Erectile dysfunction (ED) is frequently associated with diabetes mellitus. We determined if advanced glycation end products (AGEs) are involved in ED and investigated if the selective AGE and ...inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (AG) could protect against the development of ED in a diabetic rat model.
Harlan Sprague-Dawley rats were divided into 3 groups. The 9 nondiabetic rats in group 1 served as age matched controls. Diabetes was induced in the 9 rats in groups 2 and 3, respectively, by intraperitoneal injection of streptozocin (60 mg/kg). While group 2 was given free access to water and a standard diet, group 3 was treated with AG added to drinking water (1 gm/l daily). Two months after diabetes induction in vivo intracavernous pressure measurements were determined. Penile tissue glycation (furosine on high performance liquid chromatography), AGEs (pentosidine on high performance liquid chromatography and immunohistochemistry), AGE receptor (galectin-3 on immunohistochemistry and Western blot) and iNOS (Western blot) levels were measured in control and diabetic penises.
Cavernous tissue furosine, pentosidine, galectin-3 and iNOS protein levels were significantly elevated in the diabetic group compared with controls (p <0.05). On the other hand, cavernous tissue furosine, pentosidine, galectin-3 and iNOS expression were lower in diabetic rats treated with AG despite an unchanged glycemia level. Diabetic rats had a significant decrease in erectile function compared with control rats (p <0.05), while AG treated diabetic rats showed erectile function similar to that in control animals.
Glycation, AGEs, galectin-3 and iNOS levels are elevated in diabetic rat penile tissue and significantly decreased by AG treatment. Furthermore, erectile function was preserved in AG treated animals. The observation that AG improved glycation despite no effect on glycemia suggests that AG may improve penile collagen turnover.
Produtos da glicação avançada dietéticos e as complicações crônicas do diabetes Barbosa, Júnia Helena Porto(Universidade Federal de Alagoas Faculdade de Nutrição); Oliveira, Suzana Lima de(Universidade Federal de Alagoas Faculdade de Nutrição); Seara, Luci Tojal e(Universidade Federal de Alagoas Faculdade de Nutrição)
Revista de Nutrição,
2009, Letnik:
22, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A geração dos produtos de glicação avançada é um dos principais mecanismos desencadeadores das doenças associadas ao diabetes mellitus, que incluem cardiopatia, retinopatia, neuropatia e nefropatia. ...Esta revisão tem como objetivo analisar o papel dos produtos de glicação avançada presentes na alimentação como mediadores das complicações diabéticas e apresentar estratégias de redução de sua ingestão. Para tanto, foram realizados levantamentos em bancos de dados de publicações da área, dos últimos 15 anos, considerando-se artigos de revisão, estudos clínicos e experimentais. Os produtos de glicação avançada são um grupo heterogêneo de moléculas formadas a partir de reações não enzimáticas entre grupamentos amino e carbonilo, sendo a carboximetilisina e a pentosidina exemplos de produtos de glicação avançada identificados em alimentos e in vivo. Os produtos de glicação avançada ingeridos são absorvidos, somando-se aos endógenos no surgimento e na progressão das diversas complicações do diabetes, existindo uma correlação direta entre o consumo e a concentração sanguínea. Sua restrição na alimentação se correlaciona à supressão dos níveis séricos de marcadores de doença vascular e de mediadores inflamatórios diretamente envolvidos no desenvolvimento das degenerações diabéticas. As atuais orientações dietéticas centram-se na proporção em nutrientes e na restrição energética, sem considerar o risco da ingestão de produtos de glicação avançada formados durante o processamento dos alimentos. Recomendações simples, como a utilização de temperaturas baixas por períodos mais curtos, em presença de água, no preparo de alimentos, exercem efeitos importantes na prevenção das complicações do diabetes. O estudo dos mecanismos envolvidos na geração de produtos de glicação avançada e das propriedades anti-glicação de compostos presentes nos alimentos podem contribuir com a conduta terapêutica, concorrendo para a melhoria da qualidade de vida dos portadores dessa enfermidade.
The generation of advanced glycation end products is one of the principal mechanisms that lead to the pathologies associated with diabetes mellitus, which include cardiopathy, retinopathy, neuropathy and nephropathy. The objective of this revision is to analyse the role of the advanced glycation end products present in food as intermediaries of diabetic complications, presenting strategies to reduce their ingestion. For this purpose, research was carried out in databases of publications of the area, for the last 15 years, taking into account revision, experimental and clinical studies. Advanced glycation end products are a heterogenous group of molecules coming from non-enzymatic reactions between amino and carbonyl groups, examples being carboxymethyllisine and pentosidine found in food and in vivo. The advanced glycation end products ingested are absorbed and, along with endogenous advanced glycation end-products, promote the progression of the complications of diabetes. There is a direct correlation between advanced glycation end products consumption and blood concentration. Their restriction in food results in the suppression of serum levels of the markers of vascular disease and the intermediaries of inflammation directly involved in the development of diabetic degenerations. The current dietary orientations are concentrated on the proportion of nutrients and on energetic restriction. The risk of ingestion of advanced glycation end products formed during the processing of food should be taken in consideration. It is simply recommended that in the preparation of food, the use of low temperatures for short periods, in the presence of water, has important effects in the prevention of the complications of diabetes. The study of the mechanisms involved in the generation of advanced glycation end products and the antiglycation properties of compounds presented in foods can contribute to a therapeutic practice and an improvement in the quality of life of people with this disease.
Early atherosclerotic lesions develop predominantly where laminar blood flow is interrupted and mean shear stress is low, indicating that local hemodynamics influence atherosclerotic development. ...Diabetics develop diffuse atherosclerosis compared to nondiabetics, suggesting that diabetic endothelial cells fail to properly sense or respond to fluid shear forces. Using an
in vitro
model we exposed endothelial cells to shear forces using a parallel plate flow chamber. In response to flow, control cells elongate and orient in the flow direction; whereas, cells cultured in high glucose align significantly less. This impaired response is not rescued by the free radical scavenger Tempol, but it is rescued by treatment with the advanced glycation end-product inhibitor aminoguanidine. These findings indicate a glucose-induced impairment of the endothelial response to fluid flow that is likely mediated by the formation of advanced glycation end-products.
To explore the impact of advanced glycosylation end products (AGE)-modified human serum albumin (AGE-HSA) on keratinocyte migration and the mechanism thereof.
AGE-HSA was prepared in vitro. Epidermal ...keratinocytes from Sprague-Dawley rats' back were cultured and treated with AGE-HSA of the terminal concentrations of 0, 30, 60, 90, 120, and 150 microg/ml for 1, 3, 5, and 7 days respectively. MTT method was used to detect the keratinocyte adhesion rate, expressed by absorbance. Keratinocyte migration ability was assessed by scratch wound healing assay and Transwell assay. Expression of integrin alpha3 was determined by flow cytometry. Scanning electron and inverted microscopes were used to observe the pseudopodium and microfilament of the keratinocytes. Immunofluorescence staining was used to detect the form of F-actin in the cells.
The adhesion rates of the keratinocyte cultured with AGE-HSA for 12 and 24 hours were (0.112 +/- 0.022) and (0.173 +/- 0.012) respectively, both significantly lower than those of th
Sugars and sugar degradation products react in vivo readily with proteins (glycation) resulting in the formation of a heterogeneous group of reaction products, which are called advanced glycation end ...products (AGEs). AGEs notably change the structure and function of proteins so that extended protein-AGE formation is linked to complications such as nephropathy, atherosclerosis, and cataract. DNA can be glycated in vitro in a similar way as proteins, and the two diastereomers of N(2)-carboxyethyl-2'-deoxyguanosine (CEdG(A,B)) were identified as major DNA AGEs. It was postulated that DNA AGEs play an important role in aging, diabetes, and uremia. However, at the moment, sensitive methods to measure the extent and impact of DNA AGEs in vivo do not exist. In this study, we developed a monoclonal antibody, which recognized CEdG(A,B) with high affinity and specificity (MAb M-5.1.6). The I(50) value for CEdG(A,B) was 2.1 ng/mL, whereas other modified nuclueobases and AGE proteins showed negligible cross-reactivity. Unmodified 2'-deoxyguanosine was only weakly recognized with an I(50) value > 600,000 ng/mL, which is the limit of solubility. MAb M-5.1.6 was then used to measure the urinary excretion of AGE-modified nucleobases in a competitive enzyme-linked immunosorbent assay. The recovery of CEdG(A,B) from human urine was between 87.4 and 99.7% with coefficients of variations between 8.0 and 22.2%. The detection limit was 0.06 ng/mL, and the determination limit was 0.15 ng/mL with a linear range between 0.3 and 100 ng/mL. CEdG equivalents were analyzed in urine samples from 121 healthy volunteers, and concentrations between 1.2 and 117 ng CEdG equiv/mg creatinine were detected.
Obesity affects ovarian function, one of the main regulators of female fertility. Tissue levels of the proinflammatory advanced glycation end-products (AGEs) and their receptors (RAGE) are elevated ...in obesity. AGEs are key contributors to perturbations in the ovarian microenvironment. On this basis, the present review focuses on clinical and experimental studies supporting the role of AGE-RAGE system as a contributor to obesity-related ovarian dysfunction. Particular emphasis has been given to changes in AGEs, RAGE and the anti-inflammatory soluble receptor (sRAGE) levels in obesity state and following dietary interventions (high-fat diet and weight loss). Ovarian sensitivity, in particular granulosa cell function and oocyte meiosis, to the pro-inflammatory AGE-RAGE system as well as the relationship of follicular fluid AGEs and sRAGE to in vitro fertilization outcome are also discussed. Overall, obesity, with its alterations in the AGE-RAGE system, can disrupt the ovarian microenvironment potentially compromising oocyte competence and fertility. This review underscores a critical need to uncover the mechanistic actions of AGE-RAGE system in obesity-related ovarian dysfunction. Clinical and basic studies focusing on elucidating the patterns of accumulation and role of the AGE-RAGE system in human ovarian follicles are key steps in understanding their contribution to the health of human oocytes and embryos.
Objective To determine whether advanced glycosylation end products modified bovine serum albumin (AGEs-BSA) affects endothelial cell lateral junction protein, platelet-endothelial cell adhesion ...molecule-1 ( PECAM-1 ) in the presence or absence of inflammatory mediators.Methods Cultured human umbilical vein endothelial cells (HUVECs) were exposed to AGEs-BSA for 6, 12, 24, and 36 hours, and exposed to AGEs-BSA glycosylated with different concentrations of glucose, tumor necrosis factord-a (TNF-α), interferon ( IFN-γ), TNF-α + IFN-γ and AGEs-BSA +TNF-α for 24 hours, respectively. Expression of PECAM-1 mRNA was measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) with β-actin as an internal standard, and sequencing of RT-PCR products was performed to confirm the specificity of amplification for PECAM-1 gene. The endothelial cell surface expression of PECAM-1 was determined by flow cytometry (FCM).Results There were no significant changes in the expression of PECAM-1 mRNA and protein whenthe cells were exposed to AGEs-BSA with different concentrations or periods (P>0.05). However,PECAM-1 expression was reduced in the cells treated with TNF-α, IFN-γ), TNF-α + IFN-γ and AGEs-BSA + TNF-α. The level of PECAM-1 treated with AGEs-BSA + TNF-α was lower than that of TNF-αtreated alone ( P <0. 01 ).Conclusions AGEs-BSA had no effect on the expression of PECAM-1 mRNA and protein in cultured HUVEC. With the presence of inflammatory mediator TNF-α, AGEs-BSA decreased the level of PECAM-1, which might reduce the adhesion interaction between adjacent endothelial cells, enhance the permeability of endothelial cells, and might be implicated in the endothelial dysfunction and pathogenesis of atherosclerosis in patients with diabetes mellitus. The significance of this phenomenon in intracellular signal transduction remains to be determined.
To investigate the accumulation of advanced glycation end products (AGE) and the inflammatory response of skin and wound in diabetic patients, and to analyze their relationship in vitro.
Histological ...staining and immunohistochemical staining was respectively performed on skin and wound tissue specimens collected from 10 patients with Type II diabetes mellitus (diabetes group) and 12 non-diabetic patients with skin injury (control group) to observe the arrangement of collagen and the distribution of inflammatory cells, and to determine the expression levels of AGE and its receptor (RAGE). Malondialdehyde (MDA) levels in skin and wound tissue homogenates were assayed by enzyme-linked immunosorbent assay. In vitro, human neutrophils were isolated and treated with RPMI-1640 culture medium or that containing AGE-human serum albumin in the concentration of 0.315, 0.625, 1.250 mg/mL, and they were identified as normal control (NC) group, low concentration (L) group, moderate concentration (M) group, and high concent
To analyze the relationship between cutaneous glycometabolic disorders and cutaneous neuropathy in diabetic rats, and to look for the mechanism of neuropathy and impaired wound healing.
Eighty male ...SD rats were randomly divided into the normal control group (NC, n = 20), diabetic group (D, n = 20), aminoguanidine-interfered group (AI, n = 20), and insulin-interfered group (II, n = 20) by drawing lots. Diabetes was reproduced in rats of D, AI, and II groups with intraperitoneal injection of streptozotocin (STZ). Then, rats in AI group were fed with 100 mg×kg(-1)×d(-1) aminoguanidine, while rats in II group were subcutaneously injected with insulin for satisfactory control of blood glucose. Changes in mechanical and heat pain thresholds of pad of hind limb were measured at post injection week (PIW) 2, 4, 8. Skin specimens were collected during PIW 2-8 from pads for determination of contents of glucose, advanced glycation end product (AGE), substance P (SP), calcitonin gene-related peptide (CGRP), and observatio
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