Metabolism and distribution of [2,3-(14)C]acrolein in lactating goats.

The metabolism and distribution of [2,3-(14)C]acrolein were studied in a lactating goat orally administered 0.82 mg/kg of body weight/day for 5 days. Milk, urine, feces, and expired air were collected. The goat was killed 12 h after the last dose, and edible tissues were collected. The nature of the radioactive residues was determined in milk and tissues. All of the identified metabolites were the result of the incorporation of acrolein into the normal, natural products of intermediary metabolism. There was evidence that the three-carbon unit of acrolein was incorporated intact into glucose, and subsequently lactose, and into glycerol. In the case of other natural products, the incorporation of radioactivity appeared to result from the metabolism of acrolein to smaller molecules followed by incorporation of these metabolites into the normal biosynthetic pathways.

Metabolism and distribution of [2,3-(14)C]acrolein in laying hens.

The metabolism and distribution of [2,3-(14)C]-acrolein were studied in 10 laying hens orally administered 1.09 mg/kg of body weight/day for 5 days. Eggs, excreta, and expired air were collected. The hens were killed 12-14 h after the last dose and edible tissues collected. The nature of radioactive residues was determined in tissues and eggs. All of the identified metabolites were the result of the incorporation of acrolein-derived radioactivity into normal natural products of intermediary metabolism in the hen except for 1,3-propanediol, which is a known degradation product of glycerol in bacteria.

Metabolism and distribution of [2,3-14C]acrolein in Sprague-Dawley rats. II. Identification of urinary and fecal metabolites.

The metabolites of [2,3-14C]acrolein in the urine and feces of Sprague-Dawley rats were identified after either intravenous administration in saline at 2.5 mg/kg or oral administration by gavage as an aqueous solution as either single or multiple doses at 2.5 mg/kg or as a single dose of 15 mg/kg. Selected urine and feces samples were pooled by sex and collection interval and profiled by combinations of reverse-phase, anion-exchange, cation-exchange, and ion-exclusion high-performance liquid chromatography (HPLC). Feces were also profiled by size-exclusion chromatography. Metabolites were identified by comparison with well-characterized standards by HPLC and by mass spectrometry. The urinary metabolites were identified as oxalic acid, malonic acid, N-acetyl-S-2-carboxy-2-hydroxyethylcysteine, N-acetyl-S-3-hydroxypropylcysteine, N-acetyl-S-2-carboxyethylcysteine, and 3-hydroxypropionic acid. The fecal radioactivity from the oral dose groups was partitioned into methanol-soluble, water-soluble, and insoluble radioactivity, some of which could be liberated by dilute acid hydrolysis. HPLC analysis of these extracts revealed no discrete metabolites. Size-exclusion chromatography indicated a molecular weight range of 2,000 to 20,000 Da for the radioactivity, which was unaffected by hydrolysis at reflux with 6 M acid or base. This radio-activity was thought to be a homopolymer of acrolein, which was apparently formed in the gastrointestinal tract. The pathways of acrolein metabolism were epoxidation followed by conjugation with glutathione, Michael addition of water followed by oxidative degradation, and glutathione addition to the double bond either following or preceding oxidation or reduction of the aldehyde. The glutathione adducts were further metabolized to the mercapturic acids.

Metabolism and distribution of [2,3-14C]acrolein in Sprague-Dawley rats.

The metabolism and disposition of [2,3-14C]acrolein was studied in Sprague-Dawley rats after oral or intravenous dosing. Four groups of ten rats (five male and five female) were dosed with radiolabeled acrolein intravenously at 2.5 mg kg-1 (Group 2), orally by gavage at 2.5 mg kg-1, either as a single dose (Group 3) or after 14 daily doses of unlabeled acrolein (Group 4), or orally by gavage at 15 mg kg-1 (Group 5). Urine, feces, expired air and organic volatiles were collected for 7 days, after which the animals were sacrificed and tissues collected. All samples were analyzed for total radioactivity. After 7 days, the excretory patterns of male and female rats were almost identical. Urinary excretion was highest in the intravenously dosed animals (66-69%) and lowest in the Group 5 animals (36-40%), whereas the reverse was true for feces (< 2% for i.v. Group 2 animals and 28-30% for the Group 5 animals). Carbon dioxide expiration was comparable (26-31%) across all groups. Tissue concentrations of radioactivity were minimal in all groups (< 1.2%), but concentrations of radioactivity were highest in the intravenous Group 2 animals. The time course of excretion for all groups was similar with the exception of the high-dose animal group, which showed a pronounced delay in excretion during the first 12 h.

Mutagenic activity of acrolein in S. typhimurium and E. coli.

Acrolein was tested for mutagenic activity in seven strains of Salmonella typhimurium and one strain of Escherichia coli using a preincubation assay procedure. Cytotoxicity was evident at dosing levels above 33 and 67 micrograms acrolein per plate in the absence and presence of S-9 activation, respectively. Evidence of mutagenic activity was seen at non-toxic dosing levels in S. typhimurium strains TA98 and TA100 and E. coli strain WP2 uvrA. Responses in TA98 and E. coli were marginal at best, but a firm positive mutagenic activity was noted in TA100 at 20 micrograms per plate without S-9 activation and at 67 micrograms per plate with S-9 activation. The results of this study demonstrate the mutagenicity of acrolein under highly controlled conditions.

Developmental toxicity of acrolein in New Zealand white rabbits.

Pregnant New Zealand white rabbits (20 per group) were treated via stomach tube with 0.0, 0.1, 0.75, or 2.0 mg/kg/day from Days 7 through 19 of presumed gestation and subjected to cesarean sectioning on Day 29. Throughout the period of treatment, clinical observations, feed consumption, and body weights were recorded. At the termination of the study, reproductive and fetal parameters were measured. Three does died during the study, and transient effects on body weight gains and feed consumption were noted, with a subsequent rebound effect reflected in both fetal and maternal weights in the high-dose group (2 mg/kg/day). Resorptions were elevated in the high-dose group, but the effect was not statistically significant. Fetal malformations were distributed evenly among groups, and incidences were consistent with historical control data on the same strain and at the same laboratory. Higher dosage levels (range-finding study, 4.0 and 6.0 mg/kg/day) produced high incidences of maternal mortality, spontaneous abortion, resorptions, clinical signs, gastric ulceration, and/or sloughing of the gastric mucosa. Acrolein was not found to be a developmental toxicant or teratogen at doses not toxic to the does under the conditions employed in this study.

One-year toxicity of orally administered acrolein to the beagle dog.

Forty-eight dogs were separated into four groups of six males and six females. Acrolein (0.1% aqueous) was administered in gelatin capsules to three of these groups at dosing levels of 0.1, 0.5 and 1.5 mg kg-1 day-1 based on results of a range-finding study. After 4 weeks, the high dose was increased to 2 mg kg-1 day-1. The fourth group received deionized water in the same number of gelatin capsules as the high-dose group. Dosing was 7 days per week for 53 weeks. Blood and biochemical measurements were made pretest and at 3-month intervals thereafter. At termination, all dogs were subjected to full necropsy and histological examination. The major test effect noted was frequent vomiting after dosing. This was observed to be dose-dependent and the frequency decreased with time, indicating an adaptive effect. One mid-dose female died during the test and was diagnosed as having died of severe bronchial pneumonia, probably a result of vomitus aspiration. Serum albumin, calcium and total protein values were depressed in high-dose animals throughout the study. Some variability in red blood cell parameters and coagulation times were noted but the significance of these effects was not obvious.

Reproductive study of acrolein on two generations of rats.

Four groups of 30 male and 30 female rats were intubated with 70 daily doses of acrolein at levels of 0, 1, 3, or 6 mg/kg in a dosing volume of 5 ml/kg. Rats within each dosing group (F0 generation) were then assigned to a 21-day period of cohabitation and dosing for females continued through cohabitation gestation and lactation. Males were euthanized after cohabitation. F1 generation rats were chosen from pups, and a similar pretreatment, cohabitation, gestation, and lactation regimen was accomplished resulting in F2 generation pups. Reproductive parameters, body weights, food consumption, and clinical signs were recorded and necropsies were carried out on all treated animals. Histopathologic exams were accomplished on selected reproductive tissues. In addition, gross lesions, target tissues, stomachs, and lungs were examined. For the most part, reproductive parameters were unaffected by acrolein treatment with the exception of reduced pup weights in the F1 generation pups at the high-dose level (6 mg/kg/day). Gastric lesions were noted consistently in high-dose animals and some mid-dose (3 mg/kg/day) rats. Erosions of glandular mucosa and hyperplasia/hyperkeratosis of the forestomach were the most frequent stomach lesions observed. Effects on body weight gains were noted frequently for the high-dose animals and achieved statistical significance in the mid-dose animals on several occasions. Mortality in all high-dose animals was elevated relative to control animals. Acrolein, therefore, cannot be considered a selective reproductive toxin in the rat, but does produce toxicological effects down to a dosing level of 3 mg/kg/day.

Two-year toxicity and carcinogenicity study of acrolein in rats.

Five-hundred and sixty Sprague-Dawley rats were randomized into one control and three treatment groups (70 of each sex per group). Animals were treated by daily gavage with 0.0, 0.05, 0.5 and 2.5 mg kg-1 acrolein in water (10 ml kg-1). These dosing levels were selected as a result of a 6-week range-finding study. Ten rats of each sex per group were sacrificed at 1 year, and the remainder of the animals were treated for 102 weeks. Daily observations wer made, and various clinical, hematological and urine parameters were measured after 3, 6, 12 and 18 months of treatment and immediately prior to termination. All animals, whether found dead or sacrificed, were subject to necropsy and both absolute and relative organ weights were recorded. An extensive array of tissues were examined microscopically for all test animals. The only effects noted for treated rats that were statistically different from controls were consistent depression of creatinine phosphokinase levels, which was difficult to explain, and consistent increases in early cumulative mortalities in both males and females. There was no significantly increased incidence of microscopic lesions in treated rats, whether neoplastic or non-neoplastic. This study clearly demonstrates the lack of neoplastic response in Sprague-Dawley rats as a result of being treated with acrolein by gavage.

Gene mutation assay of acrolein in the CHO/HGPRT test system.

The mutagenic potential of acrolein has been studied with a wide range of in vitro and in vivo genetic toxicity assays. The data often have been conflicting, especially with the Ames assay. This study was undertaken to assess the mutagenic potential of acrolein using the CHO/HGPRT assay, both with and without metabolic activation. This assay system was chosen because it provides eukaryotic DNA as the target and is capable of detecting a range of mutational events. Because of its considerable toxicity, acrolein was tested over a very narrow dose range of 0.2-2 nl ml-1 without exogenous activation and 0.5-8 nl ml-1 with rat S-9 activation. Multiple assays were performed under both conditions. The results indicated that while acrolein was clearly very cytotoxic, it did not induce a significant mutagenic response in the presence or absence of metabolic activation.

Reproduction and subchronic feeding study of carnauba wax in rats.

The reproductive performance of Wistar rats fed carnauba wax at levels of 0.1, 0.3 or 1% in the diet and the effects of subchronic administration of carnauba wax at these dose levels on the resultant progeny were studied. Reproductive indices, body-weight gain, food consumption, haematological and clinical chemical data, ophthalmic, gross and histopathological examinations were used to study the possible toxic or pathological effects. Serum free fatty acid levels were found to be decreased in male and female rats fed carnauba wax at dietary levels of 0.3 and 1.0%. No other effects of feeding carnauba wax at levels up to 1.0% of the diet were observed.

Subchronic feeding study of carnauba wax in beagle dogs.

Carnauba wax fed at levels of 0.1, 0.3 and 1% in the diet to beagle dogs for 28 wk did not produce evidence of toxicity or pathological effects. Body weight gain, food consumption, clinical chemical, haematological, and urine analysis data, and organ weights of animals fed carnauba wax were comparable with those of control animals. Ophthalmic, gross and histopathological examinations revealed no significant treatment-related findings.

Combined two-generation reproduction-teratogenesis study of zearalenone in the rat.

The toxicity of zearalenone was studied in two generations of Wistar rats over approximately 10 months. Zearalenone was administered in the diet; the dose levels used were 0, 0.1, 1.0 and 10.0 mg per kg body weight per day in all generations. Animals in the F0 generation were bred twice to produce F1A and F1B generations. The F1A generation was bred to produce the F2A generation. The only lesion found at necropsy that could be attributed to zearalenone administration was increased medullary trabeculation of the femur in animals given the high dose. A dose-related increase in absolute and relative thyroid, pituitary and adrenal gland weights occurred in male and female rats of both the F1 and F1A generation. The alteration in the weights of these endocrine organs is probably a result of the estrogenic activity of zearalenone. Feeding of zearalenone caused decreases in fertility, number of viable offspring per litter and numbers of corpora lutea, implantations and resorptions per dam. Statistically significant differences were noted in the incidences of a number of skeletal and soft tissue abnormalities in both the F1B and F2A1 fetuses, especially at doses of 1.0 and 10.0 mg kg-1. These lesions most likely indicate a delay in fetal development. Unequivocal teratogenic effects could not be defined.

Reproduction study in rats or ginseng extract G115.

The effect of ginseng extract G115 on reproductive performance was studied in two generations of Sprague-Dawley rats. Animals of both sexes were fed wither control diet or diet supplemented with ginseng extract G115 at dose levels of 1 . 5, 5 or 15 mg/kg body weight/day. Parameters of reproduction and lactation in the treated groups were comparable to those of the controls for two generations of dams and pups. For F1 males and females, no treatment-related effects were seen in weekly body weights and food consumption, haematological and clinical chemical data, and ophthalmic, gross and histopathological examinations. The gross autopsies of F1 and F2 animals also revealed no significant treatment-related findings.

Teratogenicity study of N-methylpyrrolidone after dermal application to Sprague-Dawley rats.

Teratogenicity studies were performed in rats given N-methylpyrrolidone, a solvent used in chemical processing. Dosages of 75,237 and 750 mg of N-methylpyrrolidone/kg body weight/day were administered dermally to groups of 25 pregnant Sprague-Dawley rats on days 6 through 15 of gestation. Additionally, the study used a positive dermal control. Hexafluoroacetone, was chosen based on its dermal teratogenic activity. An oral positive control, aspirin, was included in order to add significance to the data generated in the experimental positive dermal control group. All animals were killed and subjected to uterine examination on day 20 of gestation. Maternal toxicity was indicated at 750 mg of N-methylpyrrolidone/kg by reduced body weight gain during gestation. Treatment with N-methylpyrrolidone resulted in dose-dependent brightly colored yellow urine and dry skin. Treatment at the high dosage level resulted in fewer live fetuses per dam, an increase in the percentage of resorption sites and skeletal abnormalities. These effects could be the result of maternal toxicity. There was no evidence of teratogenic effects nor effects on the dams at 75 and 237 mg/kg of body weight.

Long-term carcinogenicity and toxicity studies of patulin in the rat.

Patulin is a mycotoxin produced by a variety of Penicillium and Aspergillus species which are likely natural contaminants of various foods. The present study was conducted to determine the effects of lifetime administration of patulin in FDRL Wistar rats. Animals received patulin by gastric intubation three times per week at the level of 0.0, 0.1, 0.5 and 1.5 mg per kg body weight. The animals used in this lifetime study were derived from F0 parents exposed to equivalent levels of patulin for 4 weeks before mating, and throughout mating, gestation and lactation. Patulin treatment at 0.5 and 1.5 mg kg-1 to male rats caused a significant decrease in body weight gain in comparison to controls. Body weights of treated female rats were similar to that of control rats. No consistent significant differences among groups were noted in the hematology, clinical chemistry or urine analysis parameters measured during or at the termination of the study. Patulin administered to male and female rats at 1.5 mg kg-1 caused a significantly increased mortality rate as compared to respective control animals. The cause of death appeared to be increased pulmonary and laryngotracheal inflammation. No tumorigenic effect of patulin was observed.

Reproduction and teratology study of 1,3-butanediol in rats.

The effect of 1,3-butanediol on reproductive performance as well as its teratogenic, dominant lethal and cytogenetic effects were studied in five generations of Wistar rats. Animals of both sexes were fed either control diet or diet supplemented with 1,3-butanediol at dose levels of 5, 10 or 24% of the diet by weight. Reproduction and lactation parameters were comparative to controls for four of five generations of dams and pups. In contrast, the pregnancy rate of F1A rats decreased during five successive mating cycles; no pups were obtained in the high-dose level group of the fifth series of litters (F2E generation). Excluding this group, the viability of F2 generation pups revealed no significant differences between litters or between control and test groups. No definitive dose-related teratological findings were found in either soft or skeletal tissue examinations of F3B generation rats. However, incomplete ossification of sternebrae occurred frequently in mid- and high-dose fetuses, whereas missing sternebrae were noted especially in high-level fetuses. Both skeletal tissue findings suggest slight delayed fetal growth. For the dominant lethal assay of the F1B generation, the mutagenic index (percentage resorptions per implant sites) revealed no dose-related trend. In the three-generation cytogenetic study, no 1,3-butanediol related chromosomal aberrations were noted.