Teratogenicity of metals to chick embryos.

The present study examines the effects of heavy metals on chick embryogenesis. The metals included were cadmium, arsenic, cobalt, copper, indium, iron, manganese, and molybdenum. Salts of each of the metals were dissolved in saline and injected into the air sacs on d 2 of incubation. Dose levels varied with the metal to be tested. Control eggs were injected with an equivalent volume of saline (0.1 ml/egg). On d 14, the live embryos were removed from the eggs and examined for gross malformations. From the LD50 values, the toxicity relationship between the metals is cadmium greater than arsenic greater than cobalt greater than copper greater than indium greater than molybdenum greater than manganese greater than iron. The LD50 values were 3, 9, 38, 58, 121, 333, 765, and 1185 micrograms/egg, respectively. The gross malformations observed were reduced body size, micromelia, twisted neck, hemorrhage, everted viscera, and microphthalmia. Arsenic and cobalt were observed to be more teratogenic than other metals. This study showed that the metals tested were both toxic and teratogenic to varying degrees in chick embryogenesis.

The effects of minoxidil on the development of the chick embryo.

The effects of minoxidil were studied on chick embryos of 24 and 48 hours of incubation. Minoxidil (3%) was injected into the air sacs of the eggs at doses of 20, 30, 40, and 50 microliters per egg. The controls received 100 microliters of physiological saline. All the embryos, including controls, were examined at day 13. The total number of eggs used in this study was 300. At 24 hours incubation, the percentage of survival ranged from 87 to 21 as the dosages of minoxidil were increased from 20 microliters to 50 microliters per egg (controls = 87%). The survival of the embryos ranged from 79% to 9% after the 48-hour treatment with the similar dosages of minoxidil utilized for the 24-hour group (controls = 83%). A low incidence of gross malformations such as twisted limbs, abnormal beak, short neck and everted viscera were observed; however, the increased incidence was not statistically significant when compared to controls. Body hemorrhage and edema were of high occurrence among the treated embryos. These effects are probably secondary to the known pharmacological effects of minoxidil. The frequency and types of gross malformations did not vary much in the 24 or 48-hour treated groups.

Embryopathic effects of ethanol in the chick.

The chick embryo is considered a highly sensitive system for the screening of drugs for possible teratogenicity. The effects of varying concentrations of ethanol on the early development of chick embryos were studied. The mean weight of embryos exposed to ethanol was reduced compared to that of the control groups, but the difference was not significant. However, embryolethality and the incidence of abnormal embryos were significantly increased and related to the dose of ethanol.

Teratogenicity of cytochalasin D in chick embryos.

The effects of cytochalasin D on chick embryos were analyzed in the present study. Cytochalasin D was dissolved in DMSO and injected into embryonating chicken eggs at dosages ranging from 0.001 to 0.014 mg per egg. The injections were made into the air sacs of eggs at days 0, 1, 2 and 3 of incubation. The volume of each injection was 0.1 ml per egg. In all, 864 chicken eggs were used for this study. All embryos were examined on day eleven. The following malformations were observed: exencephaly, microphthalmia, everted viscera, body hemorrhage, edema, anophthalmia and a reduced body size. The dose-response relationship was observed in all of the groups tested. The results of the present study indicate that cytochalasin D is embryolethal and has some tendency to cause malformations in the chick embryos tested.

Acrolein and embryogenesis: an experimental study.

The effects of acrolein were studied on the chick embryos of 48 and 72 hr of incubation. Acrolein was dissolved in physiological saline and injected into the air sacs of the eggs at doses ranging from 0.001 to 0.1 mg per egg. The controls received and equal amount of saline only (0.1 ml per egg). All the embryos including controls were examined at Day 13. In all, 600 eggs were utilized for this investigation. At 48 hr incubation, the percentage survival ranged from 80 to 0 as the dosage of acrolein was increased. Embryonic mortality following 72 hr incubation did not increase significantly at any dose level. Gross malformations such as short and twisted limbs, everted viscera, microphthalmia, short and twisted neck, and hemorrhage over the body were observed. The frequency and the types of gross abnormalities did not vary much in the 48- or 72-hr-treated groups. The incidence of malformation in the controls was low. The results of this study indicate that acrolein is embryotoxic at higher doses and moderately teratogenic to chick embryogenesis.

Chick embryonic development following exposure to caffeine and nicotine.

Because cigarette smoking is considered to be deleterious to the fetus and caffeine is held in suspect as a potential human teratogen, the combined effects of caffeine and nicotine on early chick embryos were investigated. Treatment of the embryos at 48 h incubation with both caffeine (1 mg) and nicotine (1 mg) resulted in a high incidence of embryonic death and developmental defects. At 72 h incubation teratogenicity was potentiated following the same treatment. Embryonic growth was not affected. Embryotoxic interactions of this nature might account for congenital anomalies of doubtful etiology.

Chick embryonic development following exposure to ethanol and pyrazole.

The mechanism of alcohol-induced dysmorphogenesis is not clear. Pyrazole is a potent inhibitor of alcohol dehydrogenase. Treatment of chick embryos at 96 h incubation with pyrazole (0.1 mg) and ethanol (0.1 ml, 40-60% v/v) enhanced the embryopathic response, compared with individual treatments. The results suggest that ethanol itself is embryotoxic.

Embryotoxic effects of doxorubicin and N-trifluoroacetyladriamycin-14-valerate (AD-32).

Anthracyclines are mutagenic, carcinogenic, and also cardiotoxic. Concern has been shown over the use of anthracycline anticancer drugs during pregnancy as these may be teratogenic to the human fetus. We have performed a series of experiments using the chick embryo to investigate and compare the toxic and teratogenic effects of doxorubicin (DX) and its new analog N-trifluoroacetyladriamycin-14-valerate (AD-32). DX and AD-32, dissolved in 1:1 emulphor/ethanol and diluted to 1:4 with water, were injected into the air sac of white leghorn chick eggs at dose levels of 1-20 micrograms (DX) and 5-100 micrograms (AD-32) per egg. Eggs received a single injection of the drugs on days 1 and 2 of incubation. Control eggs were injected with an equivalent volume of the drug vehicle (0.05 ml per egg). Both of the drugs caused embryonic death, stunted growth, and various gross morphological malformations. Surviving embryos were sacrificed when they reached 13 days of incubation. The LD50 values for days 1 and 2 were as follows: (DX, 2.5 micrograms/egg on day 1 and 0.9 microgram/egg on day 2; AD-32, 10.6 micrograms/egg on day 1 and 11.8 micrograms/egg on day 2). Stunting of growth, a common anomaly with both drugs, decreased sharply from day 1 to day 2. The studies demonstrate that both DX and AD-32 are toxic and teratogenic during the period of early organogenesis in the chick embryos. However, the toxic and teratogenic potentials of DX and AD-32 differ quantitatively. AD-32 is a more potent teratogen than DX when injected on day 1.

Embryopathic effects of ethanol and caffeine in the chick.

The combined effects of ethanol (20 and 40%, 0.1 ml/egg) and caffeine (0.5 and 1 mg/egg) on early chick embryos were investigated. After treatment with 0.5 mg caffeine and 20% ethanol at 48 h incubation, teratogenicity was potentiated, but without affecting embryonic growth. Embryotoxic interactions of this nature might account for congenital defects of doubtful etiology.

Effect of chronic ethanol ingestion on the metabolism of copper, iron, manganese, selenium, and zinc in an animal model of alcoholic cardiomyopathy.

Alcoholic cardiomyopathy (AC) is one of the diseases caused by alcohol abuse, and there has been considerable debate about the possibility that nutritional factors may be important in the etiology of AC. In addition, there is evidence that ethanol may affect the metabolism of trace elements. The purpose of this investigation was to determine if chronic ethanol administration produces changes in the metabolism of the essential metals copper, iron, manganese, zinc, and selenium using an animal model of AC. Eighteen male Sprague-Dawley rats were divided into three groups: an ad libitum control group (AL), a pair-fed control group (PF), and an ethanol-dosed group (ETOH). The latter group received gradually increasing concentrations (5-25%) of ethanol in the drinking water for 15 wk. Food intake was monitored and urine and feces collected for a 4-d period during the study to determine ethanol effects on trace-element balance. Growth of both the PF and ETOH animals was inhibited. Ethanol produced substantial increases in liver manganese and decreases in liver copper and zinc. Metal concentrations in heart and concentrations in other tissues studied (spleen, testes, brain, bone, kidney, and muscle) did not differ significantly among the groups, except for testes selenium and kidney zinc. Reduced food intake and ethanol ingestion were associated with a reduced percentage of ingested selenium excreted in the urine. Deficiencies of copper, iron, manganese, selenium, and zinc in myocardial tissue are not likely to be involved in the pathogenesis of AC in the rat.

Embryopathic effects of cyclophosphamide.

Cyclosphosphamide, dissolved in saline, was injected into the air sac of white Leghorn chick eggs in dose levels of 0.005, 0.007, 0.010, 0.012, 0.015, and 0.017 mg per egg. Eggs received a single injection of cyclophosphamide on Days 0, 1, 2, or 3 of incubation. Control eggs were injected with an equivalent volume of saline (0.1 ml per egg). In all 904 chicken eggs were used for this study. Surviving embryos were sacrificed when they reached 11 days of incubation. The LD50 values for Days 1, 2, and 3 were 0.017, 0.007, and 0.012 mg per egg, respectively. The overall incidence of abnormal embryos for Days 0, 1, 2, and 3 were 7, 6.3, 12, and 22%, respectively. Abnormalities such as reduced body size, everted viscera, short and twisted limbs, eye defects, abnormal beak, and short and twisted neck were commonly seen in survivors no matter when exposed to cyclophosphamide. The teratogenicity of cyclophosphamide was noted to be the highest in the embryos treated on Day 3. The present study has demonstrated that cyclophosphamide is toxic and teratogenic during the period of early organogenesis in the chick embryos.

Embryopathic effects of caffeine in the chick.

There is increasing concern about the potential teratogenic effects of caffeine. Laboratory rodents were widely used for the teratological evaluation of caffeine. However, few studies have been carried out in non-mammalian organisms. Caffeine, dissolved in sterile water, was injected into the air sacs of fertile White Leghorn chick eggs at doses of 100, 200, 300, 400, 500, 700, 900, and 1,100 micrograms per egg. Control eggs were injected with an equivalent volume of sterile water (0.1 ml/egg). The embryos were treated at either 48, 72, or 96 hours incubation. On day 9, live embryos were recovered and examined for external malformations after staging and weighing. Treatment with 400 and 1,100 micrograms caffeine at 48 hours incubation resulted in a significantly high incidence of abnormal embryos, compared to the controls. The most common malformations included reduced body, microphthalmia, exencephaly, everted viscera and short neck. A significant number of embryos died following treatment with 1,100 micrograms caffeine at 48 hours incubation, and 400 and 700 micrograms at 72 hours incubation. Embryonic growth was not affected. Even though it is not possible to extrapolate these findings directly to humans, moderation in the consumption of caffeine-containing beverages during pregnancy is recommended.

Development of the chick embryo following PGE1 treatment.

Chick embryos were treated with prostaglandin E1 (10, 20, 30, and 50 micrograms) at 48 and 72 hours incubation. Live embryos were recovered on day 9, staged, and examined for external malformations after weighing. There was no significant increase in embryonic mortality and malformation rates compared to the controls. Embryonic growth was also not affected.

Embryopathic effects of thromboxane B2 in the chick.

Several prostaglandins of the E and F series are now known to be involved in reproduction and developmental events. However, there is as yet no such evidence for any of the other arachidonate metabolites. Thromboxane B2 is the stable metabolic end product of the biologically active but unstable intermediate thromboxane A. Administered to developing chick embryos at 48 and 72 hours incubation, thromboxane B2 caused growth retardation and induced a high incidence of anomalies, in particular, everted viscera.

Congenital abnormalities in nickel poisoning in chick embryos.

Experiments were conducted to evaluate the teratogenic potential of nickel chloride given to developing chick embryos. Nickel chloride was dissolved in saline and injected into chicken eggs at dosages ranging from 0.02 to 0.7 mg per egg. The injections were made into the air sacs of eggs at days 0, 1, 2, 3, and 4 of incubation. Control eggs were injected with an equivalent volume of saline (0.1 ml per egg); in all, 840 chicken eggs were used. All embryos were examined on day eight. The following malformations were observed: exencephaly, everted viscera, short and twisted neck, short and twisted limbs, microphthalmia, hemorrhage, and reduced body size. The dose-response relationship was observed in all of the groups tested. The toxicity and teratogenicity of nickel chloride was the highest in the embryos treated at day 2. The results of the present study indicate that nickel chloride is teratogenic.

Abnormal embryogenesis induced by thiopental.

The effects of thiopental on chick embryos were analyzed in the present study. Thiopental was dissolved in saline and injected into embryonating chicken eggs at doses ranging from 0.2 to 4.0 mg per egg. The injections were made into the air sacs of eggs after two to four days of incubation. Control eggs were injected with an equivalent volume of saline (0.1 ml per egg). In all 1080 chicken eggs were used for this study. All embryos were examined on day 7. The LD50 for eggs injected on days 2, 3 and 4 was 2.1, 1.9, and 4.1 mg per egg, respectively. The principal malformations observed were exencephaly, anencephaly, twisted limbs, twisted neck, microphthalmia, everted viscera, and hemorrhage above the left eye and in both cerebral hemispheres. The results of the present study indicate that thiopental has a tendency to cause malformations in the chick embryos tested.