The effect of mixed function oxidase induction and inhibition on salicylate-induced nephrotoxicity in male rats

Proximal Tubule Dysfunction Secondary to Salicylate Intoxication

Aspirin overdose is still a common cause of presentation to the emergency department and is commonly seen in the setting of one-time, accidental or intentional ingestion of large amounts of salicylate-containing compounds, though can occur with long-term ingestion of super-therapeutic doses of medications. Salicylate toxicity has a predictable progression from early respiratory alkalosis to late metabolic acidosis. We present the case of a 14-year-old girl who intentionally ingested a handful of Aspirin and despite appropriate therapy, developed transient proximal tubule dysfunction. This case highlights the need for a change in the short-term medical management of children presenting with salicylate toxicity.

El Deib M. Protective Effect of Curcumin against Sodium Salicylate-Induced Oxidative Kidney Damage, Nuclear Factor-Kappa Dysregulation, and Apoptotic Consequences in Rats

This study examined the effect of sodium salicylates (SS), alone and in combination with curcumin (CUR), on kidney function and architecture in rats. Five rat groups were given 1 mL physiological saline/rat orally, 1 mL olive oil/rat orally, 50 mg CUR/kg bwt orally, 300 mg SS/kg bwt intraperitoneally, or CUR+SS for 15 days. The hematological indices, serum protein profile, serum electrolytes balance, oxidative stress, and lipid peroxidation of kidney tissues were assessed. The histopathological examination and immune expression of Caspase-3 and nuclear factor kappa (NF-κB) were conducted. The findings showed that SS injection induced nephrotoxic activity, including increased serum urea, creatinine, and uric acid levels. It also caused apparent pathological alterations with increased Caspase-3 and NF-κB immuno-expression. In addition, thrombocytopenia, leukocytosis, neutrophilia, hyponatremia, hypochloremia, hypocalcemia, and hypomagnesemia but not hyperkalemia and hyperphosphatemia were evident in SS-injected rats. Moreover, SS exposure increased serum α1 globulin, renal tissue malondialdehyde, and Caspase-3 levels but superoxide dismutase, glutathione peroxidase, and Bcl-2 levels declined. Meanwhile, CUR significantly counteracted the SS harmful impacts on kidneys but SS+CUR co-administration induced an anemic condition. Overall, CUR has an evident protective role against SS-induced renal damage, but the disturbed hematological alterations should be carefully taken into consideration in their combined use.

Salicylate-Induced Proximal Tubular Dysfunction

We describe the case of a 17-year-old girl who was admitted to our clinic for drug poisoning. Twelve hours after the ingestion of 25 tablets of aspirin (12.5 g of acetylsalicylic acid), the patient had a generalized proximal tubular dysfunction characterized by glucosuria (in the face of normal serum glucose levels), proteinuria, and uric acid wasting. Further characterization of the tubular dysfunction using high-resolution proton nuclear magnetic resonance spectroscopy of the urine showed a pattern consistent with proximal tubular injury. An important characteristic of the salicylate-induced proximal tubular dysfunction in our patient was its rapid reversibility. A trend toward normalization of fractional excretion values of electrolytes was observed 2 days after ingestion. Determination of serum and urine metabolites and spectroscopy of urine 15 days later showed no evidence of tubular dysfunction. The mechanisms potentially implicated in the pathogenesis of salicylate-induced Fanconi syndrome are discussed and a brief review of the relevant literature is provided.

Is local biotransformation the key to understanding the pharmacological activity of salicylates and gold drugs?

It is suggested that some drugs may be converted by inflammatory cells to yield active species. The transformation may be non-enzymatic, although being driven by the enzymatic production of highly reactive species which are normal products of activated leukocytes, such as singlet oxygen, hydrogen peroxide, hypochlorite, hydroxyl radical and nitric oxide. Drugs which may be transformed in this fashion are the anti-rheumatic gold complexes which may be converted either to aurocyanide or to Au(III) complexes by myeloperoxidase in polymorphonuclear leukocytes. Salicylate may also be activated by its oxidation to dihydroxybenzoates although evidence for its transformation is weaker than for the gold complexes.

Hepatotoxicity of piperonyl butoxide in male F344 rats

Male F344 rats were given 0, 0.6, 1.2 or 2.4% of piperonyl butoxide in the diet. At 1, 2, 4 or 12 weeks after the beginning of the experiment, liver and kidney weight and serum clinical parameters were determined and livers and kidneys were examined with light microscopy. From 1 or 2-12 weeks, distinct increase of liver weight, changes in serum clinical parameters for liver damage, oval cell proliferation, bile duct hyperplasia, single cell necrosis, enlarged and vacuolated hepatocytes, enlarged nuclei and anisonucleosis were seen in treated rats. From 4-12 weeks, cell infiltration, focal necrosis, multinucleated hepatocytes and prominent nucleoli of hepatocytes were seen in treated rats. At 12 weeks microgranulomas were seen in treated rats. Especially in rats of the 2.4% group at 12 weeks, severe enlargement of hepatocytes, severe enlargement of nuclei and multinucleated hepatocyte were seen, suggesting preneoplastic alteration. Relative kidney weights and serum urea nitrogen levels were increased in treated rats from 1 or 2-12 weeks and at 12 weeks, atrophy of proximal tubules, dilation of tubules, cell infiltration, fibrosis and accumulation of yellow-brown pigment in the proximal tubular cells were seen.

Sub-acute toxicity of piperonyl butoxide in F344 rats

Piperonyl butoxide, alpha-[2-(2-Butoxyethoxy)ethoxy]-4,5-methylenedioxy- 2-propyltoluene, is a pesticide synergist. F344 rats of both sex were maintained on diets containing 0, 0.6, 1.2 or 2.4% of piperonyl butoxide for 13 weeks. At the end of experimental period, they were necropsied. Selected organs were weighted and serum was analyzed by clinical chemistry. In male and female rats of the 2.4%-group, body weight gains were depressed, macroscopically, hepatomegaly was marked and liver weights were significantly higher than those of the control group. In male and female rats of all treated groups, relative kidney weights were significantly increased in a dose-dependent manner. Rats of the 2.4%-group had increased levels of albumin, cholesterol, urea nitrogen and gamma-glutamyl transpeptidase. Examination of livers of the male 2.4%-group by light microscopy showed enlarged hepatocytes with glassy cytoplasm and fatty deposition. On occasion, there was coagulative necrosis of a few hepatocytes in the periportal area and oval cell proliferation. The kidney of treated rats showed atrophy of epithelium in the proximal convoluted tubules. These results indicated that toxicity of piperonyl butoxide in rats was directed primarily to the liver and kidney.

Acetaminophen-induced inhibition of hepatic mitochondrial respiration in mice

Morphological changes are observed in mitochondria early in the course of acetaminophen (APAP) hepatotoxicity. In order to determine if functional deficits also occur, this study examined the effect of APAP, in vivo and in vitro, on mitochondrial respiration in fasted, male CD-1 mice (3-4 months old). After a hepatotoxic dose of APAP (600 mg/kg, po), when glutamate was used as the respiratory substrate, state 3 respiration (ADP-stimulated) was inhibited and this was reflected in a decreased respiratory control ratio (RCR). In contrast, when succinate was the respiratory substrate, the decreased RCR was reflective of an increase in state 4 (resting) respiration. There was no detectable effect after a nonhepatotoxic dose of APAP (300 mg/kg, po). These APAP-induced respiratory effects and hepatotoxicity were prevented by piperonyl butoxide pretreatment, and were absent in 1- and 2-month-old mice, which are resistant to APAP-induced damage. Since the APAP-induced inhibition of mitochondrial respiration, in vivo, correlated with age-related and piperonyl butoxide-dependent differences in toxicity, the data suggest that the in vivo effects result, at least in part, from a mixed-function oxidase generated metabolite. In vitro, both state 3 and state 4 respiration, as well as the RCR, were inhibited by APAP in a concentration-dependent manner with glutamate as substrate. However, no effects were observed with succinate as substrate, thereby contrasting with results obtained following in vivo exposure. Therefore the in vitro effects of APAP are different from those observed in vivo and may result from a direct insult of the parent compound. These studies suggest that early alterations in mitochondrial function may be mechanistically important in APAP hepatotoxicity.

Metabolism of salicylate by isolated kidney and liver mitochondria

Mitochondria are known to contain a P-450 like system similar to that found in microsomes. Since previous in vivo studies from this laboratory have suggested that renal mitochondria may metabolize salicylate (SAL) to a reactive intermediate capable of protein binding, the ability of isolated kidney and liver mitochondria to activate salicylate was investigated. Renal mitochondria were 4 times more active than liver in converting SAL to a reactive intermediate and metabolized approx. 1% of the SAL to 2,3-dihydroxybenzoic acid, the catechol analogue of SAL. The formation of 2,3-dihydroxybenzoate (2,3-DHBA) and the amount of radiolabel bound to mitochondrial protein was decreased in the presence of SKF 525-A; however, excess unlabeled metabolite had no effect on binding. These data indicate that kidney mitochondria activate SAL via a cytochrome P-450 like system, but suggest that the binding species is not 2,3-DHBA itself. Oxidation of SAL and covalent binding of radiolabel, however, were also observed after the addition of ferrous iron and ascorbic acid to a model system containing [14C]SAL and bovine serum albumin. Mannitol decreased SAL oxidation and covalent binding, suggesting radical formation may represent a non-enzymatic mechanism for SAL activation.