ABSTRACT
Con el propósito de estudiar el efecto de la vitamina E sobre el estrés oxidativo desencade- nado por hiperfibrinogenemia (HF) en un modelo experimental de aterogénesis y la posible normalización de los indicadores de estrés oxidativo, se evaluaron: óxido nítrico (NO), L-citrulina, superóxido dismutasa (SOD) e involución de lesiones histopatológicas en la aorta torácica. El estudio se realizó en 36 ratas, cepa Wistar, que se dividieron en tres grupos (n = 12 cada uno): A, control; B, HF × 90 días; C, HF × 90 días + vitamina E. La HF se indujo mediante inyecciones de adrenalina (0,1 ml/día/rata) por 90 días. La dosis de vitamina E fue de 2 mg/día/rata durante 75 días. Se dosaron en plasma los niveles de fibrinógeno (mg/dl), NO (uM) y L-citrulina (mM) y en lisado de glóbulos rojos, por espectrofotometría, se determinó la actividad de la SOD (U/ml). Se analizaron cortes de la aorta torácica por microscopia óptica (MO). Para el análisis estadístico se emplearon MANOVA y la prueba de Fisher; se estableció un nivel de significación de p < 0,05. Se observó un aumento significativo de fibrinógeno en el grupo B (407 ± 8,9 mg/dl) en comparación con los grupos A (203 ± 9 mg/dl) y C (191,58 ± 17,79 mg/dl) (p < 0,001). El NO disminuyó significativamente en el grupo B (13,73 ± 1,76 uM) frente a los grupos A (23,58 ± 0,08 uM) y C (26,64 ± 3,65 uM) (p < 0,001). La L-citrulina aumentó en forma significativa en los grupos B (4,99 ± 0,18 mM) y C (6,60 ± 0,16 mM) en comparación con el grupo A (3,03 ± 0,13 mM) (p < 0,001). El SOD incrementó su actividad en los grupos B (251,67 ± 10,34 U/ml) y C (304,75 ± 10,43 U/ml) frente al grupo A (139,44 ± 4,74 U/ml) (p < 0,001). La microscopia óptica mostró denudación endotelial, engrosamiento intimal y protrusión de la pared en el grupo B (90%) y recuperación de la denudación endotelial y disminución del 50% del engrosamiento intimal en el grupo C (p < 0,001). Niveles aumentados de SOD serían insuficientes para impedir alteraciones en la vía del estrés oxidativo inducido por la HF. La vitamina E actuaría deteniendo la reacción en cadena iniciada por los radicales libres y en consecuencia disminuiría el anión superóxido, estimulando de esta manera un incremento en la biodisponibilidad del NO y normalizando las concentraciones de fibrinógeno plasmático.
We used an experimental model of atherogenesis to evaluate the effect of vitamin E on oxidative stress induced by hyperfibrinogenemia (HF) and the possible normalization of oxidative stress markers. The following variables were studied: nitric oxide (NO), L-citrulline, superoxide dismutase (SOD) activity and regression of histopathological lesions in the thoracic aorta. The study was performed in 36 Wistar rats that were divided into three groups of 12 rats each: A, control group; B, HF for 90 days; C, HF for 90 days + vitamin E. Hyperfibrinogenemia was induced by the injection of epinephrine (0.1 ml/day/rat) during 90 days. The dose of vitamin E was 2 mg/day/rat during 75 days. We measured the plasma levels of fibrinogen (mg/dl), NO (uM) and L-citrulline (mM); SOD activity (U/ml) was assayed in red cell lysates using spectrophotometry. The histopathological sections of the thoracic aorta were examined using light microscopy (LM). Statistical analysis was performed using MANOVA and Fisher's test; a p value <0.05 was considered statistically significant. Rats in group B had a significant increase in fibrinogen levels B (407±8.9 mg/dl) compared to groups A (203±9 mg/dl) and C (191.58±17.79 mg/dl) (p<0.001). We observed a significant decrease in NO in group B (13.73±1.76 uM) versus groups A (23.58±0.08 uM) and C (26.64±3.65 uM) (p<0.001). L-citrulline increased significantly in groups B (4.99±0.18 mM) and C (6.60±0.16 mM) compared to group A (3.03±0.13 mM) (p<0.001). SOD activity was greater in groups B (251.67±10.34 U/ml) and C (304.75±10.43 U/ml) versus group A (139.44±4.74 U/ml) (p<0.001). Light microscopic examination revealed the presence of endothelial denudation, intimal thickening and vessel wall protrusion in group B (90%), while recovery of endothelial denudation and a 50% reduction in intimal thickening was observed in group C (p<0.001). High SOD activity might be insufficient to prevent abnormalities in the oxidative stress pathway induced by HF. Vitamin E would stop the chain reaction initiated by free radicals and thus decrease the superoxide anion, stimulating the bioavailability of NO with normalization of fibrinogen plasma levels.
ABSTRACT
INTRODUCTION: We studied plasmatic TNF-alpha, nitric oxide (NO) and citrulline behaviors and probable morphological mitochondrial alterations in aortic smooth muscle cells, in rats with atherogenesis induced by hyperfibrinogenemia in: A) control, B) multiple injured for 30 days and C) multiple injured for 60 days. MATERIAL AND METHODS: Hyperfibrinogenemia induction: adrenaline injection (0,1 mg/rat/day). TNF-alpha (pg/dL) was determined by Elisa and NO (microM) and citrulline (mM) by spectrophotometry. Morphological mitochondrial alterations were studied by electronic microscopy. Variables were analized: ANOVA, r coefficient and chi2 test. RESULTS: We observed a significant increment of TNF-alpha in multiple injured for 30 days (B) (50.05 +/- 2.29) as well as in multiple injured for 60 days (C) (74.99 +/- 2.82) related to control (A) (33.01 +/- 1.49) (p<0.001 in both groups). Citrulline presented a significant increased in (B) (5.56 +/- 0.20) and (C) (6.84 +/- 0.13) when compared to (A) (4.41 +/- 0.23) (p<0.001 in both situations). Mean while NO biodisponibility diminished significantly in (B) (8.97 +/- 0.70) and in (C) (5.32 +/- 0.68) when compared to (A) (21.65 +/- 1.74) (p<0.001 in both situations). CONCLUSIONS: Hyperfibrinogenemia could modify the NO physiopathological pathway and produced morphological mitochondrial alterations in aortic smooth muscle cells, probably producing ischemic lesions in the vascular wall and altering the vasodilatation response.