Toxicological Study of Sodium Selenite on Fetal Development and DNA Fragmentation in Liver Cells of Pregnant Rats

The present study was carried out to evaluate the effects of sodium selenite on fetal development and DNA in liver of rats. Pregnant rats were divided into three groups: control group, group treated orally with 5 μg Se/kg body wt. and group treated orally with 10 μg Se/kg body wt. Dams were treated orally with sodium selenite from day 7 to 19 of gestation. Sodium selenite treatment revealed decrease in maternal body weight, reduction in fetal weight, length and number of viable fetuses, increased number of resorbed fetuses and post-implantation loss at the two doses tested. Fetal skeleton showed signs of developmental delay in skull and limbs of the treated groups. Sodium selenite treatment revealed significant reduction of placental and liver weights in treated dams. Sodium selenite-induced oxidative stress in liver tissue of rats as evidenced by increase in lipid peroxidation and glutathione peroxidase activity, while catalase was significantly decreased. Also, increase in DNA fragmentation, marked reduction of hepatic DNA content, and many histopathological changes in the liver were recorded. The results demonstrated that treatment of pregnant rats with sodium selenite at the toxic dosages chosen showed maternal and fetal toxicity that may be concerned with hepatic oxidative stress accompanied with DNA fragmentation and depletion of total DNA content.     

Alterations in methylation and expression levels of imprinted genes H19 and Igf2 in the fetuses of diabetic mice

The study aimed to reveal alterations in expression and methylation levels of the growth-related imprinted genes H19 and Igf2 in fetuses of diabetic mice. Diabetes was induced in female mice by intraperitoneal injection of streptozotocin. DNA and total RNA were extracted from fetuses obtained from diabetic and control dams on embryonic day (E) 14. Real-time RT-PCR analysis revealed that the mRNA expression of Igf2 in fetuses from diabetic mice was 0.65-fold of the control counterparts. Bisulfite genomic sequencing demonstrated that the methylation level of the H19-Igf2 imprint control region was 19.1% higher in diabetic fetuses than in those of control dams. In addition, the body weight of pups born to diabetic dams was 26.5% lower than that of the control group. The results indicate that maternal diabetes can affect fetal development by means of altered expression of imprinted genes. The modified genomic DNA methylation status of imprinting genes may account for the change in gene expression.     

Influence of doxycycline administration on rat embryonic development during organogenesis

This experiment was performed to evaluate the possible embryotoxic and teratogenic effects of doxycycline during rat development. Twenty‐one female rats were used and distributed into three groups equally (seven animals/group). The low dose group received doxycycline at a dose of 5 mg/kg bw/day orally from the 6th to 14th day of gestation. The high dose group received 10 mg/kg bw/day orally for the same period, the Control group received 1 mL distilled water orally for the same period. The dams were dissected on the 20th day of gestation and their fetuses were subjected to morphological, skeletal, and histological examination. Moreover, DNA damage analysis of liver cells of pregnant rats and their fetuses or fetal skull was assessed by Comet assay. The obtained results showed a significant decrease in fetal body weight, several morphological anomalies, and severe lack of ossification on the skull bones, phalanges, and sternum bone as well as shortness in the ulna and radius bones. Histological studies of pregnant rats revealed congestion and dilatation of the central vein of the liver lobules and fatty degeneration of the hepatocytes. In addition, 20 day‐fetuses showed a marked increase of necrotic hepatocytes associated with an increased average of megakaryocytes and periportal leukocytic infiltration. Moreover, doxycycline induced a significant increase in the percentage of DNA damage and tail length of examined samples. Conclusively, doxycycline caused certain fetal abnormalities, so it is advisable to avoid using this drug during pregnancy.     

Inhibiting matrix metalloproteinases with prinomastat produces abnormalities in fetal growth and development in rats

BACKGROUND: Matrix metalloproteinases (MMPs) play key roles in remodeling of the extracellular matrix during embryogenesis and fetal development. The objective of this study was to determine the effects of prinomastat, a potent selective MMP inhibitor, on fetal growth and development. METHODS: Prinomastat (25, 100, 250 mg/kg/day, p.o.) was administered to pregnant female Sprague-Dawley rats on gestational days (GD) 6-17. A Cesarian section was carried out on GD 20 and the fetuses were evaluated for viability and skeletal and soft tissue abnormalities. RESULTS: Prinomastat treatment at the 250 mg/kg/day dose produced a decrease in body weight and food consumption in the dams. A dose-dependent increase in post-implantation loss was observed in the 100 and 250 mg/kg/day-dose groups, resulting in only 22% of the dams having viable litters for evaluation at the 250 mg/kg/day dose. Fetal skeletal tissue variations and malformations were present in all prinomastat treated groups and their frequency increased with dose. Variations and malformation in fetal soft tissue were also increased at the 100 and 250 mg/kg/day doses. Prinomastat also interfered with fetal growth of rat embryo cultures in vitro. CONCLUSIONS: These data confirm that MMP inhibition has a profound effect on fetal growth and development in vivo and in vitro.     

In vivo antimutagenic effect of vitamins C and E against rifampicin-induced chromosome aberrations in mouse bone-marrow cells

-The genotoxic effect of rifampicin (RMP), one of the most active antituberculosis agents is studied. Also, the possible protection provided by the natural antioxidant vitamins C (VC) and E (VE) against the genotoxic effect of RMP is assessed.Mice were orally treated by gavage with 10, 50, 150 and 300 mg RMP kg(-1) body weight (bw). Also, oral treatment was conducted with RMP plus the vitamins. Mice received 300 mg RMP kg(-1) bw plus 100, 200 and 400mg VC or VE kg(-1) bw. Samples were taken 24h after the treatment. Repeated treatments with: (1) the therapeutic dose of RMP (10 mg kg(-1) bw); (2) RMP plus a dose of 25, 50 and 75 mg VC kg(-1); (3) RMP plus 10, 20 and 40 mg VE kg(-1) bw for 30 consecutive days were conducted.The tested doses of RMP induced a significant increase in the percentage of chromosome aberrations. However, a lower percentage of chromosome aberrations was observed when animals were treated with the therapeutic dose for 30 consecutive days.The obtained results revealed that chromosome aberrations induced by RMP decreased to a significant extent when mice were treated with RMP plus VC. The repeated doses of VC reduced the percentage of chromosome aberrations induced by RMP in a significant and dose-dependent manner. On the other hand, repeated doses of VE were not very effective in reducing the percentage of chromosome aberrations induced by RMP. Only the highest dose (3 x 40 mg kg(-1) bw) showed a significant effect (P<0.01).The results on the induction of chromosome damage clearly show that only VC appears able to efficiently protect the bone-marrow cells when given together with RMP, while no significant reduction in the yield of chromosome aberrations was observed for VE in combination with the antituberculosis drug.     

Cytogenetic and dominant lethal studies on captan.

Possible mutagenic activity of captan was investigated by in vitro and in vivo cytogenetic studies and by the dominant lethal study in mice. In vitro cytogenetic study with cultured human diploid cells revealed a significant increase in the frequency of cells showing stickiness and a severe mitotic inhibition at concentrations of 3.0 and 4.0 microgram of captan per ml. although no chromosomal aberrations were observed. In in vivo cytogenetic study, no chromosomal aberrations were induced in the bone marrow cells of rats treated orally with captan at a single dose of 500, 1000 or 2000 mg/kg or at five consecutive doses of 200, 400 or 800 mg/kg/day. Dominant lethal study also failed to show any mutation induction after treatment of male mice with daily oral dose of 200 or 600 mg of captan per kg bw for five days.     

Developmental toxicity evaluation of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) in Wistar rats

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) is a genotoxic chlorination by-product in drinking water. There is some evidence that it has developmental toxic effects in vitro but its potential to cause developmental effects in vivo is not known. The developmental effects were evaluated in Wistar rats. Rats (22-26 dams per dose group) were administered MX by gavage at the dose levels of 3, 30, or 60 mg/kg in water on gestation days 6-19. Control animals received plain water. Clinical signs, body weight, and food and water consumption were recorded for the dams. On gestation day 20, a cesarean section was performed and the ovaries anduterine contents of the dams were examined and the liver, kidneys, spleen, and thyroid glands weighed. The fetuses of all dose groups were weighed, sexed, and observed for external and skeletal malformations and the fetuses of the two highest dose groups were evaluated for visceral malformations. The highest dose, 60 mg/kg of MX, was slightly toxic to the dams. It decreased the corrected body weight gain of dams by 32% and the water consumption by 16-17%. Kidney and liver weights were slightly increased. MX did not affect the number of implantations nor did it cause any resorptions. The body weights of fetuses were not significantly affected. MX did not cause external malformations or skeletal anomalies. Two fetuses at 60 mg/kg and one fetus at 30 mg/kg had major visceral malformations (persistent truncus arteriosus, diaphragmatic hernia, dilated aorta with a stenosis of pulmonary arteries) and two minor artery abnormalities were observed in those animals. The frequency of unilateral displaced testis was slightly higher (9.2%) in the 60-mg/kg dose group than in controls (1.6%). Since the abnormalities did not form a consistent pattern and occurred most at maternally toxic dose, we conclude that MX can be regarded as non-teratogenic.     

Studies on the genotoxic effect of beryllium chloride and the possible protective role of selenium/vitamins A, C and E

The genotoxic potential of beryllium chloride (BeCl2) was evaluated in vivo in mice using different endpoints. Chromosomal aberrations in bone marrow cells and in spermatocytes as well as sperm abnormalities were determined in the tested mice. The protective role of an orally administered drug consisting of selenium and vitamins A, C and E (selenium-ACE) was also studied. For analysis of chromosomal aberrations, both single and repeated oral treatments for a period of 3 weeks were performed. The doses used were 93.75, 187.50, 375, and 750 mg BeCl2/kg bw, which corresponds to 1/16, 1/8, 1/4, and 1/2 of the experimental LD50. BeCl2 induced a statistically significant increase in the percentage of chromosomal aberrations in both somatic and germ cells, with a dose- and time-response. The percentage of induced chromosomal aberrations was significantly reduced in all BeCl2-treated groups after oral administration of selenium-ACE. Beryllium chloride also induced a significant increase in the percentage of abnormal sperm. This percentage reached values of 9.62 +/- 0.32 and 5.56 +/- 0.31 in mice treated with the highest test dose of BeCl2 and with BeCl2+selenium-ACE, respectively, compared with 1.96 +/- 0.14 for the control. In conclusion, the results demonstrate the genotoxic effect of beryllium chloride and confirm the protective role of selenium-ACE against the genotoxicity of beryllium chloride.     

Developmental toxicity of fungicide carbendazim in female mice

This study investigated the developmental toxicity of carbendazim during the organogenesis period in mice. Mated CD-1 mice were administered carbendazim at dose levels 0, 150, 300, and 600 mg/kg/day by gavage. Body weights, weight gains, and feed consumption were significantly reduced in mice administered with 300 and 600 mg/kg/day. Carbendazim exposure increased maternal levels of cholesterol, triglyceride, glucose, protein, and creatinine; and reduced the levels of estradiol and progesterone in the 300- and 600-mg/kg/day groups. In addition, exposure to carbendazim significantly reduced the number of live fetuses and increased the number of dead and resorptions at the same dose levels. External, visceral, and skeleton malformations were observed in the 300- and 600-mg/kg/day. In conclusion, exposure of pregnant mice to carbendazim induced maternal and developmental toxicity at 300 and 600 mg/kg/day. 150 mg/kg/day carbendazim produced a very slight increase in postimplantation loss, which was within the range of historical controls, and no evidence of maternal toxicity.     

Efficacy of Ginkgo biloba on Vaginal Estrous and Ovarian Histological Alterations for Evaluating Anti‐Implantation and Abortifacient Potentials in Albino Female Mice

Ginkgo extract, EGb 761 is known as a vasoregulatory variable for the conventional reproduction therapy. EGb 761 was orally administered in 0 (control), 3.7, 7.4, and 14.8 mg/kg bw/day for 28 days (thereafter mated with normal fertile male), from day 1 to day 7 of pregnancy or from the 10th to 18th day of pregnancy, respectively. Vaginal smears were performed daily. On 20th day of pregnancy, the females were killed by cervical dislocation and their kidneys, liver, brain, placenta, spleen and ovaries were removed and weighed. The ovaries were prepared for histological examinations, and then ovarian follicles were counted. Maternal toxicity, estrous cycle, reproductive hormones, ovarian follicle counts, resorption index, implantation index, fetal viability and fetuses, and placenta mean weights were evaluated. There was a dose‐dependent ovarian toxic effect of EGb 761. Ovarian follicle counts, resorption index, implantation index, fetal viability were significantly reduced in 14.8 mg/kg bw/day dose. Treatment with 14.8 mg/kg bw/day EGb 761 induced disruption of estrous cycle and caused maternal toxicity, in addition to fetal toxicity. Therefore, the data obtained indicate that Ginkgo biloba extract at 14.8 mg/kg bw/day dose level exhibit toxic effect on reproductive cyclicity and could have anti‐implantation and abotifacient properties in female mice.     

Preventive role of aluminosilicate clay against induction of micronuclei and chromosome aberrations in bone-marrow cells of Balb/c mice treated with Zearalenone

Zearalenone (ZEN) is a potent estrogenic metabolite produced by some Fusarium species. No treatment has been successfully employed to remove ZEN contamination in foods. This study was conducted to evaluate the ability of hydrated sodium calcium aluminosilicate (HSCAS) to protect Balb/c mice against cytotoxicity and genotoxicity induced by ZEN. HSCAS was given via the oral route, either alone or simultaneously with a toxic intra-gastric dose of ZEN. The experimental approach comprised treatments of seven groups of mice. The first three groups received 400, 600 or 800 mg/kg bw of HSCAS. Two experimental groups received, respectively, ZEN alone (40 mg/kg bw, representing 8% of the LD(50)) and ZEN in combination with HSCAS at 400 mg/kg bw. The two control groups received distilled water and olive oil, respectively. The positive control groups received colchicine (4 mg/kg bw) for the micronucleus assay and mitomycin C (1mg/kg bw) for the chromosome aberration test. Forty-eight hours after treatment, the femur and tibia were dissected out and analyzed. The results show that ZEN was cytotoxic and genotoxic to Balb/c mice, as indicated by the increase in the frequencies of micronucleated polychromatic erythrocytes (PCEMN) and of chromosomal aberrations in bone-marrow cells. The simultaneous intra-gastric administration of HSCAS with ZEN resulted in a reduction in the number of PCEMN and a decrease of the chromosomal aberration frequency, and an increase in the number of polychromatic erythrocytes (PCE) in bone-marrow cells, compared with those in the group treated with ZEN alone. It could be concluded that HSCAS itself was safe and efficient in the prevention of the toxic effects of ZEN in the gastrointestinal tract.     

A reproductive and developmental screening study of the fungal toxin ochratoxin A in Fischer rats

The presence of the mycotoxin ochratoxin A (OTA) in cereal grains is due to the growth of toxigenic Penicillium mold on stored crops. Human exposure to OTA is higher in infants, toddlers, and children than in adolescents and adults, based on exposure assessments of ng OTA consumed/kg body weight/day. Ochratoxin A is nephrotoxic and teratogenic in animals, but its effects on juveniles exposed during the reproduction and development period have not been studied. To address this, Fischer rats were exposed to 0, 0.16, 0.4, 1.0, or 2.5 mg OTA/kg diet throughout breeding, gestation, and lactation and its adverse effects were assessed in adult rats and their offspring on postnatal day (PND) 21. There were no effects on implantation but post-implantation fetotoxicity was observed in the 2.5 mg/kg dose group, corresponding to a calculated dose of 167.0 μg/kg bw/day in dams. Adverse effects on body and kidney weights and on clinical parameters indicative of renal toxicity were significant in adult rats exposed to 1.0 mg OTA/kg diet (55.2 and 73.3 μg/kg bw/day in adult males and females, respectively) and in PND21 rats at the 0.4 mg/kg dose (33.9 μg/kg bw/day in dams), suggesting that weanling rats were more sensitive to OTA than adults. Overall, nephrotoxicity was the primary effect of OTA in weanling rats exposed throughout gestation and lactation at sub-fetotoxic concentrations in diet.     

Zearalenone induces chromosome aberrations in mouse bone marrow: preventive effect of 17beta-estradiol, progesterone and Vitamin E

The cytogenetic effect of zearalenone (ZEN), a non-steroidal estrogenic mycotoxin, was evaluated in vivo, in mouse bone marrow cells, by assessing the percentage of cells bearing different chromosome aberrations. The studies included different conditions for animal treatment, as follows: (1) single intraperitoneal (ip) injection, (2) repeated ip injections, (3) pre-treatment for 24h with Vitamin E (Vit E), and (4) pre-treatment for 4h with 17beta-estradiol (17beta-Est) or progesterone (Prog). ZEN induced different types of chromosome aberrations, which was concentration-dependent (2-20 mg/kg bw). These doses corresponded to 0.4-4% of the LD50 in the mouse. Interestingly, when the dose of ZEN (40 mg/kg) was fractionated into four equivalent doses (4 x 10 mg/kg bw), into three doses (15 + 10 + 15 mg/kg bw), or into two equivalent doses (2 x 20 mg/kg bw), given every 24 h, the percentage of chromosome aberrations increased significantly. This finding suggests that ZEN proceeds by reversible binding on receptors that could become saturated, and that it damages the chromosomes in a 'hit and go' manner. Furthermore, pre-treatment of animals with 17beta-estradiol or progesterone significantly decreased the percentage of chromosome aberrations, suggesting that (i) these hormones bind to the same cytoplasmic receptors transported into the nucleus to elicit DNA damage, (ii) they may play a role in preventing chromosome aberrations induced by ZEN. Similarly, Vit E prevented these chromosome aberrations indicating that Vit E, previously reported to prevent most of the toxic effects induced by ZEN, may also bind to the same receptors.     

Direct fetal injections of diethylstilbestrol and 17 beta-estradiol: a method for investigating their teratogenicity

The synthetic estrogen, diethylstilbestrol (DES), causes urogenital malformations in humans, primates, and rodents. This study was designed to determine whether these effects of DES are related to its estrogenicity. Therefore, DES (0.1, 1, and 10 micrograms) or the natural estrogen, estradiol (E2) (10 and 100 micrograms) was injected directly into day 19 rat fetuses. In the 6- to 7-week-old female offspring exposed to DES, a dose-related incidence of cleft phallus, hypospadias, and incomplete coiling of oviducts was observed. The single fetal injection of E2 elicited similar urogenital malformations, but was approximately 100-fold less potent than DES. A single subcutaneous dose of either DES (0.025, 0.25, or 2.5 mg/kg) or E2 (2.5 or 25 mg/kg) to dams on day 19 of pregnancy induced a spectrum of malformations similar to that following fetal injection. The offspring of treated dams, but not those injected directly as fetuses, had nonfunctioning ovaries (no corpora lutea) yet vaginal signs of estrous were present. It is concluded that DES can act directly in the fetus and its teratogenicity does not require maternal mediation. Since a high dose of E2 produced similar malformations when given to fetuses, it appears that excess estrogen during prenatal life is teratogenic. Thus, at least those endpoints of the teratogenicity of DES that were measured are accounted for by its estrogenic activity.     

Adsorption of sterigmatocystin by montmorillonite and inhibition of its genotoxicity in the Nile tilapia fish (Oreachromis nilaticus)

Sterigmatocystin (Stg) is closely related to the mycotoxin aflatoxin as a precursor in aflatoxin biosynthesis and classified as an IARC Group-2B carcinogen. The aim of this study was to investigate the efficacy of Egyptian montmorillonite (EM), a clay mineral, to adsorb Stg, to test the stability of the resulting complex under different conditions in vitro, and to utilize the Nile tilapia fish as an in vivo model to evaluate the protective effect of EM against Stg-induced toxicity and clastogenicity. In the in vitro study, four concentrations of EM (0.5, 1, 2 and 4 mg/L aqueous solution) and three concentrations of Stg (5, 10 and 50 microg/ml) were tested. The results show that EM had a high capacity of adsorbing Stg at different concentrations tested. The adsorption ranged from 93.1 to 97.8% of the available Stg in aqueous solutions. The complex was stable at different pHs at 37 degrees C in different organic solvents. An in vivo experiment was conducted to evaluate the ability of EM to prevent the toxicity and chromosomal aberrations induced by Stg in the Nile tilapia fish. Fish received an intragastric dose of EM in corn oil (0.5 mg/kg bw) with or without Stg (1.6 microg/kg bw) twice a week for 4 weeks. Body weight was recorded during dosing, and blood and tissue samples were collected at the end of treatment. Stg residues were determined in fish tissue. The results show that Stg was toxic and clastogenic to fish as indicated by the significant decrease of body weight and the increase in frequencies of micronucleated red blood cells (MN RBC) and chromosomal aberrations in the kidney. The intragastric administration of EM combined with Stg to fish resulted in a reduction of the number of MN RBC and the frequency of chromosomal aberrations in the kidney compared with the group treated with Stg alone. It could be concluded that EM itself was safe and successful in the prevention of Stg toxicity and clastogenicity.     

Zearalenone induces chromosome aberrations in mouse bone marrow: preventive effect of 17β-estradiol, progesterone and Vitamin E

The cytogenetic effect of zearalenone (ZEN), a non-steroidal estrogenic mycotoxin, was evaluated in vivo, in mouse bone marrow cells, by assessing the percentage of cells bearing different chromosome aberrations. The studies included different conditions for animal treatment, as follows: (1) single intraperitoneal (ip) injection, (2) repeated ip injections, (3) pre-treatment for 24 h with Vitamin E (Vit E), and (4) pre-treatment for 4 h with 17β-estradiol (17β-Est) or progesterone (Prog). ZEN induced different types of chromosome aberrations, which was concentration-dependent (2–20 mg/kg bw). These doses corresponded to 0.4–4% of the LD₅₀ in the mouse. Interestingly, when the dose of ZEN (40 mg/kg) was fractionated into four equivalent doses (4 × 10 mg/kg bw), into three doses (15 + 10 + 15 mg/kg bw), or into two equivalent doses (2 × 20 mg/kg bw), given every 24 h, the percentage of chromosome aberrations increased significantly. This finding suggests that ZEN proceeds by reversible binding on receptors that could become saturated, and that it damages the chromosomes in a ‘hit and go’ manner. Furthermore, pre-treatment of animals with 17β-estradiol or progesterone significantly decreased the percentage of chromosome aberrations, suggesting that (i) these hormones bind to the same cytoplasmic receptors transported into the nucleus to elicit DNA damage, (ii) they may play a role in preventing chromosome aberrations induced by ZEN. Similarly, Vit E prevented these chromosome aberrations indicating that Vit E, previously reported to prevent most of the toxic effects induced by ZEN, may also bind to the same receptors.     

Evaluation of genotoxic effects of fumagillin by cytogenetic tests in vivo

Fumagillin is a naturally secreted antibiotic of the fungus Aspergillus fumigatus. It is used in veterinary medicine against microsporidiosis of bees and fish. In this study, the genotoxicity of fumagillin (in the form of fumagillin dicyclohexylamine) was evaluated in mouse bone-marrow cells using the mitotic index (MI), the chromosome aberration (CA) assay, and the micronucleus (MN) test. Fumagillin was administered to BALB/c mice by gavage, at doses of 25, 50, 75 mg/kg body weight (bw), repeated for 7 days at 24-h intervals, with water-sugar syrup as a negative control and cyclophosphamide (40 mg/kg bw) as a positive control. All experimental doses of fumagillin induced a significant decrease (p<0.001) in MI (3.47+/-0.04%, 3.17+/-0.01%, and 2.27+/-0.02%, respectively) in comparison with the negative control (6.00+/-0.01%). Fumagillin significantly (p<0.001) increased the frequency of MN (4.98+/-0.35, 8.45+/-0.57, and 12.02+/-0.37, respectively) over negative control (1.04+/-0.28). Significantly increased frequencies (p<0.01 or p<0.001) of numerical chromosomal aberrations (aneuploidies and polyploidies) and structural chromosomal aberrations such as gaps, breaks, and centric rings were observed at the highest experimental dose of fumagillin (75 mg/kg bw) compared with the negative control. However, with respect to the induction of Robertsonian translocations, both the intermediate (50 mg/kg bw) and highest (75 mg/kg bw) experimental dose caused a significant (p<0.001) increase (7.12+/-0.26 and 9.00+/-0.10, respectively) in comparison with the negative control (0.00+/-0.00). Chromosomes 4 and 19 participated in these Robertsonian translocations. Regarding total cytogenetic changes, a significant increase (p<0.001) was observed in both the intermediate dose group (17.36+/-1.83) and the highest dose group (59.49+/-1.92) compared with the negative control (7.00+/-1.35). These results suggest that fumagillin has genotoxic (clastogenic) potential in mammals in vivo.     

Conduct and interpretation of a dermal developmental toxicity study with KBR 3023 (a prospective insect repellent) in the Sprague-Dawley rat and Himalayan rabbit

KBR 3023, 1-(1-methyl-propoxycarbonyl)-2-(2-hydroxyethyl)piperidine, a prospective insect repellent being developed by Bayer Corporation, was evaluated for developmental toxicity in the Sprague-Dawley rat and Himalayan rabbit. As the intended human usage of the test compound is topical, the test systems were exposed to the compound via the dermal route. Specifically, the animals were fitted with Elizabethan collars, to reduce the likelihood of oral ingestion, and dermally administered either 0, 50, 200, or 400 mg KBR 3023/kg (rat), and 0, 50, 100, or 200 mg KBR 3023/kg (rabbit) on gestation days 0-19 (rat) and 0-28 (rabbit). Maternal toxicity, as demonstrated by clinical signs and changes in body weight gain and food consumption during gestation, was characterized. Animals were sacrificed on gestation day 20 (rat) and 29 (rabbit), at which time fetuses were removed by cesarean section and a gross maternal necropsy was performed. All fetuses were evaluated for external anomalies. With rats, approximately half of each litter was examined for visceral effects; the other half underwent a skeletal examination. With rabbits, all fetuses underwent both visceral and skeletal examinations. No effects were observed on maternal body weight gain or food consumption in either the rat or rabbit. In the rat, dermal effects (scaling/sloughing), were observed at the dose site of all test substance-treated groups from approximately gestation day 7 until termination of the study. Also noted were an increase in both absolute and relative liver weights in rats in the 400-mg/kg dose group. In the rabbit, dermal effects (slight erythema, squamous and cracked skin) were noted at the dose site of virtually all does administered the test compound, from approximately gestation day 7 until termination. Also observed in the rabbits was a potentially compound-related increase in soft stool, particularly at the highest dose level. In both species, there were no statistically significant effects on any reproductive parameters, or any embryonic endpoints, including pre/post-implantation loss and resorptions. There were no statistically significant effects on litter size or fetal or placental weights. No test compound-related external, visceral, or skeletal findings were observed. No effect on the individual fetal or litter incidence of total malformations or variations was observed and there was no difference in the incidence of malformations between males and females. KBR 3023 Technical, administered as described in these studies, produced maternal effects in the rat (liver weight) at a dose of 400 mg/kg, and in the rabbit (soft stool) in the 200-mg/kg dose group. No developmental toxicity was observed at any dose level.     

Early-in-life dietary zinc deficiency and supplementation and mammary tumor development in adulthood female rats

Zinc deficiency during pregnancy and postnatal life can adversely increase risk of developing human diseases at adulthood. The present study was designed to evaluate whether dietary zinc deficiency or supplementation during the pregnancy, lactation and juvenile stages interferes in the development of mammary tumors induced by 7,12-dimethylbenzanthracene (DMBA) in female Sprague–Dawley (SD) rats. Pregnant female SD rats were allocated into three groups: zinc-adequate diet (ZnA - 35-mg/kg chow), zinc-deficient diet (ZnD - 3-mg/kg chow) or zinc-supplemented diet (ZnS - 180-mg/kg chow) during gestational day 10 (GD 10) until the litters' weaning. Female offspring received the same diets as their dams until postnatal day (PND) 51. At PND 51, the animals received a single dose of DMBA (50 mg/kg, ig) and zinc-adequate diets. At PND 180, female were euthanized, and tumor samples were processed for histological evaluation and gene expression microarray analysis. The ZnD induced a significant reduction in female offspring body weight evolution and in mammary gland development. At late in life, the ZnD or ZnS did not alter the latency, incidence, multiplicity, volume or histological types of mammary tumors in relation to the ZnA group. However, the total tumor number in ZnS group was higher than in ZnA group, accompanied by distinct expression of 4 genes up- and 15 genes down-regulated. The present findings indicate that early-in-life dietary zinc supplementation, differently to zinc deficiency, has a potential to modify the susceptibility to the development of mammary tumors induced by DMBA.