Evaluation of the renal effects of an antisense phosphorothioate oligodeoxynucleotide in monkeys.

Antisense phosphorothioate oligodeoxynucleotides are therapeutic agents that provide target specificity resulting from Watson-Crick base pairing. However, there are nonspecific effects that in some instances result in toxicity. These compounds accumulate in the kidney and induce renal proximal tubular degeneration at high doses. The relationship between accumulation of phosphorothioate oligodeoxynucleotides in the kidney, indicators of renal toxicity, and histomorphology were investigated in rhesus monkeys. Monkeys received vehicle or an escalating dose regimen of 3, 10, 40, and 80 mg/kg of ISIS 2105 and were then evaluated for changes in clinical pathology indices, urinalysis parameters, and renal histopathology. Urinalysis revealed an increase in protein levels and a slight increase in blood content following the third 40 mg/kg dose and continuing through the 80 mg/kg doses, whereas other urinary markers of renal toxicity were unchanged. Creatinine clearance was slightly decreased in monkeys during the 80 mg/kg dose cycle. Granulation in the cytoplasm of proximal tubular epithelial cells was evident by microscopic examination of kidney and was present at all doses examined and increased with dose. Immunohistochemical staining localized the oligodeoxynucleotide within these granules. Histopathologic changes consisting of minimal to moderate tubular degeneration were present only at the higher doses of 40 and 80 mg/kg and at high tissue concentrations, and these changes occurred concurrent with functional alterations, whereas lower doses (< or = 10 mg/kg) did not affect a pathologic or functional change.     

Plasma protein extravasation and vascular endothelial growth factor expression with endothelial nitric oxide synthase induction in gentamicin-induced acute renal failure in rats

Microvascular hyperpermeability to plasma proteins via vascular endothelial growth factor (VEGF) with endothelial nitric oxide synthase (eNOS) induction may contribute to wound healing through matrix remodeling. However, vascular hyperpermeability is not examined in acute renal failure (ARF), a unique form of wound healing. Subcutaneous injection of gentamicin (400 mg/kg per day for 2 days in divided doses every 8 h) in rats increased serum creatinine levels and induced tubular damage, which peaked at day 6, after the last gentamicin injection. Ki67-positive regenerating proximal tubules (PTs) peaked in number at day 6 and almost covered the bare tubular basement membrane (TBM) by day 10. Staining of fibrinogen and plasma fibronectin began to increase in the peritubular regions as early as day 0, steadily increased in TBM and tubular lumen until day 6 and then decreased. Hyperpermeable peritubular capillaries were identified by extravasation of perfused-fluoresceinated dextran (both 70 kDa and 250 kDa) into peritubular regions as early as day 0 and prominently into TBM and tubular lumen at day 6. Electron microscopy further suggested the intraendothelial pathway of dextran. Immunoreactive VEGF increased in the damaged and regenerating PTs. Immunoreactive VEGF receptors-1 and -2 did not change, but immunoreactive eNOS increased in the peritubular capillaries after induction of ARF. Western blotting for VEGF and eNOS supported the immunostaining findings. In addition, we assessed the effects of NOS inhibitor N-nitro-l-arginine methyl ester (l-NAME) on vascular hyperpermeability during the recovery phase of this model. Treatment with l-NAME (s.c. at a dose of 100 mg/kg/day from day 3 to day 6) decreased extravasation of perfused-250-kDa dextran and significantly inhibited the regenerative repair of PTs at day 6 when compared with vehicle-treated rats. In conclusion, plasma protein extravasation occurred, leading to matrix remodeling, such as the process of wound healing during the tubular repair in gentamicin-induced ARF. Since VEGF-induced vascular hyperpermeability may depend on NO production, VEGF/VEGF receptor system with eNOS induction might be responsible for this process.     

Teratogenic effects of retinoic acid on neurulation in mice embryos.

Retinoic acids (RA) are natural chemicals that exert a hormone-like activity and a variety of biological effects on early development of mouse. In this study, the probable teratogenic effects of RA on CNS have been investigated in pregnant mice (n = 20) divided into four groups: (1) untreated controls, (2) controls which received a single dose of DMSO, (3) a group that received 40 mg/kg, and (4) a group that received 60 mg/kg of all-trans RA in DMSO, respectively on the eighth day of gestation. Embryos whose dams had received 40 and 60 mg/kg doses of RA, showed malformations and decreased size. At 40 mg/kg dosage level, 50% of the embryos had closed neural tubes while at 60 mg/kg dosage level the neural tube failed to close. The neuroblast mantle layers were disorganized in the 40 mg/kg and even more in the 60 mg/kg exposed group compared to the controls. In mitosis, the density of chromatin was increased in the 60 mg/kg dose group. Compared to controls the 40 and 60 mg/kg dose groups of RA treated dams decreases in the luminal longitudinal and internal measures were observed. Also the thickness of ventricular, mantle and marginal layers was smaller. Wide intercellular spaces due to the degenerated cells at high doses of RA as well as an accumulation of intercellular fluid were observed. Therefore, the wedge shape of neuroepithelium was abolished, preventing the elevation of the neural wall.     

Biomarkers of collecting duct injury in Han-Wistar and Sprague-Dawley rats treated with N-phenylanthranilic Acid

N-phenylanthranilic acid is a chloride channel blocker that causes renal papillary necrosis in rats. Studies were conducted in two strains of male rats to evaluate novel biomarkers of nephrotoxicity. Han-Wistar rats were given daily oral doses of 50, 350, or up to 700 mg/kg/day of NPAA, and Sprague-Dawley rats were given 50 or 400 mg/kg/day of NPAA. Rats were euthanized on days 8 and 15. The candidate kidney injury biomarkers renal papillary antigen-1 (RPA-1, for collecting duct injury), clusterin (for general kidney injury), α-glutathione-S-transferase (a proximal tubular marker), and μ-glutathione-S-transferase (a distal tubular marker) were measured in urine by enzyme immunoassay. Characteristic degeneration and necrosis of the collecting duct and renal papilla were observed in Han-Wistar rats at the high dose on day 8 and at the mid and high doses on day 15, and in Sprague-Dawley rats given the high dose on days 8 and 15. Increases in urinary RPA-1, and to a lesser extent urine clusterin, were generally associated with the presence of collecting duct injury and were more sensitive than BUN and serum creatinine. On the other hand, decreases in α-glutathione-S-transferase without proximal tubule lesions in both strains and decreases in μ-glutathione-S-transferase in Sprague-Dawley rats only were not associated with morphological proximal or distal tubule abnormalities, so both were of less utility. It was concluded that RPA-1 is a new biomarker with utility in the detection of collecting duct injury in papillary necrosis in male rats.     

Effect of prolonged saline loading on HgCl2-induced renal tubular damage

Male Porton-Wistar rats, 32 weeks old, were given i.p. one of the following doses of HgCl2; 0.5, 1.0 or 1.5 mg Hg/kg. In the preceding 4-week period and throughout the experiment the animals had free access to either tap water or 1.0% saline. The urinary excretion of alkaline phosphatase measured in urine samples, collected during the first 24 h after treatment with mercury, indicated that chronic saline loading significantly attenuated tubular damage caused by 0.5 mg or 1.0 mg Hg/kg, but not by 1.5 mg Hg/kg. Tubular necrosis 12 and 24 h after mercury was also less severe and extensive in saline than in tap water-drinking rats. This difference was still noticeable 4 days after mercury treatment in rats dosed with 0.5 mg Hg/kg, but death in the two higher dose groups prevented further pair-to-pair histological comparison. At the selected dose levels chronic saline loading did not decrease renal mercury content at 12 or 24 h and therefore protection was not associated with decrease in renal mercury uptake. The experiment indicates that chronic saline drinking, which at higher doses attenuates HgCl2-induced acute renal failure but not tubular necrosis, is able to moderate the severity of tubular necrosis when the dose of HgCl2 is as low as 0.5 mg Hg/kg. This protective effect diminishes as the dose is increased.     

Effect of prolonged saline loading on HgCl2-induced renal tubular damage.

Male Porton-Wistar rats, 32 weeks old, were given i.p. one of the following doses of HgCl2; 0.5, 1.0 or 1.5 mg Hg/kg. In the preceding 4-week period and throughout the experiment the animals had free access to either tap water or 1.0% saline. The urinary excretion of alkaline phosphatase measured in urine samples, collected during the first 24 h after treatment with mercury, indicated that chronic saline loading significantly attenuated tubular damage caused by 0.5 mg or 1.0 mg Hg/kg, but not by 1.5 mg Hg/kg. Tubular necrosis 12 and 24 h after mercury was also less severe and extensive in saline than in tap water-drinking rats. This difference was still noticeable 4 days after mercury treatment in rats dosed with 0.5 mg Hg/kg, but death in the two higher dose groups prevented further pair-to-pair histological comparison. At the selected dose levels chronic saline loading did not decrease renal mercury content at 12 or 24 h and therefore protection was not associated with decrease in renal mercury uptake. The experiment indicates that chronic saline drinking, which at higher doses attenuates HgCl2-induced acute renal failure but not tubular necrosis, is able to moderate the severity of tubular necrosis when the dose of HgCl2 is as low as 0.5 mg Hg/kg. This protective effect diminishes as the dose is increased.     

Glomerular basement membrane alterations induced by gentamicin administration in rats

The widespread therapeutic use of the aminoglycoside antibiotic gentamicin (GM) is limited by its nephrotoxic side effect, which can lead to acute renal failure. This study aimed at examining effects of high, supratherapeutic doses of gentamicin on morphological, structural and functional alterations of the glomerular basement membrane in adult rats. Experiments were done on 30 male Wistar rats, divided into two experimental groups. GM-group (20 rats) received gentamicin at a dose of 100mg/kg intraperitoneally during eight consecutive days. Control or C-group (10 rats) received 1 ml/day saline intraperitoneally. For histological analysis, 5 microm thick sections were stained with hematoxylin and eosin (HE), periodic acid Schiff (PAS), and Jones methenamine silver. Glomerular basement membrane thickness, glomerular area, major and minor axes, perimeter, diameter, roundness and mean optical density were analyzed. Biochemical analyses were used to determine concentrations of blood urea, serum creatinine, sodium and potassium. In GM-group rats, glomeruli were larger and glomerular basement membrane was diffusely and irregularly thickened with neutrophil cell infiltration. Glomerular area, major axis, minor axis, diameter and perimeter were significantly higher in GM-group compared to C-group rats. Opposite to this, glomerular optical density and average roundness were larger in C-group than in gentamicin-treated animals. Our results clearly showed morphological and structural alterations of glomeruli and glomerular basement membrane as well as alterations of proximal tubules in adult rats exposed to high doses of gentamicin.     

Tubulointerstitial nephritis and glomerulonephritis in Brown-Norway rats immunized with heterologous glomerular basement membrane.

Tubulointerstitial nephritis and glomerulonephritis were produced in Brown-Norway rats (BN) by a single immunization with 2 mg of lyophilized bovine glomerular basement membrane. Tubulointerstitial nephritis was evident before glomerulonephritis. Antibody first bound to tubular basement membranes (TBM), and then the renal cortex was infiltrated with inflammatory cells. The TBM was split, and many renal tubules, especially proximal tubules, were destroyed. Approximately 14 days after the beginning of the tubular phase, antibody was observed to be bound to glomerular basement membranes (GBM) in linear fashion. There was epithelial and mesangial cell proliferation, splitting and reduplication of GBM, crescent formation, and glomerular scarring and atrophy.     

Immunolocalization of Kim-1, RPA-1, and RPA-2 in kidney of gentamicin-, mercury-, or chromium-treated rats: relationship to renal distributions of iNOS and nitrotyrosine

Immunohistochemical studies for kidney injury molecule-1 (Kim-1), renal papillary antigen-1 (RPA-1), and renal papillary antigen-2 (RPA-2) were conducted to explore their relationship to inducible nitric oxide synthase (iNOS) and nitrotyrosine expression. Male Sprague-Dawley rats were exposed to gentamicin (100 mg/kg/day Gen, sc, for 3 days), mercury (0.25 mg Hg/kg, iv, single dose), or chromium (5 mg Cr/kg, sc, single dose) and kidney tissue was examined 24 hours or 72 hours after the last dose of the nephrotoxicant. Another group of kidneys was evaluated 24 hours after rats were administered 3 daily doses (50, 100, 150, 200, or 300 mg/kg/day) of Gen. Gen- and Cr-treated rats exhibited increased immunoreactivity of Kim-1, RPA-1, and RPA-2 largely in the S1/S2 segments and to a lesser extent in the S3 segments of the proximal tubule of the kidney, whereas Hg-treated rats showed increased immunoreactivity of Kim-1, RPA-1, and RPA-2 in the S3 segments. Up-regulation of Kim-1, RPA-1, and RPA-2 expression correlated with injured tubular epithelial cells and also correlated with immunoreactivity of iNOS and nitrotyrosine. It is possible that iNOS activation with nitrotyrosine production in injured nephron segments may be involved in the induction of Kim-1, RPA-1, and RPA-2 following exposure to nephrotoxicants.     

Cyclosporine A-Induced Kidney Alterations Are Limited by Melatonin in Rats: An Electron Microscope Study

The effect of melatonin on experimental prolonged cyclosporine A (CsA) nephrotoxicity was analyzed by electron microscopy and morphometry. Twenty female Wistar rats were divided into groups that received (1) CsA at a therapeutic dose (15 mg/kg/day) sc for 40 days; (2) olive oil, CsA vehicle, as controls; (3) CsA plus melaton (1 mg/kg) ip for the same time; (4) melatonin alone, as additional controls. All controls had normal renal ultrastructure. However, in CsA group, both tubular and glomerular alterations were observed. The authors found apoptotic and necrotic proximal tubules with disrupted brush border, swollen mitochondria, abundant lysosomes; in the glomerulus, amorphous basement membrane, and abnormal mesangial matrix. CsA plus melatonin administration partly prevented these changes. Nevertheless, fibrillar deposits in podocytes and basolateral membrane dilatations in proximal tubules were observed. Histopathological analysis on semithin sections and ultrastructural morphometry were also performed. CsA induced interstitial fibrosis, atrophy, and PAS positive inclusions in the proximal tubules. Moreover, CsA reduced glomerular and mesangial volume but enhanced mesangial matrix volume and basement membrane thickness. After CsA plus melatonin, these parameters were reduced in the proximal tubules and restored in the glomerulus. In conclusion, melatonin attenuated morpho-quantitative alterations induced by CsA in the rat kidney.     

Cyclosporine A-induced kidney alterations are limited by melatonin in rats: an electron microscope study

The effect of melatonin on experimental prolonged cyclosporine A (CsA) nephrotoxicity was analyzed by electron microscopy and morphometry. Twenty female Wistar rats were divided into groups that received (1) CsA at a therapeutic dose (15 mg/kg/day) sc for 40 days; (2) olive oil, CsA vehicle, as controls; (3) CsA plus melaton (1 mg/kg) ip for the same time; (4) melatonin alone, as additional controls. All controls had normal renal ultrastructure. However, in CsA group, both tubular and glomerular alterations were observed. The authors found apoptotic and necrotic proximal tubules with disrupted brush border, swollen mitochondria, abundant lysosomes; in the glomerulus, amorphous basement membrane, and abnormal mesangial matrix. CsA plus melatonin administration partly prevented these changes. Nevertheless, fibrillar deposits in podocytes and basolateral membrane dilatations in proximal tubules were observed. Histopathological analysis on semithin sections and ultrastructural morphometry were also performed. CsA induced interstitial fibrosis, atrophy, and PAS positive inclusions in the proximal tubules. Moreover, CsA reduced glomerular and mesangial volume but enhanced mesangial matrix volume and basement membrane thickness. After CsA plus melatonin, these parameters were reduced in the proximal tubules and restored in the glomerulus. In conclusion, melatonin attenuated morpho-quantitative alterations induced by CsA in the rat kidney.     

Dose-related protecting effects of vitamin C in gentamicin-induced rat nephrotoxicity: a histopathologic and biochemical study

Gentamicin remains the mainstay in treatment of gram-negative infections, despite its potential ototoxicity and nephrotoxicity. In this study, we investigated dose-related protecting effects of vitamin C against gentamicin-induced rat nephrotoxicity. Hence, 50 male albino Wistar rats were randomly divided into five equal groups to receive a corresponding dose of either normal saline as control, vitamin C (200 mg/kg/bw, i.m.) or gentamicin alone (80 mg/kg/bw, i.m.) or in combination with vitamin C at low dose (200 mg/kg/bw, i.m.; LVG) and high dose (600 mg/kg/bw, i.m.) for 9 days. Daily administration of gentamicin at a dose of 80 mg/kg resulted in a significant increase in oxidative stress in renal tissues and plasma and a concomitant decrease in the creatinine clearance and renal blood flow as result of early hemodynamic toxicity. Histopathological examinations revealed acute tubular necrosis with hyaline cast formation triggered by gentamicin over 9 days of experiment, in addition to interstitial nephritis and tubular epithelial loss. Further biochemical studies showed protecting effects of supplemented vitamin C at a high dose, including slowdown in the urinary enzyme activity, a significant decrease in plasma lipid peroxidation, and an increased tissue superoxide dismutase activity with recovery in the glomerular hemodynamicity and the ATPase activity up to 50% when compared to controls and low-dose rats (LVG). In high-dose animals, normal glomerular and tubular function on recovery from toxic renal failure led us to conclude that antioxidant properties of vitamin C consistently increase with dose intensity. The present study also provided evidence that high dose of vitamin C prevented both functional and histological renal changes induced by gentamicin in rats, more efficient than low dose of the vitamin.     

Glomerular thrombosis and cortical infarction in cyclosporin-treated rabbits with acute serum sickness.

Rabbits given acute serum sickness (ASS) and treated with cyclosporin A (CyA) developed glomerular capillary thrombosis and cortical infarction, lesions not seen in unmodified ASS. Thirty-three NZW rabbits received a single intravenous injection of 250 mg/kg bovine serum albumen (BSA) with or without endotoxin (5 micrograms/kg) on day 0. Groups of rabbits were given intramuscular CyA as follows: 15 mg/kg from day -2 to +8, or 25 mg/kg/day from day -20 to +3 or day 0 to 5. Signs of this renal injury were haematuria, transient proteinuria, glycosuria and oliguria and they occurred during the rapid phase of antigen elimination when immune complexes were being formed. Seventeen of the 33 rabbits developed glomerular capillary thrombi and 11 of 17 also had glomerular and tubular infarction. Electron microscopic examination showed that these lesions were associated with severe endothelial injury and platelet-fibrin-leucocyte thrombi. These changes were more severe in the groups given 25 mg/kg. The lesions were not seen in untreated rabbits and ASS, nor in normal rabbits given equivalent doses of CyA alone. A strikingly similar renal lesion has been seen in patients receiving CyA following bone marrow transplantation, and also in the haemolytic uraemic syndrome. The model we describe may be valuable for the study of the mechanisms of endothelial injury and thrombosis in the kidney.     

Renal tubular basement membrane changes in tubulointerstitial damage in patients with glomerular diseases

Injury to renal tubules and interstitium occur in various glomerular diseases, leading to functional impairment. Tubular basement membrane (TBM) is an important component in maintaining tubular epithelial cell integrity. Because ultrastructural changes in these structures had not been studied in detail, the authors analyzed 30 patients with various types of glomerular diseases, including minimal change disease (MCD), focal segmental glomerular sclerosis, IgA nephropathy, diffuse proliferative glomerulonephritis, membranous nephropathy, and lupus nephritis, by light, electron, and immunofluorescence microscopy. Ultrastructural changes in the TBM were studied and morphometric measurements were performed. The tubular basement membranes showed membranous structures, lucent or lytic areas, and tubular epithelial detachment. There was significant linear correlation between these tubular basement membrane changes and terminal complement complex neoantigens. The interstitial widening was due to banded collagen fibers, with anchoring fibers in the TBM. The various glomerular diseases lead to tubulointerstitial damage via changes in the TBM, leading to renal dysfunction.     

Renal Tubular Basement Membrane Changes in Tubulointerstitial Damage in Patients with Glomerular Diseases

Injury to renal tubules and interstitium occur in various glomerular diseases, leading to functional impairment. Tubular basement membrane (TBM) is an important component in maintaining tubular epithelial cell integrity. Because ultrastructural changes in these structures had not been studied in detail, the authors analyzed 30 patients with various types of glomerular diseases, including minimal change disease (MCD), focal segmental glomerular sclerosis, IgA nephropathy, diffuse proliferative glomerulonephritis, membranous nephropathy, and lupus nephritis, by light, electron, and immunofluorescence microscopy. Ultrastructural changes in the TBM were studied and morphometric measurements were performed. The tubular basement membranes showed membranous structures, lucent or lytic areas, and tubular epithelial detachment. There was significant linear correlation between these tubular basement membrane changes and terminal complement complex neoantigens. The interstitial widening was due to banded collagen fibers, with anchoring fibers in the TBM. The various glomerular diseases lead to tubulointerstitial damage via changes in the TBM, leading to renal dysfunction.     

Vitamin B6 dose-dependently ameliorates renal hemodynamic toxicity of cisplatin in rat model of nephrotoxicity: the histopathologic and biochemical findings

Despite its significant anticancer activity, the clinical use of cisplatin is often limited by its undesirable side effects in the kidney known as nephrotoxicity. It is a common and often overlooked clinical entity that presents itself in the setting of oxidative stress-associated diseases in older individuals with renal failure. In this study, we investigated the antioxidant-protecting effects of vitamin B₆ in the kidney, with a view on the vasoregulatory role of renal pyridoxal 5′-phosphate at reducing the hemodynamic toxicity of cisplatin. Hence, 50 male Sprague–Dawley rats were randomly assigned in one of five groups of the study to receive a corresponding dose of either normal saline, vitamin B₆ (200 mg/kg/bw; i.m.) or cisplatin alone (7 mg/kg/bw; i.m.), or in combination with vitamin B₆ at low (100 mg/kg/bw; i.m.) and high dose (200 mg/kg/bw; i.m.) for 10 days as animal model of renal failure. Daily administration of cisplatin at a dose of 7 mg/kg/bw resulted in a significant increase in local and systemic oxidative stress of the kidney and a decrease in glomerular function as a result of early hemodynamic toxicity. Histopathological examinations of renal tissues revealed acute tubular necrosis with hyaline cast formation triggered by cisplatin over 9 days of the study, in addition to interstitial nephritis and tubular epithelial loss. Further biochemical studies in HVB group showed the protecting effects of supplemented vitamin B₆ at a high dose, including a slowdown in urinary enzyme activity, a significant decrease in plasma lipid peroxidation, and an increased tissue superoxide dismutase activity with recovery in the glomerular hemodynamicity and ATPase activity up to 50 % when compared to the low-dose rats and controls. In high-dose animals, the normal glomerular and tubular function on recovery from toxic renal failure led us to conclude that the antioxidant property of vitamin B₆ consistently increases with the dose intensity. The present study also provided evidence that high dose of vitamin B₆ prevented both functional and histological renal changes induced by cisplatin in rats, more efficient than low dose of the vitamin.     

Antioxidant protecting effects of vitamin B6 at reducing hemodynamic toxicity of gentamicin in rat model of nephrotoxicity

Routine therapeutic use of gentamicin in patients with preexisting renal failure may confront us with the toxic effects of aminoglycosides in the kidney known as nephrotoxicity. It is a common and often overlooked clinical entity that presents itself in the setting of oxidative stress-associated diseases in older individuals with renal failure. In this study, we investigated the antioxidant protecting effects of vitamin B₆ in the kidney, with a view on vasoregulatory role of renal pyridoxal 5′-phosphate at reducing the hemodynamic toxicity of gentamicin. Hence, 50 male Sprague–Dawley rats were randomly assigned in five groups to receive a corresponding dose of either normal saline, vitamin B₆ (100 mg/kg/bw; i.m.) or gentamicin alone (80 mg/kg/bw; i.m.), or in combination with vitamin B₆ at low (100 mg/kg/bw; i.m.) and high dose (200 mg/kg/bw; i.m.) for 10 days as animal model of nephrotoxicity. Daily administration of gentamicin at a dose of 80 mg/kg resulted in a significant increase in local and systemic oxidative stress and a decrease in glomerular functions as result of early hemodynamic toxicity. Histopathological examinations of renal tissues revealed acute tubular necrosis with hyaline cast formation triggered by gentamicin over 9 days of the experiment, in addition to interstitial nephritis and tubular epithelial loss. Further biochemical studies in HVB group showed the protecting effects of supplemented vitamin B₆ at a high dose, including a slowdown in urinary enzyme activity, a significant decrease in plasma lipid peroxidation, and an increased tissue superoxide dismutase activity with recovery in the glomerular hemodynamicity and ATPase activity up to 50 % when compared to low-dose rats and controls. In high-dose animals, normal glomerular and tubular function on recovery from toxic renal failure led us to conclude that antioxidant properties of vitamin B₆ consistently increase with dose intensity. The present study also provided evidence that high dose of vitamin B₆ prevented both functional and histological renal changes induced by gentamicin in rats, more efficient than low dose of the vitamin.     

Effects of in vivo and in vitro exposure to rhodamine dyes on mitochondrial function of mouse embryos

Cationic rhodamines (Rh 123 and Rh 6G) can cause developmental toxicity in mice and inhibit embryonic mitochondrial respiration following in vivo or in vitro dye exposure. Rh B, a neutral rhodamine, fails to show such effects at comparable doses. To assess effects of rhodamines on development, F0F1ATPase activity and ADP translocation were measured on gestation day (GD) 12 in embryonic and adult mitochondria. ATP synthesis in embryonic mitochondria transplacentally exposed to Rh 123 (15 mg/kg/day) or Rh 6G (0.5 mg/kg/day) given to dams by i.p. injection from GD 7 to 10 were inhibited 39% and 49%, respectively. When isolated mitochondria were treated, dose-dependent inhibition was seen; at 5 micrograms of dye/mg mitochondrial protein, ATP synthesis was inhibited 65% and 81% by Rh 123 and Rh 6G, respectively. When F0F1ATPase activity was assessed, in vitro Rh 123 and Rh 6G exposures at levels up to 8 micrograms/mg mitochondrial protein resulted in enzyme inhibition, but at 10 micrograms/mg, ATPase activity was stimulated. Uncoupler-stimulated ATPase activity was also inhibited. ADP translocation was decreased by 19.1% and 37.7% by Rh 123 and Rh 6G, respectively, at dye concentrations of 20 micrograms/mg. Results of in vitro exposure of maternal liver mitochondria were similar to those for embryonic mitochondria, whereas liver from dams exposed in vivo on GD 7-10 was unaffected on GD 12. In vivo or in vitro treatment with Rh B did not affect any embryonic or maternal parameters. Such results support the hypothesis that inhibition of mitochondrial energy metabolism is a mechanism for the developmental toxicity of cationic rhodamines.     

Vitamin C dose-dependently ameliorates renal hemodynamic toxicity of cisplatin in adult Swiss albino rats: a histopathologic and biochemical study

Nephrotoxicity is usually thought of as a common invariable consequence of hemodynamic toxicity whose effects, including oliguria and dysuria, has largely limited the clinical use of cisplatin. In this study, we investigated the protective effects of low and high dose of vitamin C against cisplatin-induced rat nephrotoxicity. Hence, 50 adult male Swiss albino rats were randomly divided into five equal groups to receive a corresponding dose of either normal saline as control, vitamin C (600 mg/kg/BW, i.v.), or cisplatin alone (7 mg/kg/BW, i.p.) or in combination with vitamin C at low dose (200 mg/kg/BW, i.v.) and high dose (600 mg/kg/BW, i.v.) for 9 days. Daily administration of cisplatin at a dose of 7 mg/kg/BW resulted in a significant increase in oxidative stress in renal tissues and plasma and a concomitant decrease in the creatinine clearance and renal blood flow as a result of early hemodynamic toxicity. Histopathological examination revealed acute tubular necrosis with hyaline cast formation triggered by cisplatin over 9 days of experiment. Further biochemical studies showed protecting effects of supplemented vitamin C at a high dose, illustrated by slowdown in the urinary enzyme activity, a significant decrease in plasma lipid peroxidation, and an increased tissue superoxide dismutase activity with recovery in the glomerular hemodynamicity and the ATPase activity up to 50 % when compared to controls and rats receiving low-dose. In high-dose animals, normal glomerular and tubular function on recovery from toxic renal failure led us to conclude that antioxidant property of vitamin C increases with dose, and, therefore, high dose of vitamin C prevents both functional and histological renal changes induced by cisplatin in rats, more efficient than low dose of the vitamin.     

不同剂量氯化锂对成年大鼠视神经切断后视网膜神经节细胞的保护作用

目的:研究不同剂量氯化锂(LiCl)对成年大鼠视神经切断后视网膜神经节细胞(RGCs)存活的作用。方法:眶内切断72只成年雌性SD大鼠左侧视神经且残端留置荧光金(FG)后,随机分为生理盐水对照组和低剂量(30 mg/kg/d)、中剂量(60 mg/kg/d)、高剂量(85 mg/kg/d)氯化锂实验组。术前1 d及术后每天腹腔注射生理盐水或不同剂量的氯化锂溶液,直至术后2 d、7 d或14 d处死动物。平铺视网膜后取样计数FG逆行标记的存活节细胞,并由此计算出每一视网膜内节细胞的平均密度。结果:术后2 d各剂量氯化锂组节细胞平均密度与对照组相比无显著性差异(P>0.05)。当存活时间增至7 d时,各剂量氯化锂组节细胞密度均明显高于对照组(P<0.01),且中剂量组节细胞密度增高最为显著。术后14 d时,低剂量与中剂量组节细胞密度仍显著高于对照组(P<0.01),但高剂量组节细胞密度与对照组相比无统计学差异(P>0.05)。结论:腹腔内注射氯化锂可显著促进成年大鼠视神经切断后节细胞的存活,这种神经保护作用为剂量依赖性。