Acute toxicity and hematological and serum changes caused by various cobalt salts in rats

The acute toxicities of chloride, acetate, cobalt nitrate and cobalt sulphate (II) were investigated in rats. The values obtained for the LD50 (7 days) were 133, 194, 198 and 279 mg of Co/kg respectively, when the salts were given orally. The values for intraperitoneal administration were 10.6, 8.8, 8.3 and 11.5 mg of Co/kg. The majority of deaths occurred during the first 48 hours. The physical and clinical signs appearing after the intoxication disappeared for the most part after the first 72 hours. Also, the effect produced by chloride and cobalt acetate (II) given orally and intraperitoneally, in some hematological parameters and serum parameters during the first 24 hours after intoxications, has been studied at several doses. A noteworthy increase was observed in the hemoglobin and hematocrit as well as in the plasma proteins. There was significant hyperglycemia and also significant changes in the lipid parameters such as triglycerides and cholesterol. The duration and degree of the change depended on the dose. As a general rule, no significant differences were registered between the results obtained for the two salts.     

Prevention by tiopronin (2-mercaptopropionyl glycine) of methylmercuric chloride-induced teratogenic and fetotoxic effects in mice

Previous investigations (Fuyuta et al., '76, '79) have shown that a single oral administration of 25 mg/kg methylmercuric chloride (MMC) to pregnant ICR mice on day 10 of pregnancy induced cleft palate in a remarkably high incidence in fetuses. Based on these findings, the present study dealing with the prevention of cleft palate by Tiopronin, (2-mercaptopropionyl glycine, Tp), was initiated. Twenty females in the positive control group were given 25 mg/kg MMC orally on day 10 of pregnancy and then given physiological saline intraperitoneally. Twenty females in the negative control group were given distilled water orally and then given saline intraperitoneally. Cleft palate was found in 98.1% of fetuses in the positive control group and none of them in the negative control group. Twenty females were pretreated with a single oral dose of 25 mg/kg MMC on day 10 of pregnancy and were posttreated with Tp intraperitoneally, immediately and at every 24, 48 and 72 hours after the MMC treatment. The doses of Tp were 320, 160 and 80 mg/kg/day. The incidences of cleft palate in fetuses were reduced to 1.49, 31.3 and 47.8% in the Tp-treated groups with the doses of 320, 160 and 80 mg/kg/day, respectively. Tiopronin could effectively prevent the expected incidence of cleft palate. Other types of abnormalities as well as fetotoxicity represented by reduced fetal body weight were also effectively prevented with the Tp-treatment.     

Radioprotection by mangiferin in DBAxC57BL mice: a preliminary study

The radioprotective effects of various concentrations (0, 0.25, 0.5, 1, 2, 5, 10, 17.5, 25, 50, 75 and 100 mg/kg b.wt.) of mangiferin (MGN) was studied in the DBAxC57BL mice whole body exposed to 10 Gy of gamma-irradiation. Treatment of mice with different doses of MGN, one hour before irradiation reduced the symptoms of radiation sickness and delayed the onset of mortality when compared with the non-drug treated irradiated controls. The radioprotective action of MGN increased in a dose dependent manner up to 2mg/kg and declined thereafter. The highest radioprotective effect was observed at 2mg/kg MGN, where greatest number of animals survived against the radiation-induced mortality. The administration of 0.5, 1, 2, 5, 10 and 17.5 mg/kg MGN reduced the radiation-induced gastrointestinal death as evident by a greater number of survivors up to 10 days in this group when compared with the DDW + 10 Gy irradiation group. A similar effect of MGN was observed for the radiation-induced bone marrow deaths also. Our study demonstrates that mangiferin, a gluosylxanthone, present in the Mangifera indica protected mice against the radiation-induced sickness and mortality and the optimum protective dose of 2mg/kg was 1/200 of LD50 dose (400 mg/kg) of MGN. The administration of 400 mg/kg MGN induced 50% mortality, therefore LD50 of the drug was considered to be 400 mg/kg.     

Administration-route-related differences in the micronucleus test with N-ethyl-N-nitrosourea

Administration-route-related differences in the micronucleus test were examined by giving N-ethyl-N-nitrosourea (ENU) to male mice of the MS/Ae and CD-1 strains by 2 different routes, intraperitoneally (i.p.) and orally (p.o.). The experiments consisted of 3 parts: (1) a simplified acute toxicity study, which gave LD50s of 490 (i.p.) and 840 mg/kg (p.o.) in MS/Ae and 640 (i.p.) and 960 mg/kg (p.o.) in CD-1 mice: (2) a pilot experiment for the full-scale micronucleus test to determine appropriate dosages and sampling time: and (3) the micronucleus test at doses of 12.5, 25, 50, and 100 mg/kg with a sampling time of 24 h. The results indicated that no route-related differences existed at the 2 lowest doses. At 50 mg/kg, markedly higher numbers of micronucleated polychromatic erythrocytes (MNPCEs) were induced in both mouse strains by the i.p. route. At 100 mg/kg, the difference between the routes decreased in strain CD-1 and even reversed in MS/Ae. Thus, route-related differences appeared to depend on the dose. Such differences became small, however, in both strains when the comparison was made on the basis of LD50 values.     

Genotoxic effect of 2,4-dichlorophenoxy acetic acid and its metabolite 2,4-dichlorophenol in mouse.

The cytogenetic effect of 2,4-dichlorophenoxy acetic acid (2,4-D) and its metabolite 2,4-dichlorophenol (2,4-DCP) was studied in bone-marrow, germ cells and sperm head abnormalities in the treated mice. Swiss mice were treated orally by gavage with 2,4-D at 1.7, 3.3 and 33 mg kg(-1)BW (1/200, 1/100 and 1/10 of LD(50)). 2,4-DCP was intraperitoneally (i.p.) injected at 36, 72 and 180 mg kg(-1)BW (1/10, 1/5, 1/2 of LD(50)). A significant increase in the percentage of chromosome aberrations in bone-marrow and spermatocyte cells was observed after oral administration of 2,4-D at 3.3 mg kg(-1)BW for three and five consecutive days. This percentage increased and reached 10.8+/-0.87 (P<0.01) in bone-marrow and 9.8+/-0.45 (P<0.01) in spermatocyte cells after oral administration of 2,4-D at 33 mg kg(-1)BW for 24 h. This percentage was, however, lower than that induced in bone-marrow and spermatocyte cells by mitomycin C (positive control). 2,4-D induced a dose-dependent increase in the percentage of sperm head abnormalities. The genotoxic effect of 2,4-DCP is weaker than that of 2,4-D, as indicated by the lower percentage of the induced chromosome aberrations (in bone-marrow and spermatocyte cells) and sperm head abnormalities. Only the highest tested concentration of 2,4-DCP (180 mg kg(-1)BW, 1/2 LD(50)) induced a significant percentage of chromosome aberrations and sperm head abnormalities after i.p. injection. The obtained results indicate that 2,4-D is genotoxic in mice in vivo under the conditions tested. Hence, more care should be given to the application of 2,4-D on edible crops since repeated uses may underlie a health hazard.     

Particulate 1,3-β-d-glucan, carboxymethylglucan and sulfoethylglucan—Influence of their oral or intraperitoneal administration on immunological respondence of mice

The effect of orally or intraperitoneally administered particulate 1,3-β-d-glucan (PBG), carboxymethylglucan (CMG) or sulfoethylglucan (SEG), obtained from the culture filtrate ofSaccharomyces cerevisiae, on the functions of murine peritoneal adherent cells (PC) (peroxidase activity, nitric oxide synthesis), on relative organ mass and on proliferation of splenocytes was determined. The modulating activities after parenteral and non-parenteral administration of these polysaccharides were compared. Significant enhancement of NO production was observed only afterin vitro cultivation of PC in the presence of lipopolysaccharide (LPS) in groups of mice treated repeatedly orally with CMG, PBG and SEG at a dose of 50 mg/kg body mass. Peroxidase activity increased significantly after repeated oral administration of CMG and PBG at doses 150 and 50 mg/kg, SEG 150 mg/kg body mass. The peroxidase activity and NO synthesis in mice given a single intraperitoneal injection of glucans (15 mg/kg body mass) were slightly higher than those after oral administration. Neither a significant enhancement of relative organ mass nor enhancement of the proliferative response of splenocytes toin vitro added stimuli (LPS, phytohemagglutinin) after repeated oral or single intraperitoneal administration of β-glucans was observed.     

Micronucleus test with 6-mercaptopurine monohydrate administered intraperitoneally and orally

The effect of route of administration on the induction of micronucleated polychromatic erythrocytes (MNPCEs) was examined. 6-Mercaptopurine monohydrate (6-MP) was administered intraperitoneally (i.p.) or orally (p.o.) to 2 strains of mice, MS/Ae and CD-1. From the results of an acute toxicity test and a pilot micronucleus test, the doses selected for the final micronucleus test were 12.5-100 mg/kg for the i.p. route and 25-200 mg/kg for the p.o. route. The sampling time was 48 h. Frequencies of MNPCEs increased dose-dependently by the i.p. route but peaked at 50 or 100 mg/kg for the p.o. route. 6-MP induced MNPCEs more efficiently after p.o. administration than after i.p. treatment in both strains.     

Acute cytogenetic effects of tyramine, MTCAs, NaCl and soy sauce on rat bone marrow cells in vivo

The acute cytogenetic effects of tyramine and MTCAs, precursors of the mutagen present in soy sauce, were studied with the in vivo chromosome aberration test in rat bone marrow cells. The chemicals were administered intraperitoneally. Statistically significant positive results were obtained with tyramine at a dose of 5 mmole/kg (686 mg/kg) body weight and with MTCAs at doses over 0.50 mmole/kg (115 mg/kg) body weight, respectively. Chromosome aberrations (CA) induced by L-proline co-administered with either tyramine or MTCAs were significantly lower than those induced by each chemical alone. These data suggest that L-proline, after endogenous nitrosation, became nitrosoproline and suppressed CA, and that, as a result of in vivo nitrosation of tyramine and MTCAs, they became mutagenic nitroso compounds showing positive results. Statistically significant positive results were obtained by administration of 40 mmole NaCl/kg body weight (2338 mg/kg). The cocarcinogenic role of NaCl with tyramine was suggested because soy sauce contains about 18% NaCl.     

Administration-route-related differences in the micronucleus test with benzene

The effect of route of administration on the outcome of the micronucleus test was studied in 2 laboratories by administering the model chemical benzene intraperitoneally (i.p.) and orally (p.o.) to 2 strains of mice: MS/Ae and CD-1. On the basis of results obtained in a small-scale acute toxicity study and in a pilot micronucleus test, full-scale micronucleus tests were performed with a 24-h sampling time at doses of 250, 500, 1000, and 2000 mg/kg i.p. and 500, 1000, 2000, and 4000 mg/kg p.o. In both strains of mice, a higher incidence of micronucleated polychromatic erythrocytes (MNPCEs) was observed after p.o. administration. The ratio of polychromatic erythrocytes (PCEs) to total erythrocytes decreased more markedly at higher doses i.p. in both strains. Thus, benzene induced more micronuclei via the p.o. route, while inhibitory effects on bone marrow cells were stronger after i.p. administration.     

Isolation, characterization and pathology of the toxin from a Microcystis aeruginosa (= Anacystis cyanea) bloom.

The nature of the toxicity of a bloom of blue-green alga, M. aeruginosa (= Anacystis cyanea), that occurred in a man-made lake was investigated. Crude algal bloom extracts were toxic to laboratory mice when injected intraperitoneally. The lethal dose (LD100) of these extracts was 15-30 mg of lyophilized algal bloom per kilogram body weight. The toxin was purified by a procedure that included ammonium sulphate fractionation, solvent extraction, acid precipitation, Sephadex G25 and DEAE-Sephadex chromatography, and high-voltage electrophoresis at pH 6.5. The preparation gave a single spot on high-voltage electrophoresis at pH 9.0, had no free amino group, and was characterized by a simple amino acid composition of equimolar quantities of L-methionine, L-tyrosine, D-alanine, D-glutamic acid, erythro beta-methyl aspartic acid and methylamine. The LD50 for the purified toxin was estimated to be 0.056 mg/kg of mice, and the approximate LD100 is 0.070 mg/kg, based on the total material found from amino acid analysis. Parenteral administration of the purified toxin to mice produced extensive liver lobular haemorrhage and death within 1-3 h. Repeated inoculation of sublethal doses daily over some weeks produced progressive hepatocyte degeneration and necrosis and the development of fine hepatic fibrosis.     

Complex role of 5-HT in the regulation of TSH secretion in the male rat

The role of 5-hydroxytryptamine (5-HT) in the regulations of TSH secretion was studied in male rats using both peripheral and central administration of the drugs. Basal TSH levels were not modified by moderate doses of 5-HT (subcutaneously) or its precursors or antagonists (intraperitoneally) given 1 h before decapitation. The cold-stimulated TSH secretion was decreased by L-tryptophan (L-TRP, 400 mg/kg i.p.), quipazine (10 mg/kg i.p.) and 5-HT (1 or 5 mg/kg s.c. or i.v.) as well as by p-chlorophenylalanine (pCPA, 20 or more mg/kg i.p.) when the drugs were given 1 h before sampling. pCPA (100-400 mg/kg i.p.) was active 24-48 h after the injection but repetitive administration did not affect TSH levels. 5-HT (5 mg/kg s.c.) was effective also in pinealectomized animals. L-TRP and 5-hydroxytryptophan potentiated the TRH-stimulated TSH secretion when given 1 h before killing. 5-HT (10 microgram/rat) infused into the third ventricle enhanced the cold-stimulated TSH secretion when given 30-45 min before sampling. When injected into the medial basal hypothalamus, 50-HT (1-10 microgram/rat) had no effect on basal or stimulated TSH levels. The results suggest: (1) 5-HT does not play any role in the regulation of basal TSH secretion; (2) in the cold-stimulated TSH secretion 5-HT has a stimulatory action evidently inside the blood-brain barrier and also an inhibitory effect obviously outside this barrier.     

EFFECTS OF CHRONIC TREATMENT WITH AMINO-OXYACETIC ACID OR SODIUM n-DIPROPYLACETATE ON BRAIN GABA LEVELS AND THE DEVELOPMENT AND REGRESSION OF COBALT EPILEPTIC FOCI IN RATS

Abstract– Acute treatment of cobalt-induced epilepsy in rats with amino-oxyacetic acid (20-60 mg/kg intraperitoneally) resulted in a short period (30-90 min) of epileptic spike suppression. In contrast sodium n -dipropylacetate (100-400 mg/kg intraperitoneally) had no effect on spike frequencies. Chronic treatment of cobalt epileptic rats with amino-oxyacetic acid (2.5-10 mg/kg intraperitoneally daily) or sodium n -dipropylacetate (200-400 mg/kg intraperitoneally daily) elevated brain GABA concentrations significantly and reduced brain glutamate decarboxylase activity relative to control saline-injected cobalt epileptic rats. Brain γ-aminobutyrate aminotransferase activity was significantly reduced by chronic treatment with amino-oxyacetic acid, whereas chronic sodium n -dipropylacetate had no effect on brain γ-aminobutyrate aminotransferase activity although elevating brain GABA. Amino-oxyacetic acid (2.5-10 mg/kg intraperitoneally per day) reduced the frequency of epileptic spikes in the secondary foci of cobalt epileptic rats. The anticonvulsant action of amino-oxyacetic acid was most marked at 5 mg/kg intraperitoneally where a secondary focus failed to develop in treated cobalt epileptic rats. However, there was no simple relationship between the elevation of brain GABA and the anticonvulsant action of amino-oxyacetic acid. Thus focal GABA was higher in rats given intraperitoneal amino-oxyacetic acid (10 mg/kg) but the anticonvulsant action of amino-oxyacetic acid was less marked at this dose. Sodium n -dipropylacetate (200-400 mg/kg intraperitoneally per day) had no long-term anticonvulsant action in this model of epilepsy. It is concluded that the anticonvulsant action of sodium n -dipropylacetate, and probably that of amino-oxyacetic acid, is not likely to be mediated through a mechanism involving elevation of brain GABA.     

Acute and subacute cytogenetic effects of the trihalomethanes on rat bone marrow cells in vivo

The mutagenic effects of the trihalomethanes (THMs: chloroform, CHCl3; dichlorobromomethane, CHCl2Br; dibromochloromethane, CHClBr2; bromoform, CHBr3), found in chlorinated drinking water have been studied for their ability to induce chromosome aberrations (CA) in vivo in rat bone marrow cells. THMs were administered intraperitoneally (i.p. acute) and orally (subacute). Using a maximal dose of 1 mmole/kg body weight, positive results were noted for CHCl3, CHCl2Br, CHClBr2 and CHBr3 with i.p. treatment, and for CHCl3 and CHBr3 with oral treatment. The time-dependent increase in CA showed a maximum level at 12 h after i.p. injection and at 18 h after the fifth and last day of oral treatment.     

Induction of chromosome aberrations, micronucleus formation and sperm abnormalities in mouse following carbofuran exposure

Carbofuran was tested to study in vivo cytogenetic effects in mouse bone marrow cells and morphological alterations in sperms. The acute oral and intraperitoneal (i.p.) LD(50) of carbofuran was determined to be 9.5 or 2.0 mg/kg b.w. in mice, respectively. The animals were orally administered 1.9, 3.8 or 5.7 mg/kg b.w. (20, 40 and 60% of LD(50)) of carbofuran for 24 h or 1.9 mg/kg b.w. for 4 consecutive days (cumulative 7.6 mg/kg or 80% of LD(50)) to analyse chromosome aberrations (CAs). For micronucleus test (MT) animals were orally exposed to 5.7 mg/kg b.w. for 24 and 48 h or 1.9 mg/kg b.w. for 4 consecutive days. For reference mice were exposed to peanut oil (negative control) and cyclophosphamide (20 mg/kg) or ethyl methanesulfonate (EMS: 100 mg/kg) positive control for CAs and MT respectively. To analyse the effect on sperm morphology mice were exposed to single i.p. dose of 1 and 2 mg/kg b.w. of carbofuran and repeatedly to 0.5 mg/kg for 5 consecutive days. Cytogenetic analysis revealed that all the test doses induced mitotic inhibition, CAs, micronucleus (MN) formation and sperm abnormalities in a dose dependent manner. Present observations concurrent with earlier reports substantiate the genotoxic potential of carbofuran and possible risk to human beings.     

Pharmacological investigation of the mechanisms of platelet-activating factor induced mortality in the mouse

Although the platelets of the mouse are refractory to the direct effects of platelet-activating-factor (PAF), tail vein injection of 10-150 micrograms/kg PAF produces lethal anaphylactic shock. Sensitivity varies with strain and source: Swiss Webster mice show a range of sensitivity and DBA/2 (complement C5-deficient) mice are very resistant. At lethal doses of PAF, animals show labored respiration and general depression; death occurs within 15-45 min. Dexamethasone administered at least 1.5 hr prior consistently protects, whereas the cyclooxygenase inhibitors do not. Antihistamines, adrenergic antagonists, and methysergide have no effect, but cyproheptadine is partially protective at near lethal doses. Calcium entry blockers and calcium chelators, tetracycline and chlortetracycline are partially protective at very high doses consistent with non-specific effects on calcium dependent processes. The arachidonic acid lipoxygenase inhibitors BW755c, phenidone, nordihydroguaiaretic acid and diphenyldisulfide provide nearly complete protection after oral administration of 50-200 mg/kg. Phosphodiesterase inhibitors and dapsone are also effective orally. The leukotriene antagonist FPL55712 administered intraperitoneally (10 mg/kg) 5 min. prior to PAF challenge provides almost complete protection. PAF-induced mortality in the mouse represents a small animal model of systemic anaphylaxis particularly useful for the systemic testing of arachidonic acid lipoxygenase inhibitors and leukotriene antagonists.     

Evaluation of DNA damage induced by norfloxacin in liver and kidney of adult rats and in fetal tissues after transplacental exposure

Norfloxacin, a recently developed antimicrobial fluoroquinolone, was investigated for DNA-damaging activity in rat liver and kidney. After oral administration of single doses ranging from 1 to 8 mmole/kg, DNA fragmentation was absent in liver and kidney both 2 and 6 h after treatment. However, when administered to pregnant rats, the highest doses produced a detectable amount of DNA damage in fetal tissues. This damage appears to be an aspecific consequence of maternal and fetal toxicity rather than a specific genotoxic effect.     

Alleviation of lindane induced toxicity in testis of Swiss mice (Mus musculus) by combined treatment with vitamin C, vitamin E and alpha-lipoic acid

Mitigation of lindane induced toxicity in testis of Swiss mice by combined treatment with vitamin C, vitamin E and alpha-lipoic acid has been evaluated. Male healthy mice (40), 8-10 weeks old were randomly selected and divided into 4 groups, control (C); lindane (L); antioxidant (A) and antioxidant plus lindane (A+L). Group C animals were administered only the vehicle (olive oil); in group L lindane was administered orally at a dose of 40 mg/kg body wt.; in group A combination of antioxidants at a dose of 125 mg/kg body wt.(vitamin C: 50 mg/kg body wt., vitamin E: 50 mg/kg body wt. and alpha-lipoic acid: 25 mg/kg body wt.) was administered orally; in group A+L both antioxidants (125 mg/kg body wt.) and lindane (40 mg/kg body wt.) were administered at their respective doses. In group A+L antioxidants were administered 1 h prior to lindane administration. All treatments were continuously given for 60 days. Histopathological changes due to lindane intoxication indicated shrunken and distorted seminiferous tubules, sparse Leydig cells and blood vessels and atrophy in the tissue. The testis weight also decreased significantly. Lindane treated group showed increased lipid peroxidation, whereas glutathione, glutathione peroxidase, superoxide dismutase, catalase and protein were significantly decreased compared to control. Lindane induced damage was minimized by administration of antioxidants. Results suggest that combined pretreatment with antioxidants can alleviate the damage caused to testis by lindane.     

The action of L-cysteine in acute cobalt chloride intoxication

A study in rats was made of the effects produced by L-cysteine on the acute toxicity of cobalt chloride given orally and intraperitoneally. The decrease in lethality was absolute for the different doses tested, except when the CoCl2 was given orally and L-cysteine intraperitoneally in which only 40% efficiency was obtained. No specially significant changes were observed in the blood parameters of the animals treated with the CoCl2-cysteine complex after one week. Significant differences were noted between serum parameters: glucose, triglycerides and cholesterol, measured in rats after twelve hours of receiving the CoCl2-cysteine complex, compared with the same parameters measured when the CoCl2 was given without complex.     

Micronucleus test with 2-acetylaminofluorene by intraperitoneal injection and oral administration

The effect of route of administration on the outcome of the mouse micronucleus test was evaluated in 2 laboratories by administering 2-acetylaminofluorene (2-AAF) by intraperitoneal injection (i.p.) and oral gavage (p.o.) to 2 mouse strains, MS/Ae and CD-1. On the basis of a small-scale acute toxicity study and a pilot micronucleus test, the full-scale experiment was performed with a 24-h sampling time at doses ranging from 75 to 600 mg/kg by both routes. The results indicated that 2-AAF induced micronucleated polychromatic erythrocytes (MNPCEs) at all doses tested by both routes. In the MS/Ae strain, higher doses were required by p.o. than by i.p. to reach a similar level of MNPCE incidence. On the other hand, similar responses were recorded by both administration routes with CD-1 mice. Since the LD50 for the p.o. route was higher than that for the i.p. route in both strains, the route-related difference with MS/Ae mice became small when the comparison between i.p. and p.o. was made on the basis of the LD50. Thus both i.p. and p.o. routes are acceptable in the micronucleus test of this chemical.     

Analgesic efficacy of orally administered buprenorphine in rats

The analgesic effect of orally administered buprenorphine was compared with that induced by a standard therapeutic injected dose (0.05 mg/kg of body weight, s.c.) in male Long-Evans rats. Analgesia was assessed by measuring pain threshold, using the hot-water tail-flick assay before and after administration of buprenorphine. The results suggest that a commonly used formula for oral buprenorphine in flavored gelatin, at a dose of 0.5 mg/kg, does not increase pain threshold in rats. Instead, oral buprenorphine doses of 5 and 10 mg/kg were necessary to induce significant increases in pain threshold. However, these doses had to be administered by orogastric infusion because the rats would not voluntarily eat flavored gelatin containing this much buprenorphine. The depth of analgesia induced by these infused doses was comparable to that induced by the clinically effective s.c. treatment (0.05 mg/kg).