Effects of pretreatment with SKF-525A or sodium phenobarbital on thiabendazole-induced teratogenicity in ICR mice

To study the effects of SKF-525A, an inhibitor of cytochrome P-450, and of sodium phenobarbital (PB), a drug-metabolizing enzyme inducer, on the teratogenicity of thiabendazole (TBZ), pregnant mice were given ip either a single dose of 40 mg SKF-525A/kg 1 hr before oral dosing with 250 or 500 mg TBZ/kg or a dose of 75 mg PB/kg/day on three consecutive days before oral administration of a dose of 500 or 1000 mg TBZ/kg. In either case the TBZ dose was given on day 9 of gestation. All foetuses were removed from the uterus on day 18 of gestation, and were examined for external and skeletal anomalies. The spectrum of malformations in the groups of mice pretreated with SKF-525A or PB was similar to that in mice treated only with TBZ. In the group pretreated with SKF-525A, however, the incidence of resorbed foetuses was higher than in the group treated with TBZ alone and there was a tendency towards an increase in the number of foetuses with skeletal fusion and reduction deformity of the limbs, an anomaly characteristically induced by TBZ. On the other hand, in mice pretreated with PB, the incidence of resorbed foetuses tended to be lower, the numbers and body weights of live foetuses were higher and the incidence of external and skeletal malformations was lower than in the groups treated with TBZ only. No reduction deformity of the limbs was observed in the groups pretreated with PB. These results suggest that with TBZ the ultimate teratogen may be the parent compound rather than its metabolites.     

Prevention of fumonisin-induced maternal and developmental toxicity in rats by certain plant extracts

In earlier work we have reported that garlic and cabbage extracts can protect laboratory animals from the toxic effects of different mycotoxins. Previous research demonstrated that fumonisin (FB) induced developmental effects in mice, rats and hamsters. The objectives of the present study were to utilize the pregnant rat as an in vivo model to compare the potential of garlic and cabbage seed extracts to prevent the developmental toxicity of FB and the effects of these extracts on sphingolipid metabolism in dam and foetus livers. Six treatment groups included a control group, a group fed on an FB-containing diet (150 mg kg(-1) feed) and groups treated orally with garlic or cabbage extracts (5 mg kg(-1) body wt.) with or without FB during gestation days 6-15. Evaluations of toxicity were performed on day 20. These include: maternal (mortality, body weight, feed intake and litter weight), developmental (embryonic resorption, foetal body weight, foetal soft-tissue anomalies and foetal skeletal examinations) and maternal and foetal sphingolipid metabolism. Fumonisin alone resulted in significant decreases in feed intake, body weight gain, litter weight, number of live foetuses and foetal body weight, whereas it increased significantly the number of resorbed foetuses and the number of skeletal malformations (30.4% for skull and 26.08% for sternebrae) and also increased the sphinganine/sphingosine (Sa/So) ratio in dam but not fetus livers. Garlic alone or plus FB was comparable to the control regarding all the tested parameters. On the other hand, cabbage seed extract alone or plus FB resulted in 10% maternal mortality and a decrease in maternal body weight and litter weight. It resulted in 4.65% skull malformations in foetuses but it was comparable to the control with regard to the other tested parameters. It could be concluded that both garlic and cabbage seed extracts have protective effects in pregnant rats. Moreover, garlic extract was found to have a greater protective effect than cabbage seed extract.     

A teratogenic study of carbaryl in Swiss albino mice

To study the teratogenicity of carbaryl, groups of 10 pregnant mice were dosed, by gavage, with 0, 100, 150 or 200 mg carbaryl/kg body weight, in corn oil, on day 8 or day 12 of pregnancy or daily (as daily doses) from day 6 to day 15. The two higher doses were toxic to both dams and foetuses regardless of the timing of treatment. Treated dams generally showed reduced weight gains but total weight gain was significantly reduced only for dams given 200 mg carbaryl on day 8 or day 12 of gestation. Maternal mortality was increased in most groups given 150 or 200 mg carbaryl. Carbaryl treatment tended to reduce litter size, to increase the percentage of resorbed foetuses, and to reduce foetal weight. There were increased incidences of open eye, of certain visceral abnormalities, and of reduced ossification in virtually all treated groups. The variety of abnormalities in treated foetuses reflected the dysmorphogenic potential of the pesticide. More aberrations were seen in foetuses from dams treated throughout organogenesis than in those from dams given a single dose.     

Teratogenicity and embryotoxicity study of carmine of cochineal in the rat

Groups of 30 mated female rats were given daily doses of 0, 200, 500 or 1000 mg carmine/kg body weight by oral intubation throughout pregnancy. A group of 17 similar animals was given a solution of chlorides to provide an intake of sodium, potassium and ammonium equal to that resulting from the highest dose level of carmine. There were no effects of carmine treatment on body weights, pregnancy rates, pre-implantation losses, the average numbers of live young, litter weights or foetal weights. The group given the highest dose of carmine and the cation control had increased numbers of implantations and post-implantation losses. The latter was considered to be due to an inability to maintain the increased numbers of implantations rather than to an embryotoxic effect. The foetuses showed no malformations and those from the carmine-treated rats tended to have a slightly more advanced degree of ossification of certain skeletal elements than foetuses of the control animals. On the basis of the results obtained it is considered that there were no untoward effects on embryo development in rats given oral doses of up to 1000 mg carmine/kg body weight/day throughout pregnancy.     

Study of the teratogenic potential of FD & C Yellow No. 5 when given by gavage to rats

FD & C Yellow No. 5 (tartrazine) was given to Osborne-Mendel rats by gavage at dose levels of 0, 60, 100, 200, 400, 600 or 1000 mg/kg body weight/day on days 0–19 of gestation. No maternal or developmental toxicity was observed when the rats were killed on day 20. The mean daily food consumption for the entire period of gestation was significantly greater in the females given 1000 mg/kg body weight/day than in the controls, but maternal body-weight gain was not affected. No dose-related effects were observed in implantations, foetal viability or external foetal development. Foetal skeletal and visceral development was similar among foetuses from all groups. At the doses given, FD & C Yellow No. 5 was neither toxic nor teratogenic.     

Glutathione and cysteine enhance and diethylmaleate reduces thiabendazole teratogenicity in mice

The effects of cysteine (CYS), glutathione (GSH) and diethylmaleate (DM) on the teratogenicity of thiabendazole (TBZ) were investigated. On day 9 of gestation mice were given ip a dose of 0, 50 or 100 mg CYS/kg body weight, or 0, 400 or 800 mg GSH/kg, or 0, 0.05, 0.10, 0.15 or 0.60 DM/kg. One hr later they were dosed orally with 0, 250, 500 or 1000 mg TBZ/kg. All foetuses were removed from the uterus on day 18 of gestation, and were examined for external and skeletal anomalies. The number of malformed foetuses was increased in mice pretreated with CYS or GSH and was decreased in those pretreated with DM, in comparison with numbers in the corresponding group treated with TBZ alone GSH pretreatment enlarged the area under the curve (AUC) of TBZ and 5-hydroxyTBZ, a representative metabolite, in foetal tissue. DM pretreatment reduced the AUC of TBZ and 5-hydroxyTBZ.     

Studies of Embryotoxicity and the Incidence of External Malformations after Continuous Intravenous Infusion of α-Chaconine in Pregnant Rats

Abstract: Embryotoxicity and effects on the incidence of external malformations of the major potato glycoalkaloid α-chaconine (α-cha) were studied in rats. Pregnant Sprague-Dawley rats (n = 17) were given a continuous intravenous infusion of α-cha via implanted osmotic minipumps (1.7 mg/kg/day), to maintain a stable blood concentration on days 6–13 of gestation. Control animals recevied physiological saline solution or were left untreated, respectively. Blood serum levels of α-cha were monitored at selected time intervals during the treatment using a specific HPLC method. The foetal body weights and the number of resorbed or dead foetuses per litter in the α-cha treated group were not significantly different from the control groups. No case of malformation was detected among 143 foetuses inspected in the treated group. The average maternal blood serum concentration of α-cha measured during the experiment was 340 ng/ml. This is more than 20 times the average peak serum level previously reported for human volunteers after intake of potatoes with a total glycoalkaloid content at the upper safe limit for acute adverse effects. The results support the view that potato glycoalkaloids, at levels normally found in potatoes, do not present a risk for teratogenicity in humans.     

Developmental toxicity assessment of the new fluoroquinolone antibacterial DW-116 in rabbits

DW-116 is a newly developed fluoroquinolone antibacterial with a broad spectrum against both Gram-positive and Gram-negative bacteria. We have reported recently that DW-116 is embryotoxic and teratogenic in rats. The present study was conducted to investigate the teratogenicity of DW-116, together with maternal toxicity and developmental toxicity using New Zealand White rabbits. The test chemical was administered by gavage to pregnant rabbits from gestational day (GD) 6 through to GD 18 at dose levels of 0, 5, 19.5 and 76.1 mg kg(-1) day(-1). All does were subjected to caesarean section on day 28 of gestation and their foetuses were examined for external, visceral and skeletal abnormalities. In the 76.1 mg kg(-1) group, a minimal maternal toxicity, as evidenced by decreased body weight gain during treatment period, was observed in pregnant rabbits. Significant embryo-foetal toxicity, including increased number of foetal deaths and delayed foetal ossification, was seen. However, no treatment-related morphological changes were detected in foetal external, visceral and skeletal examinations. There were no adverse effects on either pregnant dams or embryo-foetal development at 19.5 and 5 mg kg(-1). It was concluded that administration of DW-116 during the major organogenetic period in rabbits produced decreased maternal body weight gain, increased number of foetal deaths and foetal developmental delay but no evidence of teratogenicity. The no-observed-adverse-effect levels (NOAELs) of DW-116 are considered to be 19.5 mg kg(-1) day(-1) for does and embryo-foetuses, respectively.     

Teratogenicity of thiabendazole in ICR mice

Thiabendazole (TBZ) was tested for teratogenicity using Jcl:ICR mice. TBZ suspended in olive oil was given orally to pregnant mice at different stages of organogenesis. All foetuses were removed from the uterus on day 18 of gestation, and were examined for external and skeletal anomalies. In mice given 700, 1300 or 2400 mg TBZ/kg body weight/day on days 7–15 of gestation, dose-dependent external and skeletal anomalies, especially cleft palate and fusion of vertebrae, were observed. In mice given a single dose of TBZ (2400 mg/kg) on any one of days 6–13, an increased number of malformations was observed. Various types of malformation occurred, especially in the mice treated on day 9. Reduction deformity of limbs was found in mice given TBZ on days 9–12, a change that has not previously been observed to occur spontaneously in normal ICR mice in our laboratory. In order to determine a dose-response relationship, groups of mice were given one of 17 doses of TBZ (30–2400 mg/kg) on day 9 of gestation. The number of litters having foetuses with reduction deformity of limbs and of those having foetuses with skeletal fusion increased in proportion to the dose of TBZ. The regression lines of Y (probit response) on X (log dose) for reduction deformity of limbs and for skeletal fusion were Y = 2.47X ? 3.65 and Y = 1.54X + 0.48, respectively. The effective doses (ED₁) for the two malformations were 362.0 and 26.4 mg/kg, respectively.     

Study of the teratogenic potential of gum arabic

Gum arabic in the diet at 0, 1, 2, 4, 7.5 or 15% was available ad lib. to male and female Osborne-Mendel rats during premating and mating and throughout gestation. During gestation, the treated females consumed from 683 mg gum/kg body weight/day in the 1% group to 10,647 mg gum/kg/day in the 15% group. The animals were killed on gestation day 20. There were no dose-related changes in maternal findings, number of foetuses, foetal viability or external, visceral or skeletal variations. No terata were seen.     

Teratological evaluation of picloram potassium salt in rabbits

The embryotoxic and teratogenic potential of orally administered picloram potassium salt was evaluated in New Zealand white rabbits. Artificially inseminated rabbits were given 0, 40, 200 or 400 mg picloram acid equivalent/kg body weight/day in the form of picloram potassium salt in aqueous solution on days 6 to 18 of gestation. The foetuses were removed for examination on day 29 of gestation. Transient weight loss was observed among rabbits given 200 or 400 mg/kg/day of the test material, though the total weight gain of the treated groups during gestation was comparable to that of controls. A few isolated, sporadic cases of foetal malformations were observed in the dosed groups, but there was no indication of a dose-related embryotoxic or teratogenic response to treatment.     

Teratogenicity of thujaplicin in ICR mice.

Beta-thujaplicin (TP) was studied by in vitro and in vivo tests for teratogenicity using ICR mice. In the in vitro study, TP (0, 3.125, 6.25, 12.5 microg/ml medium) dissolved in dimethyl sulfoxide (DMSO) was administered to cultured embryos on 9 day of gestation. After 24 hr of exposure to TP, the embryos were examined for developmental parameters and external anomalies. Growth retardation and embryos with facial dysplasia or hydrocyst of the tail tip were observed among the embryos given 12.5 microg/ml. In the in vivo study, TP (0, 420, 560, 750 or 1000 mg/kg) dissolved in olive oil was administered orally to pregnant mice on day 9 of gestation. All foetuses were removed from the uterus on day 18 of gestation, and were examined for external and skeletal anomalies. Various types of malformations were observed in the mice given 560 mg/kg or more. The number of litters having foetuses with external or skeletal anomalies increased in proportion to the dose of TP. The regression lines of Y (probit response) on X (log dose) for external anomalies was Y = 4.87X-8.43 . The 1% effective dose (ED1) for the malformation was 190 mg/kg. The present study shows that TP has teratogenic effects on mice.     

Evaluation of the teratogenic potential of cocoa powder and theobromine in New Zealand White rabbits

Studies were conducted to determine the teratogenic potential of theobromine (TBR) and cocoa powder (CP) in rabbits. TBR was given either by gavage at dose levels of 0, 25, 75, 125 or 200 mg/kg body weight/day or administered in the diet at 0, 0.0625, 0.125 or 0.1875% (approximately 0, 21, 41 or 63 mg/kg/day, respectively). CP was given at 2.5, 5.0 or 7.5% of the diet (approximately 25, 50 or 75 mg methylxanthines/kg body weight/day). The duration of exposure was from days 6 to 29 of gestation. Significant maternal mortality (40%) and reduced food consumption were observed at 200 mg TBR/kg/day. Mean foetal weights were similar to those of the control group at 25 or 75 mg TBR/kg/day, but decreases in foetal body weight and increases in various malformations and developmental variations were observed in groups given 125 or 200 mg/kg/day. Insufficient litters were available for examination in the 200-mg/kg/day dose group because of maternal toxicity/lethality (repetitive exposure by gavage to 200 mg TBR/kg approached the maternal LD50). In the dietary CP studies, three does died and three aborted, but these deaths and abortions were not treatment related. No maternal deaths occurred during dietary TBR exposure. Maternal weight gain and food consumption, and the mean number of corpora lutea were unaffected by either dietary CP or TBR. Neither foetotoxicity nor teratogenicity was associated with dietary ingestion of CP or TBR. The foetuses exposed to 0.125% or 0.1875% TBR had a significantly higher incidence of incompletely ossified or absent sternebrae, whereas exposure to 0.1875% or 7.5% CP resulted in corresponding effects on metacarpal bones, indicating a delay in osteogenesis. The predominant compound found in serum after TBR ingestion was unchanged TBR, and there was no evidence of bioaccumulation of TBR in serum during gestation. The highest levels of CP or TBR used in these studies was 38 times greater than the maximum consumption level reported for humans in marketing surveys, and corresponds to a consumption of greater than 7.5 lb milk chocolate/day.     

Developmental toxicity study of Aquacoat ECD ethylcellulose aqueous dispersion administered orally to rats.

A developmental rat toxicity study of Aquacoat((R)) ECD was performed as part of a program to evaluate the safety of the product. Groups of 25 presumed-pregnant Charles River Sprague-Dawley CD rats received doses of 0, 903, 2709 and 4515mg/kg/day (dry weight basis) of Aquacoat ECD administered undiluted once daily via oral gavage on days 6-15 of gestation. All surviving dams underwent caesarean sectioning on day 20 of gestation. Foetuses were weighed, sacrificed and subject to external, visceral and skeletal evaluations. No test material-related maternal deaths occurred; one high-dose female died on day 14 due to gavage error. The only treatment-related clinical sign noted among dams receiving 2709mg/kg/day and greater was pale faeces which was attributed to the presence of the test material in the faeces. No statistically significant differences were noted among the measured maternal parameters. Foetal sex ratios and body weights were similar in all groups. The results of external and visceral foetal evaluations revealed no treatment-related alterations. The only statistically significant findings noted during the skeletal evaluation were increased litter incidences of incompletely ossified or wavy ribs noted among foetuses receiving 4515mg/kg/day, and a significant increase in the litter incidence of thickened ribs at doses of 2709 and 4515mg/kg/day. Given the nature of these findings and the lack of effects on any other parameter measured in this study, they were not considered adverse effects of treatment. Under the conditions of this study, the maternal and foetal no-observed-adverse-effect level (NOAEL) is in excess of 4515mg/mg/day.     

A teratology study on vomitoxin (4-deoxynivalenol) in rabbits

Diets containing 4-deoxynivalenol (vomitoxin) of greater than 98% purity were fed to rabbits on days 0-30 of gestation. The dietary concentrations of 4-deoxynivalenol were 0, 0.00075, 0.0015, 0.003, 0.006, 0.012 and 0.024% and the daily intakes of deoxynivalenol were 0, 0.3, 0.6, 1.0, 1.6, 2.0 and 1.8 mg/kg body weight/day, respectively. A pair-fed group was given a feed intake equivalent to that in the 1.6-mg/kg group. The only significant effects that were observed in foetuses examined at day 30 of gestation occurred only at doses that caused reductions in both the body weight and feed intake of does. The foetal effects consisted of a 100% incidence of resorption in the 1.8- and 2.0-mg/kg groups and decreased mean foetal weight in the 1.0- and 1.6-mg/kg and pair-fed groups. The doses that did not appear to be maternotoxic (0.6 and 0.3 mg/kg) did not show any adverse effects in foetuses at term. Vomitoxin given in the diet during pregnancy failed to show any evidence of teratogenic potential in rabbits.     

A study of the embryotoxicity of the food colour Ponceau 4 R in rats.

An embryotoxicity study on Ponceau 4 R was carried out in SPF Wistar rats. The substance was given by gavage from day 1 to 20 of the gestation period in doses of 0, 1000, 2000, and 4000 mg/kg bw per day, dissolved in distilled water. The foetuses were removed on day 21. No effect due to the treatment with the dye was observed with regard to the number of corpora luteae (CL), of implantations, of foetuses dead or alive with regard to gross malformations, to skeletal and internal malformations or to the weight of the foetuses.     

Teratogenic potential of purified pentachlorophenol and pentachloroanisole in subchronically exposed Sprague-Dawley rats

Male and female Sprague-Dawley (Spartan) rats were exposed to dietary levels of 0, 60, 200 or 600 ppm purified pentachlorophenol (PCP) or pentachloroanisole (PCA) for 181 days, through mating and pregnancy. The daily intakes of PCP were 0, 4, 13 or 43 mg/kg body weight and of PCA were 0, 4, 12 or 41 mg/kg body weight. Animals exposed to PCP generally consumed more food than control animals during pregnancy. Dams at the high-dose level of both compounds showed evidence of toxicity, weighing less on day 0 of gestation and gaining less throughout pregnancy than did the controls. Dams exposed to the high dose of PCP gained less weight during pregnancy (exclusive of the gravid uterus) than control dams. At the 43 mg/kg/day dose level PCP was embryolethal. Foetuses at the lower dose levels of PCP exhibited dose-related decreases in body weights. A reduction in crown-rump length and an increase in foetal skeletal variations were seen at 13 mg/kg/day in PCP animals only. An intake of 41 mg PCA/kg/day was associated with a decrease in the number of corpora lutea and in embryolethality. PCA exposure also resulted in reductions in foetal body weight and crown-rump lengths of males at 4 and 41 mg/kg/day. Female foetuses were unaffected.     

The effects of maternally inhaled formaldehyde on embryonal and foetal development in rats

Sprague-Dawley rats were exposed to 0, 5, 10, 20 or 40 ppm formaldehyde for 6 hr/day from day 6 to 20 of gestation. On day 21 of gestation the rats were killed for evaluation of maternal reproductive and foetal parameters. No effect on embryonic or foetal lethality, nor significant alterations in the external, visceral or skeletal appearance of the foetuses were noted in any of the exposed groups. Significant concentration-related reduction of foetal body weight occurred at 20 and 40 ppm, and at 40 ppm foetal body weights were 20% less than those of the controls. Maternal toxicity, indicated by significant reduction in body weight and absolute weight gain, was observed at 40 ppm. The results of this study show that formaldehyde is slightly foetotoxic at 20 ppm. Neither embryolethal nor teratogenic effects were observed following inhalation exposure at levels up to 40 ppm.     

Salicylate-Induced Foetal Damage in Two Mouse Strains: Studies on the Distribution of 14C-Labelled Salicylic Acid

The distribution of salicylate was studied in pregnant and non-pregnant mice of the A/Jax and CBA strains. These strains were selected because of their different susceptibility to salicylate-induced foetal damage. Labelled salicylic-1-¹⁴C-acid (1 μci) was injected intramuscularly together with 10 mg sodium salicylate as cold carrier in a volume of 0.1 ml distilled water/20 g bodyweight. The animals were sacrificed at different intervals from half an hour to 8 hours after the injection and the radioactivity in the maternal blood and liver and in the foetuses was determined by liquid scintillation counting. The non-pregnant mice showed initially a higher radioactivity in the blood than in the females on day 14 or 17 of gestation. The amount of liver radioactivity was similar in pregnant and non-pregnant animals and remained practically unchanged during the period of study. The foetal radioactivity was relatively high compared to that in the maternal liver. No strain difference were observed either on gestation day 14 or on day 17. The foetal radioactivity did not decrease during the first 4 hours after salicylate treatment on day 17 of gestation at which time foetal damage had already been produced.     

Toxicological effects of cadmium during pregnancy in Wistar albino rats

Cadmium is a heavy metal and widespread environmental toxicant. This study investigated the effects of prenatal Cd exposure on fetal growth and limb development in rats. Pregnant rats were given 0, 4 or 8 mg/kg/day (equivalent to ≈ 0, 30 or 60 ppm) of cadmium as CdSO₄ in their drinking water from conception to gestation day 20. Cd significantly (p<0.001) and dose-dependently inhibited maternal weight gain and caused abortion of pregnancy. In addition, Cd significantly (p<0.001) decreased fetal body weight, forelimb and hindlimb bone lengths, compared to controls. These effects were sex-dependent, greater in the female offspring. Furthermore, there were reductions in the weights, and alterations in the histology of maternal placenta, ovary and liver of Cd-exposed rats. The results indicate that cadmium will cause abortion of pregnancy and sex-dependent impairment of fetal growth and limb development, which may be consequent upon alterations in ovarian and placental functions.