Strain differences in teratogenic susceptibility to trypan blue between WM and BDIX rat strains

Female rats of WM (Wistar-Mishima)/Nem strain were mated with WM/Nem (group W) or BDIX/Nem males (group WB), and BDIX/Nem females were mated with BDIX/Nem (group B) or WM/Nem males (group BW). On day 8 of gestation, pregnant females were treated intraperitoneally with 1% aqueous solution of trypan blue at a dose of between 20 and 120 mg/kg of body weight. On day 20 of gestation, fetuses were examined for external, visceral, and skeletal malformations. In group W, fetal mortality increased dose dependently at doses higher than 20 mg/kg, and incidences of external, visceral, and skeletal malformations were significantly higher than control at doses of 30 mg/kg and more. In group B, fetal mortality and the incidence of external malformations were significantly higher than control only in the group treated with 120 mg/kg, and no significant increase of visceral and skeletal malformations was shown. It was confirmed that BDIX strain is much more resistant to trypan blue teratogenicity than WM strain. In group BW, nearly the same teratogenic effects were shown as in group W in terms of fetal mortality and incidence of malformations. However, in group WB, teratogenic effects were not so remarkable as in group BW, suggesting patroclinous effects in teratogenic susceptibility to trypan blue. In group BW, sex differences in teratogenic susceptibility were found; male fetuses were more susceptible to trypan blue than females.     

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.     

Cocaine as a cause of congenital malformations of vascular origin: experimental evidence in the rat

Cocaine hydrochloride was administered to pregnant Sprague-Dawley rats as a single intraperitoneal dose or as two doses 1-4 hours apart. A single dose administered on day 16 of gestation was teratogenic in a dose-dependent manner, with 40 mg/kg being a no-effect dose and 50 mg/kg the lowest teratogenic dose; 80 mg/kg was lethal to the dam. Forty-eight hours after exposure to a teratogenic dose on day 16 of pregnancy, the fetuses showed severe hemorrhage and edema in the their extremities, particularly the footplates, tail, genital tubercle, and upper lip/nose. When the fetuses were examined on day 21 of gestation, the main externally visible malformations were reduction deformities of the limbs and tail. When two doses of cocaine were administered 1-4 hours apart, the incidence of affected fetuses increased as the time interval between the two doses decreased. Two doses of cocaine administered 2 hours apart were not teratogenic on day 9, 10, 11, 12, 13, or 14 of gestation but did induce reduction deformities on days 15, 16, 17, 18, or 19. The same dose administered 1 hour apart was teratogenic on days 14-19. In general, cocaine administration on gestational days 14, 15, or 16 induced more severe and more widespread hemorrhage and edema than administration on days 17, 18, or 19. In the latter cases, damage was restricted to the distal parts of the hindlimb digits and the tail. The results show that in the rat cocaine is only teratogenic during the late organogenic or postorganogenic period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Action of the phenothiazine derivative methophenazine on prenatal development in rats.

Single doses of 100-400 mg/kg or multiple doses of 10 or 50 mg/kg of the phenothiazine derivative methophenzaine were given per osto Wistar rats at various times on the 7th-14th days fo gestation and the fetuses examined near term. Results indicated that methophenazine was mainly embryolethal when administered on the 8th-11th days, and was teratogenic at later times, producing types of malformations that depended on the day of treatment, the most susceptible period being the 13th and 14th days of gestation. Teratogenicity occurred only when the dosages were highly toxic to the pregnant rats. Ribovlavin given ip on the 14th day significantly reduced the embryolethal but not the teratogenic action of methophenazine.     

Transplacental exposure to methylene blue initiates teratogenesis in the mouse: preliminary evidence for a mechanistic implication of cyclic GMP pathway disruption

BACKGROUND: The vital dye methylene blue (MB) has been shown to be teratogenic when injected into the amnion in the second trimester. On the other hand, the teratogenic potential of transplacental exposure to MB has not been determined. METHODS: MB was administered subcutaneously to ICR (CD-1) mice at 0, 35, 50, 60, or 70 mg/kg on gestation day 8 (plug day = day 0). Teratological assessments were carried out at term gestation, on gestation day 18. Since MB inhibits soluble guanylate cyclase enzyme activity, zaprinast (ZPN), a selective cGMP-phosphodiesterase type V inhibitor, was administered to prevent developmental disorders initiated by MB at 50 mg/kg. RESULTS: There was a dose-dependent increment of embryolethality. MB treatment also produced axial skeleton and neural tube defects. Coadministration of ZPN (20 mg/kg per three times) abolished completely MB-induced neural tube defects and reduced by one-half the incidence of fetuses exhibiting axial skeletal defects. ZPN did not provide protection against the embryocidal effects of MB. CONCLUSIONS: This study showed that transplacental exposure to MB is teratogenic in the mouse. Coadministration of ZPN prevented partly MB-induced teratogenesis, which supports the hypothesis that imbalance of cGMP pathway accounts, in part, for the teratogenicity of MB.     

Embryotoxic effects of sodium metavanadate administered to rats during organogenesis

Pregnant Sprague-Dawley rats were given orally a daily dose of 0, 5, 10 or 20 mg NaVO3/kg from the sixth through the fourteenth day of pregnancy. Fetal examinations were performed on day 20 of gestation. Sodium metavanadate was neither embryolethal nor teratogenic in rats when administered orally at 20 mg/kg/day or lower. Nevertheless, this dose was embryotoxic.     

Teratogenic effects of a single oral administration of methylmercuric chloride in mice.

The teratogenic effects of methylmercuric chloride (MMC) given orally as a single dose to pregnant ICR mice on day 10 of gestation were examined. The doses tested were 25, 20, 15 and 10 mg/kg. Controls received distilled water orally. Each group consisted of 20 females. Fetuses were taken on day 18 of gestation for teratological study. The number of resorbed or dead embryos was moderately increased in the 25 mg/kg group. Fetuses from dams given 25, 20 and 15 mg/kg MMC weighed significantly less than those in the control group. Many fetuses with malformations were observed in the treated groups; cleft palate occurred in 100, 58.6 and 28.0% of fetuses from dams given 25, 20 and 15 mg/kg MMC, respectively (statistically significant). Hydronephrosis appeared in 23.8 and 18.5% of fetuses from dams given 25 and 20 mg/kg MMC, respectively (statistically significant). Skeletal variations, incomplete ossification of sternebrae, for example, were also observed in the treated groups. These results indicate that MMC is teratogenic so far as cleft palate is concerned and embryotoxic in ICR mice.     

In utero morphological effects of hydroxyurea on the fetal development in Sprague-Dawley rats

In order to investigate in utero morphological effect of hydroxyurea (HU) in Sprague-Dawley rats, HU was intraperitoneally injected to pregnant Sprague-Dawley rats at a dose of 100 or 200 mg/kg/day during the organogenetic period (days 9-12 of gestation). A dose of 200 mg/kg/day induced growth retardation, high mortality and high incidence of malformations, although a dose of 100 mg/kg/day produced no adverse effects in the next generation. In the HU 200 mg/kg/day group the incidence of malformations in pups at 4 days of age was low as compared with that in fetuses and pups at 21 days of age. Increasing perinatal mortality in fetuses and pups due to severe central nervous system (CNS) malformations and disappearance of some cases of ventricular septal defect after delivery were considered as the possible causes to induce difference in malformation rate in various stage of development. Latent effect on the development of CNS malformations was observed between 4 and 21 days of age. There was no sex difference in teratogenic effect. These findings were compared with those in Wistar rats exposed to HU 200 mg/kg/day. The incidence of perinatal malformations and the stillbirths were significantly higher in the Wistar rats as compared with those in the Sprague-Dawley rats. In addition, such morphological effects of HU as the exencephaly, dilatation of lateral ventricle, anophthalmia, cleft palate and micrognathia are less severe in Sprague-Dawley rat fetuses than in Wistar rat fetuses.     

Influence of maternal stress on uranium-induced developmental toxicity in rats

It has been demonstrated that uranium is an embryo/fetal toxicant when given orally or subcutaneously to pregnant mice. On the other hand, maternal stress has been shown to enhance the developmental toxicity of a number of metals. In this study, maternal toxicity and developmental effects of a concurrent exposure to uranyl acetate dihydrate (UAD) and restraint stress were evaluated in rats. Four groups of pregnant animals were given subcutaneous injections of UAD at 0.415 and 0.830 mg/kg/day on Days 6 to 15 of gestation. Animals in two of these groups were also subjected to restraint for 2 hr/day during the same gestational days. Control groups included restrained and unrestrained pregnant rats not exposed to UAD. Cesarean sections were performed on gestation Day 20, and the fetuses were weighed and examined for malformations and variations. Maternal toxicity and embryotoxicity were noted at 0.830 mg/kg/day of UAD, while fetotoxicity was evidenced at 0.415 and 0.830 mg/kg/day of UAD by significant reductions in fetal body weight and increases in the total number of skeletally affected fetuses. No teratogenic effects were noted in any group. Maternal restraint enhanced uranium-induced embryo/fetal toxicity only at 0.830 mg/kg/day, a dose that was also significantly toxic to the dams. As in previous studies with other metals, maternal stress enhances uranium-induced developmental toxicity at uranium doses that are highly toxic to the dams; however, at doses that are less acutely toxic the role of maternal stress would not be significant.     

Teratogenic effect of AY 9944 in rats: importance of the day of administration and maternal plasma cholesterol level

An inhibitor of cholesterol synthesis, AY 9944 (trans-1,4-bis(2-chlorobenzylaminomethyl) cyclohexane dihydrochloride) is teratogenic. A single dose of AY 9944 (50 mg/kg or 75 mg/kg) given to Wistar pregnant rats on the second, fourth, sixth, seventh, or eighth day of gestation induced malformations such as holoprosencephaly. They were often limited to isolated pituitary agenesis. The highest percentage of holoprosencephalic fetuses was found when AY 9944 was given on the fourth day of gestation. Whatever the dose and the day of administration, the lower the maternal plasma cholesterol level, the more frequent were holoprosencephalic fetuses. Therefore, it is suggested that the decrease in maternal plasma cholesterol level is at least one of the factors provoking holoprosencephaly.     

Teratologic evaluation of synthetic delta 9-tetrahydrocannabinol in rabbits.

Synthetic delta 9-tetrahydrocannabinol (THC) was dissolved in undiluted propylene glycol and administered in daily subcutaneous doses of 15.0, 30.0 or 60.0 mg/kg to pregnant New Zealand white rabbits on days 7--19 of gestation. Maternal food consumption and weight gain were markedly reduced at all dose levels. Embryotoxicity and embryocidal effects were observed in the form of reduced litter weight and number of viable fetuses, respectively, in offspring from pregnant mothers treated with THC. However, on the basis of extensive external, visceral and skeletal examination of all fetuses it may be concluded that THC is not teratogenic in the New Zealand white strain rabbit following subcutaneous administration of doses as high as 60.0 mg/kg/day during the critical period of organogenesis (days 7--19 of gestation). On the other hand, an oral dose of thalidomide (200.0 mg/kg/day), the positive control used in this study, was both embryocidal and teratogenic.     

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.     

Salicylate-induced teratogenesis in the ferret

A single subcutaneous injection of 400 mg/kg sodium salicylate produced a high resorption rate on day 13 (91%) and on day 18 (66%) of gestation. Malformations were seen in the surviving fetuses. Pregnant ferrets injected with 250 mg/kg salicylate produced a lower resorption rate of between 31% and 43%. Malformations were seen in the surviving fetuses of animals injected with lower doses of sodium salicylate both at 13 and 18 days of gestation.Salicylate-induced teratogenicity at 400 mg/kg was compared with that produced in a closed colony of Wistar rats. The concentration of salicylate in whole blood (and serum) was determined after a single injection of 125 mg/kg or 400 mg/kg sodium salicylate. Although salicylate concentration in the blood in both species showed remarkable similarity at the doses tested and the times of sampling, the results indicated that the drug was far more embryo-toxic in ferrets than in rats. The inter-order variation in the embryotoxicity of sodium salicylate is such that it would be unwise to ignore its possible teratogenic activity in man.     

Halothane prevents nitrous oxide teratogenicity in Sprague-Dawley rats; folinic acid does not

The teratogenic effects of nitrous oxide (N2O) administered with halothane or folinic acid (FA) were studied in two separate experiments using a total of 206 timed-pregnant Sprague-Dawley rats. In each experiment, rats were exposed to either 1) air (n = 30-40); 2) N2O (50-75% for 24 h on day 8 of pregnancy, n = 20-30); 3) test agent (i.e., 0.27% halothane for 24 h on day 8 of pregnancy; or 5 mg/kg/day of FA on day 5-13 of pregnancy, subcutaneously by osmotic pump, n = 20-30); or 4) N2O + test agent (n = 20-30). Cesarean sections were performed on day 20, and fetuses were examined for visceral and skeletal abnormalities. There were no differences in pregnancy rate, number of implantations and live fetuses per rat, and fetal weight among any of the groups. Treatment with N2O resulted in significantly higher incidences of resorptions and of major visceral and minor skeletal abnormalities. Halothane administered with N2O protected against these effects; folinic acid did not. Using an additional 65 nonpregnant rats, hepatic methionine synthase activity was measured after treatment with 50% N2O, 50% N2O plus 0.27% halothane, or 50% N2O plus 5 mg/kg/day of folinic acid. Methionine synthase activity was equally depressed in all groups. These findings do not support the commonly held theory that inactivation of methionine synthase is the sole cause of N2O teratogenicity; rather, they suggest a multifactorial etiology, which may include changes in uterine blood flow.     

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.     

Teratogenic effects of the plant hormone indole-3-acetic acid in mice and rats.

These studies evaluated the teratogenic potential of indole-3-acetic acid (IAA), a naturally occurring plant hormone, in CF-1 mice and Sprague-Dawley rats. Mice were given 5, 50, 200, or 500 mg IAA/kg/day by gavage on days 7 through 15 of gestation. Rats were given 50, 200, or 500 mg IAA/kg/day by gavage on days 7 through 15 of gestation. IAA was teratogenic in mice and rats at 500 mg/kg/day; cleft palate was induced in both species at this dose level. In mice, other malformations including exencephaly, ablepharia, dilated cerebral ventricles, and crooked tail were also observed. Mice given 500 mg/kg of IAA gained less than control mice during gestation; no evidence of maternal toxicity was observed in rats. IAA did not cause fetal resorptions in either species and was not teratogenic at dose levels below 500 mg/kg.     

Incidence and potentiation of external and internal fetal anomalies resulting from chlordiazepoxide and amitriptyline alone and in combination

The teratogenic potential of a combination of chlordiazepoxide (Cdz) and amitriptyline (Amt) was examined with regard to both internal and external anomalies. Timed pregnant golden hamsters were given a single intraperitoneal injection on day 8 of gestation of one of the following: chlordiazepoxide hydrochloride (28.5 mg/kg), amitriptyline hydrochloride (70.3 mg/kg), Cdz-Amt combination (28.5 mg/kg Cdz + 70.3 mg/kg Amt, in order to retain the 1:2.5 dose ratio utilized in a clinically-used preparation of these agents), or saline vehicle (control). Fetuses were recovered on gestation day 15 following maternal sacrifice. Cranial malformations were analyzed in Bouin's-fixed fetuses by making 1-mm coronal sections through each head, whereas visceral anomalies were examined following general dissection of each body. Amt alone produced a significant (P less than 0.05) incidence of bent tail and encephalocele, whereas Cdz significantly (P less than 0.05) altered the male:female ratio of surviving fetuses when compared with saline-injected controls. The Cdz-Amt combination caused significant increases in cranial malformations, open eye, bent tail, abnormal lung, and urogenital anomalies. The teratogenic effects of potentiation between the components of this combination are discussed in terms of external and internal malformations.     

Teratogenic effect of trifluoperazine in rats and mice

Trifluoperazine was administered to pregnant mice and rats by gastric intubation during the period of organogenesis. Dams were treated at doses of 0.5, 5, 50 (mice and rats) and 100 (only rats) mg/kg/day. The drug affected the pregnant weight increment in a dose-related manner in rats but only the 50 mg/kg/day dose level affected the weight gain of mice. The foetal weight was not markedly affected in either species. The drug induced cleft palate and micrognathia in rats but did not produce a teratogenic effect in mice. Trifluoperazine caused abortions in mice and there were significant increases in the number of resorptions with the top dose levels in both species.     

Combined embryotoxic action of toluene, a widely used industrial chemical, and acetylsalicylic acid (aspirin)

CFY rats were exposed to inhalation of fresh air at days 10-13 of gestation; at day 12 the dams were given 0, 125, 250, 500, or 1,000 mg/kg acetylsalicylic acid (ASA) by gavage. During the same period of gestation (days 10-13) further groups of rats were exposed to toluene at 1,000, 2,000, and 3,600 mg/m3 atmospheric concentration and were given 250 mg/kg ASA by gavage; two subgroups of animals treated with 250 mg/kg ASA in combination with 3,600 mg/m3 toluene inhalation were given 0, 2.5, or 5 gm/kg glycine 2 hours before the ASA dose. At day 21 the animals were killed and examined for teratogenic effects and histological changes. After 48 hours toluene exposure other groups of rats were treated with ASA or with ASA plus glycine (administered 2 hours earlier) on day 20 of gestation. These animals were killed 2 hours later and the salicylic acid concentration in maternal and embryonic plasma and in amniotic fluid was measured by gas chromatography. With the rising ASA doses both maternal toxicity (increased mortality, decreased food consumption, and weight gain) and embryonic toxicity (postimplantation loss, increased incidence of weight-retarded fetuses, increased minor anomalies and malformations, decreased average weight of fetuses) increased. Toluene was found to potentiate the toxic effect of ASA and to increase both maternal and embryonic toxicity. The type of ASA-induced minor anomalies and malformations was also found to be altered under the effect of toluene pretreatment. By raising the toluene concentration the salicylic acid level in the maternal and embryonic plasma and in the amniotic fluid was increased above the expected concentration. The mechanism of the potentiating interaction should be looked for in the depletion of the glycine pool by toluene (and its metabolites) and in the resultant increase of salicylic acid level. Increasing ASA embryotoxicity caused by toluene can be warded off by glycine administration.     

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.