Role of γ-glutamyltranspeptidase in renal uptake and toxicity of inorganic mercury in mice

The role of renal glutathione (GSH) metabolism as a mediating factor in the renal uptake and toxicity of inorganic mercury was investigated in mice by preadministering a γ-glutamyltranspeptidase (GGT) inhibitor, acivicin. Pretreatment with acivicin (0.25, 1.0 or 2.5 mmol/kg, i.p.) led to a dose-dependent decrease in renal mercury content and increases in mercury and GSH contents in urine measured 2 h after HgCl₂ injection (18 μmol/kg, i.v.). Acivicin pretreatment also ameliorated the renal and lethal toxicity caused by administration of inorganic mercury. Treatment of the mice with 1,2-dichloro-4-nitrobenzene (DCNB, 2.5 mmol/kg, i.p.), a specific depletor of hepatic GSH, prior to HgCl₂ injection substantially reduced renal Hg content and consequently reduced the renal damage. In addition, coadministration of GSH (36 μmol/kg, i.v.) with HgCl₂ increased the renal Hg content measured 5 min after HgCl₂ injection to 2.6 fold higher than that of mice treated with HgCl₂ alone. These results suggest that renal uptake of inorganic mercury, which is supposedly transported to the kidney as a mercury-GSH complex, is dependent on a reaction catalyzed by GGT on the outer surface of the renal brush border membrane in the same manner as the metabolism of GSH.     

Mortality in mice infected with an amyocarditic coxsackievirus and given a subacute dose of mercuric chloride

An amyocarditic strain of coxsackievirus B3 (CVB3/0) induces heart damage when inoculated into selenium (Se)-deficient mice. Mercury (Hg), an Se antagonist, is known to aggravate viral infections. The experiments reported here assessed the effect of prior Hg treatment in mice subsequently inoculated with an amyocarditic strain of coxsackievirus. A pilot study showed that under our conditions the maximum tolerated dose of HgCl2 in uninfected mice was 6 mg HgCl2/kg body weight. In the main study, doses of 0, 3 or 6 mg HgCl2/kg body weight were administered intraperitoneally (ip) to 7-wk-old male mice fed a standard chow diet. Two hours later, half the mice were inoculated ip with CVB3/0. Ten days postinoculation, no mortality was observed in mice given only virus. In mice not given virus, 10% injected with 6 mg HgCl2/kg body weight died. On the other hand, 64% of the mice given both virus and 6 mg HgCl2/kg body weight died. Fifteen percent of the hearts from virus-infected mice given 3 mg HgCl2/kg body weight and 33% of the hearts from virus-infected mice given 6 mg HgCl2/kg body weight exhibited a higher incidence of lesions than hearts from mice-given virus alone. Moreover, viral heart titers were elevated in infected mice injected with 6 mg HgCl2/kg body weight compared to infected mice receiving no Hg. Thus, an amyocarditic coxsackievirus given to mice after a nonlethal subacute dose of Hg results in mortality, increased incidence of heart lesions, and elevated viral heart titers. These results demonstrate the important role of toxic elements in determining the severity of viral infections.     

Acivicin-induced alterations in renal and hepatic glutathione concentrations and in gamma-glutamyltransferase activities

gamma-Glutamyltransferase (gamma-GT) catalyzes the hydrolysis of glutathione, glutathione S-conjugates, and gamma-substituted l-glutamate derivatives. Acivicin is an irreversible inhibitor of gamma-GT that has been used to study the role of gamma-GT in glutathione homeostasis and glutathione-dependent bioactivation reactions. The present studies were undertaken because of reported conflicting effects of acivicin on the nephrotoxicity of some haloalkenes that undergo glutathione-dependent bioactivation. The objective of this study was to test the hypothesis that acivicin may alter renal glutathione concentrations; acivicin-induced changes in renal glutathione concentrations may alter the susceptibility of the kidney to the nephrotoxic effects of haloalkenes. Hence, diurnal and acivicin-induced changes in renal and hepatic glutathione concentrations along with renal and hepatic gamma-GT activities were investigated. The previously observed diurnal variations in hepatic glutathione concentrations in fed rats were confirmed, but no diurnal variations were observed in renal glutathione concentrations or in renal or hepatic gamma-GT activities. Renal and hepatic glutathione concentrations and gamma-GT activities were measured in tissue homogenates from rats given 0, 0.1, or 0.2 mmol acivicin/kg (i.p.) and killed 0, 2, 4, 8, 12, or 24 hr later. Renal glutathione concentrations were increased above control values in acivicin-treated rats, whereas acivicin had no effect on hepatic glutathione concentrations. Renal gamma-GT activities decreased within 2 hr after giving acivicin and remained decreased for 24 hr. Acivicin had no effect on hepatic gamma-GT activities, except at 24 hr after treatment when values in acivicin-treated rats were elevated compared with controls. Although the present studies do not afford an explanation of the mechanism whereby acivicin increases the nephrotoxicity of some haloalkenes, they do indicate that acivicin is not a reliable probe to investigate the role of gamma-GT in haloalkene-induced nephrotoxicity.     

Liver damage following paraquat in selenium-deficient and diethyl maleate-pretreated mice

Human paraquat poisoning often includes a transient impairment of liver function before death due to pulmonary edema and fibrosis. The purpose of this study was to examine the effect of paraquat on liver function in mice fed normal lab chow, in mice fed a selenium (Se)-deficient diet for 5 weeks, and in diethyl maleate-pretreated mice (1.2 ml/kg). Liver function was determined by evaluating plasma activity of glutamic-pyruvic transaminase (SGPT), hexobarbital sleeping time, and plasma disappearance of indocyanine green (ICG). Paraquat, in doses as high as the LD50 (30 mg/kg, ip) did not alter hexobarbital sleeping time or SGPT activity in lab chow-fed mice. Selenium-deficient, paraquat-treated mice, however, had significantly elevated SGPT activity (31 units in control mice, > 1000 units in treated group), had longer hexobarbital sleeping times (from 30 min to > 180 min), and retained ICG in plasma (15-min plasma ICG concentrations of 8.4 mg/100 ml in Se-deficient paraquat-treated group vs 1.3 mg/100 ml in controls). Liver damage in Se-deficient treated mice was also observed histologically. In mice treated with paraquat, diethyl maleate pretreatment produced similar, but not as marked, effects as Se deficiency. The results suggest that paraquat alone is not hepatotoxic in mice; however, Se deficiency or diethyl maleate pretreatment may shift the organ specific toxicity of paraquat toward the liver.     

Influence of dietary protein levels on the fate of methylmercury and glutathione metabolism in mice.

We investigated the influence of dietary protein levels on the fate of methylmercury (MeHg), the tissue glutathione (GSH) levels and the efflux rates of GSH in C57BL/6N male mice. One group of mice was fed a 7.5% protein diet (low protein diet, LPD) and the other was fed a 24.8% protein diet (normal protein diet, NPD). The cumulative amount of Hg in urine in LPD-fed mice was approximately 3.7-times lower than in NPD group during the 7 days after oral administration of MeHg (20 mumol/kg), although the fecal Hg levels were identical in the two groups. Hg concentration in kidney, liver and blood decreased time-dependently for 7 days after the administration in both groups of mice, whereas the brain levels continued to increase during this period. Tissue Hg levels in the LPD group were significantly higher than in the NPD group except for the liver. Although the hepatic GSH level in LPD-fed mice was significantly lower than in NPD-fed mice, the levels in the kidney, brain, blood and plasma were not different between the two groups. The efflux rate (mumol/g body weight per day) of hepatic GSH in LPD-fed mice was significantly lower than in the NPD group, whereas the efflux rates of renal GSH were identical in both groups. When MeHg (20 mumol/kg)-pretreated mice were injected with acivicin, a specific inhibitor of gamma-glutamyltranspeptidase, the urinary Hg levels increased by 60- and 36-fold in groups fed LPD and NPD, respectively. As a result, the difference in urinary Hg levels between the two groups disappeared with acivicin treatment. This result indicated that LPD feeding might decrease urinary Hg excretion by increasing the retention of MeHg metabolite(s) in renal cells. Thus, our present study suggested that the dietary protein status, which could modulate the metabolism of thiol compounds, played an important role in determining the fate of MeHg.     

Differential effect of dietary selenium on the long-term neurotoxicity induced by MDMA in mice and rats

We examined the effect of dietary selenium (Se) on the long-term effect of 3,4-methylenedioxymethamphetamine (MDMA) on dopamine (DA) and 5-hydroxytryptamine (5-HT) containing neurons in the brain of mice and rats. Animals were fed either a Se-deficient (<0.02 ppm) or Se-replete (0.2 ppm) diet for 8 weeks. On the seventh week mice received three injections of MDMA (15 mg/kg, i.p. 3 h apart) or saline and rats a single dose of MDMA (12.5 mg/kg i.p.) or saline. All animals were sacrificed 7 days later. MDMA administration to mice depleted striatal DA concentration in both dietary groups, although depletion was considerably larger in the Se-deficient mice (64%) than Se-replete mice (30%). In addition, a decrease in 5-HT (17-32%) occurred in brain regions of Se-deficient but not Se-replete mice. In rats, MDMA decreased cortical [(3)H]-paroxetine binding (62%) and 5-HT content, the depletion being similar in the Se-deficient and Se-replete groups. No DA loss occurred in either group. There was no difference in the hyperthermic response induced by MDMA in Se-deficient or Se-replete animals. The Se-deficient diet decreased glutathione peroxidase (GPx) activity by 30% in mouse striatum and cortex and increased the degree of lipid peroxidation in cortical synaptosomes. Se-deficient rats also showed a decrease in brain GPx activity compared with the Se-replete group, but the degree of lipid peroxidation in synaptosomes was similar in both dietary groups. These results suggest that the antioxidant capacity of rats and mice differ leading to a differential susceptibility to the oxidative stress caused by MDMA in situations of low dietary Se.     

Effects of probenecid and acivicin on potassium dichromate-induced acute nephrotoxicity in mice.

Male OF1 mice were injected subcutaneously with 80 mg/kg potassium dichromate (K2Cr2O7). Examination of cryostat kidney sections stained for alkaline phosphatase (APP) revealed damage to about 40-70% of the proximal tubules after 8 h. Pretreatment with the organic anionic transport inhibitor probenecid (i.p., 3 x 0.75 mmol/kg) reduced the number of damaged tubules by 60% in mice treated with potassium dichromate. Pretreatment with the gamma-glutamyltranspeptidase (gamma-GT) inactivator acivicin (AT-125, 50 mg/kg p.o., plus 50 mg/kg i.p.) failed to prevent chromate-induced renal toxicity. These results support the conclusion that a probenecid-sensitive transport process, but not a gamma-GT-catalyzed degradation, is involved in the mouse renal toxicity of potassium dichromate.     

Reproductive toxicity of di(2-ethylhexyl) phthalate in selenium-supplemented and selenium-deficient rats

Phthalates are abundantly produced plasticizers, and di(ethylhexyl) phthalate (DEHP) is the most widely used derivative in various consumer products and medical devices. Animal studies show that DEHP and various other phthalates cause reproductive and developmental toxicity. Although the evidences are limited, it seems reasonable that DEHP may have a potential for similar adverse effects in humans. Such concerns are increasing, particularly for the developing reproductive system of male infants and children. By taking into account the essentiality of selenium (Se) in testicular structure and functions and the high prevalence of inadequate Se intake in various part of the world, this study was designed to investigate the testicular toxicity of DEHP in Se-deficient male rats and to examine the possible preventive effects of Se supplementation on phthalate toxicity. Se deficiency was generated by feeding 3-week-old Sprague-Dawley rats with a ≤0.05 Se mg/kg diet for 5 weeks. Supplementation groups were on a 1 mg Se/kg diet, and DEHP-treated groups received a 1,000 mg/kg dose by gavage during the last 10 days of the feeding period. Testicular histopathology, sperm count and motility, and sperm morphology were examined, and plasma levels of sex hormones were measured. Toxicity and antiandrogenic effects of DEHP were evidenced by disturbed testicular histology and spermatogenesis, diminished testosterone, leutinizing hormone (LH) and follicle stimulating hormone (FSH) levels, and sperm motility. The effects of DEHP were much more pronounced in Se-deficient rats, whereas Se supplementation was found to be protective, reflecting its regulating role in cellular redox equilibrium.     

Vetiver oil (Java) attenuates cisplatin-induced oxidative stress,nephrotoxicity and myelosuppression in Swiss albino mice

Clinical efficacy of the widely used anticancer drug cisplatin is limited due to its adverse side effects in normal tissues mediated by oxidative stress. This study was aimed to investigate the protective effects of vetiver acetate oil, Java (VO) against cisplatin-induced toxicity in Swiss albino mice. The ameliorating potential was evaluated by orally priming the animals with VO at doses 5, 10 or 20 mg/kg bw for 7 days prior to cisplatin treatment. Acute toxicity in mice was induced by injecting cisplatin (3 mg/kg bw) intraperitoneally for 5 consecutive days. Significant attenuation of renal toxicity was confirmed by histopathological examination, lowered levels of serum blood urea nitrogen, creatinine and reduced DNA damage. VO also compensated deficits in the renal antioxidant system. VO intervention significantly inhibited DNA damage, clastogenic effects, and cell cycle arrest in the bone marrow cells of mice. Hematological parameters indicated attenuation of cisplatin-induced myelosuppression. Overall, this study provides for the first time that VO has a protective role in the abatement of cisplatin-induced toxicity in mice which may be attributed to its antioxidant activity.     

Protective effects of chrysin on sub-acute diazinon-induced biochemical,hematological, histopathological alterations,and genotoxicity indices in male BALB/c mice

Chrysin (CH) is a natural flavone which possesses antioxidant, anti-cancer, and anti-inflammatory properties. The aim of the present study was to investigate the effects of CH on biochemical parameters, histopathological changes, and genotoxicity and hematological indices in diazinon (DZN)-induced toxicity in BALB/c mice. We induced sub-acute toxicity in mice using DZN (20?mg/kg/day) and treated them with CH at the 12.5, 25, and 50?mg/kg/day five times/week in 28?days. In our study, DZN increased lipid profile and liver function tests (LFTs) and creatinine (Cr) but decreased the red blood cell acetylcholinesterase (RBC-AChE) activity and glucose level. Also, CH when co-treated with DZN changed the LFTs, lipid profile, creatine phosphokinase (CPK), lactate dehydrogenase (LDH) and bilirubin total (Bili-T). Moreover, a significant decrease in RBCs, hemoglobin (Hgb), hematocrit (HCT) level, and platelet counts were seen in DZN group but WBCs, lymphocytes, and neutrophils count increased. CH 25 and 50?mg/kg significantly improved alterations of WBCs, RBCs, Hgb, HCT, lymphocytes, neutrophils, and reticulocytes count when co-treated with DZN. Moreover, the co-administration of CH plus DZN recovered histopathological alterations in liver and kidney, as well as, improved the absolute and relative weight of kidney and liver. DZN induced the formation of bone marrow micronuclei (MN) but CH 50?mg/kg decreased the MN formation when co-treated with DZN. These results suggest that CH not only restores renal and hepatic markers, and histopathological alterations but also improves hematological and genotoxicity indices induced by DZN in mice.     

Evoked potential alterations following prenatal methyl mercury exposure

Pregnant hooded rats were administered either 5 mg/kg CH3, Hg or 0 mg/kg CH3 Hg by gastric intubation on day seven of gestation. Female offspring were implanted with recording electrodes 60 days after birth and had their cortically recorded visual evoked potentials studied at four different flash intensities. Mercury exposed animals had higher P1-N1 and N1-P2 amplitudes and shorter P2 and N2 latencies than controls. The data provides evidence that a single ingestion of CH3 Hg by pregnant rats is sufficient to produce long term alterations in CNS activity.     

Profile of nonprotein thiols,lipid peroxidation and delta-aminolevulinate dehydratase activity in mouse kidney and liver in response to acute exposure to mercuric chloride and sodium selenite

The effects of mercury (Hg(2+)) and selenite (Se(4+)) on delta-aminolevulinic acid dehydratase (delta-ALA-D) activity, 2-thiobarbituric acid reactive substances (TBARS) and nonprotein sulfhydryl content (NPSH) in mouse kidney and liver were investigated. Male mice were given a single i.p. injection of Hg(2+) and/or Se(4+) (25 micromol/kg) and were killed at 6, 12, 24 and 48 h after treatment. Hg(2+) inhibited renal delta-ALA-D at 6 and 12 h after treatment. Se(4+) abolished the inhibitory effect of mercury on renal delta-ALA-D at 12 h after treatment. Renal and hepatic NPSH content decreased after Hg(2+) exposure and selenite inhibited, at least in part, the Hg-induced oxidation of renal and hepatic NPSH. Se(4+) and Hg(2+), when injected alone, did not alter hepatic or renal TBARS levels; however, simultaneous exposure to these compounds increased hepatic and renal TBARS levels at 12 and 48 h after treatment, respectively. Present results suggest that selenium abolishes the interaction of Hg(2+) with sulfhydryl groups of protein and nonprotein sources.     

Effect of selenium on serum, hepatic and lipoprotein lipids concentration in rats fed on a high-cholesterol diet

The effects of Selenium (Se) on lipid metabolism was studied in male Wistar rats which were fed a high-cholesterol diet (HCD) containing 1%(w/w) cholesterol and 0.5%(w/w) cholic acid for 10 weeks. Se was orally administered at daily doses of 0.173 mg/kg in HCD into the test rats for 10 weeks. As compared with control groups, Se/HCD suppressed the amounts of triglyceride (TG), total cholesterol (CH) and free fatty acid in the serum. Se/HCD also decreased the amounts of low-density lipoprotein cholesterol (LDL-C) in the serum. Further-more, Se/HCD inhibited the amount of liver TG and CH. The activity of fatty acid synthetase in the HCD fed group was higher than in the Se/HCD fed group. These results suggest that Se may have recuperative effects for hypercholesterolemia.     

The effects of gestational arsenic exposure and dietary selenium deficiency on selenium and selenoenzymes in maternal and fetal tissues in mice

Although toxicological and metabolic interactions of arsenic (As) and selenium (Se) have been suggested by epidemiolgical literatures, the past experimental studies mostly focused on acute, high-dose interaction, leaving the long-term, low-dose interaction unexplored. In the present study pregnant mice, fed either Se-deficient or adequate (0 or 5 micromol Se/kg diet, respectively) diet, were given oral gavage of sodium arsenite (0 or 58 micromol/kg per day; chosen as less than half of the fetotoxic dose in this protocol) from gestational day (GD) 7-16. The levels of As and Se as well as five selenoenzymes (glutathione peroxidase (GPx), thioredoxin reductase (TRxR), and type-I, -II and -III iodothyronine deiodinases (DI-I, -II and -III) were examined on GD17 in the tissues of dams and of fetus. The Se-deficient mice showed significantly enhanced accumulation of As compared to the Se-adequate mice in maternal liver (increased by 48%) and fetal brain (by 31%). Although no direct evidence of the enhanced toxicity in the Se-deficient group was obtained, the As exposure affected the levels of Se and selenoenzymes, an effect which was more discernible in Se-deficient group. Although most of theses changes were mild or moderate, the DI-II activity in Se-deficient fetal brain showed a drastic four-fold increase by As exposure, suggesting a possible disturbance of thyroid hormone environment in the fetus. These data suggested that apparently non-toxic, in utero dose of As, showed enhanced accumulation when combined with Se-deficiency and could affect the metabolism/kinetics of Se in fetal brain, which might result in developmental toxicity in mice.     

中国萝芙木的药理研究,Ⅰ.广东产萝芙木叶子及其生物硷的降压作用

中国蘿芙木经中国科学院华南植物研究所鉴定为Rauwolfia verticicillata (Lour.) Baill.赵承嘏首先报告从根中提取出“蘿芙甲素”,并说明有降压作用。在本文初报发表的同时,林吉强等也发表了“蘿芙甲素”降压作用的初报。接着罗潜等又发表了根皮有降压作用的初报。我们在肯定广东所产蘿芙木的根和叶的粗制剂能使麻醉动物的血压下降以后,还试用叶的粗制剂治疗了三只有高血压症的狗,结果表现该制剂有显著的降压作用。随后又将从叶提出的生物硷给高血压鼠口服,也有明显的降压作用。     

In utero exposure to methylmercury and Se deficiency converge on the neurobehavioral outcome in mice

Pregnant female ICR mice, maintained on torula-based diets containing various amounts of Se (0.02, 0.05, or 0.4 mg/kg diet), were given methyl-mercury (MeHg; 0, 5, or 9 mg Hg/kg in total) on the 12-14th days of gestation. The neurobehavioral function of the offspring born to these dams was evaluated with respect to reflex and motor development, thermal preference, and open-field activity. Se deficiency per se as well as exposure to MeHg exerted additive or synergistic effects on the neurobehavioral functions examined. The group of mice most affected was the group given the lowest amount of Se and the highest dose of MeHg. Thus, the neurobehavioral outcome of in utero MeHg exposure and Se deficiency converged. Although the dietary level of Se did not affect the Hg concentration in the fetal brain, the Se concentration and the activity of glutathione peroxidase, a selenoenzyme, were severely depressed by MeHg in the neural tissue. The possibility that functional Se deficiency by MeHg exposure partly accounts for the neurobehavioral toxicity of MeHg is discussed.     

Acute and subchronic toxicity studies on Sel-Plex, a standardized, registered high-selenium yeast

Selenium has been recognized as an essential nutrient for human health; however, its bioavailability is primarily dependent upon the type of selenium, elemental versus organic. In geographic areas low in selenium, there is the potential for animals (including humans) to become selenium deficient and this potential deficiency can be remedied by consumption of exogenous selenium, including selenium-enriched yeast (Saccharomyces cerevisiae) that contains high levels of organic selenium (e.g., selenized yeast). The present studies were conducted to investigate potential oral toxicity of a unique selenized yeast preparation (Sel-Plex) when administered to (1) adult female CHS Swiss mice ICo:OFI (IOPS Caw); (2) adult female CHS Sprague-Dawley rats; and (3) adult male and female Sprague-Dawley CD rats. For the 28- and 90-day toxicity studies, (1) adult male and female Sprague-Dawley CRL:CD(R)(SD) IGS BR strain rats and (2) adult male and female 6- to 7-month-old Beagle dogs were used. The LD50 for mice was >or=2000 mg Sel-Plex/kg (>or=4.06 mg Se/kg) and for rats, was greater than >or=2000 mg Sel-Plex/kg (>or=4.06 mg Se/kg). In the two 28-day studies, for rats, the no observed adverse effects level (NOAEL) was 50 mg Sel-Plex/kg/day (0.1 mg Se/kg/day), and for the dogs, the NOAEL was 22.5 mg Sel-Plex/kg/day (0.045 mg Se/kg/day). For the two 90-day studies, for rats the NOAEL for Sel-Plex was 114 mg/kg/day (0.23 mg Se/kg/day), and for dogs, the NOAEL was 30 mg Sel-Plex/kg/day (0.06 mg Se/kg/day): the latter being the NOAEL in the most sensitive species.     

Seabuckthorn attenuates cardiac dysfunction and oxidative stress in isoproterenol-induced cardiotoxicity in rats

We investigated the effects of seabuckthorn (SBT) oil in isoproterenol (ISO)-induced cardiotoxicity with reference to hemodynamic, antioxidant, histopathological, and ultrastructural parameters. Rats were administered SBT oil (5, 10, and 20 mL/kg per d) or vehicle orally for 30 days along with ISO (85 mg/kg, subcutaneously, at 24-hour interval) on 29th and 30th day. On 31st day, ISO control rats showed cardiac dysfunction, increased lipid peroxidation, depletion of cardiac injury marker enzymes, and antioxidant activities. Myocardial necrosis, edema, and inflammation were evident from the light microscopic and ultrastructural changes. Seabuckthorn oil at the dose of 20 mL/kg per d significantly modulates hemodynamic and antioxidant derangements. The preventive role of SBT oil on ISO-induced cardiotoxicity was reconfirmed by histopathological and ultrastructural examinations. Thus, the present study reveals that SBT oil mitigates myocardial damage in ISO-induced cardiac injury in rats by maintaining hemodynamic, biochemical, histopathological, and ultrastructural perturbations owing to its free radical scavenging and antioxidant activities.     

Neuroprotective effect of memantine demonstrated in vivo and in vitro

The purpose of the present study was to test whether the anticonvulsant, memantine (1-amino-3,5-dimethyladamantane), can protect neurons against hypoxic or ischemic damage. To this end, we used a rat model of transient forebrain ischemia and cultured neurons from chick embryo cerebral hemispheres. Ischemia was induced for 10 min by clamping both carotid arteries and lowering the mean arterial blood pressure to 40 mm Hg; the rats were allowed to recover for 7 days. Cultured neurons were made hypoxic with 1 mmol/l NaCN added to the incubation medium for 30 min followed by a recovery period of 3 days. The possible effects of memantine were compared with those produced by a typical non-competitive NMDA antagonist, dizocilpine. Similar effects were obtained with both drugs. The drugs reduced the damage caused by transient ischemia to neurons of the hippocampal CA1 subfield. Memantine (10 and 20 mg/kg) had a dose-dependent effect when administered intraperitoneally to the rats 1 h before ischemia. Dizocilpine was active in this model at a dosage of 1 mg/kg. When administered after ischemia, 10 mg/kg memantine significantly protected CA1 neurons against ischemic damage. Furthermore, the drugs protected cultured neurons against hypoxic damage. The lowest effective concentration was 0.1 mumol/l for dizocilpine and 1 mumol/l for memantine. Thus, memantine possesses neuroprotective activity but is less potent than dizocilpine.     

Protective effect of carnosine against cisplatin-induced nephrotoxicity in mice

The nephroprotective effect of the natural antioxidant carnosine was evaluated in mice with cisplatin-induced acute renal damage, in which generation of reactive oxygen species plays a major role. Nephrotoxicity was induced by a single i.p. injection of cisplatin (20 mg/kg). Carnosine was administered for six consecutive days in a dose of 10 mg/kg/day, i.p., starting 3 days before cisplatin injection. The results revealed that carnosine treatment significantly reduced blood urea nitrogen and serum creatinine levels elevated by cisplatin administration. Also, carnosine significantly attenuated cisplatin-induced increase in malondialdehyde and decrease in reduced glutathione, and catalase and superoxide dismutase activities in renal cortical homogenates. Additionally, histopathological examination and scoring showed that carnosine markedly ameliorated cisplatin-induced renal tubular necrosis. In conclusion, carnosine can be considered a feasible candidate to protect against nephrotoxicity commonly encountered with cisplatin treatment.