
O objetivo deste estudo foi avaliar os efeitos do Exendin-4 (EX-4) sobre o volume e número de ilhotas no pâncreas. Trinta e dois camundongos NMRI machos saudáveis e adultos foram divididos ao acaso em grupos controle e grupos experimentais. EX-4 foi injetado intraperitonealmente (i. p.) nas doses de 0,25 (grupo E1), 0,5 (grupo E2) e 1 (grupo E3), duas vezes por dia durante 7 dias consecutivos. Um dia após a injeção final, os camundongos foram sacrificados e o pâncreas de cada animal foi dissecado, pesado e fixado em solução de formaldeído 10% para avaliação do volume do pâncreas e ilhotas e do número de ilhotas por métodos estereológicos. Observou-se aumento significativo no peso de pâncreas no grupo E3. O volume do pâncreas assim como das ilhotas não apresentou alterações nos grupos E1 e E2, quando comparados ao grupo controle No grupo E3 houve aumento significativo no volume do pâncreas e das ilhotas (P<0,05). Não se observaram alterações significativas no número de ilhotas nos três grupos experimentais. Os resultados revelaram que o EX-4 provoca aumento no volume do pâncreas, bem como no volume das ilhotas em camundongos não-diabéticos. O aumento no volume total de ilhotas deve-se, provavelmente, a hipertrofia das ilhotas sem a formação de ilhotas adicionais.