The influence of pharmacokinetic parameters on the hepatic biochemical responses to the peroxisome proliferators, ciprofibrate, bezafibrate and clofibrate, was studied in the Fischer rat following a 26-week treatment period. With once daily dosing, the induction profiles of these compounds were dissimilar and the order of response was ciprofibrate > bezafibrate > clofibrate. By adjusting the frequency of dosing with respect to drug half life, i. e. clofibrate and bezafibrate twice daily and ciprofibrate once every 48 hours, the differences in response were ablated. The effect of short term ciprofibrate administration on hepatic enzyme parameters was studied in different rat strains and species. The rat (all strains), mouse, hamster and rabbit were termed responsive due to a coordinate induction of cytochrome P-452, carnitine acetyltransferase and peroxisomal beta-oxidation. No treatment related changes were observed in the guinea pig. In the marmoset a slight increase in peroxisomal beta-oxidation was demonstrated with no induction of cytochrome P-452 and carnitine acetyltransferase. In responsive species increased 12-hydroxylation of lauric acid correlated with an increase in mRNA hybridising to a cytochrome P-452 cDNA probe. The guinea pig and marmoset were designated non-responsive. In the marmoset and Fischer rat the hepatic enzyme responses to a 14-day and 26-week ciprofibrate administration were similar. A 4-week recovery group was included in the marmoset chronic study and the increase in peroxisomal beta-oxidation was found to be readily reversible whereas mitochondrial and microsomal changes were not. Electron microscopy revealed no peroxisome proliferation in the marmoset. Renal enzyme parameters were examined in ciprofibrate treated animals and considerable rat strain and species differences were observed. Renal enzyme changes were minimal. The response to ciprofibrate appeared to be largely specific for the liver in responsive species. From these results it is clear that the rat is not a suitable animal model to predict the hepatic response in the marmoset. If it is assumed that the marmoset resembles man more closely than the rat, extrapolation would indicate that peroxisome proliferators are not a toxicological hazard to man.

Thesis (Ph.D.)--University of Tennessee Health Science Center, 2009. / Title from title page screen (viewed on July 22, 2009). Research advisor: Edwards A. Park. Document formatted into pages (xi, 94 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 69-89).

Lee Wing Sum. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 206-226). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (Chinese Version) --- p.iv / Acknowledgements --- p.vii / Table of Contents --- p.viii / List of Abbreviations --- p.xiv / List of Figures --- p.xvii / List of Tables --- p.xxiv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Literature review --- p.3 / Chapter 2.1 --- Peroxisomes --- p.3 / Chapter 2.2 --- Peroxisome proliferators --- p.5 / Chapter 2.3 --- Human exposure pathways to peroxisome proliferators --- p.5 / Chapter 2.4 --- Peroxisome proliferator-induced pleiotropic effects in rodents --- p.7 / Chapter 2.4.1 --- Short-term effects --- p.7 / Chapter 2.4.1.1 --- Hepatomegaly --- p.7 / Chapter 2.4.2.1 --- Peroxisome proliferation --- p.8 / Chapter 2.4.1.3 --- Alteration of gene transcriptions --- p.8 / Chapter 2.4.2 --- Long-term effect --- p.9 / Chapter 2.5 --- Mechanisms of actions of peroxisome proliferators --- p.9 / Chapter 2.5.1 --- Substrate overload --- p.9 / Chapter 2.5.2 --- Receptor-mediated --- p.11 / Chapter 2.6 --- Peroxisome proliferator-activated receptors (PPARs) --- p.11 / Chapter 2.6.1 --- Structure of PPARs --- p.11 / Chapter 2.6.2 --- Tissue-specific expression of PPARs --- p.15 / Chapter 2.6.3 --- Physiological functions of PPARs --- p.19 / Chapter 2.6.3.1 --- PPARα --- p.19 / Chapter 2.6.3.2 --- PPARγ --- p.21 / Chapter 2.6.3.3 --- PPARδ --- p.23 / Chapter 2.7 --- Role of PPARα involved in peroxisome proliferator-induced pleiotropic responses --- p.24 / Chapter 2.7.1 --- Short-term effects --- p.24 / Chapter 2.7.2 --- Long-term effect --- p.24 / Chapter 2.8 --- Mechanisms of peroxisome proliferator-induced hepatocarcinogenesis --- p.25 / Chapter 2.8.1 --- Oxidative stress --- p.25 / Chapter 2.8.2 --- Suppression of apoptosis --- p.26 / Chapter 2.8.3 --- Increased cell proliferation --- p.27 / Chapter 2.9 --- Species difference to peroxisome proliferator-induced pleiotropic effects --- p.28 / Chapter 2.10 --- Fluorescent differential display (FDD) --- p.32 / Chapter Chapter 3 --- Objectives --- p.35 / Chapter Chapter 4 --- Materials and methods --- p.37 / Chapter 4.1 --- Animals and treatments --- p.37 / Chapter 4.1.1 --- Materials --- p.37 / Chapter 4.1.2 --- Methods --- p.37 / Chapter 4.2 --- Serum triglyceride and cholesterol analyses --- p.39 / Chapter 4.2.1 --- Materials --- p.41 / Chapter 4.2.2 --- Methods --- p.41 / Chapter 4.2.2.1 --- Serum preparation --- p.41 / Chapter 4.2.2.2 --- Triglyceride determination --- p.41 / Chapter 4.2.2.3 --- Cholesterol determination --- p.42 / Chapter 4.3 --- Statistical analysis --- p.42 / Chapter 4.4 --- Tail-genotyping --- p.42 / Chapter 4.4.1 --- Materials --- p.44 / Chapter 4.4.2 --- Methods. --- p.44 / Chapter 4.4.2.1 --- Preparation of genomic tail DNA --- p.44 / Chapter 4.4.2.2 --- PCR reaction --- p.45 / Chapter 4.5 --- Total RNA isolation --- p.45 / Chapter 4.5.1 --- Materials --- p.48 / Chapter 4.5.2 --- Methods --- p.48 / Chapter 4.6 --- DNase I treatment --- p.48 / Chapter 4.6.1 --- Materials --- p.49 / Chapter 4.6.2 --- Methods --- p.49 / Chapter 4.7 --- Reverse transcription of mRNA and fluorescent PCR amplification --- p.50 / Chapter 4.7.1 --- Materials --- p.50 / Chapter 4.7.2 --- Methods --- p.53 / Chapter 4.8 --- Fluorescent differential display (FDD) --- p.53 / Chapter 4.8.1 --- Materials --- p.53 / Chapter 4.8.2 --- Methods --- p.54 / Chapter 4.9 --- Excision of differentially expressed cDNA fragments --- p.54 / Chapter 4.9.1 --- Materials --- p.57 / Chapter 4.9.2 --- Methods --- p.57 / Chapter 4.10 --- Reamplification of differentially expressed fragments --- p.57 / Chapter 4.10.1 --- Materials --- p.60 / Chapter 4.10.2 --- Methods --- p.60 / Chapter 4.11 --- Subcloning of reamplified cDNA fragments --- p.62 / Chapter 4.11.1 --- PCR-TRAP® cloning system --- p.62 / Chapter 4.11.1.1 --- Materials --- p.63 / Chapter 4.11.1.2 --- Methods --- p.63 / Chapter 4.11.2 --- AdvaTage´ёØ PCR cloning system --- p.65 / Chapter 4.11.2.1 --- Materials --- p.65 / Chapter 4.11.2.2 --- Methods --- p.66 / Chapter 4.12 --- Purification of plasmid DNA from recombinant clones --- p.69 / Chapter 4.12.1 --- Materials --- p.69 / Chapter 4.12.2 --- Methods --- p.69 / Chapter 4.13 --- DNA sequencing of differentially expressed cDNA fragments --- p.70 / Chapter 4.13.1 --- CEQ 2000 Dye Terminator Cycle Sequence system --- p.71 / Chapter 4.13.1.1 --- Materials --- p.71 / Chapter 4.13.1.2 --- Methods --- p.71 / Chapter 4.13.2 --- ABI PRISM´ёØ dRhodamine Terminator Cycle Sequencing system --- p.72 / Chapter 4.13.2.1 --- Materials --- p.72 / Chapter 4.13.2.2 --- Methods --- p.72 / Chapter 4.13.3 --- Homology search against computer databases --- p.73 / Chapter 4.14 --- Northern analysis of differentially expressed cDNA fragments --- p.73 / Chapter 4.14.1 --- Formaldehyde gel electrophoresis of total RNA --- p.74 / Chapter 4.14.1.1 --- Materials --- p.74 / Chapter 4.14.1.2 --- Methods --- p.74 / Chapter 4.14.2 --- Preparation of cDNA probes for hybridization --- p.74 / Chapter 4.14.2.1 --- PCR DIG labeling --- p.75 / Chapter 4.14.2.1.1 --- Materials --- p.75 / Chapter 4.14.2.1.2 --- Methods --- p.75 / Chapter 4.14.2.2 --- Random Prime cDNA DIG labeling --- p.75 / Chapter 4.14.2.2.1 --- Materials --- p.75 / Chapter 4.14.2.2.2 --- Methods --- p.76 / Chapter 4.14.3 --- Purification of DNA from agarose gel --- p.77 / Chapter 4.14.3.1 --- Materials --- p.77 / Chapter 4.14.3.2 --- Methods --- p.78 / Chapter 4.14.4 --- Hybridization --- p.78 / Chapter 4.14.4.1 --- Materials --- p.78 / Chapter 4.14.4.2 --- Methods --- p.73 / Chapter 4.14.5 --- Synthesis of mouse GAPDH probe from normalization --- p.80 / Chapter 4.14.5.1 --- Materials --- p.80 / Chapter 4.14.5.2 --- Methods --- p.80 / Chapter Chapter 5 --- Results --- p.82 / Chapter 5.1 --- Liver morphology --- p.82 / Chapter 5.2 --- Liver weight --- p.82 / Chapter 5.3 --- Serum triglyceride and cholesterol levels --- p.88 / Chapter 5.4 --- Confirmation of genotypes --- p.91 / Chapter 5.5 --- DNase I treatment --- p.91 / Chapter 5.6 --- FDD RT-PCR and band excision --- p.98 / Chapter 5.7 --- Reamplification of excised cDNA fragments --- p.111 / Chapter 5.8 --- Subcloning of reamplified cDNA fragments --- p.121 / Chapter 5.9 --- DNA sequencing of subcloned cDNA fragments --- p.124 / Chapter 5.10 --- Confirmation of the differentially expressed cDNA fragments by Northern blot analysis --- p.132 / Chapter 5.11 --- Temporal expression pattern of differentially expressed genes --- p.157 / Chapter 5.12 --- Tissue distribution pattern of differentially expressed genes --- p.171 / Chapter Chapter 6 --- Discussions --- p.183 / Chapter 6.1 --- "Lack of hepatomegaly, hypotriglyceridemia and hepatic nodule formation in PPARα (-/-) mice" --- p.184 / Chapter 6.2 --- "Identification of PPARα-dependent and Wy-14,643 responsive genes" --- p.185 / Chapter 6.3 --- Functional roles of the isolated cDNA fragments --- p.186 / Chapter 6.3.1 --- Fragments B14 and H4 --- p.187 / Chapter 6.3.2 --- Fragment H1 --- p.189 / Chapter 6.3.3 --- Fragment H5 --- p.192 / Chapter 6.3.4 --- Fragment H8 --- p.194 / Chapter 6.4 --- Temporal expression patterns of the isolated cDNA fragments --- p.196 / Chapter 6.5 --- Tissue distribution patterns of the isolated cDNA fragments --- p.197 / Chapter Chapter 7 --- Conclusions --- p.200 / Chapter Chapter 8 --- Future studies --- p.204 / Chapter 8.1 --- Subcloning and characterization of the other differentially expressed genes --- p.204 / Chapter 8.2 --- Overexpression and inhibition expression of specific genes --- p.204 / Chapter 8.3 --- Generating transgenic mice with target disruption of specific gene --- p.205 / References --- p.206

Adipogenesis and ectopic lipid accumulation during aging have a great impact on the aging process and the pathogenesis of chronic diseases with age. However, at present, information on the age-related molecular changes in lipid redistribution patterns and their potential nutritional interventions is sparse. We investigated the mechanism underlying age-related lipid redistribution and its modulation using 5-, 17-, and 24-month-old male Fischer 344 rats fed ad libitum (AL) or a 3-week-long CR (40% less than AL) diet. Results revealed that the activities of adipogenic transcription factors were decreased in the white adipose tissue (WAT) of aged AL rats. In contrast, the skeletal muscle of aged AL rats showed increased fat accumulation through decreased carnitine palmitoyltransferase-1 activity, which was blunted by short-term CR. This study suggests an age-related shift in lipid distribution by reducing the adipogenesis of WAT while increasing intramyocellular lipid accumulation, and that CR can modulate age-related adipogenesis and ectopic lipid accumulation.

Introdução: Aneurisma de aorta é considerado uma doença inflamatória crônica, mas ainda é controverso se está relacionado a aterosclerose aos agentes infecciosos. Antígenos de Chlamydophila pneumoniae (CP) e Mycoplasma pneumoniae (MP) foram encontrados em grande quantidade nas placas instáveis que usualmente estão associadas a remodelamento positivo e inflamação do vaso. Metaloproteinase da matriz 9 (MMP-9) está implicada na fragilidade da parede vascular e na formação dos aneurismas. Os efeitos imunomodulatórios dos receptores ativados por proliferador de peroxissomo (PPARs) têm sido relacionados à aterosclerose. Objetivos: Comparar lesões ateroscleróticas graves com e sem aneurisma do ponto de vista inflamatório e infeccioso, analisando antígenos de MP e CP e expressão de MMP-9, TIMP-1 e PPARs. Métodos: No presente estudo quantificamos, através da técnica de imunoistoquímica, antígenos de MMP- 9, TIMP-1, PPARs a e , e dos agentes infecciosos CP e MP em fragmentos de aorta ateroscleróticos com aneurisma (n=14) e sem aneurisma (n=14). Resultados: A adventícia e o tecido adiposo periadventicial (TAP) dos aneurismas apresentaram intensa inflamação. Expressão de MMP-9 esteve aumentada no TAP e agentes infecciosos, TIMP-1 e PPAR a estiveram aumentados na adventícia e no TAP, sem diferença em relação a expressão de PPAR . Colágeno, TIMP-1 e PPARs estiveram positivamente correlacionados no grupo com aterosclerose, mas não no grupo com aneurisma. Conclusão: Nossos achados sugerem que aneurisma de aorta é uma complicação das lesões ateroscleróticas. Quantidade aumentada de Chlamydophila pneumoniae e Mycoplasma pneumoniae na adventícia e PAT sem correlação da resposta de TIMP-1 e PPARs são achados que estão associados com a presença de aneurisma nos segmentos de aorta ateroscleróticos / Introduction: Aortic aneurysm is considered a chronic inflammatory disease, but remains a controversial matter if it is related to atherosclerosis and infectious agents. Chlamydophila pneumoniae (CP) and Mycoplasma pneumoniae (MP) antigens were found in higher amount in unstable plaques that are usually associated to positive remodeling and vessel inflammation. Matrix metalloproteinase 9 (MMP-9) has been implicated in vascular wall fragility and aneurysm development. The immunemodulator effects of peroxisome proliferators - activated receptor (PPARs) have been related to atherosclerosis. Objectives: To compare severe atherosclerotic lesions with and without aneurysms by inflammatory and infectious point of view, analyzing MP and CP, MMP-9, TIMP-1 and PPARs antigens. Methods: In the present study we quantified, using immunohistochemistry technique, MMP-9, TIMP-1, PPAR a and and infectious agents CP and MP antigens in aortic atherosclerotic fragments with aneurysms. (n=14) and without aneurysms (n=14). Results: Adventitia and periadventitial adipose tissue (PAT) from aneurysms showed intense inflammation. MMP-9 expression has increased in PAT and the infectious agents, TIMP-1 and PPAR a were increased in adventitia and PAT in aneurysmatic group, without difference related to PPAR expression. Collagen, TIMP-1 and PPARs were positively correlated in atherosclerotic group, but it was not observed in aneurysmatic group. Conclusion: Our data have suggested that aortic aneurysm is a complication of aortic atherosclerotic lesions. Increased amount of Chlamydophila pneumoniae and Mycoplasma pneumoniae in the adventitia and PAT without a correlated TIMP-1 and PPARs response are findings that were associated with the presence of aneurysm in atherosclerotic aortic segments

Introdução: Aneurisma de aorta é considerado uma doença inflamatória crônica, mas ainda é controverso se está relacionado a aterosclerose aos agentes infecciosos. Antígenos de Chlamydophila pneumoniae (CP) e Mycoplasma pneumoniae (MP) foram encontrados em grande quantidade nas placas instáveis que usualmente estão associadas a remodelamento positivo e inflamação do vaso. Metaloproteinase da matriz 9 (MMP-9) está implicada na fragilidade da parede vascular e na formação dos aneurismas. Os efeitos imunomodulatórios dos receptores ativados por proliferador de peroxissomo (PPARs) têm sido relacionados à aterosclerose. Objetivos: Comparar lesões ateroscleróticas graves com e sem aneurisma do ponto de vista inflamatório e infeccioso, analisando antígenos de MP e CP e expressão de MMP-9, TIMP-1 e PPARs. Métodos: No presente estudo quantificamos, através da técnica de imunoistoquímica, antígenos de MMP- 9, TIMP-1, PPARs a e , e dos agentes infecciosos CP e MP em fragmentos de aorta ateroscleróticos com aneurisma (n=14) e sem aneurisma (n=14). Resultados: A adventícia e o tecido adiposo periadventicial (TAP) dos aneurismas apresentaram intensa inflamação. Expressão de MMP-9 esteve aumentada no TAP e agentes infecciosos, TIMP-1 e PPAR a estiveram aumentados na adventícia e no TAP, sem diferença em relação a expressão de PPAR . Colágeno, TIMP-1 e PPARs estiveram positivamente correlacionados no grupo com aterosclerose, mas não no grupo com aneurisma. Conclusão: Nossos achados sugerem que aneurisma de aorta é uma complicação das lesões ateroscleróticas. Quantidade aumentada de Chlamydophila pneumoniae e Mycoplasma pneumoniae na adventícia e PAT sem correlação da resposta de TIMP-1 e PPARs são achados que estão associados com a presença de aneurisma nos segmentos de aorta ateroscleróticos / Introduction: Aortic aneurysm is considered a chronic inflammatory disease, but remains a controversial matter if it is related to atherosclerosis and infectious agents. Chlamydophila pneumoniae (CP) and Mycoplasma pneumoniae (MP) antigens were found in higher amount in unstable plaques that are usually associated to positive remodeling and vessel inflammation. Matrix metalloproteinase 9 (MMP-9) has been implicated in vascular wall fragility and aneurysm development. The immunemodulator effects of peroxisome proliferators - activated receptor (PPARs) have been related to atherosclerosis. Objectives: To compare severe atherosclerotic lesions with and without aneurysms by inflammatory and infectious point of view, analyzing MP and CP, MMP-9, TIMP-1 and PPARs antigens. Methods: In the present study we quantified, using immunohistochemistry technique, MMP-9, TIMP-1, PPAR a and and infectious agents CP and MP antigens in aortic atherosclerotic fragments with aneurysms. (n=14) and without aneurysms (n=14). Results: Adventitia and periadventitial adipose tissue (PAT) from aneurysms showed intense inflammation. MMP-9 expression has increased in PAT and the infectious agents, TIMP-1 and PPAR a were increased in adventitia and PAT in aneurysmatic group, without difference related to PPAR expression. Collagen, TIMP-1 and PPARs were positively correlated in atherosclerotic group, but it was not observed in aneurysmatic group. Conclusion: Our data have suggested that aortic aneurysm is a complication of aortic atherosclerotic lesions. Increased amount of Chlamydophila pneumoniae and Mycoplasma pneumoniae in the adventitia and PAT without a correlated TIMP-1 and PPARs response are findings that were associated with the presence of aneurysm in atherosclerotic aortic segments

Introdução: A nefrotoxicidade dos antiretrovirais constituem atualmente fator importante na morbidade e mortalidade de pacientes com HIV. O tenofovir DF (TDF) se enquadra em um dos antiretrovirais mais lesivos ao rim. Conhecer seu mecanismo de nefrotoxicidade e estudar medidas protetoras podem melhorar seu uso clínico. Material e Métodos: Ratos foram tratados durante 30 dias com uma de duas doses de TDF (50 ou 300mg/Kg de dieta), sendo que um grupo teve adicionado em sua dieta maleato de rosiglitazona (RSG) na dose de 92mg/Kg de dieta nos últimos 15 dias. Após esse período, os ratos foram colocados em gaiola metabólica e sacrificados. Foram estudados parâmetros bioquímicos, fluxo sanguíneo renal e os rins extraídos para expressão semiquantitativa dos transportadores epiteliais tubulares. Resultados: Os animais que receberam TDF em dose alta apresentaram insuficiência renal severa acompanhada de redução da expressão da oxido-nítrico sintase endotelial e vasoconstricção renal intensa. Todos esses parâmetros foram parcialmente revertidos pela administração de RSG. Baixas doses de TDF não causou alteração significativa do ritmo de filtração glomerular, porém induziu fosfatúria, acidose tubular proximal, poliúria e redução da capacidade de concentração urinária. Essas alterações foram associadas a redução da expressão de alguns transportadores epiteliais (cotransportador sódio-fosforo, contratransportador sódio-hidrogênio tipo 3 e aquaporina tipo 2). Não foi caracterizado síndrome de Fanconi, pois não houve proteinúria ou glicosúria. O tratamento com RSG reverteu todos os parâmetros de nefrotoxicidade estudados, normalizando as alterações bioquímicas urinárias e a expressão dos transportadores de membrana. Conclusões: Os achados desses experimentos tem potencial aplicação clínica em pacientes com nefrotoxicidade induzida pelo TDF, especialmente naqueles com hipofosfatemia e/ou redução do ritmo de filtração glomerular. / Objective: To characterize the mechanisms of tenofovir disoproxil fumarate (TDF)- induced nephrotoxicity and the protective effects of rosiglitazone (RSG), a peroxisome proliferator-activated receptor-y agonist. Methods: Rats were treated for 30 days with one of two TDF doses (50 or 300 mg/kg of food), to which RSG (92 mg/kg of food) was added for the last 15 days. Biochemical parameters were measured, and renal tissue was extracted for immunoblotting. Results: Mean daily ingestion was comparable among all the treated groups. Highdose TDF induced severe renal failure accompanied by reduced expression of endothelial nitric-oxide synthase and intense renal vasoconstriction. All of these features were ameliorated by RSG administration. Low-dose TDF did not alter the glomerular filtration rate but induced significant phosphaturia, proximal tubular acidosis and polyuria, as well as reducing urinary concentrating ability. These alterations were caused by specific downregulation of the sodium-phosphorus cotransporter, sodium/hydrogen exchanger 3 and aquaporin 2. No Fanconi\'s syndrome was identified (proteinuria was normal and there was no glycosuria). Treatment with RSG reversed TDF-induced tubular nephrotoxicity, normalizing urinary biochemical parameters and membrane transporter protein expression. Conclusion: These findings have potential clinical applications in patients presenting with TFV-induced nephrotoxicity, especially in those presenting with hypophosphatemia or a reduction in glomerular filtration rate.

Introdução: A nefrotoxicidade dos antiretrovirais constituem atualmente fator importante na morbidade e mortalidade de pacientes com HIV. O tenofovir DF (TDF) se enquadra em um dos antiretrovirais mais lesivos ao rim. Conhecer seu mecanismo de nefrotoxicidade e estudar medidas protetoras podem melhorar seu uso clínico. Material e Métodos: Ratos foram tratados durante 30 dias com uma de duas doses de TDF (50 ou 300mg/Kg de dieta), sendo que um grupo teve adicionado em sua dieta maleato de rosiglitazona (RSG) na dose de 92mg/Kg de dieta nos últimos 15 dias. Após esse período, os ratos foram colocados em gaiola metabólica e sacrificados. Foram estudados parâmetros bioquímicos, fluxo sanguíneo renal e os rins extraídos para expressão semiquantitativa dos transportadores epiteliais tubulares. Resultados: Os animais que receberam TDF em dose alta apresentaram insuficiência renal severa acompanhada de redução da expressão da oxido-nítrico sintase endotelial e vasoconstricção renal intensa. Todos esses parâmetros foram parcialmente revertidos pela administração de RSG. Baixas doses de TDF não causou alteração significativa do ritmo de filtração glomerular, porém induziu fosfatúria, acidose tubular proximal, poliúria e redução da capacidade de concentração urinária. Essas alterações foram associadas a redução da expressão de alguns transportadores epiteliais (cotransportador sódio-fosforo, contratransportador sódio-hidrogênio tipo 3 e aquaporina tipo 2). Não foi caracterizado síndrome de Fanconi, pois não houve proteinúria ou glicosúria. O tratamento com RSG reverteu todos os parâmetros de nefrotoxicidade estudados, normalizando as alterações bioquímicas urinárias e a expressão dos transportadores de membrana. Conclusões: Os achados desses experimentos tem potencial aplicação clínica em pacientes com nefrotoxicidade induzida pelo TDF, especialmente naqueles com hipofosfatemia e/ou redução do ritmo de filtração glomerular. / Objective: To characterize the mechanisms of tenofovir disoproxil fumarate (TDF)- induced nephrotoxicity and the protective effects of rosiglitazone (RSG), a peroxisome proliferator-activated receptor-y agonist. Methods: Rats were treated for 30 days with one of two TDF doses (50 or 300 mg/kg of food), to which RSG (92 mg/kg of food) was added for the last 15 days. Biochemical parameters were measured, and renal tissue was extracted for immunoblotting. Results: Mean daily ingestion was comparable among all the treated groups. Highdose TDF induced severe renal failure accompanied by reduced expression of endothelial nitric-oxide synthase and intense renal vasoconstriction. All of these features were ameliorated by RSG administration. Low-dose TDF did not alter the glomerular filtration rate but induced significant phosphaturia, proximal tubular acidosis and polyuria, as well as reducing urinary concentrating ability. These alterations were caused by specific downregulation of the sodium-phosphorus cotransporter, sodium/hydrogen exchanger 3 and aquaporin 2. No Fanconi\'s syndrome was identified (proteinuria was normal and there was no glycosuria). Treatment with RSG reversed TDF-induced tubular nephrotoxicity, normalizing urinary biochemical parameters and membrane transporter protein expression. Conclusion: These findings have potential clinical applications in patients presenting with TFV-induced nephrotoxicity, especially in those presenting with hypophosphatemia or a reduction in glomerular filtration rate.