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1.
Diabetologia ; 46(9): 1234-44, 2003 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-12898011

RESUMEN

AIM/HYPOTHESIS: Increased expression of haeme-oxygenase 1 (HO1) and other antioxidant enzymes could improve pancreatic beta-cell survival under stressful conditions, including hyperglycaemia. However, how hyperglycaemia increases islet HO1 expression is not known. METHODS: Rat islets were pre-cultured for 1 week in RPMI medium containing 10 mmol x l(-1) glucose (G10), and further cultured overnight in G5-G30 plus various test substances. Islet HO1 mRNA and protein expression was measured by semiquantitative RT-PCR, western blot, and immunohistochemistry. RESULTS: Islet HO1 mRNA expression was minimal after overnight culture in G10, slightly increased in G5, and increased by five- to ten-fold in G30 in parallel with a heterogeneous increase in beta-cell HO1 protein expression. The effect of G30 was fully inhibited by agents decreasing cytosolic Ca2+ (diazoxide, nimodipine), but was only slightly reproduced by agents raising Ca2+ (tolbutamide, 30 mmol x l(-1) potassium). It was also suppressed by the alpha2-adrenoceptor agonist clonidine, whereas dibutyryl-cyclic-AMP largely increased beta-cell HO1 expression. The induction of HO1 mRNA expression by G30 was independent from changes in medium insulin concentration, but was completely inhibited by a cocktail of antioxidants. In contrast to HO1, islet mRNA expression of glutathione peroxidase and constitutive haeme-oxygenase 2 were not affected by G30, nor by dibutyryl-cyclic-AMP. CONCLUSION/INTERPRETATION: High glucose and dibutyryl-cyclic-AMP stimulate expression of HO1 in rat pancreatic beta cells. The inhibition of HO1 expression in G30 by nimodipine, clonidine, and antioxidants, suggests that Ca2+ influx and cyclic-AMP are necessary for the generation of oxidative stress by G30, or for the stimulation of beta-cell HO1 expression by increased oxidative stress.


Asunto(s)
AMP Cíclico/farmacología , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Glucosa/farmacología , Hemo Oxigenasa (Desciclizante)/genética , Islotes Pancreáticos/enzimología , Animales , Secuencia de Bases , Calcio/metabolismo , AMP Cíclico/metabolismo , Cartilla de ADN , ADN Complementario/genética , Semivida , Hemo-Oxigenasa 1 , Islotes Pancreáticos/efectos de los fármacos , Cinética , Masculino , ARN Mensajero/genética , Ratas , Ratas Wistar , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos
2.
Kidney Int ; 59(6): 2164-73, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11380818

RESUMEN

BACKGROUND: Chinese herbs nephropathy (CHN) is a new type of subacute interstitial nephritis that is attributed to aristolochic acid (AA), which inadvertently has been included in slimming pills. The contribution of other simultaneously prescribed drugs remains disputed. In the present study, the effects of a chronic intake of AA given as a single drug was evaluated through renal histology and function in rabbits. METHODS: Female New Zealand White rabbits were injected intraperitoneally with either 0.1 mg AA/kg or with saline 5 days a week for 17 to 21 months. Body weight, renal function, and urinary excretion of glucose and low molecular weight proteins were monitored prior to sacrifice at the end of the study period. RESULTS: All animals given AA developed renal hypocellular interstitial fibrosis, which was classified into three patterns. Fibrosis was confined to medullary rays (MRs) in pattern I (N = 3), extended to the outer cortical labyrinth (OCL) in pattern II (N = 2), and eventually to the inner cortical labyrinth (ICL) in pattern III (N = 6). Fibrosis in MR and OCL was associated with mainly proximal tubular epithelial cell flattening. All treated animals displayed urothelial atypia. Three of them also developed tumors of the urinary tract. No significant pathologic changes were found in control rabbits. AA-treated animals differed from controls by an impaired growth, increased serum creatinine, glucosuria, tubular proteinuria, and anemia. CONCLUSION: The observed pattern of renal histopathological lesions and disorders of the renal function, as well as urothelial atypia and malignancy, are very reminiscent of CHN. Our observations therefore support a causal role of AA alone in the genesis of this new nephropathy.


Asunto(s)
Ácidos Aristolóquicos , Medicamentos Herbarios Chinos/toxicidad , Inhibidores Enzimáticos/toxicidad , Nefritis Intersticial/inducido químicamente , Fenantrenos/toxicidad , Animales , Modelos Animales de Enfermedad , Femenino , Fibrosis , Riñón/patología , Nefritis Intersticial/patología , Tamaño de los Órganos , Conejos , Estómago/patología
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