Hydrochloride pioglitazone protects diabetic rats against podocyte injury through preserving glomerular podocalyxin expression / O cloridrato de pioglitazona protege ratos diabéticos contra a injúria aos podócitos por meio da preservação da expressão de podocalixina glomerular

Objective: We sought to test the effect of different dosages of pioglitazone (PIO) on the glomerular expression of podocalyxin and urinary sediment podocalyxin excretion and to explore the potential renoprotective mechanism. Materials and methods: Type 1 diabetes induced with streptozotocin (65 mg/kg) in 36 male Sprague-Dawley rats were randomly allocated to be treated with vehicle or 10, 20, 30 mg/kg/d PIO respectively for 8 weeks. Eight rats were enrolled in the normal control group. Results: At 8th week, rats were sacrificed for the observation of kidney injury through electron microscope. Glomerular podocalyxin production including mRNA and protein were determined by RT-PCR and immunohistochemistry respectively. Levels of urinary albumin excretion and urinary sediment podocalyxin, kidney injury index were all significantly increased, whereas expression of glomerular podocalyxin protein and mRNA were decreased significantly in diabetic rats compared to normal control. Dosages-dependent analysis revealed that protective effect of PIO ameliorated the physiopathological changes and reached a peak at dosage of 20 mg/kg/d. Conclusion: PIO could alleviate diabetic kidney injury in a dose-dependent pattern and the role may be associated with restraining urinary sediment podocalyxin excretion and preserving the glomerular podocalyxin expression. .

Objetivo: Buscamos testar os efeitos de diferentes doses de pioglitazona (PIO) sobre a expressão glomerular de podocalixina e sobre a excreção de podocalixina em células do sedimento urinário, além de explorar o potencial mecanismo de proteção renal. Materiais e métodos: O diabetes tipo 1 foi induzido em 36 ratos Sprague-Dawley machos com estreptozotocina (65 mg/kg). Os animais foram tratados apenas com o veículo, ou com 10, 20, 30 mg/kg/d de PIO por 8 semanas. Oito ratos foram colocados no grupo controle. Resultados: Na oitava semana, os ratos foram sacrificados para se observar a lesão renal em microscopia eletrônica. A produção de podocalixina glomerular, incluindo mRNA e proteína, foi determinada por RT-PCR e imuno-histoquímica, respectivamente. Os níveis urinários de albumina e podocalixina nas células do sedimento urinário e o índice de lesão renal estavam todos significativamente aumentados, enquanto a expressão glomerular da proteína podocalixina e do mRNA estava significativamente diminuída em ratos diabéticos comparados com o controle normal. A análise dos efeitos dose-dependentes revelou que o efeito protetor da PIO melhorou as mudanças fisiopatológicas e atingiu um pico na dose de 20 mg/kg/dia. Conclusão: A PIO pode melhorar a injúria renal de forma dose-dependente e este papel pode estar associado com a prevenção da excreção de podocalixina nas células do sedimento urinário e com a preservação da expressão glomerular de podocalixina. .

Increased expression of osteopontin in the spinal cords of Lewis rats with experimental autoimmune neuritis

To investigate the pattern of expression of osteopontin (OPN) in tissues of the central nervous system (CNS) responding to peripheral immunological stimulation, the expression of OPN was studied in the spinal cord of rats with experimental autoimmune neuritis (EAN). In this model system, the sciatic nerves and spinal nerve roots are the target organs of EAN and the spinal cord is a remote organ that may be indirectly affected. OPN was constitutively expressed in some astrocytes adjacent to the pia mater and neurons in normal rats. In rats with EAN, OPN was increased in the same cells and in some inflammatory cells, including macrophages in the subarachnoid space. Expression of CD44, a receptor of OPN, was weak in normal spinal cord tissue and increased in the entire spinal cord parenchyma in rats with EAN, as well as in inflammatory cells. These findings suggest that inflammatory cells as well as reactive astrocytes are major sources of OPN and CD44 in the spinal cord of rats with EAN. Further study is needed to elucidate the functional role of OPN in the spinal cord affected by EAN.

B6C3F1 mice exposed to ozone with 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone and/or dibutyl phthalate showed toxicities through alterations of NF-kappaB, AP-1, Nrf2, and osteopontin

Toxic effects of ozone, 4-(N-methyl-N-nitrosamino)-1-(3- pyridyl)-1-butanone (NNK), and/or dibutyl phthalate (DBP) were examined through NF-kappaB, AP-1, Nrf2, and osteopontin (OPN) in lungs and livers of B6C3F1 mice. Electrophoretic mobility shift assay (EMSA) indicated that mice treated with combination of toxicants induced high NF-kappaB activities. Expression levels of p105, p65, and p50 proteins increased in all treated mice, whereas IkB activity was inhibited in NNK-, DBP-, and combination-treated ones. All treated mice except ozone-treated one showed high AP-1 binding activities. Expression levels of c-fos, c-jun, junB, jun D, Nrf2, and OPN proteins increased in all treated mice. Additive interactions were frequently noted from two-toxicant combination mice compared to ozone-treated one. These results indicate treatment of mixture of toxicants increased toxicity through NF-kappaB, AP-1, Nrf2, and OPN. Our data could be applied to the elucidation of mechanism as well as the risk assessment of mixture-induced toxicity.

Decreased osteopontin expression in the rat kidney on a sodium deficient diet

Osteopontin (OPN) is a secreted phosphoprotein that is constitutively expressed in the normal kidney and is induced by various experimental and pathologic conditions. Several possible functions of OPN have been suggested, however the mechanism and significance of OPN expression are still uncertain. Since high salt concentration or salt crystal have been known to enhance OPN expression in intact kidney or cultured renal cells, in the present study we examined whether or not a low salt condition had an effect on OPN expression in the kidney. Adult male Sprague-Dawley rats were fed either a normal sodium or a sodium deficient diet for 1 week. Kidneys were processed for in situ hybridization using a digoxigenin-labeled riboprobe and for immunohistochemistry using antibodies to OPN, renin, and Na-K-ATPase. In rats fed a normal sodium diet, OPN mRNA and protein were expressed only in the descending thin limbs of Henle's loop (DTL) and in the papillary and pelvic surface epithelium (PSE). In rats fed a sodium deficient diet, there was a marked decrease in OPN immunoreactivity in the DTL, but no changes in PSE. In contrast, no changes were observed in OPN mRNA expression in the DTL by in situ hybridization, indicating that decreased OPN protein expression was a result of translational regulation. As expected, rats fed a sodium deficient diet were associated with increased immunoreactivity for Na-K-ATPase and renin compatible with activation of the renin-angiotensin system. These results suggest that dietary sodium may be involved in the regulation of OPN expression in the DTL of the rat kidney.

Individual or combined effects of enalapril and verapamil on chronic cyclosporine nephrotoxicity in rats

Previous studies have demonstrated that enalapril and verapamil seem to attenuate the cyclosporine nephrotoxicity. However, the mechanisms have not been completely understood, especially on molecular events. The aim of this study was to examine the effect of individual or combined treatment on osteopontin, TGF-beta, endothelin-1 and procollagen alpha 1(I) mRNA expressions. Enalapril (50 mg/L in drinking water) and verapamil (0.5 mg/kg/day, subcutaneously), alone or in combination, were administered to rats with chronic cyclosporine nephrotoxicity (cyclosporine, 25 mg/kg/day, subcutaneously) (n = 5 each). Five rats treated with olive oil vehicle were used as control. After 4 weeks, biochemical parameters were measured, and renal cortical mRNA levels were evaluated by Northern blot analysis. Cyclosporine reduced renal creatinine clearance significantly and induced renal cortical osteopontin, TGF-beta, endothelin-1 and procollagen alpha 1(I) gene expressions around 13.5 +/- 1.3, 2.4 +/- 0.2, 1.5 +/- 0.1, 1.9 +/- 0.1 folds, respectively. Individual treatment with enalapril or verapamil significantly suppressed the osteopontin and TGF-beta mRNA expression, but not endothelin-1 and procollagen alpha 1(I). Combined treatment also inhibited the osteopontin and TGF-beta mRNA expression but there was no difference between combined and individual treatment. In conclusion, enalapril or verapamil significantly blunted the cyclosporine-induced osteopontin and TGF-beta gene expressions. However, combined treatment did not show any additive effect.

Sialoproteínas en la interación blastocisto-endometrio en rata / Sialyproteins in blastocyst-endometrium interaction in rats

El homogenizado de rata, en la etapa de preimplatanción, es capaz de transferir residuos sialil desde citidina monofosfato-3H-siálico (CMP-[3H]-siálico) hacia substratos aceptores endógenos y exógenos (desialo fetuína). La transferencia parece ser debida a la actividad de la enzima N-acetil-neuraminil transferasa E.C. 2.4.99; esta actividad es mayor en el endometrio receptivo para el blastocisto (ER) 0.75 ñ 0.15 nmoles/h/mg de proteína, que en el endometrio no receptivo (ENR)0.40 ñ 0.14 nmoles/h/mg de proteína. La incorporación de [3H]-siálico hacia desialo fetuína es un poco mayor del 60%. Los productos de la reacción enzimática fueron sometidos a condiciones reductoras y analizadas por electroforesis en un gradiente lineal de poliacrilamida, 5 a 22% y cuantificada la radiactividad a lo alrgo del gel. La mayor radiactividad entre ER y ENR es cualitativamente semejante. Los productos de reacción tratados con neuraminidasa liberan casi el 60% del [3H]-siálico incorporado