Exposure to perfluorooctane sulfonate during pregnancy in rat and mouse. I: maternal and prenatal evaluations.

The maternal and developmental toxicities of perfluorooctane sulfonate (PFOS, C8F17SO3-) were evaluated in the rat and mouse. PFOS is an environmentally persistent compound used as a surfactant and occurs as a degradation product of both perfluorooctane sulfonyl fluoride and substituted perfluorooctane sulfonamido components found in many commercial and consumer applications. Pregnant Sprague-Dawley rats were given 1, 2, 3, 5, or 10 mg/kg PFOS daily by gavage from gestational day (GD) 2 to GD 20; CD-1 mice were similarly treated with 1, 5, 10, 15, and 20 mg/kg PFOS from GD 1 to GD 17. Controls received 0.5% Tween-20 vehicle (1 ml/kg for rats and 10 ml/kg for mice). Maternal weight gain, food and water consumption, and serum chemistry were monitored. Rats were euthanized on GD 21 and mice on GD 18. PFOS levels in maternal serum and in maternal and fetal livers were determined. Maternal weight gains in both species were suppressed by PFOS in a dose-dependent manner, likely attributed to reduced food and water intake. Serum PFOS levels increased with dosage, and liver levels were approximately fourfold higher than serum. Serum thyroxine (T4) and triiodothyronine (T3) in the PFOS-treated rat dams were significantly reduced as early as one week after chemical exposure, although no feedback response of thyroid-stimulating hormone (TSH) was observed. A similar pattern of reduction in T4 was also seen in the pregnant mice. Maternal serum triglycerides were significantly reduced, particularly in the high-dose groups, although cholesterol levels were not affected. In the mouse dams, PFOS produced a marked enlargement of the liver at 10 mg/kg and higher dosages. In the rat fetuses, PFOS was detected in the liver but at levels nearly half of those in the maternal counterparts, regardless of administered doses. In both rodent species, PFOS did not alter the numbers of implantations or live fetuses at term, although small deficits in fetal weight were noted in the rat. A host of birth defects, including cleft palate, anasarca, ventricular septal defect, and enlargement of the right atrium, were seen in both rats and mice, primarily in the 10 and 20 mg/kg dosage groups, respectively. Our results demonstrate both maternal and developmental toxicity of PFOS in the rat and mouse.     

Developmental toxicity of perfluorooctane sulfonate (PFOS) is not dependent on expression of peroxisome proliferator activated receptor-alpha (PPAR alpha) in the mouse

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are members of a family of perfluorinated compounds. Both are environmentally persistent and found in the serum of wildlife and humans. PFOS and PFOA are developmentally toxic in laboratory rodents. Exposure to these chemicals in utero delays development and reduces postnatal survival and growth. Exposure to PFOS on the last 4 days of gestation in the rat is sufficient to reduce neonatal survival. PFOS and PFOA are weak agonists of peroxisome proliferator activated receptor-alpha (PPAR alpha). The reduced postnatal survival of neonatal mice exposed to PFOA was recently shown to depend on expression of PPAR alpha. This study used PPAR alpha knockout (KO) and 129S1/SvlmJ wild type (WT) mice to determine if PPAR alpha expression is required for the developmental toxicity of PFOS. After mating overnight, the next day was designated gestation day (GD) 0. WT females were weighed and dosed orally from GD15 to 18 with 0.5% Tween-20, 4.5, 6.5, 8.5, or 10.5mg PFOS/kg/day. KO females were dosed with 0.5% Tween-20, 8.5 or 10.5mg PFOS/kg/day. Dams and pups were observed daily and pups were weighed on postnatal day (PND) 1 and PND15. Eye opening was recorded from PND12 to 15. Dams and pups were killed on PND15, body and liver weights recorded, and serum collected. PFOS did not affect maternal weight gain or body or liver weights of the dams on PND15. Neonatal survival (PND1-15) was significantly reduced by PFOS in both WT and KO litters at all doses. WT and KO pup birth weight and weight gain from PND1 to 15 were not significantly affected by PFOS exposure. Relative liver weight of WT and KO pups was significantly increased by the 10.5mg/kg dose. Eye opening of PFOS-exposed pups was slightly delayed in WT and KO on PND13 or 14, respectively. Because results in WT and KO were comparable, it is concluded that PFOS-induced neonatal lethality and delayed eye opening are not dependent on activation of PPAR alpha.     

Neonatal death of mice treated with perfluorooctane sulfonate

Pregnant mice exposure to perfluorooctane sulfonate (PFOS) causes neonatal death. Ten pregnant ICR mice per group were given 1, 10 or 20 mg/kg PFOS daily by gavage from gestational day (GD) 0 to the end of the study. Five dams per group were sacrificed on GD 18 for prenatal evaluation, the others were left to give birth. Additional studies were conducted for histopathological examination of lungs and heads of fetuses and neonates at birth. PFOS treatment (20 mg/kg) reduced the maternal weight gain and feed intake but increased the water intake. The liver weight increased in a dose-dependent manner accompanied by hepatic hypertrophy at 20 mg/kg. PFOS reduced the fetal body weight in a dose-dependent manner and caused a bilateral enlargement in the neck region in all fetuses at 20 mg/kg and mild enlargement in some fetuses at 10 mg/kg, in addition to skeletal malformations. Almost all fetuses at 20 mg/kg were alive on GD18 and showed normal lung structure; but at parturition, all neonates were inactive and weak, showed severe lung atelectasis and severe dilatation of intracranial blood vessel, and died within a few hours. At 10 mg/kg, all neonates were born alive, 27% showed slight lung atelectasis, all of them had mild to severe dilatation of the intracranial blood vessel, and 45% of neonates died within 24 hr. The cause of neonatal death in mice exposed to PFOS may be attributed either to the intracranial blood vessel dilatation or to respiratory dysfunction. The former might be a cause of the latter.     

Developmental toxicity of perfluorooctane sulfonate (PFOS) is not dependent on expression of peroxisome proliferator activated receptor-alpha (PPARα) in the mouse

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are members of a family of perfluorinated compounds. Both are environmentally persistent and found in the serum of wildlife and humans. PFOS and PFOA are developmentally toxic in laboratory rodents. Exposure to these chemicals in utero delays development and reduces postnatal survival and growth. Exposure to PFOS on the last 4 days of gestation in the rat is sufficient to reduce neonatal survival. PFOS and PFOA are weak agonists of peroxisome proliferator activated receptor-alpha (PPARα). The reduced postnatal survival of neonatal mice exposed to PFOA was recently shown to depend on expression of PPARα. This study used PPARα knockout (KO) and 129S1/SvlmJ wild type (WT) mice to determine if PPARα expression is required for the developmental toxicity of PFOS. After mating overnight, the next day was designated gestation day (GD) 0. WT females were weighed and dosed orally from GD15 to 18 with 0.5% Tween-20, 4.5, 6.5, 8.5, or 10.5 mg PFOS/kg/day. KO females were dosed with 0.5% Tween-20, 8.5 or 10.5 mg PFOS/kg/day. Dams and pups were observed daily and pups were weighed on postnatal day (PND) 1 and PND15. Eye opening was recorded from PND12 to 15. Dams and pups were killed on PND15, body and liver weights recorded, and serum collected. PFOS did not affect maternal weight gain or body or liver weights of the dams on PND15. Neonatal survival (PND1–15) was significantly reduced by PFOS in both WT and KO litters at all doses. WT and KO pup birth weight and weight gain from PND1 to 15 were not significantly affected by PFOS exposure. Relative liver weight of WT and KO pups was significantly increased by the 10.5 mg/kg dose. Eye opening of PFOS-exposed pups was slightly delayed in WT and KO on PND13 or 14, respectively. Because results in WT and KO were comparable, it is concluded that PFOS-induced neonatal lethality and delayed eye opening are not dependent on activation of PPARα.     

Neonatal mortality from in utero exposure to perfluorooctanesulfonate (PFOS) in Sprague-Dawley rats: dose-response, and biochemical and pharamacokinetic parameters

Perfluorooctanesulfonate (PFOS) is a widely distributed, environmentally persistent acid found at low levels in human, wildlife, and environmental media samples. Neonatal mortality has been observed following PFOS exposure in a two-generation reproduction study in rats and after dosing pregnant rats and mice during gestation. Objectives of the current study were to better define the dose-response curve for neonatal mortality in rat pups born to PFOS-exposed dams and to investigate biochemical and pharmacokinetic parameters potentially related to the etiology of effects observed in neonatal rat pups. In the current study, additional doses of 0.8, 1.0, 1.2, and 2.0 mg/kg/day were included with original doses used in the two-generation study of 0.4 and 1.6 mg/kg/day in order to obtain data in the critical range of the dose-response curve. Biochemical parameters investigated in dams and litters included: (1) serum lipids, glucose, mevalonic acid, and thyroid hormones; (2) milk cholesterol; and (3) liver lipids. Pharmacokinetic parameters investigated included the interrelationship of administered oral dose of PFOS to maternal body burden of PFOS and the transfer of maternal body burden to the fetus in utero and pup during lactation, as these factors may affect neonatal toxicity. Dosing of dams occurred for 6 weeks prior to mating with untreated breeder males, through confirmed mating, gestation, and day four of lactation. Dose levels for the dose-response and etiological investigation were 0.0, 0.4, 0.8, 1.0, 1.2, 1.6, and 2.0 mg/kg/day PFOS. Statistically significant decreases in gestation length were observed in the 0.8 mg/kg and higher dose groups. Decreases in viability through lactation day 5 were observed in the 0.8 mg/kg and higher dose groups, becoming statistically significant in the 1.6 and 2.0 mg/kg dose groups. Reduced neonatal survival did not appear to be the result of reductions in lipids, glucose utilization, or thyroid hormones. The endpoints of gestation length and decreased viability were positively correlated, suggesting that late-stage fetal development may be affected in pups exposed to PFOS in utero and may contribute to the observed mortality. Benchmark dose (BMD) estimates for decreased gestation length, birth weight, pup weight on lactation day 5, pup weight gain through lactation day 5, and viability resulted in values ranging from 0.27 to 0.89mg/kg/day for the lower 95% confidence limit of the BMD5 (BMDL5). Results of analyses for PFOS in biological matrices indicate a linear proportionality of mean serum PFOS concentration to maternal administered dose prior to mating and through the first two trimesters of gestation. However, at 21 days of gestation, mean serum PFOS concentrations were notably reduced from values measured earlier in gestation. Urinary and fecal elimination was low as expected from prior observations in adult rats. Significant transfer of PFOS from dam to fetus in utero was confirmed, and results suggest that dam and corresponding fetal body burdens, as indicated by serum and liver PFOS levels, correlate with neonatal survival.     

Towards a Pragmatic Alternative Testing Strategy for the Detection of Reproductive Toxicants

Exposure of rodents in utero to perfluorooctane sulfonate (PFOS) impairs perinatal development and survival. Following intravenous or gavage exposure of C57Bl/6 mouse dams on gestational day (GD) 16 to ³⁵S-PFOS (12.5 mg/kg), we determined the distribution in dams, fetuses (GD18 and GD20) and pups (postnatal day 1, PND1) employing whole-body autoradiography and liquid scintillation counting. In dams, levels were highest in liver and lungs. After placental transfer, ³⁵S-PFOS was present on GD18 at 2–3 times higher levels in lungs, liver and kidneys than in maternal blood. In PND1 pups, levels in lungs were significantly higher than in GD18 fetuses. A heterogeneous distribution of ³⁵S-PFOS was observed in brains of fetuses and pups, with levels higher than in maternal brain. This first demonstration of substantial localization of PFOS to both perinatal and adult lungs is consistent with evidence describing the lung as a target for the toxicity of PFOS at these ages.     

Developmental toxicity of perfluorononanoic acid in mice

Perfluorononanoic acid (PFNA) is a ubiquitous and persistent environmental contaminant. Although its levels in the environment and in humans are lower than those of perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA), a steady trend of increases in the general population in recent years has drawn considerable interest and concern. Previous studies with PFOS and PFOA have indicated developmental toxicity in laboratory rodent models. The current study extends the evaluation of these adverse outcomes to PFNA in mice. PFNA was given to timed-pregnant CD-1 mice by oral gavage daily on gestational day 1–17 at 1, 3, 5 or 10 mg/kg; controls received water vehicle. Dams given 10 mg/kg PFNA could not carry their pregnancy successfully and effects of this dose group were not followed. Similar to PFOS and PFOA, PFNA at 5 mg/kg or lower doses produced hepatomegaly in the pregnant dams, but did not affect the number of implantations, fetal viability, or fetal weight. Mouse pups were born alive and postnatal survival in the 1 and 3 mg/kg PFNA groups was not different from that in controls. In contrast, although most of the pups were also born alive in the 5 mg/kg PFNA group, 80% of these neonates died in the first 10 days of life. The pattern of PFNA-induced neonatal death differed somewhat from those elicited by PFOS or PFOA. A majority of the PFNA-exposed pups survived a few days longer after birth than those exposed to PFOS or PFOA, which typically died within the first 2 days of postnatal life. Surviving neonates exposed to PFNA exhibited dose-dependent delays in eye opening and onset of puberty. In addition, increased liver weight seen in PFNA-exposed offspring persisted into adulthood and was likely related to the persistence of the chemical in the tissue. Evaluation of gene expression in fetal and neonatal livers revealed robust activation of peroxisome proliferator-activated receptor-alpha (PPARα) target genes by PFNA that resembled the responses of PFOA. Our results indicate that developmental toxicity of PFNA in mice is comparable to that of PFOS and PFOA, and that these adverse effects are likely common to perfluoroalkyl acids that persist in the body.     

Social behavior of juvenile rats after in utero exposure to morphine: dose-time-effect relationship.

In the present study, the effects of morphine exposure in utero on social behavior in juvenile male rats was investigated. Pinning, a measure for play behavior, and social grooming of the offspring were measured at postnatal day 21. The subjects were offspring of Wistar rat dams given sc. injections of 1 or 10 mg/kg body weight morphine HCl daily from gestational days 8 (GD8)-GD 21 and control dams injected daily with saline. Pinning and social grooming of the morphine-treated offspring were significantly elevated compared to saline controls. The doses of morphine used neither affected the gestation of pregnant mother rats nor sensorimotor development of the juvenile rats. Prenatal exposure to morphine of 10 mg/kg daily increased both pinning and social grooming, prenatal exposure to a lower dose of 1 mg/kg increased pinning behavior but not social grooming in the offspring. To study the importance of the gestational period, offspring of dams given 10 mg/kg body weight morphine HCl from GD8-GD15 and saline from GD16-parturition or morphine from GD16-parturition and saline from GD8-GD15 was tested. Pinning was only increased when morphine exposure occurred during the third week of gestation, social grooming was increased when morphine exposure had been in the second week of gestation. Subcutaneous administration of 1 mg/kg naltrexone 1 h before the test significantly decreased play behavior in control rats, but not in animals prenatally exposed to morphine. From these experiments we conclude that the long term effect of in utero exposure to morphine on play behavior is established by affecting the endogenous opioid system.     

Lack of differential sensitivity to cholinesterase inhibition in fetuses and neonates compared to dams treated perinatally with chlorpyrifos.

Pregnant Sprague-Dawley rats were exposed to chlorpyrifos (CPF; O,O-diethyl-O-[3,5,6-trichloro-2-pyridinyl] phosphorothioate) by gavage (in corn oil) from gestation day (GD) 6 to postnatal day (PND) 10. Dosages to the dams were 0 (control), 0.3 (low), 1.0 (middle) or 5.0 mg/kg/day (high). On GD 20 (4 h post gavage), the blood CPF concentration in fetuses was about one half the level found in their dams (high-dose fetuses 46 ng/g; high-dose dams 109 ng/g). CPF-oxon was detected only once; high-dose fetuses had a blood level of about 1 ng/g. Although no blood CPF could be detected (limit of quantitation 0.7 ng/g) in dams given 0.3 mg/kg/ day, these dams had significant inhibition of plasma and red blood cell (RBC) ChE. In contrast, fetuses of dams given 1 mg/kg/day had a blood CPF level of about 1.1 ng/g, but had no inhibition of ChE of any tissue. Thus, based on blood CPF levels, fetuses had less cholinesterase (ChE) inhibition than dams. Inhibition of ChE occurred at all dosage levels in dams, but only at the high-dose level in pups. At the high dosage, ChE inhibition was greater in dams than in pups, and the relative degree of inhibition was RBC approximately plasma > or = heart > brain (least inhibited). Milk CPF concentrations were up to 200 times those in blood, and pup exposure via milk from dams given 5 mg/kg/day was estimated to be 0.12 mg/kg/day. Therefore, the dosage to nursing pups was much reduced compared to the dams exposure. In spite of exposure via milk, the ChE levels of all tissues of high-dosage pups rapidly returned to near control levels by PND 5.     

Developmental Toxicity Studies in Mice, Rats, and Rabbits with the Anticonvulsant Gabapentin

The developmental toxicity of the anticonvulsant agent gabapentinwas evaluated in mice, rats, and rabbits treated by gavage throughoutorganogenesis. Mice received 500, 1000, or 3000 mg/kg on gestationdays (GD) 6–15 and rats and rabbits received 60, 300,or 1500 mg/kg on GD 6–15 (rats) or 6–18 (rabbits).Additional groups received an equivalent volume of the vehicle,0.8% methylcellulose, or remained untreated. All dams were observeddaily for clinical signs of toxicity. In mice, body weightsand food consumption were recorded on GD 0, 6, 12, 15, and 18while in rats and rabbits these parameters were evaluated daily.Near term (mouse, GD 18; rat, GD 20; and rabbit, GD 29) eachfemale was euthanatized, necropsies were performed, and litterand fetal data were collected. Live fetuses were examined forexternal, visceral, and skeletal variations and malformations.No adverse maternal or fetal effects were observed in mice orrats given doses up to 1500 or 3000 mg/kg, respectively. Notreatment-related maternal or fetal effects were apparent inrabbits given 60 or 300 mg/kg. At 1500 mg/kg, one rabbit died,four others aborted, and reduced food consumption and body weightgain were observed. No other reproductive, litter, or fetalparameters were affected, except that the incidence of visceralvariations in rat fetuses was slightly but statistically significantlyincreased at 1500 mg/kg due to a slight increase in the incidenceof dilated renal pelvis. This finding was not considered biologicallysignificant because this degree of variability has been seenin this strain of rats. In conclusion, no evidence of teratogenicitywas found for gabapentin at doses up to 3000 mg/kg in the mouseand up to 1500 mg/kg in the rat and rabbit.     

Developmental toxicity of perfluorooctanoic acid in the CD-1 mouse after cross-foster and restricted gestational exposures.

Perfluorooctanoic acid (PFOA) is a persistent pollutant and is detectable in human serum (5 ng/ml in the general population of the Unites States). PFOA is used in the production of fluoropolymers which have applications in the manufacture of a variety of industrial and commercial products (e.g., textiles, house wares, electronics). PFOA is developmentally toxic and in mice affects growth, development, and viability of offspring. This study segregates the contributions of gestational and lactational exposures and considers the impact of restricting exposure to specific gestational periods. Pregnant CD-1 mice were dosed on gestation days (GD) 1-17 with 0, 3, or 5 mg PFOA/kg body weight, and pups were fostered at birth to give seven treatment groups: unexposed controls, pups exposed in utero (3U and 5U), lactationally (3L and 5L), or in utero + lactationally (3U + L and 5U + L). In the restricted exposure (RE) study, pregnant mice received 5 mg PFOA/kg from GD7-17, 10-17, 13-17, or 15-17 or 20 mg on GD15-17. In all PFOA-treated groups, dam weight gain, number of implantations, and live litter size were not adversely affected and relative liver weight increased. Treatment with 5 mg/kg on GD1-17 increased the incidence of whole litter loss and pups in surviving litters had reduced birth weights, but effects on pup survival from birth to weaning were only affected in 5U + L litters. In utero exposure (5U), in the absence of lactational exposure, was sufficient to produce postnatal body weight deficits and developmental delay in the pups. In the RE study, birth weight and survival were reduced by 20 mg/kg on GD15-17. Birth weight was also reduced by 5 mg/kg on GD7-17 and 10-17. Although all PFOA-exposed pups had deficits in postnatal weight gain, only those exposed on GD7-17 and 10-17 also showed developmental delay in eye opening and hair growth. In conclusion, the postnatal developmental effects of PFOA are due to gestational exposure. Exposure earlier in gestation produced stronger responses, but further study is needed to determine if this is a function of higher total dose or if there is a developmentally sensitive period.     

Developmental toxicity assessment of arsenic acid in mice and rabbits

To evaluate potential effects of exposure to inorganic arsenic throughout major organogenesis, CD-1 mice and New Zealand White rabbits were gavaged with arsenic acid dosages of 0, 7.5, 24, or 48 mg/kg/d on gestation days (GD) 6 through 15 (mice) or 0, 0.19, 0.75, or 3.0 mg/kg/d on GD 6 through 18 (rabbits) and examined at sacrifice (GD 18, mice; GD 29, rabbits) for evidence of toxicity. Two high-dose mice died, and survivors at the high and intermediate doses had decreased weight gains. High-dose-group fetal weights were decreased; no significant decreases in fetal weight or increases in prenatal mortality were seen at other dosages. Similar incidences of malformations occurred in all groups of mice, including controls. At the high dose in rabbits, seven does died or became moribund, and prenatal mortality was increased; surviving does had signs of toxicity, including decreased body weight. Does given lower doses appeared unaffected. Fetal weights were unaffected by treatment, and there were no effects at other doses. These data revealed an absence of dose-related effects in both species at arsenic exposures that were not maternally toxic. In mice, 7.5 mg/kg/d was the maternal No-Observed-Adverse-Effect-Level (NOAEL); the developmental toxicity NOAEL, while less well defined, was judged to be 7.5 mg/kg/d. In rabbits, 0.75 mg/kg/d was the NOAEL for both maternal and developmental toxicity.     

Postnatal developmental alterations following prenatal exposure to the herbicide 2,4-dichlorophenyl-p-nitrophenyl ether: a dose response evaluation in the mouse

Although nitrofen, 2,4-dichlorophenyl-p-nitrophenyl ether, is a relatively nontoxic herbicide, prenatal exposure to doses considerably less than the LD50 value for adult rats and mice produces numerous developmental defects that become apparent as the animals mature. In the present study postnatal development was observed following prenatal exposure during Days 7 to 17 of gestation at doses of 0, 6.25, 12.5, 25, 50, 100, 150, and 200 mg/kg/day. These doses did not cause maternal toxicity as indicated by the viability of the dams or maternal weight gain during pregnancy. By 3 days of age all pups in the two highest dose groups were dead and 50% had died in the 100 mg/kg/day dose group. Some of the dead and moribund pups from the 200 mg/kg/day exposure group necropsied at three days of age had cleft palate (15%) or diaphragmatic hernia (6%). In addition, about 22% of the pups at 200 mg/kg/day developed a distended abdomen from gasping and swallowing air. These pups did not suckle and eventually died. Body weights of offspring were reduced at birth in the 150 and 200 mg/kg/day groups and at 3 days of age in the 100 mg/kg/day group. Growth rates were subsequently retarded at 12.5, 25, 50, and 100 mg/kg. The Harderian glands were reduced or absent in 97, 65, and 4% of the mice in the 100, 50, and 25 mg/kg dosage groups, respectively, and the gland weights were reduced at all dosages, including the lowest dose of 6.25 mg/kg/day. Weights of other organs including lung and liver (at 6.25 and above), seminal vesicle (at 12.5 and above), and testes (at 100 mg/kg/day) were also reduced by prenatal nitrofen exposure. In addition, prenatal treatment with nitrofen produced functional deficits of the reproductive system; puberty was delayed in females and litter sizes were reduced at 50 and 100 mg/kg/day. A cross-fostering experiment with 100 mg/kg/day of nitrofen demonstrated that the effects noted in the present study were produced solely by prenatal exposure; pups exposed to nitrofen in the milk alone as a consequence of any accumulation of nitrofen in the dam during gestation were unaffected.     

Prenatal PFOS exposure induces oxidative stress and apoptosis in the lung of rat off-spring

Perfluorooctane sulfonate (PFOS) could induce neonatal pulmonary injuries in rodents. The aim of this study was to investigate the underlying mode of action. Pregnant rats were dosed orally with PFOS (0, 0.1 and 2.0mg/kgd) from gestation days (GD) 1 to 21. Lung samples from postnatal day (PND) 0 and 21 pups were analyzed for the toxic effects of PFOS. The results showed that maternal exposure to 2.0mg/kgd PFOS caused severe histopathological changes along with marked oxidative injuries and cell apoptosis in offspring lungs; at the same time, the ratio of Bax to Bcl-2, release of cytochrome c (Cyt c) from mitochondria to cytoplasm, expressions of Fas and Fas-L, and activities of caspase-3, -8 and -9 were up-regulated correspondingly. The results indicate that oxidative stress and both intrinsic and extrinsic cell death pathways were involved in prenatal PFOS exposure-induced injuries in postnatal lungs.     

Lack of selective developmental neurotoxicity in rat pups from dams treated by gavage with chlorpyrifos.

Pregnant Sprague-Dawley rats were given chlorpyrifos (O:, O-diethyl-O:-[3,5,6-trichloro-2-pyridinyl] phosphorothioate; CPF) in corn oil by gavage from gestation day 6 (GD 6) through lactation day 10 (LD 10) at dosages of 0, 0.3, 1, or 5 mg/kg/day in a developmental neurotoxicity study that conformed to U.S. Environmental Protection Agency 1991 guidelines. GD 0 was the day when evidence of mating was observed and postnatal day 0 (PND 0) was the day of birth. Toxicity was limited to the highest dosage level (5 mg/kg/day) and, in the dams, consisted of muscle fasciculation, hyperpnea, and hyperreactivity. A nonsignificant overall trend toward weight gain and feed consumption was also observed in the high-dosage dams, with a statistically significant Group x Time interaction for reduced weight gain in the 5-mg/kg/day group near the end of gestation. Although many developmental indices were normal, pups from high-dosage dams had increased mortality soon after birth, gained weight more slowly than controls, and had several indications of slightly delayed maturation. The early deaths and delayed maturation were attributed to maternal toxicity, though a possible contributing role of direct pup toxicity in delayed development cannot be eliminated. In spite of the apparent delay in physical development, high-dosage pups tested just after weaning had normal learning and memory as tested on a T-maze spatial delayed-alternation task. Habituation, a primitive form of learning, was tested in 2 tasks (motor activity and auditory startle) and was not affected. No overt effects were noted in either dams or pups at 1 or 0.3 mg/kg/day. Based on these data, chlorpyrifos produced maternal and developmental toxicity in the 5-mg/kg/day-dosage group. There was no evidence of selective developmental neurotoxicity following exposure to chlorpyrifos.     

Immunomodulatory effects of dietary potassium perfluorooctane sulfonate (PFOS) exposure in adult Sprague-Dawley rats

Perfluorooctanesulfonate (PFOS) is a stable and environmentally persistent metabolic or degradation product of perfluorooctanyl compounds that were manufactured for a variety of industrial and consumer applications. PFOS itself was sold for use as a surfactant. The structurally related contaminants perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), and N-ethyl perfluorooctane sulfonamide (N-EtPFOSA) were shown to suppress immune responses in laboratory rodents. Relatively low doses of PFOS were found to be immunosuppressive in mice. To assess effects of PFOS on the rat immune system at doses known to alter hepatic function, changes in the morphology and function of immune tissues and cells were measured in adult rats exposed to PFOS in their diet for 28 d at levels ranging from 2 to 100 mg PFOS/kg diet (corresponding to approximately 0.14 to 7.58 mg/kg body weight [bw]/d) and compared to those receiving control diet. Body weight reductions were significant in male and female rats exposed to 50 and 100 mg PFOS/kg diet. Liver/body weight was significantly increased in females exposed to 2 mg PFOS/kg diet and in males exposed to 20 mg PFOS/kg diet. Female rats exposed to 100 mg PFOS/kg diet exhibited a significant increase in spleen weight relative to body weight; these changes lacked a histologic correlate and were not observed in males. While thymus weights relative to body weights were not affected, numbers of apoptotic lymphocytes rose in thymus with increasing dietary PFOS. There was a significant dose-related increase in total peripheral blood lymphocyte numbers in female but not male rats. In both genders the percentages of cells within lymphocyte subclasses were altered. There was a significant trend toward increasing T and T-helper (Th) cells and decreasing B cells with higher PFOS dose. Serum total immunoglobulin (Ig) G1 levels were significantly reduced in males exposed to 2 and 20 mg PFOS/kg diet. The ability of male and female rats to mount delayed-type hypersensitivity (DTH) responses to the T-cell-dependent antigen keyhole limpet hemocyanin (KLH) was not altered by PFOS. There was a significant trend toward elevated KLH-specific IgG in serum from male rats exposed to increasing levels of PFOS in diet. Splenic T- and B-cell proliferation in response to ex vivo mitogen exposure was unaffected by exposure to dietary PFOS. In conclusion, changes in immune parameters in rat did not manifest as functional alterations in response to immune challenge with KLH and may be secondary to hepatic-mediated effects of PFOS in this model.     

Prenatal or postnatal exposure to bis(tri-n-butyltin)oxide in the rat: postnatal evaluation of teratology and behavior

The results of a series of screening tests to determine the potential teratogenicity and neurotoxicity of developmental exposure to TBTO in rats are presented in this paper. For prenatal exposure, pregnant Long Evans rats were intubated with 0-16 mg/kg/day bis(tri-n-butyltin)oxide TBTO from Days 6 to 20 of gestation (GD 6-20). For postnatal exposure, rat pups were intubated with 0-60 mg/kg TBTO on Postnatal Day 5 (PND 5). Following prenatal exposure, dams were allowed to litter and pups were evaluated using a postnatal teratology screen. Postnatal evaluation for both exposures included motor activity (PND 13-64), the acoustic startle response (PND 22-78), growth, and brain weight. The maximally tolerated dose (MTD) in pregnant rats was 5 mg/kg/day, which is one-third the MTD in nonpregnant rats. There were decreased numbers of live births, and decreased growth and viability at dosages greater than or equal to 10 mg/kg/day. Cleft palate was found in 3% of the 12 mg/kg/day group. There was mortality following postnatal exposure to 60 mg/kg and all prenatal dosages greater than or equal to 10 mg/kg/day. Preweaning body weight was significantly decreased for all postnatal dosages, and all prenatal dosages greater than 2.5 mg/kg/day. Body weight reductions persisted to the postweaning period only in the high dose groups (10 mg/kg/day and 60 mg/kg). Behavioral evaluation demonstrated transient alterations in motor activity development (prenatal exposure only) and the acoustic startle response (postnatal exposure only). Persistent behavioral effects were observed only at dosages that produced overt maternal toxicity and/or postnatal mortality. The demonstration of the teratogenic and neurotoxic potential of TBTO in rats is confounded by associated maternal toxicity and/or pup mortality.     

Teratogenic potential of the mycotoxin, citreoviridin, in rats

Citreoviridin produced by the fungus Penicillium citreo-viride was administered by gavage to groups of 9–16 pregnant Fisher 344 rats either on days 8–11 (group A) or on days 12–15 (group B) of gestation. Doses of 0, 5, 10 or 15 mg/kg body weight were given daily in a constant volume of 1 ml/kg body weight in dimethylsulphoxide. Six rats in each high-dose group died during the dosing period. Compared with control groups, mean daily feed consumption was significantly reduced in the 10- and 15-mg/kg animals in both groups A and B. Weight gain during pregnancy in both groups was reduced with increasing dosage; dams in control groups gained an average of 75 g/rat compared with 30 g overall gain in group A, or 9 g overall gain in group B, both at a dose of 15 mg/kg. Male and female pup weights were reduced with increasing dosage for both groups A and B. The post-implantation foetal loss rate was significantly increased to 33% in group A high-dose animals. The main effect of citreoviridin on skeletal development in both groups A and B was one of retardation. No internal abnormalities were observed in group A pups. Some smaller than average pups from dams in group B that were treated with the high dose of citreoviridin had slightly dilated lateral ventricles of the brain and, in some cases, a palate defect. The foetotoxicity induced by citreoviridin was observed only at doses that also induced maternal toxicity.