Interactions of salicylate, dietary zinc, and genetic strain in teratogenesis in rats

The influence of dietary zinc concentration on salicylate teratogenesis was studied in Wistar and Sprague-Dawley rats. Females were fed purified diets containing 0.4, 4.5, 9, 100, or 1,000 micrograms zinc/gm diet, or a stock diet (Purina Rat Chow) from day zero to day 21 of gestation, when they were killed and the fetuses were examined. On day 9, rats were given saline or 250, 500, or 750 mg sodium salicylate/kg body weight by gavage. Increasing drug dose caused increased frequency of malformed or resorbed fetuses, while increasing dietary zinc reduced the teratogenic effects of salicylate, but in different patterns in the two strains. The teratogenic effect of zinc deficiency also varied by strain. Statistical analysis showed that the frequency of malformed fetuses was significantly affected by levels of dietary zinc or salicylate dose, and interactions of zinc X salicylate and genetic strain X zinc. Frequency of resorption was affected by strain, zinc, salicylate, and interactions of strain X salicylate, zinc X salicylate, and strain X zinc X salicylate. Frequency of abnormal sites (malformed or resorbed) was affected by strain, zinc, salicylate, and interactions of strain X salicylate, zinc X salicylate, and strain X zinc X salicylate. The results suggest that marginal zinc deficiency in certain pregnant women might increase the possibility of salicylate teratogenicity.     

Embryonal disposition of salicylate: in vivo-in vitro comparisons

The distribution of salicylate to embryonal compartments for in situ and in vitro rat embryos under equivalent exposure conditions, and salicylate disposition in the in vivo mid-gestation embryo and late gestation fetus, were compared. Pregnant Sprague-Dawley CD rats were exposed to steady-state blood levels of salicylate by infusing 14C-salicylic acid iv for a 24 hour period from gestation day 11.5 to 12.5. Cultured Sprague-Dawley rat embryos (in medium consisting of 100% male rat serum) were exposed to the steady-state 14C-salicylate concentration achieved in maternal serum in vivo for the same 24 hour developmental period. At the end of the exposure period radioactivity in visceral yolk sac, extra-embryonic fluid and embryos, and in maternal tissues, was measured. The distribution of salicylate to embryonal tissues was statistically comparable in vivo and in vitro, although the embryos in vitro accumulated slightly (but not significantly) less of the chemical. There was considerable binding of salicylate by maternal serum and culture medium proteins: less than 20% of the chemical was free at the 40 micrograms/ml concentration used in this experiment. Consequently, the salicylate concentration in embryonal compartments appeared to be quite low when compared to the surrounding serum/medium, but was actually equal to or greater than the concentration of unbound salicylate in serum or culture medium. The proportion of free salicylate in serum increased at concentrations higher than 40 micrograms/ml, resulting in somewhat higher concentrations of salicylate in in vitro embryos and extraembryonic fluid (as compared to medium) when cultured in the presence of 200 or 400 micrograms/ml salicylate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of transepithelial transport of salicylate by the Malpighian tubules of Drosophila melanogaster and the effects of changes in fluid secretion rate

Abstract.  A radioisotope tracer technique is used to study mechanisms and regulation of transepithelial transport of the plant allelochemical salicylate by the Malpighian tubules of Drosophila melanogaster . Transepithelial transport of salicylate is nearly abolished in Na⁺-free saline, and inhibited by ouabain, low K⁺ or K⁺-free bathing saline. In addition, the carboxylates probenecid, unlabelled salicylate, fluorescein, and p -aminohippuric acid (PAH) significantly inhibit transepithelial transport of salicylate. The sulphonates taurocholate and phenol red also inhibit transepithelial transport of salicylate, whereas amaranth has no effect. Stimulation of fluid secretion by cAMP, cGMP or leucokinin I increases transepithelial transport of salicylate, particularly when the concentration of salicylate in the bathing saline is high. The correlation between the fluid secretion rate and transepithelial transport of salicylate shows that 64% of the changes in salicylate transport can be explained on the basis of changes in fluid secretion rate. The results show that naturally-occurring plant secondary metabolite salicylate is transported into the lumen of the Mapighian tubules of D. melanogaster by a mechanism similar to that previously described for the prototypical organic anions PAH and fluorescein. In addition, the transepithelial transport of salicylate increases in response to increases in fluid secretion rate.     

Induction of hepatic metallothionein by salicylate in adult rats

Application of salicylate increased the concentration of metallothionein (MT) in liver of pregnant rats as well as of adult male rats, whereas in fetal liver, MT was reduced by salicylate. Induction of MT synthesis by salicylate is an indirect effect because in cultured hepatocytes salicylate did not induce MT synthesis. Salicylate increased MT also in adrenalectomized rats. Indomethacin induced the same concentration of MT in maternal liver as salicylate. However, indomethacin had no effect on MT in fetal liver. Induction of MT in adult liver by salicylate and indomethacin was independent of zinc.     

Estimating Hydroxyl Radical Content in Rat Brain Using Systemic and Intraventricular Salicylate: Impact of Methamphetamine

Abstract: Free radicals have been implicated in the etiology of many neurodegenerative conditions. Yet, because these species are highly reactive and thus short-lived it has been difficult to test these hypotheses. We adapted a method in which hydroxyl radicals are trapped by salicylate in vivo, resulting in the stable and quantifiable products, 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA. After systemic (100 mg/kg i.p.) or intraventricular (4 µmol) administration of salicylate, the amount of DHBA in striatal tissue correlated with tissue levels of salicylate. After systemic salicylate, the ratio of total DHBA to salicylate in neostriatum was at least 10-fold higher than that observed after central salicylate. In addition, systemic salicylate resulted in considerably higher concentrations of 2,3- and 2,5-DHBA in plasma than in brain. Therefore, a large portion of the DHBA present in brain after systemic salicylate may have been formed in the periphery. A neurotoxic regimen of methamphetamine increased the concentration of DHBA in neostriatum after either central or systemic administration of salicylate. The increase in 2,3-DHBA after the central administration of salicylate was significant at 2 h, but not at 4 h, after the last dose of methamphetamine. These results suggest that (1) when assessing specific events in brain, it is preferable to administer salicylate centrally, and (2) neurotoxic doses of methamphetamine increase the hydroxyl radical content in brain in a time-dependent manner.     

Benorylate in Management of Still's Disease

The present recommended dose of benorylate is not satisfactory for the management of children suffering from inflammatory polyarthritis. A starting dose of 200 mg/kg/day should be used, and the salicylate level checked at seven days and the dosage adjusted to give an anti-inflammatory effect—that is, a blood salicylate level of between 25 and 30 mg/100 ml. Once a satisfactory level has been achieved, this dosage should be maintained with occasional monitoring of the salicylate level. The paracetamol level does not need to be estimated as it tends to follow the salicylate level, provided that liver function is normal; thus it is quite safe to monitor only the salicylate level. Given in an adequate dosage, benorylate seems to be an acceptable salicylate preparation for use in juveniles suffering from chronic polyarthritis.     

Salicylate-induced teratogenesis in the ferret

A single subcutaneous injection of 400 mg/kg sodium salicylate produced a high resorption rate on day 13 (91%) and on day 18 (66%) of gestation. Malformations were seen in the surviving fetuses. Pregnant ferrets injected with 250 mg/kg salicylate produced a lower resorption rate of between 31% and 43%. Malformations were seen in the surviving fetuses of animals injected with lower doses of sodium salicylate both at 13 and 18 days of gestation.Salicylate-induced teratogenicity at 400 mg/kg was compared with that produced in a closed colony of Wistar rats. The concentration of salicylate in whole blood (and serum) was determined after a single injection of 125 mg/kg or 400 mg/kg sodium salicylate. Although salicylate concentration in the blood in both species showed remarkable similarity at the doses tested and the times of sampling, the results indicated that the drug was far more embryo-toxic in ferrets than in rats. The inter-order variation in the embryotoxicity of sodium salicylate is such that it would be unwise to ignore its possible teratogenic activity in man.     

Plasmid- and chromosome-mediated dissimilation of naphthalene and salicylate in Pseudomonas putida PMD-1.

Pseudomonas putida PMD-1 dissimilates naphthalene (Nah), salicylate (Sal), and benzoate (Ben) via catechol which is metabolized through the meta (or alpha-keto acid) pathway. The ability to utilize salicylate but not naphthalene was transferred from P. putida PMD-1 to several Pseudomonas species. Agarose gel electrophoresis of deoxyribonucleic acid (DNA) from PMD-1 and Sal+ exconjugants indicated that a plasmid (pMWD-1) of 110 megadaltons is correlated with the Sal+ phenotype; restriction enzyme analysis of DNA from Sal+ exconjugants indicated that plasmid pMWD-1 was transmitted intact. Enzyme analysis of Sal+ exconjugants demonstrated that the enzymes required to oxidize naphthalene to salicylate are absent, but salicylate hydroxylase and enzymes of the meta pathway are present. Thus, naphthalene conversion to salicylate requires chromosomal genes, whereas salicylate degradation is plasmid encoded. Comparison of restriction digests of plasmid pMWD-1 indicated that it differs considerably from the naphthalene and salicylate degradative plasmids previously described in P. putida.     

Physiological role of NahW, the additional salicylate hydroxylase found in Pseudomonas stutzeri AN10

The physiological role of NahW, the second salicylate hydroxylase of Pseudomonas stutzeri AN10, has been analysed by gene mutation and further complementation. When grown on naphthalene as a unique carbon and energy source, the nahW mutant showed a strong decrease in salicylate hydroxylase activity when compared with the wild-type strain, exhibited lower specific growth rates and accumulated salicylate in culture supernatants. Similarly, lower specific growth rates and salicylate accumulation were observed for the nahW mutant when growth on naphthalene supplemented with succinate or pyruvate. When P. stutzeri AN10 was grown in Luria–Bertani medium in the presence of salicylate, or was cultivated on minimal medium supplemented with salicylate as a unique carbon and energy source, an increase in the lag phase and a decrease in the specific growth rate were observed on increasing the salicylate concentrations, suggesting a plausible toxic effect. This toxic effect of salicylate was much more evident for the nahW mutant than for the wild-type strain. Complementation of the nahW mutant restored all growth parameters. These results indicate that NahW may have two functions in P. stutzeri AN10: (1) to improve its capacity to degrade naphthalene and (2) effectively convert the salicylate produced during naphthalene degradation to tricarboxylic acid cycle intermediates, preventing its toxic effect.     

Effect of salicylate and adrenocorticotropin on the hepatic and serum cholesterol in catfish, Heteropneustes fossilis (Bloch).

A single injection of salicylate or salicylate plus ACTH was able to lower the hepatic cholesterol content within one hour after the treatment. However, their daily injection for eight days caused significant rise in the hepatic cholesterol. ACTH alone could not significantly alter the liver cholesterol content after similar treatment. A single injection of salicylate produced hypocholesterolemia within one and three hours after the treatment. ACTH or salicylate plus ACTH also brought about 50 per cent reduction in serum cholesterol level from its initial control value within one hour. Similar treatments, however, raised the serum cholesterol after three hours. The rise in the serum cholesterol level was about twofold in animals five hours after salicylate plus ACTH treatment. Daily administration of salicylate, ACTH or salicylate plus ACTH for eight days caused, however, hypocholesterolemia.     

Mutational analysis of a role for salicylic acid in iron metabolism of Mycobacterium smegmatis

The role of salicylic acid in iron metabolism was examined in two wild-type strains (mc(2)155 and NCIMB 8548) and three mutant strains (mc(2)1292 [lacking exochelin], SM3 [lacking iron-dependent repressor protein IdeR] and S99 [a salicylate-requiring auxotroph derived in this study]) of Mycobacterium smegmatis. Synthesis of salicylate in SM3 was derepressed even in the presence of iron, as was synthesis of the siderophores exochelin, mycobactin, and carboxymycobactin. S99 was dependent on salicylate for growth and failed to grow with the three ferrisiderophores, suggesting that salicylate fulfills an additional function(s) other than being a precursor of mycobactin and carboxymycobactin. Salicylic acid at 100 microgram/ml repressed the formation of a 29-kDa cell envelope protein (putative exochelin receptor protein) in S99 grown both iron deficiently and iron sufficiently. In contrast, synthesis of this protein was affected only under iron-limited conditions in the parent strain, mc(2)155, and remained unaltered in SM3, suggesting an interaction between the IdeR protein and salicylate. Thus, salicylate may also function as a signal molecule for recognition of cellular iron status. Growth of all strains and mutants with p-aminosalicylate (PAS) at 100 microgram/ml increased salicylate accumulation between three- and eightfold under both iron-limited and iron-sufficient growth conditions and decreased mycobactin accumulation by 40 to 80% but increased carboxymycobactin accumulation by 50 to 55%. Thus, although PAS inhibited salicylate conversion to mycobactin, presumptively by blocking salicylate AMP kinase, PAS also interferes with the additional functions of salicylate, as its effect was heightened in S99 when the salicylate concentration was minimal.     

Both Central and Peripheral Auditory Systems Are Involved in Salicylate-Induced Tinnitus in Rats: A Behavioral Study

Objective

This study was designed to establish a low dose salicylate-induced tinnitus rat model and to investigate whether central or peripheral auditory system is involved in tinnitus.

Methods

Lick suppression ratio (R), lick count and lick latency of conditioned rats in salicylate group (120 mg/kg, intraperitoneally) and saline group were first compared. Bilateral auditory nerves were ablated in unconditioned rats and lick count and lick latency were compared before and after ablation. The ablation was then performed in conditioned rats and lick count and lick latency were compared between salicylate group and saline group and between ablated and unablated salicylate groups.

Results

Both the R value and the lick count in salicylate group were significantly higher than those in saline group and lick latency in salicylate group was significantly shorter than that in saline group. No significant changes were observed in lick count and lick latency before and after ablation. After ablation, lick count and lick latency in salicylate group were significantly higher and shorter respectively than those in saline group, but they were significantly lower and longer respectively than those in unablated salicylate group.

Conclusion

A low dose of salicylate (120 mg/kg) can induce tinnitus in rats and both central and peripheral auditory systems participate in the generation of salicylate-induced tinnitus.     

Sodium Salicylate Reduced Insulin Resistance in the Retina of a Type 2 Diabetic Rat Model

Sodium salicylate has been reported to reduce markers of diabetic retinopathy in a type 1 rat model. Because rates of type 2 diabetes are on the rise, we wanted to determine whether salicylate could improve insulin resistance in a type 2 rat model, as well as improve retinal function. We treated lean and obese BBZDR/Wor type 2 diabetic rats with salicylate in their chow for 2 months. Prior to salicylate treatment, rats underwent an electroretinogram to measure retinal function. After 2 months of treatment, rats underwent an additional electroretinogram prior to sacrifice. In addition to the animal model, we also treated retinal endothelial cells (REC) and rat Müller cells with salicylate and performed the same analyses as done for the rat retinal lysates. To investigate the role of salicylate in insulin signaling, we measured TNFα and caspase 3 levels by ELISA, as well as performed Western blotting for insulin receptor substrate 1, insulin receptor, SOCS3, and pro- and anti-apoptotic markers. Data demonstrated that salicylate significantly improved retinal function, as well as reduced TNFα and SOCS3-induced insulin resistance in all samples. Overall, results suggest that salicylate is effective in reducing insulin resistance in the retina of type 2 diabetic rat models.     

scpA, a new salicylate hydroxylase gene localized in salicylate/caprolactam degradation plasmids

Both caprolactams and salicylate biodegradation by Pseudomonas salicylate/caprolactam degraders are controlled by large conjugative plasmids (SAL/CAP). Some of these plasmids have been assigned to the P-7 incompatibility group. The new salicylate 1-hydroxylase gene (scpA) has been detected in SAL/CAP plasmids and partially sequenced. The scpA gene was equally related to the closest homolog genes nahG (NAH7), salA (P. reinekei MT1), and nahU (pND6-1); however, the identity rate did not exceed 72–74%. The synthesis of salicylate 1-hydroxylase ScpA was not induced by salicylate. This enzyme had wide substrate specificity and exhibited the highest specific activity toward 4-methylsalicylate and nonsubstituted salicylate substrates. Furthermore, conjugative pseudomonads’ plasmids of salicylate degradation without the classical nah2 operon, which harbors only salicylate 1-hydroxylase gene nahU have been described for the first time.     

Drastic changes in the peptidoglycan composition of penicillin resistant laboratory mutants of Streptococcus pneumoniae

Abstract Rhodococcus erythropolis strain S1 uses the gentisate pathway to metabolize salicylate and m -hydroxybenzoate and the protocatechuate pathway to degrade p -hydroxybenzoate. m -Hydroxybenzoate 6-hydroxylase was induced by growth on m -hydroxybenzoate or gentisate, and salicylate 5-hydroxylase only by growth on salicylate. p -Hydroxybenzoate 3-hydroxylase could be induced only by growth on p -hydroxybenzoate. m -Hydroxybenzoate or p -hydroxybenzoate could repress the induction of salicylate 5-hydroxylase. Maleylpyruvate isomerase in the gentisate pathway did not require reduced glutathione.     

水杨酸钠对螺旋神经节Caspase 3mRNA及蛋白表达的影响

目的：水杨酸是阿司匹林的活性成分,是导致耳鸣的主要原因。而本实验主要探讨水杨酸钠对耳蜗螺旋神经节（SGN）调亡相关基因Caspase 3的mRNA及蛋白表达水平的影响,并初步探讨水杨酸钠对耳蜗毒性的机制。方法：分离取出大鼠蜗轴螺旋管,用酶消化后原代培养SGN,采用荧光定量PCR法检测5 mM水杨酸钠处理前后（1 h,3 h,6 h）Caspase 3 mRNA的变化,WesternBlot检测其蛋白的变化情况。结果：5 mM水杨酸钠处理细胞后1 h,Caspase 3 mRNA表达水平没有明显改变（P〉0.05）,但是当水杨酸钠处理3 h后,其表达水平明显上调（P〈0.05）,并呈时间依赖关系。而其蛋白表达水平也同样明显升高（P〈0.05）。结论：本实验取蜗轴螺旋管进行原代培养,获得较多的SGN,而水杨酸钠能上调这些原代培养SGN的Caspase 3 mRNA及蛋白的表达,导致SGN调亡,这对水杨酸钠耳蜗毒性的研究有一定应用价值。     

Catabolic role of a three-component salicylate oxygenase from Sphingomonas yanoikuyae B1 in polycyclic aromatic hydrocarbon degradation

Sphingomonas yanoikuyae B1 possesses several different multicomponent oxygenases involved in metabolizing aromatic compounds. Six different pairs of genes encoding large and small subunits of oxygenase iron-sulfur protein components have previously been identified in a gene cluster involved in the degradation of both monocyclic and polycyclic aromatic hydrocarbons. Insertional inactivation of one of the oxygenase large subunit genes, bphA1c, results in a mutant strain unable to grow on naphthalene, phenanthrene, or salicylate. The knockout mutant accumulates salicylate from naphthalene and 1-hydroxy-2-naphthoic acid from phenanthrene indicating the loss of salicylate oxygenase activity. Complementation experiments verify that the salicylate oxygenase in S. yanoikuyae B1 is a three-component enzyme consisting of an oxygenase encoded by bphA2cA1c, a ferredoxin encoded by the adjacent bphA3, and a ferredoxin reductase encoded by bphA4 located over 25kb away. Expression of bphA3-bphA2c-bphA1c genes in Escherichia coli demonstrated the ability of salicylate oxygenase to convert salicylate to catechol and 3-, 4-, and 5-methylsalicylate to methylcatechols.     

Effects of salicylate on stomatal resistance in detached tobacco leaves

Salicylate administered to detached tobacco (Nicotiana tabacum L.) leaves kept in the light rapidly induced an increase in stomatal resistance. This effect was not the result of water stress. Both the concentration of salicylate and the duration of the application to leaves affected the extent of the stomatal response. Application of salicylate for short periods showed that, once the stomatal response started, it was maintained for long period of time in the absence of further supply. K⁺ or Ca²⁺ were able to lower the stomatal resistance induced by salicylate, but only when both the ions were administered together with salicylate the stomatal closure was prevented. The results suggest that salicylate elicits some alterations interfering with the control of, stomatal movements, possibly affecting the integrity of cell membranes.