Axial skeletal malformations induced by acetazolamide in rabbits.

In order to evaluate the teratogenic potential of acetazolamide in rabbits, three groups of 18 artificially inseminated females were treated orally with 50, 100, or 150 mg/kg/day of acetazolamide on days 6-18 of gestation. These doses induced maternal acidosis and electrolyte changes, consistent with those reported in rats and considered to be a result of carbonic anhydrase inhibition, as well as reductions in maternal body weight gain. At cesarean sections, average fetal body weights in the acetazolamide groups were dose-dependently decreased compared with controls. There were no effects of acetazolamide on embryonic survival or external morphology of live fetuses. In the fetal skeletal examination, thoracic and lumbar vertebral malformations occurred in 0.7%, 3.9%, and 6.1% of fetuses in the 50, 100, and 150 mg/kg/day groups, respectively, compared with none in the control group. In addition, missing vertebra was seen in a small number of fetuses in the 100 and 150 mg/kg/day groups. These axial skeletal malformations were, in some cases, associated with costal malformations. These results indicate that acetazolamide at maternotoxic doses can produce axial skeletal malformations in the rabbit.     

Teratology of intravaginally administered contraceptive jelly containing octoxynol-9 in rats

Octoxynol-9, a nonionic surfactant used as a spermicidal agent in ORTHO-GYNOL (registered trademark) Contraceptive Jelly (Ortho Pharmaceutical Corporation, Raritan, NJ), was administered intravaginally to pregnant Sprague Dawley COBS CD rats at dosages of 0.5 mg/kg/day and 5 mg/kg/day (two-thirds and six times the clinical dosage) on days 6-15 of gestation in order to assess its teratogenic potential. Untreated, sham, and vehicle control groups were also incorporated into the study protocol. No meaningful differences were observed between the treated and control groups in maternal toxicity, maternal reproductive parameters, fetal toxicity, and the incidence of external, visceral, and skeletal malformations or developmental variations. It is concluded that octoxynol-9 is not embryotoxic or teratogenic when administered intravaginally to rats during organogenesis.     

Embryotoxic and teratogenic effects of aluminum nitrate in rats upon oral administration

In order to determine the embryotoxic and teratogenic potential of aluminum, pregnant Sprague-Dawley rats were treated by gavage with a daily dose of 180, 360, or 720 mg/kg of aluminum nitrate from the sixth through to the fourteenth day of gestation. Fetal examinations were performed on day 20. The number of corpora lutea, total implants, and resorptions as well as the number of live and dead fetuses in the treated animals were not significantly different from the control group. Therefore, embryolethality of aluminum cannot be induced (as a measure of percent dead and resorbed fetuses). However, exposure of rats to aluminum nitrate resulted in decreased fetal body weight and increased the incidence and types of external, visceral, and skeletal malformations and variations in all the treated groups. Consequently, teratogenic effects of aluminum-nitrate administration may result in rats given high oral doses that induce concomitant maternal toxicity.     

Evaluation of developmental toxicity in rats exposed to the environmental estrogen bisphenol A during pregnancy.

Bisphenol A (BPA) is an essential component of epoxy resins used in the lacquer lining of metal food cans, as a component of polycarbonates, and in dental sealants. The present study was conducted in an attempt to evaluate the adverse effects of the environmental estrogen BPA on initiation and maintenance of pregnancy and embryofetal development after maternal exposure during the entire period of pregnancy in Sprague-Dawley rats. The test chemical was administered by gavage to mated females from days 1 to 20 of gestation (sperm in varginal lavage = day 0) at dose levels of 0, 100, 300, and 1000 mg/kg. All females were subjected to caesarean section on day 21 of gestation and their fetuses were examined for external, visceral and skeletal abnormalities. In the 1000 mg/kg group, significant toxic effects including abnormal clinical signs, decreased maternal body weight and body weight gain, and reduced food consumption were observed in pregnant rats. An increase in pregnancy failure was also found in the successfully mated females. In addition, increased number of embryonal deaths, increased postimplantation loss, reduced litter size and fetal body weight, and decreased number of fetal ossification centers of several skeletal districts were seen. On the contrary, no significant changes induced by BPA were detected in the number of corpora lutea and implantation sites and by fetal morphological examinations. In the 300 mg/kg group, suppressed maternal body weight and body weight gain, decreased food intake and reduced body weight of male fetuses were seen. There were no adverse signs of either maternal toxicity or developmental toxicity in the 100 mg/kg group. It was concluded that BPA administration during the entire period of pregnancy in rats produced pregnancy failure, pre- and postimplantation loss, fetal developmental delay and severe maternal toxicity, but no embryo-fetal dysmorphogenesis at an oral exposure level of 1000 mg/kg.     

Reduction of all-trans-retinoic acid-induced teratogenesis in the rat by glycine administration

BACKGROUND: Prenatal rat embryo exposure to retinoids induces severe malformations in various organs; the most active and teratogenic metabolite is all-trans-retinoic acid (atRA). The mechanisms of this embryopathy are only partly known. In the present study, the influence of glycine on the teratogenicity of atRA was investigated. METHODS: Embryos from 5 groups of white rats were studied: Group 1 remained untreated; Group 2 received glycine 2% in drinking water ad libitum from the first gestational day (GD 1); Group 3 was administered vehicle (corn oil); Group 4 was treated with atRA (50 mg/kg of body weight) injected (IP); and Group 5 was treated with atRA (50 mg/kg of body weight IP) plus glycine 2% in drinking water ad libitum from GD 1. atRA was administrated daily from GD 8-10. Dams were killed on the 21st day of pregnancy, and their fetuses were examined to detect external, visceral, and skeletal malformations. RESULTS: The results show that the atRA-administered dose is not toxic for the dams, and that although fetal death was not observed, it produced abnormalities in the fetuses. Glycine reduced atRA-induced teratogenic effects (external and skeletal defects). CONCLUSIONS: The results indicate that glycine effectively reduces the teratogenic effects of atRA. Thus, glycine might be useful for the prevention of vitamin A teratogenicity.     

Preventive effect of piperonyl butoxide on cyclophosphamide-induced teratogenesis in rats

BACKGROUND: Cyclophosphamide induces fetal defects through metabolic activation by cytochrome P-450 monooxygenases (CYP). The effects of piperonyl butoxide (PBO), a CYP inhibitor, on the fetal development and external, visceral, and skeletal abnormalities induced by cyclophosphamide were investigated in rats. METHODS: Pregnant rats were daily administered PBO (400 mg/kg) by gavage for 7 days (the 6th to 12th day of gestation), and intraperitoneally administered with cyclophosphamide (12 mg/kg) 4 h after the final treatment. On the 20th day of gestation, maternal and fetal abnormalities were determined by Cesarean section. RESULTS: Cyclophosphamide reduced fetal body weights by 30–40% without increasing resorption or death. In addition, it induced malformations in live fetuses: 100, 98, and 98.2% of the external (head and limb defects), visceral (cerebroventricular dilatation, cleft palate, and renal pelvic/ureteric dilatation), and skeletal (acrania, vertebral/costal malformations, and delayed ossification) abnormalities, respectively. The pre-treatment of PBO greatly decreased mRNA expression and activity of hepatic CYP2B, which metabolizes cyclophosphamide into teratogenic acrolein and cytotoxic phosphoramide mustard. Moreover, PBO remarkably attenuated cyclophosphamide-induced body weight loss and abnormalities of fetuses; score 3.57 versus 1.87 for exencephaly, 75.5% versus 42.5% for limb defects, 65.3% versus 22% for cerebroventricular dilatation, 59.2% versus 5.1% for cleft palate, score 1.28 versus 0.93 for renal pelvic/ureteric dilatation, 71.9–82.5% versus 23–45.9% for vertebral/costal malformations, and 84.2% versus 57.4% for delayed ossification in cyclophosphamide alone and PBO co-administration groups. CONCLUSIONS: These results suggest that repeated treatment with PBO may improve cyclophosphamide-induced body weight loss and malformations of fetuses by down-regulating CYP2B. Birth Defects Res (Part B) 86:402–408, 2009. © 2009 Wiley-Liss, Inc.     

A teratogenicity study on hydroxyurea and diphenylhydantoin in cats

Hydroxyurea, an antitumor drug and known teratogen in rat, miniature swine and dog, and diphenylhydantoin, a teratogen in mouse and rat, were assessed for teratogenic effects in cat. Pregnancies were induced, by synchronizing gonadotropin-stimulated estrus and ovulation with natural copulations. Hydroxyurea at 50 or 100 mg/kg, and sodium diphenylhydantoin at 1 or 2 mg/kg dosages, were administered orally in single daily doses from gestation days 10-22. Appropriate controls given empty capsules, were included for each drug. Cats were necropsied on gestation day 43. Fetuses were examined for external, visceral and skeletal malformations. Hydroxyurea at 50 mg/kg dose produced a low teratogenic activity and at 100 mg/kg a high incidence of non-pregnancy and resorptions with, consequently, fewer live fetuses. Diphenylhydantoin gave no clear evidence of teratogenicity at any test dose but was embryolethal at the maternally toxic dose of 2 mg/kg. So far, studies conducted suggest that the cat is a useful species for screening drugs and chemicals for their teratogenic potential.     

Developmental toxicity evaluation of trimethylolpropane caprylate caprate in Sprague-Dawley rats

The developmental toxicity potential of trimethylolpropane caprylate caproate (TMPCC, CAS no. 11138-60-6) was evaluated in rats. Sprague-Dawley rats were administered TMPCC in a corn oil suspension dermally at dose levels of 0, 200, 600, or 2,000 mg/kg/day on gestation days (GD) 6-15 (sperm positive day=GD 0). Caesarean sections were performed on GD 20 and fetuses were evaluated for viability, growth, and external, visceral, and skeletal abnormalities. Each group consisted of 25 females, with at least 22 per group being pregnant. The two highest dose levels caused some local irritation at the site of application, but no decreases in maternal weight gain. There were no differences from control in any of the developmental parameters measured, including embryo/fetal viability, fetal weight, malformations, or variations. TMPCC did not cause any developmental toxicity in the Sprague-Dawley rat at dermal dosages up to 2,000 mg/kg/day.     

The effects of continuous exposure to 20-kHz sawtooth magnetic fields on the litters of CD-1 mice.

Mated CD-1 mice were exposed to 20-kHz sawtooth magnetic fields similar to those associated with video display terminals (VDT). Four groups of animals were continuously exposed from day 1 to day 18 of pregnancy to field strengths of 0, 3.6, 17, or 200 microT. There were no less than 185 mated dams in each exposure group. On day 18, the dams were sacrificed and assessed for weight gain and pregnancy. The litters were evaluated for numbers of implantations, fetal deaths and resorptions, gross external, visceral and skeletal malformations, and fetal weights. There were no less than 140 pregnant females in each group, and there were no significant differences between any of the exposure groups and the sham group (0 microT) for any of the end points. The results of this study do not support the hypothesis that the 20-kHz VLF magnetic fields associated with video display terminals are teratogenic in mammals.     

Teratogenicity of zinc deficiency in the rat: study of the fetal skeleton

Zinc deficiency (ZD) is teratogenic in rats, and fetal skeletal defects are prominent. This study identifies fetal skeletal malformations that affect calcified and non-calcified bone tissue as a result of gestational zinc deficiency in rats, and it assesses the effect of maternal ZD in fetal bone calcification. Pregnant Sprague-Dawley rats (180-250 g) were fed 1) a control diet (76.4 micrograms Zn/g diet) ad libitum (group C), 2) a zinc-deficient diet (0 microgram/g) ad libitum (group ZD), or 3) the control diet pair-fed to the ZD rats (group PF). On day 21 of gestation, laparotomies were performed. Fetuses were weighed, examined for external malformations, and stained in toto with a double-staining technique for the study of skeletal malformations. Maternal and fetal tissues were used for Zn, Mg, Ca, and P determinations. Gross external malformations were present in 97% of the ZD fetuses. No external malformations were found in fetuses from groups C and PF. Ninety-one percent of cleared ZD fetuses had multiple skeletal malformations, whereas only 3% of the fetuses of group PF had skeletal defects; no skeletal malformations were found in fetuses from group C. Some of the skeletal malformations described in the ZD fetuses, mainly affecting non-calcified bone, were not mentioned in previous reports, thus stressing the importance of using double-staining techniques. Examination of stained fetuses and counting of ossification centers revealed important calcification defects in ZD fetuses. These effects were confirmed by lower Ca and P concentrations in fetal bone with alteration of the Ca:P ratio.     

Developmental toxicity evaluation of butylparaben in Sprague-Dawley rats

The developmental toxicity potential of butylparaben (CAS No. 94-26-8) was evaluated in rats. Sprague-Dawley rats were administered butylparaben in 0.5% carboxymethylcellulose by oral gavage at dose levels of 0, 10, 100, or 1,000 mg/kg/day on gestation days (GD) 6-19 (sperm positive day = GD 0). Caesarean sections were performed on GD 20 and fetuses were evaluated for viability, growth, and external, visceral, and skeletal abnormalities. Each group consisted of 25 females, with at least 21 per group being pregnant. The highest dose level caused decreases in maternal weight gain during some of the measurement intervals and was statistically significant during the GD 18-20 interval. Maternal food consumption was significantly decreased in the highest dose group over the dosing period (GD 6-20). There were no differences from control in any of the developmental parameters measured, including embryo/fetal viability, fetal weight, malformations, or variations. Based on the results of this study, the maternal NOAEL for butylparaben was 100 mg/kg/day. Butylparaben does not have the potential to cause developmental toxicity in the Sprague-Dawley rat at oral dosages up to 1000 mg/kg/day.     

Micro‐computed tomographic evaluation of fetal skeletal changes induced by all‐trans‐retinoic acid in rats and rabbits

BACKGROUND: Our laboratory has been conducting positive control studies to evaluate the utility of micro‐computed tomography (micro‐CT) for qualitative evaluation of fetal skeletal morphology. All‐trans‐retinoic acid (atRA) was used to produce a different spectrum of defects compared to our previous studies with boric acid and hydroxyurea. METHODS: Groups of five mated Crl:CD(SD) female rats each were administered vehicle or atRA (2.5–50 mg/kg) on GD 10, and groups of four mated Dutch Belted rabbits each were dosed with vehicle or atRA (6.25–25 mg/kg) on GD 9. Cesarean sections were performed on GD 21 and 28, respectively. Following external examination the viscera were removed and fetuses scanned in a micro‐CT imaging system. Fetuses were subsequently stained with alizarin red. Skeletal morphology was evaluated by each method without the knowledge of treatment group. Total bone mineral content (BMC) of each fetus was quantitated using the micro‐CT images. RESULTS: In rats there were dose‐related increases in the incidence of extra lumbar vertebra and non‐dose‐related increases in supernumerary ribs at all dose levels. There were decreases in mean number of ossified sacrocaudal vertebra at ≥5 mg/kg, and increases in skull bone malformations at ≥10 mg/kg. Rabbits were less sensitive on a mg/kg basis since skeletal malformations and a decrease in mean number of ossified sacrocaudal vertebra were observed only in the 25‐mg/kg group. Micro‐CT evaluation detected essentially the same incidence of skeletal abnormalities as seen in alizarin red‐stained rat and rabbit fetuses. BMC analysis showed a trend toward slight decreases in atRA‐treated rats, but no notable changes in rabbits. CONCLUSIONS: These results add support to our previous work that demonstrates that micro‐CT imaging can effectively assess rat and rabbit fetal skeletal morphology. Birth Defects Res (Part B) 89:408–417, 2010. © 2010 Wiley‐Liss, Inc.     

Teratogenic and postnatal developmental studies of morphine in Sprague-Dawley rats

The teratogenic and postnatal developmental effects of morphine exposure during pregnancy were studied in Sprague-Dawley rats in three separate experiments using chronically implanted osmotic minipumps in order to avoid respiratory depression. In the first experiment, the teratogenic effects of three different morphine dosages were studied: a low dose (10 mg/kg/day), an intermediate dose (35 mg/kg/day), and a high dose (70 mg/kg/day). On day 5 of gestation, osmotic minipumps that deliver their contents at a constant rate for 15 days were implanted subcutaneously on the back of the rats. On day 20 of gestation, cesarean sections were performed, reproductive indices were determined, and fetuses were examined externally and then preserved for subsequent visceral and skeletal examinations. The pregnancy rate was significantly reduced at the intermediate and high doses to 57% and 6%, respectively (control, 83%). No teratogenic effects were observed at any dosage, but growth retardation was present in the intermediate-dose group. In the second experiment, postnatal survival of the offspring of dams treated with either normal saline, morphine (35 mg/kg/day), or the synthetic opioid, fentanyl (500 micrograms/kg/day) were studied. Offspring of morphine-treated dams had a significantly higher mortality rate, which peaked at 56% within 2 days. No effect was seen after fentanyl treatment. In the third experiment, pups of morphine-treated dams were cross-fostered by saline-treated dams; the postnatal mortality in offspring of morphine-treated dams remained high (62%). Our results indicate that doses of morphine up to 35 mg/kg/day delivered by osmotic minipumps are not teratogenic in rats but cause other adverse fetal effects that result in increased postnatal mortality.     

Licorice extract increases cyclophosphamide teratogenicity by upregulating the expression of cytochrome P-450 2B mRNA

BACKGROUND: Since cyclophosphamide is metabolically activated to teratogenic acrolein and cytotoxic phosphoramide mustard by cytochrome P‐450 type 2B (CYP2B), we assessed the effects of licorice, a CYP2B inducer, on the fetal defects induced by cyclophosphamide. METHODS: Pregnant Sprague‐Dawley rats were daily administered with licorice (100 mg/kg) by gavage for 7 days, from the 6th to 12th day of gestation, and intraperitoneally administered with cyclophosphamide (11 mg/kg) 1 hr after the final licorice treatment. On the 20th day of gestation, maternal and fetal abnormalities were determined by Cesarian section. RESULTS: Cyclophosphamide was found to reduce fetal and placental weights without increasing resorption or death. In addition, it induced malformations in live fetuses; 93.8, 41.1, and 100% of the external (skull and limb defects), visceral (cleft palate and ureteric dilatation), and skeletal (acrania, vertebral/costal malformations, and delayed ossification) abnormalities, respectively. When pre‐treated with licorice, cyclophosphamide‐induced body weight loss and abnormalities of fetuses were remarkably aggravated. Moreover, repeated treatment with licorice greatly increased mRNA expression and activity of hepatic CYP2B. CONCLUSIONS: The results indicate that repeated intake of licorice may aggravate cyclophosphamide‐induced body weight loss and malformations of fetuses by upregulating CYP2B. Birth Defects Res (Part B) 92:553–559, 2011. © 2011 Wiley Periodicals, Inc.     

Maternal treatment with teratogen causes congenital malformations in mouse embryos

Heterozygotes for the tail-short (Ts) mutant gene in the Balb/c strain have minor skeletal defects and a short, kinky tail. If heterozygote Ts/+ mothers are mated with normal-tail +/+ males and are treated with teratogenic doses of trypan blue on the eighth day of pregnancy, the mutant F1 heterozygotes develop exencephaly, folded neural tube and spina bifida significantly more often than non-mutants. This is indicative of gene-teratogen interaction, with the Ts gene increasing the embryo's susceptibility to trypan blue-induced neural tube defects.     

Developmental toxicity of orally administered technical dimethoate in rats

BACKGROUND: Dimethoate (O,O-dimethyl-S-(N-methylcarbamoyl-methyl) phosphorodithioate), an organophosphate insecticide, was examined for its potential to produce developmental toxicity in rats after oral administration. METHODS: Pregnant Fischer 344 rats were given sublethal doses of 0 (corn oil), 7, 15, and 28 mg/kg/day dimethoate by gavage on gestation days (GD) 6-15. Maternal effects in 15 and 28 mg/kg/day dose groups included cholinergic signs such as tremors, diarrhea, weakness, and salivation, and depression in the maternal and fetal brain acetylcholinesterase (AChE) activities. Other maternal toxicity that included reduction in body weight and feed consumption was observed only in the treated group of 28 mg/kg/day. No maternal toxicity was apparent in the 7 mg/kg/day dose group. RESULTS: Maternal exposure to dimethoate during organogenesis significantly affected the number of live fetuses, early resorption, and mean fetal weight in the 28 mg/kg/day dose group. No external, visceral, and skeletal abnormalities were observed in any of the treated groups compared to the control. CONCLUSIONS: On the basis of the present results dimethoate can produce clinical signs of toxicity and significant inhibition of the maternal and fetal AChE activities in dose groups of 15 and 28 mg/kg/day and showed fetotoxicity without teratogenic effects at 28 mg/kg/day.     

Effects of natalizumab,an α4 integrin inhibitor,on the development of Hartley guinea pigs

BACKGROUND : Natalizumab is a humanized monoclonal immunoglobulin G4 antibody directed against the human α4 integrin subunit, disrupting interaction with its ligands. Natalizumab inhibits the interaction of α4 integrins with fibronectin, vascular cell adhesion molecule-1, and mucosal addressin cellular adhesion molecule-1, which are of potential importance in development. Two studies were undertaken to evaluate the effects of natalizumab on embryo/fetal development in guinea pigs. METHODS : In the first study, pregnant guinea pigs were treated with intravenous injections of 3, 10, or 30 mg/kg natalizumab or vehicle every other day from gestational day (GD) 4 to 30. In the second study, females were treated on alternate days starting at least 28 days prior to mating through GD 30. Fetal examinations and histopathologic examination of the liver, heart, thymus, spleen, and intestinal tract were performed following maternal euthanasia on GD 59–62. RESULTS : Natalizumab had no significant effect on embryo/fetal development in either study. Exposure to natalizumab during organogenesis did not result in treatment-related external, visceral, or skeletal variations or malformations or histopathologic changes. CONCLUSION : No fetotoxicity or teratogenic effects were attributable to natalizumab in these studies. Birth Defects Res (Part B)86: 98-107, 2009. © 2009 Wiley-Liss, Inc.     

Developmental toxic effects of antifungal flusilazole administered by gavage to mice

BACKGROUND: The developmental toxicity of flusilazole was studied in CD-1 mice after oral administration. METHODS: Pregnant mice were given flusilazole at doses of 0 (corn oil), 10, 20, and 40 mg/kg/day, by gavage, on gestational days (GD) 6-15. RESULTS: Maternal toxicity, as evidenced by reduction in body weight gain and signs of toxicity, was observed at the middle- and high-dose groups. No significant incidence of resorptions or death was observed in any of dose groups. There was a pronounced reduction in fetal weight, which was significantly lower than control from 20 and 40 mg/kg/day. There was no significant increase in the incidence of fetuses with external or visceral malformations in any of dose groups, but there was a significant increase in the incidence of skeletal malformations was observed at 20 and 40 mg/kg/day. CONCLUSIONS: The results of this study reported marked maternal toxicity, growth retardation, and skeletal abnormalities in the mid- and high-dose groups. It seems likely that marked maternal toxicity contributed to the observed alterations in fetal growth retardation and skeletal development. The no-observed-effect level in the present study for maternal and developmental toxicity was 10 mg/kg/day.     

Embryotoxicity of oral administered chlorothalonil in mice

BACKGROUND: Chlorothalonil (2,4,5,6-tetrachloroisophthalonitril), the nephrotoxic fungicide, was examined for its potential to produce developmental toxicity in mice after oral administration. METHODS: Pregnant ICR (CD-1) mice were given sublethal doses of 0 (corn oil), 100, 400, and 600 mg/kg/day chlorothalonil by gavage on gestation days (GD) 6-15. RESULTS: Maternal effects in 400 and 600 mg/kg/day dose groups included signs of toxicity such as weakness and depression in the maternal activity, and reduction in body weight and weight gain. No maternal toxicity was apparent in the 100 mg/kg/day dose group. Maternal exposure to chlorothalonil during organogenesis significantly affected the number of live fetuses, early resorption, and mean fetal weight in the 400 and 600 mg/kg/day dose groups. No external, visceral, and skeletal abnormalities were observed among any of the treated groups compared to the control. CONCLUSIONS: On the basis of the present results chlorothalonil can produce clinical signs of toxicity and fetotoxicity without teratogenic effects at 400 and 600 mg/kg/day dose groups.