Aims/hypothesis The impact of AGEs and advanced lipoxidation end-products (ALEs) on neuronal and Müller glial dysfunction in the diabetic retina is not well understood. We therefore sought to identify dysfunction of the retinal Müller glia during diabetes and to determine whether inhibition of AGEs/ALEs can prevent it. Methods Sprague-Dawley rats were divided into three groups: (1) non-diabetic; (2) untreated streptozotocininduced diabetic; and (3) diabetic treated with the AGE/ ALE inhibitor pyridoxamine for the duration of diabetes. Rats were killed and their retinas were evaluated for neuroglial pathology. Results AGEs and ALEs accumulated at higher levels in diabetic retinas than in controls (p<0.001). AGE/ALE immunoreactivity was significantly diminished by pyridoxamine treatment of diabetic rats. Diabetes was also associated with the up-regulation of the oxidative stress marker haemoxygenase-1 and the induction of glial fibrillary acidic protein production in Müller glia (p<0.001). Pyridoxamine treatment of diabetic rats had a significant beneficial effect on both variables (p < 0.001). Diabetes also significantly altered the normal localisation of the potassium inwardly rectifying channel Kir4.1 and the water channel aquaporin 4 to the Müller glia end-feet interacting with retinal capillaries. These abnormalities were prevented by pyridoxamine treatment. Conclusions/interpretation While it is established that AGE/ALE formation in the retina during diabetes is linked to microvascular dysfunction, this study suggests that these pathogenic adducts also play a role in Müller glial dysfunction.

Background: Studies of gene expression in post mortem human brain can contribute to understanding of the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Quantitative real-time PCR (RT qPCR) is often used to analyse gene expression. The validity of results obtained using RT qPCR is reliant on accurate data normalization. Reference genes are generally used to normalize RT qPCR data. Given that expression of some commonly used reference genes is altered in certain conditions, this study aimed to establish which reference genes were stably expressed in post mortem brain tissue from individuals with AD, PD or DLB.

Aims/hypothesis Methylglyoxal (MG) is an important precursor for AGEs. Normally, MG is detoxified by the glyoxalase (GLO) enzyme system (including component enzymes GLO1 and GLO2). Enhanced glycolytic metabolism in many cells during diabetes may overpower detoxification capacity and lead to AGE-related pathology. Using a transgenic rat model that overexpresses GLO1, we investigated if this enzyme can inhibit retinal AGE formation and prevent key lesions of diabetic retinopathy. Methods Transgenic rats were developed by overexpression of full length GLO1. Diabetes was induced in wild-type (WT) and GLO1 rats and the animals were killed after 12 or 24 weeks of hyperglycaemia. N ε -(Carboxyethyl)lysine (CEL), N ε -(carboxymethyl)lysine (CML) and MG-derivedhydroimidazalone-1 (MG-H1) were determined by immunohistochemistry and by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MSMS).Müller glia dysfunction was determined by glial fibrillary acidic protein (GFAP) immunoreactivity and by spatial localisation of the potassium channel Kir4.1. Acellular capillaries were quantified in retinal flat mounts. Results GLO1 overexpression prevented CEL and MG-H1 accumulation in the diabetic retina when compared with WT diabetic counterparts (p<0.01). Diabetes-related increases in Müller glial GFAP levels and loss of Kir4.1 at the vascular end-feet were significantly prevented by GLO1 overexpression (p<0.05) at both 12-and 24-week time points. GLO1 diabetic animals showed fewer acellular capillaries than WT diabetic animals (p<0.001) at 24 weeks' diabetes.A.K. Berner, O. Brouwers and R. Pringle contributed equally to this study.Electronic supplementary material The online version of this article