Franny Jongbloed

14 CHAPTER 1 To improve efficacy of a diet in a clinical setting, experiments were initiated to discriminate whether the calorie restriction per se or absence of one of the nutrients is responsible for the effects of DR. Data from fruit flies in aging studies hint towards a different role of individual macronutrients, where Drosophila lived up to 50% longer when restricted in their protein intake 34 . Further studies confirmed the key role of protein in the protective effects on both the long-term and short-term effects 3,35 . In animal models of IRI, a protein- free diet given up to six days prior to IRI was found to be protective against oxidative stress and surgery-related outcome 36,37 . However, mice on protein-restricted or protein-free diets restricted themselves in food, and thus calorie intake, which made it difficult to distinguish between the effects of protein restriction and calorie restriction 36 . Also, the role of the other macronutrients, carbohydrates and fats, as well as the amino acids had not been investigated sufficiently to disentangle their contribution to the beneficial effects of DR 38-40 . Therefore, in the work described this thesis, my colleagues and I set out to further narrow down the duration and deprivation of nutrient components prior to acute stress-related injury in order to find a safe and effective diet that would be applicable to study in a clinical setting. AIMS AND OUTLINE OF THIS THESIS The aims of this thesis were to assess the effects of current short-term DR regimens in different mouse models, to investigate the effects of macronutrients and amino acids in the effects of DR, to broaden the knowledge about the molecular mechanisms underlying DR, and to develop a safe and effective DR regimen to investigate in a clinical surgical setting. In chapter 2 , we extended our previous studies on nutritional preconditioning by testing the hypothesis that preoperative fasting induces the same beneficial effects on renal IRI in mice of a different genetic background and that were overweight, aged, and of both male and female gender. We compared general changes on a transcriptional level between young-lean and aged-overweight male mice, and focused on pathways and individual genes that could be involved in the protective effect of DR on renal IRI. In chapter 3 , the reduction of chemotherapy-related toxicity by fasting was investigated on a transcriptional level. Tumor-bearing mice were subjected to fasting and subsequent irinotecan treatment, and the transcriptome of both liver and tumor was compared to that of mice that were ad libitum fed and/or were not given any chemotherapy. In chapter 4 , we investigated to role of short-term macronutrient-free diets on renal IRI on both a phenotypical and transcriptional level. Together with the gene expression profiles of DR and fasting, we collected an extensive dataset of different DR strategies that are either protective or non- protective against renal IRI. Microarray analyses enabled us to further unravel potential key pathways and transcription factors mediating the effects of DR, fasting and protein