neuropeptide-y and Diabetic-Retinopathy

Diabetic retinopathy (DR) is one of the most severe clinical manifestations of diabetes mellitus and a major cause of blindness. DR is principally a microvascular disease, although the pathogenesis also involves metabolic reactive intermediates which induce neuronal and glial activation resulting in disruption of the neurovascular unit and regulation of the microvasculature. However, the impact of neural/glial activation in DR remains controversial, notwithstanding our understanding as to when neural/glial activation occurs in the course of disease. The objective of this study was to determine a potential protective role of neuropeptide Y (NPY) using an established model of DR permissive to N-methyl-D-aspartate (NMDA)-induced excitotoxic apoptosis of retinal ganglion cells (RGC) and vascular endothelial growth factor (VEGF)-induced vascular leakage. In vitro evaluation using primary retinal endothelial cells demonstrates that NPY promotes vascular integrity, demonstrated by maintained tight junction protein expression and reduced permeability in response to VEGF treatment. Furthermore, ex vivo assessment of retinal tissue explants shows that NPY can protect RGC from excitotoxic-induced apoptosis. In vivo clinical imaging and ex vivo tissue analysis in the diabetic model permitted assessment of NPY treatment in relation to neural and endothelial changes. The neuroprotective effects of NPY were confirmed by attenuating NMDA-induced retinal neural apoptosis and able to maintain inner retinal vascular integrity. These findings could have important clinical implications and offer novel therapeutic approaches for the treatment in the early stages of DR.

Topics: Animals; Apoptosis; Cellular Microenvironment; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Endothelial Cells; Humans; Mice; N-Methylaspartate; Neuropeptide Y; Rats; Retina; Retinal Ganglion Cells; Retinal Neovascularization; Vascular Endothelial Growth Factor A

Diabetic retinopathy (DR) is one of the major complications of diabetes, which eventually leads to blindness. Up to date, no animal model has yet shown all the co-morbidities often observed in DR patients. Here, we investigated whether obese 42 weeks old ZSF1 rat, which spontaneously develops diabetes, hypertension and obesity, would be a suitable model to study DR. Although arteriolar tortuosity increased in retinas from obese as compared to lean (hypertensive only) ZSF1 rats, vascular density pericyte coverage, microglia number, vascular morphology and retinal thickness were not affected by diabetes. These results show that, despite high glucose levels, obese ZSF1 rats did not develop DR. Such observations prompted us to investigate whether the expression of genes, possibly able to contain DR development, was affected. Accordingly, mRNA sequencing analysis showed that genes (i.e. Npy and crystallins), known to have a protective role, were upregulated in retinas from obese ZSF1 rats. Lack of retina damage, despite obesity, hypertension and diabetes, makes the 42 weeks of age ZSF1 rats a suitable animal model to identify genes with a protective function in DR. Further characterisation of the identified genes and downstream pathways could provide more therapeutic targets for the treat DR.

Topics: Animals; Blood Glucose; Crystallins; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Diabetic Retinopathy; Disease Models, Animal; Gene Expression Profiling; Hypertension; Male; Metabolic Syndrome; Neuropeptide Y; Obesity; Rats; Retina

Several studies have shown genetic predisposition for diabetic complications. The leucine7 to proline7 (Leu7Pro) polymorphism of preproNPY has been shown to be a risk factor for diabetic retinopathy in type 1 diabetes. In the current study we examined the contribution of this polymorphism on the progression of retinopathy in Caucasian type 1 and type 2 diabetes patients. Patients with type 2 diabetes and the Leu7Pro polymorphism developed retinopathy at younger age because of markedly earlier disease onset of diabetes (RC- 6.8, 95% CI-12.2 - [- 1.5]), but no association of the Leu7Pro polymorphism with the current severity of retinopathy was detected. A strong association of the polymorphism with proteinuria in type 2 diabetes patients with retinopathy could be detected (OR 3.1, 95% CI 1.1-8.8); 31% of subjects having both retinopathy and proteinuria had the polymorphism compared to only 13% of retinopathy patents without concomitant proteinuria (p = 0.032). Plasma concentrations of NPY were increased in subjects with proteinuria (79.2+/-28.4 and 64.7+/-26.2 pmol/l, p = 0.001). These results suggest that the Leu7Pro polymorphism could be used to predict earlier onset of type 2 diabetes and retinopathy, and increased risk for diabetic nephropathy.

Topics: Adult; Age Factors; Aged; Amino Acid Substitution; Cross-Sectional Studies; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diabetic Retinopathy; Female; Humans; Male; Middle Aged; Neuropeptide Y; Polymorphism, Genetic; Predictive Value of Tests; Protein Precursors; Proteinuria; Retrospective Studies; Risk Factors; White People

Neuropeptide Y is a sympathetic neurotransmitter, a potent endothelium-derived angiogenic factor and a vascular mitogen. We have studied the role of the functional leucine7 to proline7 polymorphism of the signal peptide region of preproneuropeptide Y (prepro-NPY) as a genetic susceptibility factor for diabetic retinopathy. In addition, we investigated the role of the NPY Y2-receptor as a putative mediator of angiogenic NPY signaling in the retina.. Frequencies of proline7 (Pro7) carriers in the prepro-NPY were determined in type 1 and type 2 diabetes patients having retinopathy, in type 2 diabetes patients without retinopathy and in healthy control subjects. The role of Y2-receptor in hyperoxemia-induced retinal neovascularization was investigated in Y2-receptor knockout mice (Y2-/-) and in rats administered Y2-receptor mRNA antisense oligonucleotide.. The carriers having Pro7 in the preproNPY are markedly over-represented among type 2 diabetes patients with retinopathy compared to type 2 diabetes patients without retinopathy and to the population control. Neonatal exposure to hyperoxia resulted in development of retinal neovascularization that was prevented in Y2(-1-) -mice, and significantly inhibited in rats treated with the Y2-receptor antisense oligonucleotide.. NPY and Y2-receptor play important roles in diabetic retinopathy and retinal neovascularization and are thus potential new targets for drug molecules for treatment of retinopathy.

Topics: Adult; Aged; Animals; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Female; Humans; Male; Mice; Middle Aged; Neuropeptide Y; Rats; Receptors, Neuropeptide Y; Retinal Neovascularization

In this study we tested the hypothesis that the Leu7Pro7 polymorphism in prepro neuropeptide Y (NPY) gene could be a risk marker for the development of diabetic retinopathy and analyzed a well characterized cohort of patients with Type 2 diabetes followed-up for 10 years from the time of diagnosis. The frequency of Leu7/Pro7-polymorphism was 9.3% (8 out of 86). At baseline, the frequency of retinopathy in patients with the Leu7/Pro7-polymorphism was 25% (2 out of 8) and in those without it 6.4% (5 out of 78) (p=0.126). At 10-year the respective figures were 88% and 50% (p=-0.040). The odds ratio for Leu7/Pro7-polymorphism in logistic regression analysis adjusted for age, gender and HbA1c was 8.97 (95% confidence intervals 1.09-98.0; p=0.049). Our finding based on elderly Finnish Type 2 diabetic subjects suggests that the Leu7Pro7-genotype in preproNPY gene is associated with the development of diabetic retinopathy.

Topics: Aged; Amino Acid Substitution; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Female; Finland; Follow-Up Studies; Glycated Hemoglobin; Humans; Leucine; Male; Middle Aged; Neuropeptide Y; Polymorphism, Genetic; Proline; Time Factors

Neuropeptide Y (NPY) is a potent vasoconstrictor peptide that is abundant in the brain and the peripheral sympathetic nervous system. In the present study we investigated possible changes in plasma immunoreactive (IR)-NPY concentrations and urinary IR-NPY excretion in patients with non-insulin dependent diabetes mellitus (NIDDM) and the relationship to diabetic complications, such as nephropathy and neuropathy. IR-NPY in plasma and urine was measured by radioimmunoassay in 69 patients with NIDDM. Plasma IR-NPY concentrations in patients with advanced nephropathy (creatinine clearance <30 ml/min) (100.5 +/- 10.3 pmol/l, n=9, mean +/- SEM) were higher than in the control subjects (55.0 +/- 6.8 pmol/l, n=15) (P<0.02). Urinary excretion of IR-NPY and fractional excretion of NPY were also increased in the patients with advanced nephropathy. Sephadex G-50 column chromatography of the urine extracts obtained from healthy subjects, diabetic patients with renal failure and non-diabetic patients with renal failure showed an immunoreactive peak eluting in the NPY position. On the other hand, neither plasma nor urinary IR-NPY was high in patients with retinopathy, or in patients with peripheral neuropathy. The present study has, for the first time, shown high plasma IR-NPY concentrations and urinary IR-NPY excretion in NIDDM patients with advanced nephropathy.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Blood Glucose; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Female; Glycated Hemoglobin; Humans; Male; Middle Aged; Neuropeptide Y; Reference Values