Hepatic ornithine decarboxylase activity in the rat as influenced by retinyl acetate and ethanol or tryptophan

Ethanol and tryptophan have been demonstrated earlier to induce a rapid stimulation of hepatic ornithine decarboxylase (ODC) activity in overnight-fasted rats. In this study the effect of the administration of retinyl acetate prior to administering ethanol or tryptophan was investigated. The levels of ODC activity in the livers of control and experimental rats were assayed in vitro by measuring the release of 14CO2 from DL-[1-14C]ornithine. Intraperitoneal administration of retinyl acetate (1 microgram/100 g body wt) 1 hr before tube feeding ethanol (0.75 g as a 50% solution/100 g body wt) or L-tryptophan (30 mg in 3 ml water/100 g body wt) and 3 hr before killing caused an enhanced stimulation of hepatic ODC activity compared to that when each agent was administered alone. In vitro [14C]leucine incorporation into protein using hepatic microsomes of tryptophan-treated rats with or without retinyl acetate was increased in comparison with that of controls while decreases were observed when using microsomes of ethanol-treated rats with or without retinyl acetate. Although retinyl acetate has been reported earlier to inhibit the stimulation of hepatic ODC activity due to a variety of agents, including some agents known as carcinogens or promoters, it did not act in this manner against the acute administration of ethanol or tryptophan.     

Stage of palate closure as one indication of “liability” to cleft palate

A new inbred mouse strain, SW/Fr, developed from a random-bred SW stock has a 6% incidence of spontaneous cleft palate without cleft lip. SW/Fr mice close their palates comparatively late in development. After cortisone treatment, the mean of the distribution (mean time to reach palate stage 5) is shifted towards later gestational ages. There is no change in the variance of the distribution. These data lend further support to the hypothesis that cleft palate in mice may fit a model where a continuous distribution is separated into discontinuous parts by a developmental threshold, and that time of palate closure is an important component of liability to cleft palate.     

Comparative teratogenicity of triamcinolone acetonide, triamcinolone, and cortisol in the rat

Pregnant rats were injected im with 0.5 mg/kg triamcinolone acetonide (TAC) on day 12, 13, or 14 of gestation and the fetuses were examined for cleft palate on day 20. All three TAC-treated groups showed an increased proportion of fetuses with cleft palate compared to an untreated control group. Only the group treated on day 13 showed a significant increase in the proportion of litters affected. This indicates that day 13 of gestation is the most sensitive day for cleft palate induction by TAC in the rat. Pregnant rats were then treated on day 13 of gestation with either TAC, triamcinolone (TA), or cortisol. TAC was 59 times as potent as TA in inducing cleft palate, with ED50 values of 1.1 mg/kg and 65 mg/kg respectively. Cortisol induced a significant increase in cleft palates at 500 mg/kg, but the efficacy of this compound was too low to calculate an ED50 and relative teratogenic potency value. Other developmental abnormalities including umbilical hernias, resorption, and fetal death resulted from TAC treatment. Fetal growth retardation was produced by all three compounds. The rank order of teratogenic potency was determined to be TAC greater than TA greater than cortisol.     

Prenatal influence of alcohol following a single exposure in two inbred strains of mice.

The effect of a single dose of ethanol on embryonic development was investigated in two inbred strains of mice. Ethanol (25% v/v solution, 0.02 ml/g body weight) was administered intraperitoneally on either gestational day 6, 9 or 12 to C57BL/6J and DBA/2J mice. All fetuses recovered near term were alive and appeared normal. The incidence of fetal death was not affected. Fetal weight was significantly reduced in the C57BL/6J strain of mice. Maternal exposure to a single and moderate dose of ethanol did not have any profound effect on the conceptus. For the development of laboratory models to mimic fetal alcohol effects in humans, the selection of appropriate genotype is important.     

Effects of N-acetylcysteine on fetal development and on phenytoin teratogenicity in mice

The teratogenicity of phenytoin may result from its enzymatic bioactivation to a reactive intermediate, which interacts irreversibly with fetal tissues. Since glutathione (GSH) is involved in the detoxification of many reactive intermediates, N-acetylcysteine (NAC), a glutathione precursor, was evaluated for its effects on murine fetal development and phenytoin teratogenicity. NAC, 100 to 275 mg/kg, was given intraperitoneally (ip) or per os (po), or as 266 to 410 mg/kg in the drinking water, at various times before or after phenytoin, 65 to 75 mg/kg ip, on gestational days 12 and 13. Dams were killed on gestational day 19, fetal resorptions were noted, and fetuses were examined for anomalies. Significant reductions in phenytoin-induced fetal weight loss and cleft palates were observed when NAC was given by gavage 6 hours after phenytoin or in the drinking water with the lower dose of phenytoin. NAC administered in the drinking water also reduced the incidence of resorptions produced by the higher dose of phenytoin and enhanced postpartum survival in fetuses exposed to 65 or 75 mg/kg phenytoin (P less than .05). Conversely, the incidence of resorptions increased when NAC was given by gavage at other times before or after phenytoin, by single or repetitive ip injections, or in high concentrations in the drinking water (P less than .05). When given with the higher dose of phenytoin, NAC administered via the drinking water significantly increased the incidence of phenytoin-induced cleft palates and fetal weight loss (P less than .05). Similar results were obtained with a single ip injection of NAC and a lower dose of phenytoin. Thus, when given orally, NAC can partially reduce phenytoin teratogenicity and embryopathy. However, altering the route of NAC administration, or increasing the dose of phenytoin and/or NAC, enhanced phenytoin embryotoxicity, and NAC alone at higher doses had embryopathic effects.     

Circadian modification of ethanol damage in utero to mice

This study evaluates the ethanol toxicity for fetal development at different circadian stages. Pregnant mice were given a single intraperitoneal ethanol injection on day 7, 8, or 10 of gestation at one of four circadian stages (0700, 1300, 1900, or 0100 hr). The dams were killed on the day before term (day 18). Prenatal exposure to ethanol resulted in an increased number of resorptions, reduced fetal body weight, and produced an increased incidence of external alterations. The severity of damage was related to the dose, the period of gestation, and particularly to the circadian stage at the time of treatment. Ethanol had the greatest effect on the embryo of a mouse when administered at the mid-dark span. Consequently exposure to a single dose of ethanol at one time or another along the 24-hr time scale during organogenesis has important implications for the substantially increased risk.     

Cortisone-induced hypertension and cardiovascular lesions in mice

Daily subcutaneous injections of cortisone acetate (0.5, 1.5 or 2.5 mg) were given to three groups of mice for seven consecutive days. Daily systolic blood pressures of the anesthetized mice were obtained by adapting the method of Friedman and Freed ('49). The maximal arterial pressure increase for the 0.5, 1.5 and 2.5 mg groups was 22%, 31% and 41% respectively. This supports the conclusion that cortisone produces hypertension in mice when administered in large doses. Mural hyalinization, vacuolization and cellular proliferation of coronary arteries were greatest in the 0.5 mg group. The highest incidence of myocardial necrosis, 56%, was in the group receiving 2.5 mg of cortisone daily. The frequency and severity of myocardial and renal cortical necrosis were directly related to the size of the cortisone dose. Adrenal medullary vacuolization and lipid infiltration of the liver were common in all experimental groups.     

Prenatal loss in the rat following moderate consumption of alcohol incorporated in a liquid diet

The teratogenic potential of alcohol in humans has now been confirmed, and a characteristic pattern of anomalies (Fetal Alcohol Syndrome) is found in infants born to mothers who are chronic alcoholics. The pathogenesis of the fetal alcohol syndrome is unclear: very little is known about the way alcohol acts during pregnancy and alters fetal growth and morphogenesis. The objective of this investigation was to determine the effects of a widely used ethanol liquid diet in the pregnant rat. The ethanol liquid test diet is based on the Lieber-De Carli formula. 20 Sprague-Dawley rats were matched closely by weights and assigned in pairs to either an alcohol treated or a pair-fed control group. Control animals received the same amount of the liquid diet with maltose-dextrins substituted isocalorically for the ethanol. Graduated tubes were used for the oral delivery of the diets. Ethanol was gradually introduced into the diet as follows: 100 Kcal/l, days 1-2; 200 Kcal/l, days 3-5; 350 Kcal/l, days 6-12. Following this initial treatment period, all animals were then given rodent pellets and tap water ad libitum. The mothers showed no overt signs of gross toxicity. The mean maternal weight gain of the ethanol treated animals did not differ significantly from the controls. The incidence of fetal resorptions was increased, intrauterine growth was not affected and the offspring at term appeared normal. The results indicate that moderate alcohol consumption during early gestation in the rat led to significant prenatal loss but proved to be non-teratogenic.     

Effect of cortisone acetate on 19S and 7S haemolysin antibody: A time course study

A single subcutaneous injectio of cortisone acetate (400–500 mg/kg body weight) depressed the serum haemolysin response of adult Swiss mice to sheep erythrocytes when administered near the time of antigen injection. The greatest suppression of the early haemolysin response occurred when cortisone was injected 3–4 days prior to antigen, while the late antibody response (20–30 days after antigen injection) was markedly decreased when cortisone was given up to 4 days after antigen. Cortisone depressed both 19S and 7S haemolysin when given prior to antigen, but depressed only the 7S antibody when administered after antigen. An attempt was made to correlate the depression of the immune response with the decrease in lymphoid tissue following cortisone treatment and a striking correlation was observed between the number of circulating lymphocytes at the time of antigen injection and the 7 day titres of total and 19S antibody.     

The effect of cortisone acetate on the metabolism of Hymenolepis microstoma (Cestoda: Cyclophyllidea)

Summary Hymenolepis microstoma grown in mice, treated with 1.25 mg cortisone acetate every second day, are heavier and have a significantly higher glycogen content than those in control mice. The dry/wet weight ratio and protein content however are unaffected. It is suggested that the increase in glycogen reserve and weight in H. microstoma from cortisone-treated mice is due to an immunosuppressive effect and better nutritional environment rather than hormonal action. Inclusion of 0.1 mg of cortisone per 100 ml of culture medium produces no change in worm weight in vitro.Single worm infections result in 100% recovery, but 30 worm infections provoke a rejection process which can be suppressed partially by administration of cortisone acetate. Present address: Vakgroep Dierkunde, Landbouwhogeschool, Ritzema Bosweg 32A, Wageningen, The Netherlands. The senior author acknowledges gratefully a fellowship from the University of Gent.     

Fetal mortality in oral cleft families: data from Indiana and Montreal

Analysis of 418 sibships of oral cleft probands from Indiana, and 288 sibships from Montreal indicate that the incidence of fetal mortality is significantly greater in sibships of probands with cleft lip and cleft palate (CLP) as compared to that in sibships of probands with cleft lip (CL) alone. These findings support a multifactorial-two-threshold concept, according to which a lower level of liability results in clefting whereas a higher level of liability causes fetal deaths. They add confirmatory evidence in support of the authors' earlier work, utilizing data from two different sources.     

唇腭裂相关基因研究进展

唇腭裂是一种常见的先天性畸形,其病因非常复杂,目前倾向认为是由多种基因和环境因素共同作用的结果。常见的引起唇腭裂相关的基因有TGFA,TGFβ3, BCL3, F13A等;环境因素在唇腭裂发生中的遗传修饰作用也很重要,主要的环境激发因素包括致畸因子（如烟草、酒精、糖皮质激素等）、感染和营养缺乏。基于基因打靶技术建立的鼠基因敲除模型很好地模拟了人类疾病的表现型,成为研究唇腭裂的一种强有力手段。     

Benomyl-induced craniocerebral anomalies in fetuses of adequately nourished and protein-deprived rats

Benomyl, a benzimidazole fungicide, produced craniocerebral and systemic malformations in fetal rats when administered by gavage in doses of 31.2, 62.5, and 125 mg/kg of maternal body weight on days 7-21 of gestation. Malformations increased in incidence and severity with increasing benomyl dosage and nearly doubled when coupled with a protein-deficient diet. Protein deficiency alone produced only decreased fetal weight. High benomyl doses produced higher percentages of fetal resorptions and late fetal deaths, and these percentages also increased with protein deficiency. A benomyl dose of 62.5 mg/kg in protein-deficiency dams, the optimal combination for a high incidence of anomalies and low fetal wastage, produced hydrocephalus in 69.4% of fetuses, meningocele in 8.2%, encephalocele in 14.3%, exencephaly in 44.9%, anencephaly in 14.3%, corpus callosum agenesis in 26.5%, periventricular necrosis in 26.5%, and periventricular cellular "overgrowth" in 55.1%. The most common combination of anomalies was hydrocephalus, exencephaly, and periventricular "overgrowth." Common systemic malformations included cleft palate, micromelia, hydroureter, and misshapen tails. No fetus was entirely normal at the highest benomyl dose. Benomyl has been shown by others to bind tubulin and inhibit the formation of microtubules that are important in neurulation, mitosis, and cell migration during early brain development. Thus, it is suggested that benomyl, coupled with a protein-deficient diet, offers a teratogenic model with a spectrum of abnormalities similar to hypervitaminosis A but with a higher yield of specific craniocerebral anomalies.     

Some new aspects of dexamethasone-induced cleft palate in mice

Pregnant mice were treated intramuscularly with dexamethasone in a single dose of 10 or 50 mg/kg once on day 13 of pregnancy at one of 4 fixed times. On day 18 palate condition of live fetuses and the number of resorptions were recorded and the relation of the incidence of palatal defect and serum corticosterone level was examined. The results suggest that there are different susceptibilities to teratogen-induced cleft palate during a 24-h period. The frequency of cleft palate was increased among term fetuses when there was a drop in the endogenous glucocorticoid of the dams.     

Validation of an in vivo developmental toxicity screen in the mouse

A test system for identifying toxicity, including potential teratogenicity has been developed that is based on growth and viability of embryonic, fetal, and postnatal mice (J Toxicol Environ Health 10:541-550, 1982). To test the utility of this assay, a series of 55 compounds was administered to timed-pregnant ICR/SIM mice during organogenesis. The test compounds included known teratogens, known nonteratogens, and equivocal teratogens. They represented a wide variety of classes including pesticides, organic solvents, metals, steroids, nutrients, food additives, antimetabolites, alkylating agents, and pharmaceutical agents. A single dose level, at or near the level producing overt maternal toxicity in preliminary range-finding studies, was administered by gavage on gestation days 8 through 12. Females were allowed to deliver; litter size and weight on the day of birth and 2 days postpartum were recorded, and stillborns were examined. Dams that had not given birth by gestation days 21 or 22 were killed and their uteri were examined. The results confirmed a strong correlation between reported teratogenic activity and embryo/fetal viability, and/or postnatal growth and viability. The results indicate that this test system is an effective, cost-efficient means of prioritizing compounds for more detailed teratogenicity testing.     

18号染色体三体NMRI小鼠发育畸形的实验研究

目的 通过对１８三体在ＮＭＲＩ小鼠发生率的研究及１８三体胚鼠和正常胚鼠的大体形态学对照观察，进一步认识１８三体ＮＭＲＩ小鼠的生长发育畸开。方法 ６０只Ｈａｎ－ＮＭＲＩ母鼠及１１只具有Ｒｂ（２．１８）６Ｒｍａ／Ｒｂ（１．１８）１０Ｒｍａ染色体结构的雄鼠，分别在妊娠第１６和１７天随机分两组断颈处死母鼠，６０只母鼠共有８２３只子代胚胎着床，其中５６９只为活胚。并对所获得的子代活胚进行染色体分体和大体莆态     

Comparative developmental toxicity study of indium in rats and mice

The developmental toxicity of indium was examined in both rats and mice using comparable experimental protocols. Pregnant rats received a single intravenous administration of indium trichloride (InCl(3)) at 0.4 mg In/kg, on day 9, 10, or 11 of pregnancy and their fetuses were examined on day 20. Pregnant mice were treated in the same manner at 0.8 or 1.6 mg In/kg on day 7, 8, or 9 of pregnancy and their fetuses were examined on day 18. In rats, indium caused fetal weight decrease and fetal gross malformations, such as brachyury, kinked tail, cleft palate, and oligodactyly, most severely by the administration on day 10. In mice, however, indium did not cause fetal gross malformations, although it caused fetal weight decrease at 0.8 mg In/kg or more and fetal death at 1.6 mg In/kg, most severely by the administration on day 8. It was concluded from these results that rats and mice were susceptible to the embryotoxicity of indium at similar developmental stages in the early organogenetic period, but mice were less susceptible to the teratogenicity of indium than rats in terms of gross malformation. Toxicokinetic factors may be involved in this different susceptibility. Teratogenesis Carcinog. Mutagen. 20:219-227, 2000.     

Fetal mortality and cleft lip with or without cleft palate

Analysis of fetal mortality in sibships of 406 probands with cleft lip with or without cleft palate (CL(P)) indicates that the incidence of fetal mortality is significantly greater in sibships of probands with bilateral CL(P) than in those of unilateral CL(P). The difference is even greater when fetal mortality in sibships of male probands with unilateral CL(P) is compared with that of female probands with bilateral CL(P). These findings support a multifactorial two-threshold concept in which a lower level of liability results in clefting while a higher level of liability causes fetal mortality.     

Relationship between ossification and body weight of the CD-1 mouse fetus exposed in utero to anticonvulsant drugs

The anticonvulsant drugs carbamazepine, Na valproate, and phenytoin have been suspected as a cause of human congenital defects. The malformations produced may include cleft lip and/or palate, heart defects, skeletal defects, and low body weights. Since the toxic effects of these anticonvulsant drugs manifest themselves in terms of fetal growth retardation, evaluation of the state of ossification attained in the fetus is important. In the present study, pregnant CD-1 mice received on gestational days 8-16 an oral dose of 375, 563, 938 mg/kg of carbamazepine; or 225, 338, 563 mg/kg of Na valproate; or 50, 75, 125 mg/kg of phenytoin. These groups were compared to two control groups. On day 17, the dams were killed by cervical dislocation and one-third of the live fetuses were weighed and fixed for skeletal examination. Photographs were taken of the fore- and hindlimb skeletons. From these photographs, the length and width measurement of ossified regions of the humerus and femur were determined using a Zeiss Video-Plan Morphometrics Computer. Of the three anticonvulsant drugs studied, the greatest correlation between reduced fetal weights and retarded ossification of the long bones was phenytoin at the 125 mg/kg dosage. Our results also showed that long bone ossification, when compared to the fetal weight, indicated that 59-66% of variability in weight is predictable by bone measurements.