In vitro embryotoxicity study of n,n-dimethylacetamide and its main metabolite N-monomethylacetamide

N,N-Dimethylacetamide (DMAC) is a widely used industrial solvent. Previous teratological studies in vivo reported discording results. Using the postimplantation rat whole embryo culture (WEC) method, the direct embryotoxic effects of DMAC and its main metabolite (N-monomethylacetamide, MMAC) have been investigated in the present work. Both chemicals showed specific embryotoxic and teratogenic effects at similar concentration levels. The no-observed-effect level (NOEL) was 0.85mm.Macroscopically, the main target organs were somites, brain and branchial bars. Histological examination revealed an increase in cell death at the effective concentrations on the neuroepithelium and branchial bars mesenchyme. The results of this work, together with those obtained in in vivo studies, suggest that the exposure limits in workplaces could be inappropriate for the safety of fertile women.

Study on the common teratogenic pathway elicited by the fungicides triazole-derivatives

Triazole-derivatives alter the pharyngeal apparatus morphogenesis of rodent embryos cultured in vitro. The hindbrain segmentation and the rhombencephalic neural crest cell (NCCs) migration are altered by Fluconazole exposure in vitro. The aim of the present work is to identify if a common pathogenic pathway is detectable also for other molecules of this class of compounds. 9.5 days post coitum (d.p.c.) old rat embryos were exposed in vitro to the teratogenic concentrations of Flusilazole, Triadimefon and Triadimenol and cultured for 24, 48 or 60 h. The expression and localisation of Hox-b1 and Krox-20 proteins (used as markers for hindbrain segmentation) were evaluated after 24 h of culture. The localisation and distribution of NCC was evaluated after 24, 30 and 48 h of culture. The morphology of the embryos was analysed after 48 h, while the branchial nerve structures were evaluated after 60 h of culture. Hindbrain segmentation and NCC migration alteration as well as pharyngeal arch and cranial nerve abnormalities were detected after exposure of the tested molecules. A common severe teratogenic intrinsic property for the tested molecules of this chemical class has been found, acting through alteration of the normal hindbrain developmental pattern.

Atlas of rat fetal skeleton double stained for bone and cartilage

BACKGROUND

The double staining of fetal skeleton for bone and cartilage is a very useful method to evidence skeletal abnormalities in laboratory animals. However, this method has been rarely used in routine developmental toxicity tests. One reason could be the difficulty of comparing the single skeletal pieces and of having reference points. In this paper the fetal rat skeleton double stained with Alizarin red S and Alcyan Blue is described in detail to produce an atlas for developmental toxicity laboratories.

Antifungal triazoles induce malformations in vitro

Triazole-derivatives are antimycotics used in agriculture as well as in clinical and veterinary therapy. The aim of the present work is the in vitro comparative study of the teratogenic activity of triazole (the parental compound), flusilazole (an agricultural triazole mono-derivative fungicide), and fluconazole (a clinically used bis-triazole derivative). Rat embryos, 9.5 days old (1 to 3 somites) were exposed in vitro to triazole 500 to 5000 microM, flusilazole 3.125 to 250 microM, or fluconazole 62.5 to 500 microM. After 48 h in culture, the embryos were morphologically examined and processed for histologic and biochemical analysis. Flusilazole and fluconazole showed similar teratogenic effects (abnormalities at the branchial apparatus level and cell death at the level of the branchial mesenchyme) at concentration levels of 6.25 microM and higher for flusilazole and of 125 microM and higher for fluconazole. By contrast, only slight developmental retardation and blood discoloration were observed at the highest concentrations of triazole, suggesting no teratogenic activity for the triazole group.

Reproductive toxicity of exemestane, an antitumoral aromatase inactivator, in rats and rabbits

Exemestane is an orally active, irreversible inactivator of aromatase, structurally related to the natural substrate androstenedione, in clinical use at 25 mg daily for the treatment of advanced breast cancer in postmenopausal women. The reproductive and developmental toxicity of exemestane was assessed in rats and rabbits with oral administration. Pivotal experiments included a fertility study (Segment I), in which female rats received exemestane doses of 4, 20, or 100 mg/kg/day from two weeks premating until GD 20 (cesarean-sectioned dams), or until GD 15 and then from D 1 to D 21 postpartum (dams allowed to deliver), and developmental toxicity studies (Segment II), in which rats and rabbits were treated from GD 6 through GD 17 (rats) or GD 18 (rabbits) at doses of 10, 50, 250, or 810 mg/kg/day and 30, 90, or 270 mg/kg/day, respectively. All rabbits and two-thirds of the rats were cesarean sectioned toward the end of pregnancy to determine litter parameters and examine structural abnormalities in the fetuses; the remaining one-third of the rats was allowed to litter and rear pups to weaning. No pivotal male fertility or peri- and postnatal studies were performed, taking into consideration the therapeutic use. Postnatal effects on the first generation offspring were assessed in both studies in rats, in the portion of dams allowed to deliver. Their F1 offspring were raised to adulthood, when they were evaluated for reproductive performance, and the F1 females were terminated on GD 20. The dosing schedule for the Segment I study in rats, which included a postnatal component, was established to exclude exposure before and during parturition (by withdrawing treatment from GD 16 until the end of parturition). This withdrawal of treatment was put in place because in a preliminary study with treatment including the peripartum period, doses from 5 to 200 mg/kg/day prolonged gestation and interfered with parturition.Overall, studies in rats showed that female fertility was not affected up to 100 mg/kg/day, but doses higher than 4 mg/kg/day, which is approximately the pharmacologically active dose (ED50 = 3.7 mg/kg), prolonged gestation and impaired parturition, leading to maternal deaths in labor and perinatal deaths of offspring. Rats killed on GD 20 showed nondose-related increases in resorptions at doses higher than 10 mg/kg/day, a reduction in fetal body weights at 20 and 100 mg/kg/day (fertility study) and 810 mg/kg/day (developmental toxicity study), and an increase in placental weights at all doses. Female fetuses exposed in utero until GD 20 at 100 mg/kg/day showed an increase in the anogenital distance, very likely related to an increase of the potent androgen DHT as a consequence of aromatase inhibition. Morphologic examinations in fetuses and born pups that were exposed in utero up to the end of the organogenesis period, as well as postnatal investigations on offspring up to adulthood, showed no treatment-related effects. In a developmental toxicity study in rabbits, treatment at 270 mg/kg/day affected maternal food intake and body weight gain, caused abortion or total resorption in about 30% of pregnant females, and reduced body weight and numbers of live fetuses, but did not affect fetal morphology. It was concluded that exemestane did not affect parturition in rats at 4 mg/kg/day or pregnancy in rabbits at 90 mg/kg/day (about 1.5 and 70 times the human dose, respectively, on a mg/m2 basis) and was not teratogenic in rats and rabbits. Exemestane is marketed for use only in postmenopausal women. Its labeling includes a contraindication to use in pregnant or lactating women.

Acetaldehyde in vitro exposure and apoptosis: a possible mechanism of teratogenesis

Alcohol abuse by pregnant women can result in fetal alcohol effects (FAE) and fetal alcohol syndrome (FAS). Both ethanol itself and its main metabolite, acetaldehyde (Ach), are able to produce specific FAS-related malformations. In previous in vitro studies, we documented that 10-day-old rat embryos exposed to Ach show a characteristic embryonic Ach syndrome, histologically characterized by marked cellular death. As both necrosis and pathological apoptosis are teratological mechanisms, the aim of this work was to evaluate if cellular death, observed in Ach-exposed embryos, can be related to necrotic or apoptotic events. Ten-day-old rat embryos were cultured in the presence of Ach 30-60 microg/ml and stained with the vital dye acridine orange to visualize apoptotic areas. After fixation, the TUNEL [3' terminal deoxynucleotide transferase (TdT)-mediated dUTP-biotin nick end labeling] method was used to histologically identify apoptosis. Both acridine orange and TUNEL staining showed signs of physiological apoptosis in controls and abnormal apoptotic regions in Ach-exposed embryos. Our results show a clear correlation between malformed organs and apoptotic embryonic districts, suggesting the role of apoptosis in Ach-induced abnormalities.

Expression of Fhit protein during mouse development

Fhit protein has a putative tumor suppressor function in several types of human and experimental cancers. To assess whether Fhit is involved in fetal development we have examined the distribution of Fhit protein in the 12- through 16-day postcoitum mouse fetus and in postnatal day 0 mouse pups by immunocytochemistry. High levels of Fhit protein were observed in the endodermal derivatives, namely, bronchi, trachea, esophagus, stomach, and intestine, in the 12- to 16-day postcoitum mouse fetus and in the postnatal day 0 pup. Other tissues showed a more restricted pattern of Fhit protein expression. These results suggest that Fhit may play a role in the development of specific tissues during mouse development.

Development of rat embryos cultured in serum from diabetic rats

Experimental studies carried out in vitro suggest a role of oxidative stress in diabetes-induced embryopathies. Glutathione is the main defense against free radicals in embryonic as it is in adult tissues. In this experiment, using postimplantation whole-embryo culture, we analyze: (1) the effects of serum from streptozotocin-induced diabetic rats on embryonic development and on glutathione distribution between the yolk sac and embryonic tissues and (2) the role of glutathione in preventing embryopathies (using the inhibitor of glutathione synthesis buthionine sulfoximine). Our data show that in rat embryos cultured in diabetic serum, the only observed effects are at the yolk sac level. No effects on the glutathione content were observed. The addition of buthionine sulfoximine reduced the glutathione content and produced signs of developmental delay in embryos cultured in diabetic serum, suggesting a role of the oxidative stress in producing diabetes-related embryotoxicity.

In vitro teratogenic potential of two antifungal triazoles: triadimefon and triadimenol

The teratogenic potential of two antifungal triazoles (Triadimefon and Triadimenol) has been investigated in vitro by the rat postimplantation whole embryo culture method. Rat embryos 9.5 d old were cultured for 48 h in rat serum with Triadimefon (12.5-250 microM) or Triadimenol (6.25-125 microM) and then examined. Some embryos exposed to Triadimenol (6.25-125 microM) were cultured for 12 extra hours in control serum to improve their developmental degree and then immunostain cranial nerves and ganglia. The exposure to the highest doses of triazoles only moderately reduced some morphometrical developmental parameters. By contrast, 25-250 microM Triadimefon and 25-125 microM Triadimenol induced specific concentration-related teratogenic effects at the level of first and second branchial arches. After immunostaining, embryos exposed to 12.5-125 microM Triadimenol showed specific cranial nerve and ganglia abnormalities. The possible implication of neural crest cell alterations on triazole-related abnormalities is discussed.

Morphological alterations induced by sodium valproate on somites and spinal nerves in rat embryos

The antiepileptic drug valproic acid is a well-known teratogenic agent; its main target organ is the neural tube, though skeletal malformations have also been described. In our recent work, respecifications of vertebrae were described in rat fetuses after treatment with 400 mg/kg of sodium valproate at specific somitogenic stages. The observed malformations were stage-dependent. Morphological segmental respecification was observed at the level of segments in formation at the moment of exposure and at the level of more posterior segments. Recently, specific alterations in the development of cranial nerves and ganglia were described in mouse embryos after in vitro exposure to VPA. The aim of the present work was to analyze dysmorphogenetic effects of VPA on embryonic metameric structures: somites, spinal and cranial nerves, and ganglia. Sodium valproate (400 mg/kg) was subcutaneously injected at specific gestational times corresponding to embryonic stages: presomitic or at about 2, 6, 10, 14, 18, or 22 somites. Females were sacrificed on the day 12 post coitum, and embryos were examined. Morphological examination of somites was performed by staining with acridine orange. Morphological examination of nerves and ganglia was performed by immunostaining, using monoclonal antibodies to the 160-kD neurofilament protein. No abnormalities were observed in the cranial nerves and ganglia. Specific and stage-dependent alterations were observed both at the level of the somites and at the level of the spinal nerves. The following characteristic malformations were observed: fusions, duplications, and reductions of somites and corresponding spinal nerves and ganglia. Our morphological data suggest a morphogenetic action of VPA at the level of the axial segments, with a possible respecification of the identity of the interested segments and their derivatives.

Postcoital antifertility activity of aminoalcohols

Previously, postcoital antifertility effects of a number of aminoalcohols, including 2-(isopropylamino)-ethanol, have been demonstrated in rodents. In this experiment, we compared the antifertility activity of 2-(isopropylamino)-ethanol to the following analogs: hydroxyethylpiperidine, hydroxyethylpiridine, hydroxyethylpirrolidine, and hydroxyethylpirrolidone. Female rats were gavaged on Days 0 through 5 of gestation with 0.7 mmol/kg/d of these substances. Only 2-(isopropylamino)-ethanol and hydroxyethylpirrolidine showed a strong antifertility activity: females treated with 2-(isopropylamino)-ethanol had no signs of implantation, whereas those treated with hydroxyethylpirrolidine had 100% early resorptions. Treatments with these two substances during the periimplantation period (Days 4 and 5) produced 100% early resorptions. Histologic examination of the implantation sites showed signs of embryonic degeneration starting from Day 6.5 of gestation. The flushing of the uteri of females treated with 2-(isopropylamino)-ethanol on Days 0 through 3 post coitum showed 78% of the embryos at the stage of 1 to 3 blastomeres, whereas the embryos of females treated during the same period with hydroxyethylpirrolidine were normal blastocysts. Therefore, 2-(isopropylamino)-ethanol and hydroxyethylpirrolidine are able to kill embryos during the early implantation stages, whereas 2-(isopropylamino)-ethanol is also able to stop the development of preimplantation embryos.

Stage-dependent skeletal malformations induced by valproic acid in rat

In this work we study the skeletal teratogenic response in rats exposed to NaVP at different embryonic stages. Crl:CD female rats were treated subcutaneously with 400 mg/Kg b.w. NaVP at presomitic stage (group II) or nearly at 2, 6, 10, 14, 18 or 22 somites (groups III-VIII). The females on group I were treated with saline and served as controls. No treatment-related effects were observed at the level of resorptions, live fetuses and fetal or placental weight. The skeletal examination showed characteristic patterns of malformations strictly related to the period of treatment. In particular, groups II and III showed a significant increase of alterations of cervical vertebrae (mainly 1st to 3rd segment) and a decrease of the frequency of extra lumbar ribs in comparison to control. Group IV showed severe abnormalities localized at the 4th to 7th cervical segment and at the level of the 1st and 2nd thoracic segments, including duplications of thoracic segments 1, 2 or 3. The fetuses of group V were characterized by several alterations of the thoracic segments distributed without a clear specificity. In group VI, the thoracic region was also affected with some specificity at the level of the segments 4th to 9th; in group VII, last thoracic and lumbar segments were affected (mainly duplications) and in group VIII only lumbo-sacral abnormalities were recorded. These results confirm the specific effect of NaVP at the level of the axial skeleton and suggest a possible interaction with the expression of genes identifying the vertebral segments.

Glutathione status in diabetes-induced embryopathies

The mechanism involved in diabetes-induced embryotoxicity is still unclear. Mitochondrial alterations probably produced by oxidative stress have been described in embryos developing in a diabetic environment. Furthermore, oxygen radicals-scavenging enzymes can reduce the embryotoxic effects induced by diabetic conditions. In this work we tried to test if glutathione (GSH), a tripeptide implicated in cellular protection against reactive oxygen species, is involved in diabetes-related embryotoxicity. Rat embryos were explanted on day 11 on gestation from normal and from streptozotocin-diabetic mothers. The embryos were examined morphologically, then protein, DNA and GSH were determined both in embryos and in their visceral yolk sacs. The embryos explanted from diabetic mothers showed signs of developmental retardation and 16% were morphologically abnormal. GSH content was reduced in these embryos in comparison to control, but the GSH/protein in the visceral yolk sacs of conceptuses explanted from diabetic mothers was higher than in control visceral yolk sacs. Our hypothesis is that the reduction of embryonic GSH is a consequence of the alteration in GSH transport across the yolk sac endodermal cells damaged by diabetic conditions. The observed reduction in embryonic GSH could reduce the protection against the oxidative stress condition described in diabetic pathology.

Teratogenic effects of sodium valproate in mice and rats at midgestation and at term

This experiment was carried out with the aims of comparing the embryotoxic potential of valproic acid (VPA) in rats and mice, better defining the malformation pattern in these species, and comparing the embryotoxic effects detectable in mid-pregnancy to those observed in fetuses at term. Pregnant CD:Crl rats were treated subcutaneously (s.c.) at 08:00, 16:00, and 00:00 on day 9 of gestation with 0, 150, or 300 mg/ kg VPA; pregnant NMRI mice were treated s.c. at 00:00 on day 7 of gestation, and at 08:00 and 16:00 on day 8 of gestation with 0,75, 150, or 300 mg/kg VPA. Groups of females were killed on day 9 (mice) or day 11 (rats) of pregnancy and their embryos were carefully examined under a dissecting microscope. The remaining females were killed 1 day before parturition and their fetuses were examined for external, visceral, and skeletal malformations. A very high frequency (84%) of malformed embryos was recorded in the group of mice treated with 300 mg/kg, including open brain folds (73%), somite defects (36%), and heart malformations (20%). The rat embryos were less sensitive: only 43% of them were malformed after treatment with 300 mg/ kg, however, the pattern of malformations was quite similar to that observed in mice. The treatment with 150 mg/kg produced about 32% malformed embryos in mice and only 8.5% in rats. More than 84% of mouse fetuses from mothers treated with the highest dose showed a severe form of exencephaly. The axial skeleton was also severely affected. The postimplantation loss reached 52%. Exencephaly and skeletal malformations were also recorded in mouse fetuses from mothers exposed to 150 mg/kg. The dose of 75 mg/kg was without effects. Exencephaly was not observed in rat fetuses at term. In this species the axial skeleton was the most severely affected region at 300 mg/kg, while the lowest dose produced only sporadic malformations. These results confirm that the mouse is the more sensitive species for the teratogenic effects of VPA. Furthermore, it has been shown that, in both species, the axial skeleton is a system which is very sensitive to the teratogenic effects of VPA. The observed alterations show a possible link between axial specification and VPA and suggest further studies of embryos exposed to VPA for the expression of genes controlling the identity of vertebral segments.

In vitro development of rat embryos obtained from diabetic mothers

Rat embryos of 9.5 or 10 days of gestation were removed from control or streptozotocin-diabetic mothers and cultured in normal rat serum (180 mg% glucose) or in diabetic serum (600 mg% glucose). The development of control embryos in normal serum was adequate. Embryos from normal mothers cultured in diabetic serum showed signs of developmental retardation. The development of embryos obtained from diabetic mothers was severely impaired, regardless of the gestational age or the culture medium. These results suggest that a diabetic maternal milieu produces irreversible effects in the embryo very early in gestation.

Long-term changes of somatotrophic function induced by deprivation of growth hormone-releasing hormone during the fetal life of the rat

We have studied the effects of intra-amniotic administration of an anti-GH-releasing hormone serum (GHRH-Ab) on day 16 of fetal life in the rat, when the ontogenetic development of the GHRH neuronal system occurs. Control animals received normal rabbit serum. Following delivery, body weight was monitored for the next 30 days as an index of somatic growth, and the following indices of somatotrophic function were determined: plasma and pituitary GH, pituitary GH mRNA, hypothalamic GHRH and somatostatin mRNA, and the in vivo GH responsiveness to GHRH. At birth, GHRH-Ab-treated rats had a body weight that was equivalent to that of control rats but, starting from postnatal day 6 up to day 30, they had a significantly reduced body weight. Pituitary weight, the absolute pituitary GH content and GH mRNA levels were lower in experimental compared with control rats, while pituitary GH concentrations were similar in the two groups, thus implying that there was a defect, not only in GH synthesis, but also in GH release. In agreement with this theory, basal GH levels and GHRH-stimulated GH secretion were reduced in GHRH-Ab-treated rats but, in contrast, hypothalamic regulation of GH secretion appeared to be working in these rats as they were still able to respond to the low plasma GH by increasing GHRH and decreasing somatostatin mRNA levels. These findings indicate that deprivation of GHRH during fetal life induces long-lasting changes of growth rate and somatotrophic function.(ABSTRACT TRUNCATED AT 250 WORDS)

The protective effects of N-acetyl-L-cysteine against methyl mercury embryotoxicity in mice

N-Acetyl-L-cysteine (NAC) has been widely used in the protection against the toxic effects produced by several chemicals because of its radical scavenger properties and because NAC is a precursor of glutathione, one of the most important intracellular defenses against oxidants. The aim of this investigation was to verify the potential protective activity of NAC against the well-known embryotoxicity induced by methyl mercuric chloride (MMC) in mice. Three experimental approaches were carried out. In the first investigation, acute treatment of MMC (25 mg/kg po) was given in CD female mice on Day 10 of pregnancy, and was followed immediately and/or after 24, 48, and 72 hr by administrations of NAC (800 mg/kg i.v.). The embryolethal effects caused by MMC poisoning were completely antagonized by just a single administration of NAC, while the incidence of palatoschisis was reduced in relation to the number of NAC administrations. In the second experiment MMC was chronically gavaged (3 mg/kg/day po) during the period of organogenesis on Days 5 to 14 of gestation. During the same period of time some of these females were also exposed to 1% NAC dissolved in drinking water. MMC poisoning reduced the body weight of viable fetuses and induced many cases of palatoschisis. The body weight of fetuses from MMC-poisoned mothers treated with NAC was improved and the incidence of palatoschisis was in the normal range. In the last experiment the treatment with NAC (400 mg/kg i.v., during the period of organogenesis) drastically reduced the severe embryolethality induced by MMC (6 mg/kg/day po) administered during the same period of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of diets with different content in protein and fiber on embryotoxicity induced by experimental diabetes in rats

Three groups of streptozotocin-diabetic rats were maintained during pregnancy on three hyperproteic diets with different protein contents. These differences were compensated by an equal quantity of fiber (group 1: protein 55.0%, fiber 4.5%; group 2: 45.0%, 14.0%; group 3: 35.0%, 24.0%). Three groups of nondiabetic pregnant rats were fed with the same diets and served as control. The differences of the daily protein intake among the diabetic groups were less pronounced than those expected on the basis of the diet composition, and the embryopathic effects (reduced fetal weight, increased in malformation and resorption rate) were not statistically different among the three groups of diabetic animals. The frequency of congenital malformations was higher than that observed in a previous experiment in diabetic rats maintained on a standard diet, but much lower than that observed in animals fed on a purified, fiber-poor, normoproteic diet. When the caloric intake of the diabetic rats in the different groups was determined it was found to be similar for all of them and also similar to the caloric intake of the rats given a standard nonteratogenic diet (in previous experiments), while the rats maintained on a normoproteic, teratogenic diet increased their caloric intake. These results seem to indicate that the diet composition greatly influences the intake of food and calories of pregnant diabetic rats and this may play a role in modulating the embryopathic effect of diabetes.

Effects of ethanol and acetaldehyde on rat embryos developing in vitro

Rat embryos were explanted on Days 9.5 or 10 of gestation and cultured for 48 to 30h, respectively, in rat serum containing 0, 3, 6, 9 mg/ml of Ethanol (Eth); 0, 10, 20 micrograms/ml of Acetaldehyde (Ach); 3 mg/ml Eth + 10 micrograms/ml Ach. At the end of the culture period the embryos were evaluated for vitality, and scored. Some of them were also examined histologically. Embryos exposed to Eth from Day 9.5 showed a dose-related growth retardation associated with a high frequency of malformations (open neural tube, heart defects, branchial arch hypoplasia). The exposure of 9.5-day embryos to 20 micrograms/ml Ach resulted in 100% embryolethality, whereas 10 micrograms/ml induced growth retardation and teratogenic effects. When 10-day embryos were exposed to 3 mg/ml Eth or 10 microliters/ml Ach no effects were observed, but the highest levels of Eth produced a moderate growth retardation and morphologic defects. Exposure to 20 micrograms/ml Ach induced hypoplasia of the first arch, but did not alter the score value. The histologic examination of these embryos revealed severe lesions at the level of the neuroepithelium and of the branchial mesenchyma. Similar effects were observed in embryos exposed simultaneously to 3 mg/ml Eth and 10 micrograms/ml Ach. These results should make us reevaluate the role of Ach in the Eth-induced embryopathies.

Damage to the crystalline lens in infants of diabetic mothers: a pathology so far neglected?

Congenital cataract occurs in 90-95% of diabetic rat fetuses. The pathogenetic mechanism is triggered by fetal hyperglycemia and presents the following steps: (1) a high glucose concentration in the lens; (2) reduction of glucose to sorbitol by aldose reductase; (3) accumulation of sorbitol into the fibers of the lens creating a hyperosmotic effect, leading to (4) an infusion of liquid into the fibers, which (5) become hydropic and degenerate (vacuolization). This series of manifestations might also occur in fetuses of pregnant diabetic mothers. Post birth glycemia diminishes rapidly, and this favorable condition which decreases vacuolization is perhaps the reason why such degeneration has not yet been observed. Since the fibers of the lens are permanent cells, damage in the fetal period might later bring about negative consequences. We hope that someone will study whether this ocular pathology occurs in human infants born to diabetic mothers.

Diet composition modifies embryotoxic effects induced by experimental diabetes in rats

Despite improvements in prenatal care, the incidence of congenital malformations in diabetic pregnancies is still 3-4 times higher than in normal pregnancies. These defects could be attributed to alterations of intrauterine environment due to disorder of the maternal metabolism. If this were true, the quality of food could play a role in diabetes-induced embryotoxicity. To check this hypothesis, female CD rats were made diabetic by injecting intravenously 50 mg/kg of streptozotocin 2 weeks before mating. From the first day of pregnancy they were divided into three groups and maintained on the following diets: (1) standard diet (Italiana Mangimi); (2) purified high protein diet (protein 55%, carbohydrates 25.5%, fat 7.5%, fiber 4.5%, ash 7.5%); (3) purified normoprotein diet (protein 19%, carbohydrates 62.5%, fat 7.5%, fiber 4%, ash 7%). Nondiabetic pregnant females fed with standard diet served as negative control. No significant differences were observed in blood glucose levels among the groups (range 410-500 mg/dl). The group fed on normoprotein diet showed at term of pregnancy: (1) higher rate of resorptions; (2) lower fetal weight; (3) higher frequency of major malformations than the groups fed standard and hyperproteic diets. Although we are not able at this time to discriminate between a protective effect of a diet with a high protein content and a disruptive effect of a diet containing high quantity of carbohydrates, the results of this trial support the hypothesis of a fuel-mediated teratogenesis in diabetic pregnancy.

Congenital malformations in offspring of diabetic rats: experimental study on the influence of the diet composition and magnesium intake

In spite of improvements in the treatment of diabetes, the risk of congenital malformations in diabetic pregnancy is three to four times higher than in normal pregnancy. This might be due to the metabolic abnormalities of diabetic pregnancy that also affect mineral metabolism. Since diabetes can lower both maternal and fetal blood Mg levels, and Mg deficiency has been shown to be teratogenic in laboratory animals, we decided to investigate which effects Mg deficiency would have in inducing embryopathy in diabetic animals. Female CD rats were divided into six groups. Groups 1 and 2 were fed a standard diet (Mg content 4,200 ppm), groups 3-6 a purified diet (Mg contents 4,200, 500, 250, or 125 ppm). Groups 2-6 had been made diabetic by an intravenous injection of 50 mg/kg streptozocin 1 week before mating. The rats were killed on day 21 of pregnancy, and the live fetuses were examined for external, skeletal, and visceral malformations. The maternal and fetal blood glucose levels were the same in all diabetic groups. The maternal Mg levels in groups 2 and 3 were the same as in controls, but definitely lower in groups 4-6. Embryotoxicity (embryonic deaths, delayed development, congenital malformations) was higher in the groups fed the purified diet than in group 2, but without a clear relation to the dietary Mg levels. We cannot draw any conclusions about the effects of Mg deficiency in diabetic pregnancy from our results, but they show that the quality of the diet is of major importance in the manifestation of embryotoxicity in diabetes.

Morphogenesis of diabetes-induced congenital cataract in the rat

The eye development of rat fetuses and pups from normal and streptozotocin-diabetic mothers was studied histologically in order to verify the morphopathogenesis of congenital cataract. The first signs of lens alterations were observed in 17-day-old fetuses from diabetic mothers. The fibres swelled up, became hydropic and subsequently degenerated, giving rise to large cysts filled with amorphous material in the middle of the lens. The pathogenic route observed suggests an osmotic disturbance in the physiology of the lens fibres, probably related with an accumulation of some polyols.

Induction of micronuclei and toxic effects in embryos of pregnant rats treated before implantation with anticancer drugs: cyclophosphamide, cis-platinum, adriamycin

To evaluate a possible relationship of maternal exposure to anticancer drugs during the preimplantation period to blastopathies and postimplantation embryotoxicity, CD female rats were injected intraperitoneally on day 3 of pregnancy with 15 and 30 mg/kg of cyclophosphamide (CPA), 2 and 4 mg/kg of Adriamycin (ADR), 3 and 6 mg/kg of cis-platinum (Cis-Pt), or with 5 ml/kg of saline. Blastocysts were collected on day 5 of gestation and evaluated for gross morphology, cell number, and micronuclei. Some females were sacrificed on day 21 of pregnancy in order to evaluate postimplantation embryotoxicity. A reduction in cell number/blastocyst was observed only in animals exposed to Cis-Pt 6 mg/kg; vice versa, a dose-related increase of micronuclei and of blastocysts with micronuclei was found in all groups treated with the anticancer agents. A significant increase of postimplantation loss was recorded in the groups treated with high doses of Cis-Pt and ADR, but no clear signs of teratogenicity were observed.

Induction of micronuclei in pre-implantation rat embryos in vivo

To test the capability of different chemicals to induce clastogenic effects in pre-implantation embryos in vivo, rat blastocysts were collected on the afternoon of the 4th day of gestation from the uterus of females treated on the morning of the 3rd day. Cyclophosphamide (40 mg/kg) and daunomycin (10 mg/kg) did induce micronuclei, but methotrexate (10 mg/kg) and CuSO4 (8 mg/kg) did not. The micronucleus frequency was dose-related when 3, 9, or 18 mg/kg of mitomycin C were administered. These results confirm the sensitivity of the rat pre-implantation embryo to clastogenic chemicals also after in vivo exposure.

Effects of streptozotocin-induced diabetes on fetal development of the rat

The purpose of this study was to determine whether or not in rats with experimentally induced diabetes there is an increased frequency of congenital malformations; data in the literature are not consistent on this point. Virgin CD females rats were injected with 40-50 mg/kg streptozotocin (Stz) before mating (SIBM group) or on the first day of pregnancy (SI1). Both SIBM and SI1 females were divided into two groups according to their blood glucose levels: severely diabetic (SD, greater than 300 mg%) and mildly diabetic (MD, 120-250 mg%). Food and water consumption by the control and MD groups were the same, but the SD females developed polyphagia, polyuria, and polydypsia, which continued to increase throughout pregnancy, as did the blood glucose levels. All the MD females mated and carried to term. In SD females both frequency of mating and fertility were only slightly lower than in the controls. All the females were killed on the 21st day of pregnancy. Pre- and postimplantation losses were the same for diabetic and control rats, but SIBM-SD females ovulated less than other groups. Weights of fetuses of SD dams were lower and blood sugar levels higher than those of the other groups. The placentas of SD rats were significantly heavier and there was cystic degeneration of spongiosa. The incidence of major malformations was minimal (approximately 2%) in fetuses of SD females and there were none at all in controls or MD females. In conclusion, our data are in agreement with those of other investigators who have found that rats with experimentally induced diabetes have smaller fetuses and increased placental weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Teratogenesis study of dioxane in rats

The industrial solvent dioxane (1,4-diethylene dioxide) was evaluated for teratogenic potential in Sprague-Dawley rats. The compound was administered on days 6-15 of gestation by gavage (0, 0.25, 0.5 and 1.0 ml/kg/day). A slight maternal toxicity, as evidenced by reduced weight gain, was observed with 1.0 ml/kg. Animals were killed and subjected to uterine examination on day 21 of pregnancy. There were no differences between control and dioxane-treated groups in implantation numbers, live fetuses, postimplantation loss or major malformations. Embryotoxicity, manifested by reduced fetal weight, occurred only at the highest dose level.

Developmental toxicity during the preimplantation period: embryotoxicity and clastogenic effects of chlorambucil in the rat

To evaluate the toxicological effects of chemicals on preimplantation mammalian embryos, pregnant rats were treated with chlorambucil (0, 3, 6, and 12 mg/kg IP) on day 1, 2, or 3 of gestation (positive vaginal smear = day 0). Blastocysts were collected on day 4 and evaluated for gross morphology, cell number, and mitotic index. Some females treated on day 3 post coitum were sacrificed on day 20 and fetuses were evaluated for teratogenic effects. On day 4 of gestation a dose-related reduction of cell number/embryo was recorded; this effect was most manifest with treatment on day 3 post coitum. The mitotic index was significantly higher in all treated groups. A dose-related increase in "micronucleus-like bodies" has been observed in treated embryos. A comparison with the micronucleus test in the bone marrow revealed a major sensitivity of the embryonic material. No malformations have been observed in fetuses at term, but their weights were significantly reduced and a dose-related increase of postimplantation loss was recorded in treated females.

Pre- and postimplantation embryotoxic effects of zinc dimethyldithiocarbamate (Ziram) in the rat

Zinc dimethyldithiocarbamate (Ziram) was administered to pregnant CD rats by tube during the first 5 days of pregnancy (preimplantation study, 0, 25, 50, and 100 mg/kg) or during the organogenetic period (teratogenic study, 0, 12.5, 25, 50, and 100 mg/kg). All females were sacrificed on Day 21 of gestation. Their reproductive status was recorded and live fetuses were examined for external, visceral, and skeletal malformations. In the preimplantation study the only observed embryotoxic effect was a reduced fetal weight at 50 and 100 mg/kg dose level. The teratogenic study revealed a slight dismorphogenic effect of Ziram at 100 mg/kg; embryofetotoxic effects appeared at 25 mg/kg dose level and higher. Maternal toxicity was evident at all tested doses.

Embryotoxic effects of 2,3,7,8 tetrachlorodibenzo-p-dioxin administered to female rats before mating

2,3,7,8-Tetrachlorodibenzo-p-dioxin was administered to female rats by gavage for 2 consecutive weeks at daily doses of 0, 0.125, 0.5, and 2 micrograms/kg. After treatment females were caged with untreated males. All dams were killed on Day 21 of gestation. Their reproductive statuses were recorded and live fetuses were examined for external, visceral, and skeletal malformations. At 0.125 micrograms/kg no effects were observed on both maternal and fetal toxicity; 0.5 micrograms/kg reduced maternal weight gain and increased postimplantation loss. At 2 micrograms/kg the following features became evident: reduction of both maternal weight gain and ovulation rate, increase of pre- and postimplantation loss, and fetal growth retardation. Also, malformed fetuses were observed at this dose level.

Embryotoxic effects of 5-hydroxytryptamine during the peri-implantation period in the rat

Administration of 5-hydroxytryptamine creatinine sulphate (5-HT) 5-10-20 mg/kg s.c. to pregnant rats during the preimplantation period (1200 h, Days 1 through 5) did not inhibit implantation. Experiment 2: Administration to pregnant rats during the peri-implantation period (0900 h, Day 6) of 5-HT 5 mg/kg s.c. did not affect implantation or embryo-fetal development. 5-HT 10 mg/kg s.c. produced a significant increase (P greater than 0.01) in the resorption rate (31.8%) and severe cardiovascular or ophthalmic malformations in 5.3% of viable fetuses. 5-HT 20 mg/kg produced a resorption rate (97.2%) virtually incompatible with the continuance of pregnancy. Experiment 3: Histological examination of uterine preparations made from Day 6 pregnant rats sacrificed 6, 24, and 30 h after receiving 5-HT 20 mg/kg s.c. showed, in 30 h post-injection preparations, toxic effects at implantation sites (uterine lumen completely deprived of epithelial layer and filled with cellular debris, and complete degeneration of implanted embryos) but no toxic effects between implantation sites. Experiment 4: Administration of 5-HT 10 mg/kg s.c. to pregnant rats during the postimplantation period (Days 10 and 11) produced a 63.2% resorption rate, a reduction in the mean weight of viable fetuses, and severe malformations in 24% of viable fetuses. The embryotoxic activity of 5-HT may be attributed to its vasoconstrictive action which renders the uterine mucosa or trophoblast ischemic, thus causing irreversible damage to the luminal epithelium at the implantation sites.

Placental transfer and tissue localization of [14C]carmoisine in the pregnant rat

Pregnant Sprague-Dawley rats received [14C]Carmoisine (200 mg/kg; 25 microCi) by gavage, on days 16-19 of gestation. Animals were killed on day 19 of gestation, 2, 16, 64 h after dosing and blood, maternal tissues, amniotic fluids, placentae, fetal membranes and fetuses were analyzed for radioactivity. No evidence for the transplacental transfer of [14C]Carmoisine or its metabolites was obtained. More than 90% of the radioactivity was excreted in feces and urine within 64 h.

Morphogenesis of aortic arch malformations in rat embryos after maternal treatment with glycerol formal during pregnancy

The morphogenesis of the aortic arch system was studied in rat embryos whose mothers had been treated with glycerol formal (GF) during pregnancy. The fetuses were removed from the uterus on days 13-17 of gestation and India ink was injected into their vascular system while they were still alive. The teratogenic effect of GF manifested itself by developmental retardation of the aortic arch system, vessel dilatation and persistence or anomalous regression of embryonic vessels. These conditions result in several aortic arch malformations: right aortic arch, double aortic arch and persistence of the 3rd aortic arch.

Cardiovascular malformations experimentally induced in the rat

Sprague-Dawley rats were treated with glycerol formal during days 6-15 of gestation. 76 to 193 fetuses of these rats examined for visceral malformations showed abnormalities of the heart and great vessels. The principal cardiac malformation was ventricular septum defect associated in 40% of the cases with anomalies of the aortic arch: double aortic arch, right aortic arch and coarctation of the aorta. An attempt was made to explain the specific cardiovascular defects.

The effects of actinomycin D and chloramphenicol on the rat preimplantation embryos

Actinomycin D and chloramphenicol, injected in the rat on day 3 or 4 of gestation, induce embryolethality and embryotoxicity. These effects are revealed on day 5 of pregnancy by reduced number of blastocysts and by decrease of mean blastomeres number.

The extent of fetal ossification as an index of delayed development in teratogenic studies on the rat

In teratogenic studies toxic effects may manifest themselves in retarded fetal development, such as a reduction in fetal weight. In searching for an additional index, the number of centers of ossification in seven skeletal districts (sternum, metacarpus, metatarsus, cervical and caudal vertebrae, anterior and posterior proximal phalanges) of rat fetuses delivered on days 19, 20 and 21 of gestation were counted and compared. Results showed uneven ossification in day-19 and -20 fetuses, but sufficiently advanced, homogeneous and uniform ossification in day-21 fetuses to provide a reliable quantitative index for evaluating retarded fetal development. It is therefore proposed that the stage of skeletal ossification in day-21 fetuses be used in teratogenic studies in the rat to evaluate retarded fetal development.

[Effect of glycerol formal on the embryonic development of the rat]

In order to evaluate the effect on embryonic development of a solvent commonly used in pharmacological investigations, glycerol formal was administered to pregnant rats from days 6 through 15 of gestation at the daily doses of 0.25, 0.50 and 1.0 ml/Kg i.m. Glycerol formal did not induce systemic toxicity in the mothers, but showed an embryotoxic and teratogenic activity on the products of conception.