Project description:Patients with long-duration diabetes develop cardiovascular complications resulting in highly increased mortality and complications which affect the kidneys, eyes and peripheral nerves associated with high morbidity. Among the diabetic complications, damage in the eye, diabetic retinopathy, is the most common microvascular complication of diabetes. Diabetic retinopathy is a leading cause of vision-loss globally. It is characterized by a number of different patho-mechanisms including changes in vascular permeability, capillary degeneration, and finally at a late stage overshooting formation of new blood vessels. This expression analysis focused on the use of different experimental models for Diabetes Mellitus and its complications (for a review see 1: Al-Awar et al: Experimental Diabetes Mellitus in Different Animal Models. J Diabetes Res. 2016; doi: 10.1155/2016/9051426). By that, we wanted to uncover the relative contributions of systemic hyperinsulinaemia and/or hyperglycemia to molecular regulations. The following models have been used: As insulinopenic, hyperglycemic model reflecting Type 1 diabetes, male STZ-Wistar rats (60mg/kg BW; i.p.) were used. Wistar rats without STZ injection served as non-diabetic controls. Male obese ZDF rats (Fa/Fa) were used as type-2 diabetes model characterized by persisting hyperglycemia and transient hyperinsulinemia. Male lean ZDF rats (Fa/-) served as non-diabetic controls. Male obese ZF rats (Fa/Fa) hyperglycemia were used reflecting euglycemia and severe insulin resistance. Male lean ZF rats (Fa/-) served as controls. ZDF and ZF rats were obtained in two genotypes, obese (genotype fa/fa) and lean littermates (genotype Fa/?). All rats were housed in standard cages under a normal light-dark cycle for 16 weeks. All animals had free access to food and water. ZF and Wistar rats received a standard chow (Ssniff R/M) and ZDF rats received Purina 5008 chow. A group size of n=8 were used for all study groups. Wistar rats were rendered type-1 like hyperglycemic and hypoinsulinemic via a single injection of streptocotocin (STZ, 60mg/kg; i.p.) at 7 weeks of age. Obese ZDF rats (fa/fa) develop spontaneously a type-2 diabetes phenotype with persisting hyperglycemia and transient hyperinsulinemia (hyperglycemic, hypoinsulinemic). Obese ZF rats (fa/fa) develop insulin resistance with permanent hyperinsulinemia without concomitant hyperglycemia and no overt diabetes phenotype. Non STZ treated Wistar rats, lean ZDF littermates (Fa/?), and lean ZF littermates (Fa/?) served as controls. All groups were kept for 12 weeks on respective conditions together with appropriate age-matched controls. Unbiased gene expression analysis was performed per group using Affymetrix gene arrays.

Project description:Skeletal muscle mitochondrial dysfunction is secondary to T2DM and can be improved by long-term regular exercise training Mitochondrial dysfunction has long been implicated to play a causative role in development of type 2 diabetes (T2DM). However, a growing number of recent studies provide data that mitochondrial dysfunction is a consequence of T2DM development. The aim of our study is to clarify in further detail the causal role of mitochondrial dysfunction in T2DM by a comprehensive ex vivo analysis of mitochondrial function combined with global gene expression analysis in muscle of pre-diabetic newly diagnosed untreated T2DM subjects and long-standing insulin treated T2DM subjects compared with age- and BMI-matched controls. In addition, we assessed the impact of long-term interval exercise training on physical activity performance, mitochondrial function and glycemic control in long-standing insulin-treated T2DM subjects. Ex vivo mitochondrial density, quality and functioning was comparable between pre-diabetic subjects and matched controls, however, gene expression analysis showed a switch from carbohydrate toward lipids as energy source in pre-diabetes subjects. In contrast, long-term insulin treated T2DM subjects had slightly decreased mitochondrial density and ex vivo function. Expression of Krebs cycle and OXPHOS related genes were decreased, indicating a decreased capacity to use lipids as an energy source. The insulin-treated T2DM subjects had a lower physical activity level than pre-diabetic and normoglycemic subjects. A 52 weeks exercise training of these subjects increased submaximal oxidative efficiency, increased in vivo PCr recovery rate, as well as mildly increased in vitro mitochondrial function. Gene expression of β-oxidation, Krebs cycle and OXPHOS-related genes was increased. Our data demonstrate that mitochondrial dysfunction is rather a consequence than a causative factor in T2DM development as it was only detected in overt diabetes and not in early diabetes. Regular exercise training stabilized exogenous insulin requirement and improved mitochondrial functioning, fatty acid oxidation and general physical work load capacity in long-standing insulin-treated T2DM subjects. As such, the present study shows for the first time that long-term exercise interventions are beneficial in this group of complex diabetes patient and may prevent further metabolic deterioration. Insulin-treated T2DM subjects before and after 52 weeks of exercise training (T2DM_0 and T2DM_52), normoglycemic controls (NGT) and pre-diabetes subjects (IGT) and were selected. RNA was extracted from skeletal muscle biopsies and hybridized on Affymetrix microarrays.

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