The Effect of Tadalafil on Renal Fibrosis Induced by Ureteral Obstruction / Efecto del Tadalafil en la Fibrosis Renal Inducida por Obstrucción Uretral

ABSTRACT Objective: It has been reported that phosphodiesterase-5 (PDE-5) inhibitors improve kidney function during acute and chronic renal failure. This study aimed to determine the possible therapeutic effects of tadalafil, a specific PDE-5 inhibitor, on renal fibrosis induced by unilateral ureteral obstruction (UUO). Methods: Male Sprague-Dawley rats were used and randomly divided into three groups (n = 6) as sham-operated, UUO and tadalafil-treated (10 mg/72 hours, ig) UUO (UUO+T) groups. Unilateral ureteral obstruction was induced by complete ligation of the left ureter and 14 days after surgery creatinine clearance, urinary cyclic guanosine monophosphate (cGMP), renal alpha-smooth muscle actin (α-sma) and transforming growth factor βeta (TGF-β) levels, as well as histologic changes, were observed in all the animals. Results: Unilateral ureteral obstruction-induced renal fibrosis was confirmed by increased α-sma level, collagen deposition, tubular dilation, inflammatory cell infiltration and necrosis. An increased renal TGF-β level and decreased urinary cGMP level was also observed in obstructed animals in addition to reduced creatinine clearance. Tadalafil treatment, which restored the animals 'urinary cGMP level, significantly attenuated the fibrotic changes and TGF-β increase in their kidneys. Conclusion: This study suggests that tadalafil treatment ameliorates renal fibrosis by reducing TGF-β expression and may have important clinical relevance since tadalafil is currently used clinically to treat erectile dysfunction and pulmonary hypertension.

RESUMEN Objetivo: Se ha reportado que los inhibidores de la fosfodiesterasa-5 (PDE-5) mejoran las funciones renales durante la insuficiencia renal aguda y crónica. Este estudio tuvo por objetivo determinar los posibles efectos terapéuticos del tadalafil - un inhibidor específico de la PDE-5 - sobre la fibrosis renal inducida por una obstrucción ureteral unilateral (OUU). Métodos: Se utilizaron ratas machos Sprague-Dawley, divididas de manera aleatoria en tres grupos (n = 6): operación simulada, OUU y tratamiento con tadalafil (10 mg/72 horas, IG), y OUU (OUU+T). La obstrucción uretral unilateral fue inducida por una ligadura completa del uréter izquierdo y 14 días después de la cirugía, se observaron niveles de monofosfato de guanosina cíclico (GMP) urinario, alfa-actina de músculo liso (α-SMA), y factor de crecimiento transformante βeta (FCT-β), así como cambios histológicos en todos los animales. Resultados: La fibrosis renal inducida por obstrucción uretral unilateral fue confirmada por un aumento del nivel de α-SMA, deposición de colágeno, dilatación tubular, infiltración de células inflamatorias y necrosis. También se observó un aumento del nivel de FCT-β renal y una disminución del nivel de GMP urinario en los animales con obstrucción, además de una reducción del aclaramiento de la creatinina. El tratamiento con tadalafil, que restauró el nivel de GMP urinario de los animales, atenuó significativamente los cambios fibróticos y el aumento de FCT-β en los riñones. Conclusión: Este estudio sugiere que el tratamiento con tadalafil mejora la fibrosis renal al reducir la expresión de FCT-β y puede tener una importante relevancia clínica por cuanto el tadalafil se usa hoy día clínicamente para tratar la disfunción eréctil y la hipertensión pulmonar.

Acute acetaminophene-induced hepatotoxicity and nephrotoxicity; therapeutic effect of dexmedetomidine.

OBJECTIVE AND BACKGROUND: Acute acetaminophen (APAP) overdose has been shown to cause toxicity and the primary treatment medication is N-acetylcysteine (NAC). Dexmedetomidine (DEX) is a sedative drug with known antioxidant properties. We researched whether DEX has an injury-reducing effect on toxicity. METHODS: Rats were divided into: Group I (control), Group II (APAP) Group III (NAC) Group IV (DEX) and Group V (NAC+DEX). Histopathologic investigations of tissues were performed and glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA), myeloperoxidase (MPO) and beta trace protein (PGD2S) levels were studied in blood samples. RESULTS: DEX administration for hepatotoxicity and nephrotoxicity induced with APAP, caused a significant reduction in oxidative injury markers like MDA and MPO, a significant increase in GSH-Px level and a significant degree of amelioration in liver histopathologic scores. CONCLUSION: DEX administration for APAP toxicity causes a reduction in oxidative injury biomarkers, increased antioxidant biomarker levels and significant reduction in liver histopathologic scores. The beneficial effect of DEX use for detection of toxicity induced by acute APAP overdose, was shown in this study for the first time (Tab. 5, Fig. 2, Ref. 41).

Effects of GYKI 52466 on early vasospasm in rats.

OBJECTIVE: The pathogenesis and treatment of cerebral vasospasm (CV) after subarachnoid hemorrhage (SAH) remains a matter of discussion. The authors investigated the efficacy of GYKI 52466, a 2,3-benzodiazepine that is a selective and potent alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) receptor antagonist, in a rat femoral artery vasospasm model. METHODS: Twenty-seven Wistar albino rats were used in this study. The animals were divided into 3 groups of 9 animals each: sham-operated control (group 1), vasospasm group (group 2), and vasospasm-plus-treatment group (group 3). In groups 2 and 3, autologous blood (0.1 mL) was applied to a 1-cm segment of the femoral artery, which was then wrapped with a silicone cuff. One minute after blood application, the rats in group 3 received an intraperitoneal injection of 15 mg/kg GYKI 52466 every 12 h for 24 h. Responses to blood application and treatment were evaluated with light and electron microscopy examinations of femoral artery specimens at 72 h. RESULTS: On light microscope examination, the mean diameters of the arterial lumens in groups 1, 2, and 3 were 514.47+/-15.3, 317.63+/-12.1, and 503.91+/-9.6 microm, respectively. At 24 h, the mean arterial wall thickness in group 1 was 77.69+/-4.2 microm. This mean thickness in group 2 increased to 164.82+/-9.1 microm. After GYKI treatment in group 3, the mean arterial wall thickness measured 95.37+/-5.3 microm. In group 2 rats, electron microscopy demonstrated various changes including marked luminal narrowing and increased wall thickness in the femoral arterial wall. The most striking finding were the degenerative changes in the endothelium, which presented as a corrugated appearance of the internal elastic lamina. Rats in group 3 had endothelia that were slightly constricted and smooth muscle cells that were relaxed; changes in the vessel wall and internal elastic lamina were less prominent in these rats than in the rats of group 2. CONCLUSIONS: The results of the present study suggest that GYKI 52466 inhibited AMPA receptors and induced relaxation of smooth muscle cells in the wall of the femoral artery in a rat model. This substance may be a protective and therapeutic agent in the treatment of cerebral vasospasm.

Expression of insulin-like growth factor in the placenta of intrauterine growth-retarded human fetuses.

Many cases of intrauterine growth retardation (IUGR) are the result of placental and fetal tissue insufficiency. Insulin-like growth factor-I (IGF-I) is known to play a role in placental and fetal growth. An immunocytochemical study was performed to localize IGF-I peptides in human placenta and umbilical cords of normal (n = 3) and IUGR (n = 3) fetuses. The peripartum fetal conditions were evaluated as well. Immunoreactive IGF-I was detected in the cytotrophoblast, syncytiotrophoblast, amnion, endothelial cells of fetal capillaries and in the decidua in both normal and IUGR placental tissue. A more robust immunostaining and increased numbers of positively stained cells were found in the decidua of IUGR placenta (p < 0.001). Intense immunostaining was also found in endothelial cells, smooth muscle cells and fibroblasts of the umbilical vein. IGF-I immunoreactivity was also present in stroma (Hofbauer cells and/or fibroblasts) of IUGR villi. Our results indicate that expression of IGF-I is high in specific sites in placenta and umbilical cords, which indicates a paracrine and/or endocrine function. The increased expression of IGF-I in placenta of IUGR fetuses indicates its involvement in restoring normal growth by means of a positive feed-back mechanism.

Protective effects of vitamin E and selenium on the renal morphology in rats fed high-cholesterol diets.

The histopathological effects of cholesterol and the protective effects of vitamin E and selenium (Se) on renal histology were examined in Sprague-Dawley rats. Light-microscopic evaluation of the renal cortex revealed: glomerular fibrosis, cellular and mesangial proliferation, capillary obliteration and cholesterol crystals in the tubular lumina of the cholesterol-fed group. These results suggest that oxidated LDL (O-LDL) is a cytotoxic factor which stimulates mesangial cell and matrix proliferation. Ultrastructurally, small and large lipid vacuolization in intracapillary lumina, adhesion of epithelial foot processes, mesangial foam cells and polymorphonuclear leukocytes were seen in the cholesterol-fed group. In the groups fed cholesterol + vitamin E, cholesterol + Se and cholesterol + vitamin E + Se, morphological improvements were observed. It appeared that an excess in O-LDL, reactive oxygen species and growth factors might play an important role in the pathogenesis of glomerulosclerosis. In addition, it was concluded that antioxidant therapy may prevent LDL oxidation and generation of free radicals.