RESUMO
Dipterex was teratogenic after administration by gavage (t.i.d.) at a dose level of 480 mg/kg-day to the CP rat on days 6 through 15 of gestation, but not when administered only on days 8 or 10 of gestation. A positive teratogenic response also occurred in the hamster after administration on days 7 through 11 of gestation at 400 mg/kg-day; the apparent no-effect level for the criteria studied was 200 mg/kg-day. Embryotoxicity, but not teratogenicity, occurred after administration of 400 mg/kg-day on day 8 of gestation. In both species, the teratogenicity seen was not merely due to reduced maternal food consumption during the period of exposure. The mouse was less susceptible to Dipterex than were the rat and hamster, but a significant increase in the incidence of cleft palates resulted from exposure on days 10 through 14, or on days 12 through 14 of gestation.
Assuntos
Teratogênicos , Triclorfon/toxicidade , Animais , Inibidores da Colinesterase , Cricetinae , Relação Dose-Resposta a Droga , Feminino , Feto/efeitos dos fármacos , Idade Gestacional , Masculino , Camundongos , Gravidez , Ratos , Especificidade da Espécie , Triclorfon/administração & dosagemRESUMO
The structural development of fetuses was altered when Dipterex was administered by diet to pregnant rats from days 6 through 15 of gestation. Major external and skeletal alterations occurred after consumption of 432 or 519 mg/kg body weight per day, only minor skeletal changes occurred in the 375 mg/kg dose group and the incidence of alterations in the 145 mg/kg dose group was not significantly different from that in the pair-fed controls. The malformations seen at the two highest doses did not result directly from the associated decrease in food consumed. Dipterex was not shown to have teratogenic potential when given for the same time span, once daily by gavage, even at levels that produced maternal lethality. Imidan was not teratogenic when similarly given, either by diet at concentrations that resulted in a 45% reduction in food consumption, or by gavage at dose levels that resulted in some maternal lethality. Data collected from pair-fed control females revealed that limitation of food consumption to 13--15 g/rat per day from days 6 through 15 of gestation did not result in increased fetal mortality or stunting. However, fetal weight was reduced slightly, and the incidence of minor skeletal changes was approximately three to four times that among fetuses of control dams that were not pair-fed.
Assuntos
Anormalidades Induzidas por Medicamentos/etiologia , Inseticidas/efeitos adversos , Fosmet/efeitos adversos , Prenhez/efeitos dos fármacos , Administração Oral , Animais , Dieta , Feminino , Morte Fetal/induzido quimicamente , Inseticidas/administração & dosagem , Intubação Gastrointestinal , Fosmet/administração & dosagem , Gravidez , Ratos , Fatores de TempoRESUMO
Evaluations of studies for four well-known human developmental toxicants clearly suggest that a margin of exposure of 1/100th the NOAEL for the most sensitive animal species tested provides adequate safety for the human conceptus. The lowest reported human teratogenic exposures occurred at doses at least one log above the estimated "safe" or acceptable daily exposure based on the most sensitive animal species, that is, 1/100th animal NOAEL. (The MOE ranged from < 1 to 10.). The data and analyses are consistent with the conclusion that, regardless of the type of in utero effect produced in animals, the margin of safety of 100 is likely to protect the human conceptus in utero from developmental perturbation, and it is a scientifically reasonable and conservative default number.
Assuntos
Feto/efeitos dos fármacos , Toxicologia/métodos , Anormalidades Induzidas por Medicamentos , Animais , Relação Dose-Resposta a Droga , Feminino , Humanos , Isotretinoína/efeitos adversos , Isotretinoína/toxicidade , Macaca mulatta , Metotrexato/efeitos adversos , Metotrexato/toxicidade , Camundongos , Gravidez , Coelhos , Ratos , Especificidade da Espécie , Talidomida/efeitos adversos , Talidomida/toxicidade , Ácido Valproico/efeitos adversos , Ácido Valproico/toxicidadeAssuntos
Prenhez , Estilbenos/farmacologia , Animais , Clomifeno , Implantação do Embrião , Feminino , Injeções Subcutâneas , Gravidez , Pseudogravidez , RatosAssuntos
Indução da Ovulação/métodos , Transporte do Óvulo/efeitos dos fármacos , Fosfatase Alcalina/metabolismo , Animais , Anidrases Carbônicas/metabolismo , Gonadotropina Coriônica/farmacologia , Cobre/farmacologia , Endométrio/enzimologia , Feminino , Hormônio Luteinizante/farmacologia , CoelhosRESUMO
Two categories of collaborative studies are defined. Examples of each type are presented through teratologic studies conducted at the National Institute for Environmental Health Sciences (NIEHS) in collaboration with an Environmental Protection Agency laboratory and a laboratory in the USSR. These studies and the few pertinent studies found in the literature point out the problem of obtaining repeatability and uniformity of results among tests conducted to determine teratogenic potential. Collaborating laboratories should take more time to select the procedures to be used, to standardize the intended protocol in greater detail, to train participating personnel uniformly, and to test for repeatability by use of a known teratogen, before tackling major interests. Establishment of an archives would improve duplication of published results by making available additional pertinent unpublished information. Finally, possible advantages of collaborative studies for the testing of teratogenic potential are offered.
Assuntos
Teratogênicos/toxicidade , Animais , Avaliação Pré-Clínica de Medicamentos/métodos , Cooperação Internacional , National Institutes of Health (U.S.) , Projetos de Pesquisa , Toxicologia/métodos , Estados UnidosRESUMO
Ethylenethiourea (ETU) was given by gavage at a dose of 40 mg/kg/day from Days 7 through 15 of gestation to hypothyroid and euthyroid rats, and to rats given exogenous thyroxine, to determine whether ETU teratogenicity occurs through alteration of maternal thyroid function. At sacrifice on Day 20 of gestation 84-100% of the fetuses in all groups given ETU were malformed regardless of the thyroid status of the dams. Ten percent of the fetuses of dams thyroparathyroidectomized at 75 days of age that were not given ETU were malformed; no malformations were noted among the fetuses of the other groups not given ETU. Hence, ETU was found to induce teratogenicity in rats but not through alteration of maternal thyroid status. In addition, it was determined that ETU lowered serum thyroxine concentration, that hypothyroidism itself increased the background level of malformations in the rat, and that hypothyroidism qualitatively and quantitatively increased the incidence of specific malformations after ETU administration.
Assuntos
Etilenotioureia/farmacologia , Imidazóis/farmacologia , Teratogênicos , Glândula Tireoide/fisiologia , Animais , Peso Corporal/efeitos dos fármacos , Feminino , Fertilidade/efeitos dos fármacos , Hipertireoidismo/fisiopatologia , Hipotireoidismo/fisiopatologia , Tamanho do Órgão/efeitos dos fármacos , Gravidez , RatosRESUMO
Medroxyprogesterone acetate (MPA) was given once daily sc at 0.1-3,000 mg/kg/day for 3, 6, or 9 consecutive days during gestation days 7 to 15 to CD1 and A/J mice, and New Zealand (NZ) and Dutch Belted (DB) rabbits, and during days 8 to 16 to CD rats. Malformations attributable to MPA did not occur in fetuses of mice or rats exposed to the largest dosage tested. However, 1, 3, or 10 mg/kg on days 13 to 15 to NZ rabbits resulted in 6, 28, and 42% cleft palate, respectively. Comparable cleft palate frequencies were seen in DB offspring.
Assuntos
Anormalidades Induzidas por Medicamentos , Fissura Palatina/induzido quimicamente , Medroxiprogesterona , Animais , Peso Corporal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Morte Fetal , Idade Gestacional , Troca Materno-Fetal , Medroxiprogesterona/toxicidade , Camundongos , Gravidez , Coelhos , RatosRESUMO
Outbred albino (CD-1) mice were given the following biphenyl isomers by gavage in cottonseed oil on Days 6-15 of gestation: 4,4'-dichlorobiphenyl (DCB) at 16, 32, and 64 mg/kg/day; 3,3',4,4'-tetrachlorobiphenyl (3,4-TCB) at 1,2,4,8,16,32, and 64 mg/kg/day; 3,3',5,5'-tetrachlorobiphenyl (3,5-TCB) at 64 mg/kg/day; and 3,3',4,4'-tetramethylbiphenyl (TMB) at 64 mg/kg/day. The mice were killed on Day 18 of gestation, necropsies were performed on the dams, and the fetuses were examined for external, visceral, and skeletal malformations. Although DCB was toxic to the dams at 64 mg/kg/day, developmental toxicity was not detected. 3,4-TCB administration was followed by a significant (p less than 0.01) increase in the average percentage of malformed fetuses per litter at 4 (7.2%), 8 (9.8%), 16 (25.4%), 32 (50.0%), and 64 (75.0%) mg/kg/day versus the vehicle control group (1.1%). None of the dosages tested was lethal to any of the dams. Significant decreases in maternal weight gain were observed at 16 mg/kg/day and above; however, the differences from the control value most likely were due to significant decreases in the mean number of live fetuses per dam, as the result of reductions in the number of implants per dam, and significant increases in the incidence of resorptions. Vaginal bleeding and other evidence of abortifacient effects also were present in several dams in groups receiving 3,4-TCB at 16 mg/kg/day and above. Cleft palate and hydronephrosis (significantly increased at dosages of 4 mg/kg/day and above) were the predominant malformations detected. Thus, 3,4-TCB was found to be toxic to the conceptus at dosages of 4 mg/kg/day and above. Neither 3,5-TCB nor TMB showed indications of maternal or developmental toxicity at 64 mg/kg/day.
Assuntos
Desenvolvimento Embrionário e Fetal/efeitos dos fármacos , Bifenilos Policlorados/toxicidade , Teratogênicos , Animais , Compostos de Bifenilo/toxicidade , Peso Corporal/efeitos dos fármacos , Feminino , Masculino , Camundongos , Gravidez , Reprodução/efeitos dos fármacosRESUMO
Pregnant CD-1 mice were given phencyclidine by gavage on days 6-15 of gestation, at dose levels of 60, 80, 100, and 120 mg/kg/day. The mice were killed on day 18 and the offspring were examined for external, visceral, and skeletal alterations. There was a significant increase in the average percent of malformed fetuses per litter only at the 120 mg/kg/day dose level (6.1% versus 1.2% for the control), a dose level which resulted in the death of 8 of 18 dams before scheduled sacrifice. At dose levels less than 120 mg/kg/day, the incidence of malformations was not significantly higher than the control value, in spite of the presence of overt maternal toxicity. Because a significant number of malformations was not seen at dose levels which were not highly toxic to the dams, it was concluded that phencyclidine was not demonstrated to be a teratogen in the mouse.
Assuntos
Fenciclidina/farmacologia , Teratogênicos , Anormalidades Induzidas por Medicamentos/epidemiologia , Animais , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Feminino , Camundongos , Fenciclidina/toxicidade , GravidezRESUMO
Pregnant outbred albino mice (CD-1) received n-hexane once daily be gavage at doses up to 2.20 g/kg/day on days 6-15 of gestation. Other pregnant mice received higher hexane doses (up to 9.90 g/kg/day), employing a three times a day injection schedule. At the lower, once-daily doses only one dam died and no teratogenic effects occurred. Higher hexane doses (t.i.d.) were toxic: 2 of 25 dams treated with 2.83 g/kg/day, 3 of 34 treated with 7.92 g/kg/day and 5 of 33 treated with 9.90 g/kg/day died. At the 7.92 and 9.90 g/kg/day doses, the average fetal weight was significantly (p less than 0.05) reduced, but the incidence of malformations in treated and vehicle (cotton-seed oil) control groups did not differ significantly. Thus, n-hexane was not teratogenic even at doses toxic to the dam.
Assuntos
Embrião de Mamíferos/efeitos dos fármacos , Feto/efeitos dos fármacos , Hexanos/toxicidade , Teratogênicos , Animais , Feminino , Masculino , Camundongos , GravidezRESUMO
The embryofetal toxicity and teratogenicity of plane-wave 2.45 GHz continuous wave (CW) microwave radiation at different intensities were investigated in the CD-1 mouse. Mice were exposed on days 1-15 of gestation to an incident power density of 5 mW/cm2 (specific absorption rate of 6.7 mW/gm) and either on days 1-6 or 6-15 of gestation to 21 mW/cm2 (specific absorption rate of 28.14 mW/gm) or to 30 mW/cm2 (specific absorption rate of 40.2 mW/gm) for 8 hours daily. Exposure either on days 1-6 or 6-15 of gestation to a power density of 21 or 30 mW/cm2 caused an increase in colonic temperature of exposed dams of 1 degree C and 2.3 degrees C, respectively. To distinguish between "thermal" and "nonthermal" effects of 21 or 30 mW/cm2, groups of mice were also exposed to elevated ambient temperature to raise their body temperature to the level of those animals exposed to microwave. Ambient temperatures of 30 degrees C and 31 degrees C increased the deep colonic temperature to that obtained with the 21 and 30 mW/cm2 microwave exposure, respectively. The temperature-exposed mice were handled in exactly the same manner as the microwave-exposed mice. A significant reduction in maternal weight gain, either during treatment on days 1-6 or 6-15 of gestation was observed in females of all handled groups. Handling plus exposure to elevated ambient temperature (30 degrees C or 31 degrees C) during days 6-15 of gestation increased this reduction in maternal weight gain. A significant decrease in implantation sites per litter and reduction in fetal weight was noted in the group exposed to 30 mW/cm2 during days 1-6 of gestation. Exposure of mice to a power density of 30 mW/cm2 (days 6-15 of gestation) resulted in a slight, but significant increase in the percentage of malformed fetuses, predominantly with cleft palate, when compared to all other groups.
Assuntos
Feto/efeitos da radiação , Micro-Ondas/efeitos adversos , Animais , Temperatura Corporal/efeitos da radiação , Anormalidades Congênitas/etiologia , Feminino , Fertilidade/efeitos da radiação , Morte Fetal/etiologia , Idade Gestacional , Camundongos , Gravidez , Doses de RadiaçãoRESUMO
Ammonium perfluorooctanoate (APFO, greater than 95% pure) was administered to Sprague-Dawley rats from Days 6 through 15 of gestation by inhalation as a dust (whole body exposure) for 6 hr/day at 0, 0.1, 1, 10, and 25 mg/m3, or by gavage at 100 mg/kg body wt/day in corn oil. Maternal deaths occurred in the groups given the highest level of APFO by each route and overt toxicity was evident among the surviving dams of these groups and among those of the 10-mg/m3 group. The fetuses were examined for external, visceral, and skeletal alterations and for APFO-related macroscopic and microscopic alterations of the eyes. In the postpartum period, pups from additional control and experimental dams were examined externally and ophthalmoscopically, and the usual fertility and viability indices were calculated. A teratogenic response was not demonstrated. Toxic effects on the conceptus were noted only in the groups given the highest level of APFO by each route. Hence, APFO was not demonstrated to represent a unique hazard to the conceptus of the rat.
Assuntos
Caprilatos/toxicidade , Fluorocarbonos/toxicidade , Teratogênicos , Aerossóis , Animais , Ingestão de Alimentos/efeitos dos fármacos , Embrião de Mamíferos/efeitos dos fármacos , Feminino , Reabsorção do Feto/induzido quimicamente , Feto/efeitos dos fármacos , Intubação Gastrointestinal , Fígado/efeitos dos fármacos , Tamanho do Órgão/efeitos dos fármacos , Gravidez , Ratos , Ratos EndogâmicosRESUMO
Pregnant outbred albino mice were given formaldehyde or Sonacide (potentiated acid glutaraldehyde) by gavage on days 6--15 of gestation. The mice were killed on day 18, the general health and reproductive status of the dam evaluated, and the fetuses examined and processed in order to characterize external, visceral, and skeletal malformations. Although formaldehyde (stock solution containing 12--15% methanol as a preservative) was lethal to 22 of 34 dams treated with 185 mg/kg/day, and one of 35 dams treated with 148 mg/kg/day, these doses did not produce statistically significant (two-sided p < 0.05 versus controls) teratogenic effects in the fetuses of the surviving dams. Sonacide was also judged not to be teratogenic to the mice employed in this study, in spite of the fact that relatively high doses were employed. The highest doses of Sonacide studied (5.0 ml/kg/day, which is equivalent to 100 mg/kg/day of glutaraldehyde) killed 19 of 35 dams and caused a significant reduction in the mean weight gain of the surviving mothers. In addition, this dose produced a significant increase in the number of stunted fetuses.
Assuntos
Anormalidades Induzidas por Medicamentos/embriologia , Aldeídos/toxicidade , Embrião de Mamíferos/efeitos dos fármacos , Feto/efeitos dos fármacos , Formaldeído/toxicidade , Glutaral/toxicidade , Animais , Desinfetantes/toxicidade , Feminino , Morte Fetal/induzido quimicamente , Doenças Fetais/induzido quimicamente , Retardo do Crescimento Fetal/induzido quimicamente , Camundongos , Polímeros/toxicidade , Gravidez , Prenhez/efeitos dos fármacosRESUMO
Different noise exposure paradigms were studied to determine their teratogenic and embryo-fetotoxic potential in the CF-1 mouse. Female mice were exposed from days 1-6 or from days 6-15 of gestation to one of three noise exposure paradigms which differed widely in level, spectral, and temporal characteristics. Paradigms for noise exposure were chosen to represent semi-continuous exposure to extremely high-intensity noise (jet engine noise at 126 dBA, from noon to midnight); to represent startling type noise composed of alarm bells, jet engine noise, or narrow band warning devices at 110 dBA, with pseudorandom onset and duration of each controlled by a microprocessor (exposure time of 18% over each 24 hour period); and finally to represent very high frequency noise (18-20 kHz tones, derived from a device commercially marketed for repelling rodents, with exposure from noon to midnight). On day 18 of gestation the females were sacrificed, their reproduction status determined, and the concepti were examined for toxicity and for external, visceral, and skeletal alterations. Maternal plasma corticosterone levels were measured at different periods of gestation. Significantly decreased pregnancy rate was noted in all groups exposed to noise except in the group exposed to the very high frequency noise from days 6-15 of gestation. Significant embryolethal effects occurred in the group exposed to the extremely high intensity jet noise paradigm, from days 1-6 of gestation, and significant fetolethal effects occurred in the group exposed to the very high frequency noise paradigm from days 6-15 of gestation. No significant noise-related changes were noted in the incidence of structural alterations or in the concentration of plasma corticosterone.
Assuntos
Anormalidades Congênitas , Corticosterona/sangue , Ruído/efeitos adversos , Animais , Perda do Embrião , Desenvolvimento Embrionário , Feminino , Camundongos , Gravidez , Fatores de TempoRESUMO
Pregnant outbred albino rats (CD) and mice (CD-1) were given epichlorohydrin by gastric intubation on d 6-15 of gestation. The rats were killed on d 21 (d 18 for mice) and the offspring checked for gross, visceral, and skeletal malformations. Epichlorohydrin caused a significant reduction in the weight gain of pregnant rats at 80 mg/kg.d as compared with the control group treated only with the vehicle. However, there was no evidence of teratogenicity in the rat fetuses even at a dose level (160 mg/kg.d) that caused the death of some of the treated dams. Epichlorohydrin also did not produce a statistically significant increase in the average percent of malformed mouse fetuses, even at 160 mg/kg.d, a dose that killed 3 of 32 treated dams. The 120 and 160 mg/kg.d levels did cause a significant (p less than 0.05) reduction in the average fetal weight as compared with controls. In addition, the 120 mg/kg.d dose produced the statistically significantly increase in the liver weight of the pregnant mouse. These observations indicate that the 120 and 160 mg/kg.d dose levels were toxic toward the dams and their unborn offspring. In a similar mouse study, glycidol showed no evidence of teratogenicity. There was a significant increase in the number of stunted fetuses at 200 mg/kg.d, but all of these were present in a single litter. Further, the same dose killed 5 of 30 dams.
Assuntos
Cloridrinas/toxicidade , Epicloroidrina/toxicidade , Compostos de Epóxi/toxicidade , Éteres Cíclicos/toxicidade , Propanóis , Teratogênicos , 1-Propanol/toxicidade , Animais , Peso Corporal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Camundongos , Gravidez , Ratos , Reprodução/efeitos dos fármacosRESUMO
Pregnant CF-1 mice, Sprague-Dawley rats and New Zealand white rabbits were given 15% ethanol in their drinking water during the period of major organogenesis, from day 6 through 15 of gestation in mice and rats and days 6 through 18 of gestation in rabbits. Maximum blood alcohol levels, measured in non-pregnant animals, were about 200 mg percent in mice and 25-50 mg percent in rats and rabbits. Maternal toxicity in the form of decreased liquid intake and decreased maternal body weight occurred in all species during the experimental period. A significant increase in the incidence of external or soft tissue alterations was not observed in the alcohol-exposed groups of any species, but a significant increase in minor skeletal variants was observed in mice and rats. These were probably due to retarded fetal growth rather than to a specific effect of the ethanol. Teratogenic effects were not observed in any of the three species.
Assuntos
Etanol/toxicidade , Teratogênicos , Animais , Etanol/sangue , Feminino , Idade Gestacional , Troca Materno-Fetal , Camundongos , Gravidez , Coelhos , Ratos , Especificidade da EspécieRESUMO
Pregnant CD-1 mice drank either chlorinated tap water obtained at NIEHS from the City of Durham, North Carolina municipal water supply or this same water passed in sequence through an organic removal cartridge and a demineralizer, followed by glass distillation. No significant overall differences in the reproductive status of pregnant mice were noted when the two groups were compared. Similarly, no significant overall influence on the incidence of malformed fetuses could be traced to the purity of drinking water. Month by month comparisons indicated that there were three statistically significant differences; all of which indicated improved performance for the mice that drank tap water. When the results for both groups were combined and a month by month comparison was made there was a significant difference in the pregnancy rate for February (68%) as compared with an overall pregnancy rate of 80% and a 79-93% spread for the other months, but the decrease was due to the low incidence of pregnancy in the group that drank the purified water.