Number Of Live Pups Research Articles

Interaction of dimethylsulfoxide and arachidonic acid with the teratogenic effects of caffeine in mice.

Dose-response of the teratogenic effect of caffeine (CA) and the potential role of facial hematomas in the pathogenesis of caffeine-induced cleft palate were investigated using CD1 mice treated with 150, 200, or 250 mg CA/kg i.p. on gestational day (GD) 12. Dimethylsulfoxide (DMSO; 20%) and arachidonic acid (AA, 200 mg/kg) were administered along with CA (200 mg/kg) to study their interaction with CA-induced teratogenesis and elevation in maternal glucocorticoids (MGC, measured by RIA) on GD 13 and 14. Dose-dependent increase in the incidence of cleft palate (CP) was noted in CA-exposed mice. High maternal deaths, an increased number of resorptions, gross facial hematomas (GFH), and club foot (CF) were produced only by the highest (250 mg/kg) dose of CA. Palates from all offspring with GFH were clefted at this dose level. None of the control or CA-treated nonclefted offspring had GFH or microscopic hematomas (MH). At 200 mg/kg of CA, DMSO in combination with CA actually increased CA-induced CP from 30% to 100% and also produced 100% GFH as compared to 0% by CA alone at this dose. Greater than 50% of clefted offspring without GFH, given either dose (200 or 250 mg/kg) of CA, had MH. Very high levels of MGC were present in CA-treated mice on GD 13 and 14. Although simultaneous administration of DMSO reduced the magnitude of CA-induced MGC elevations on GD 14, the MGC levels remained high for greater than 24 hours following CA exposure. Increase in maternal mortality and fetal resorptions, a decrease in the number of live pups and their body weights, and no change in the incidence of CP were seen when CA-treated mice were simultaneously exposed to AA. These results suggest a correlation between caffeine-induced FH and CP; a role for increased hematomagenic effects of DMSO in its potentiation of the cleft-palatogenic effect of caffeine; and absence of a role for AA-mediated effects of MGC in the causation of CA-induced CP and other malformations.

Toxicology of Diethylene Glycol Butyl Ether 4. Dermal Subchronic/Reproduction Study in Rats

The subchronic and reproductive toxicity of diethylene glycol butyl ether (DGBE) by the dermal route was evaluated in Sprague-Dawley rats using a novel combined protocol. DGBE was administered dermally at 10 or 30% v/v in aqueous solutions or undiluted (100%) for 13 weeks under occlusion, 6 hr/day, 5 days/week at a maximum attainable volume of 2 mL/kg. Satellite groups of male and female rats were treated with the top dose of DGBE for 13 weeks, mated, and the females were treated through day 20 of gestation and allowed to deliver and nurse their offspring through day 21 of lactation (weaning). DGBE produced dermal irritation, which was dependent on concentration in incidence, severity, and time of onset and was more severe in females than in males. No corresponding histopathology was evident. The only suggestion of a systemic effect was a slightly increased incidence of urinary occult blood at study termination in the females receiving the 30% or 100% DGBE dose. There was no evidence of histopathologic changes in the testes, and vaginal cytology indicated no adverse effect on estrous cycling. There were no effects on reproductive performance of the DGBE-treated males and females. Litters delivered by treated females contained the same number of live pups as control litters and the growth and survival of pups within the treated litters was comparable to control. No reproductive or systemic toxicity was observed at the highest dose tested—2 g/kg/day.

Limiting effects of uterine crowding on the number and weight of live pups at birth in hemiovariectomized and normal rabbit does.

Variation in the number, total weight, mean individual weight and minimum individual weight of live pups at first and second litter were studied in hemiovariectomized (H = 54 does) and normal (N = 55 does) rabbit does. The total number of implanted embryos in 25 unoperated (N) and 54 hemiovariectomized (H) does were recorded by laparoscopy on the 12th day of their second pregnancy. The total number of implanted embryos was not statistically different between experimental groups (m +/- SEM; H: 11.0 +/- 0.4; N: 12.4 +/- 0.5; P = 0.06). The number of total pups at birth (H: 7.7 +/- 0.2 vs N: 9.8 +/- 0.2; P < 0.01) was affected by hemiovariectomy even when analyzed as a constant total number of implanted embryos. The number of live pups (H: 7.0 +/- 0.2 vs N: 9.0 +/- 0.3; P < 0.01), the total weight of live pups (H: 395 +/- 11 g vs N: 479 +/- 12 g; P < 0.01), the mean litter weight (H: 58.9 +/- 1.1 g vs N: 54.1 +/- 0.7 g; P < 0.01) and the minimum individual weight of live pups at birth (H: 46.5 +/- 1.4 g vs N: 42.1 +/- 1.0 g; P < 0.05) were also affected by hemiovariectomy. The significance of hemiovariectomy effect disappeared when analyzed as a constant total number of pups at birth. A positive non-linear relationship between the total number of pups at birth and the total weight of live pups was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive toxicity evaluation of acetaminophen in Swiss CD-1 mice using a continuous breeding protocol

Acetaminophen (APAP) was evaluated for reproductive toxicity in Swiss CD-1 mice using a continuous breeding protocol. APAP was administered in the diet at 0, 0.25, 0.5, and 1.0% (w/w), which represented average daily intakes of 0, 357, 715, and 1430 mg APAP/kg/day, respectively. Exposure of parental (P) breeding pairs to 1% APAP in the diet for 14 weeks during cohabitation significantly decreased the number of litters per pair, and reduced, although not significantly, the number of live pups per litter. Importantly, 6 of 19 high-dose P pairs failed to produce a fifth litter, and this fully accounted for the diminished number of litters in this group. In addition, the fifth litter that was produced by the 13 high-dose P pairs averaged only about 9 live pups per litter, which correspondingly reduced the overall group average for this parameter. In comparison, the control and two lower-dose P pairs produced 11 or 12 live pups per litter on average. Although the birth weights for F 1 pups in the final litter were unaffected by prenatal APAP exposure, postnatal growth was adversely affected as evidenced by retarded weight gain as measured at 28 and 74 ± 10 days of age for all three dietary levels. At 1% APAP this weight gain effect was more pronounced at Day 28 than at Day 74 ± 10, suggesting that nursing pups may have been exposed to higher concentrations or may be more sensitive to APAP and/or an active metabolite than were the young adults. A mating trial of F 1 pairs at 74 ± 10 days of age indicated that mating, fertility, and reproductive performance were normal, except that the birth weight of F 2 pups was significantly depressed at 1% APAP. This latter effect may have been attributable to maternal toxicity in that body weight and relative pituitary weight were significantly decreased, and relative brain and liver weight significantly increased, in high-dose F 1 females. In addition, body weight was significantly reduced in the high-dose F 1 males at necropsy. No treatmentrelated effects on reproductive organ weights and no gross or histological changes in the reproductive tissues of the high-dose F 1 male and female mice were observed. Continuous exposure of F 1 males at 1% APAP, however, significantly increased the percentage of abnormal epididymal sperm, while sperm density and percentage of motile sperm were unaffected. Collectively, these data indicated that continuous exposure to 1% APAP via the diet (1.43 g/kg/day) led to cumulative effects on reproduction in the P pairs, to retarded growth and abnormal sperm in the F 1 mice, and to reduced birth weight of F 2 pups.

Developmental toxicity screen: Results of rat studies with diethylhexyl phthalate and ethylene glycol monomethyl ether

The purpose of these investigations was to develop a protocol for an in vivo developmental toxicity screen (DETS) that would provide sufficient data to determine whether to 1) do a full developmental toxicity evaluation without additional range-finding studies, or, depending on the results, to 2) do no further testing of a chemical. In order to evaluate this screen, we compared results obtained by using the DETS protocol with results of previously conducted developmental toxicity evaluations of diethylhexyl phthalate (DEHP) and ethylene glycol monomethylether (EGME). Five groups (n greater than or equal to 17) of F344 rats were treated on days 6-15 of gestation by dosed feed (DEHP levels = 0, 0.5, 1.0, 1.5, 2.0%) or gavage (EGME doses = 0, 12.5, 25, 50, 100 mg/kg/day). One half of the rats in these studies were killed on day 16 of gestation, and the remaining animals were allowed to deliver litters which were killed on day 4. EGME caused only a small decrease in maternal weight gain during treatment (100 mg/kg group) that was accompanied by a decrease in gravid uterine weight. The percentage of resorptions was increased in the 50 and 100 mg/kg groups. The number of live pups was decreased in the 25, 50, and 100 mg/kg groups, and litter weight and postnatal survival were decreased in the 100 mg/kg group. These results are consistent with those reported in developmental toxicity studies on EGME conducted by the inhalation and dermal routes. With DEHP, there were treatment-related reductions in maternal body weight and weight gain. There was also a nonstatistical increase in percentage of resorptions per litter that was also observed, but at relatively high levels, in a definitive study in which F344 dams were treated on days 0-20 of gestation. The results of studies on these two chemicals compare well with published results and would have led to the selection of proper dose levels for subsequent FDA segment 2 studies.

Reproductive effects of four phthalic acid esters in the mouse

These studies compared the reproductive toxicity of four phthalates by a continuous breeding protocol. Mice were given diets with diethyl phthalate (DEP) (0.0, 0.25, 1.25, or 2.5%), di- n-butyl phthalate (DBP) (0.0, 0.03, 0.3, or 1.0%), di- n-hexyl phthalate (DHP) (0.0, 0.3, 0.6, or 1.2%), or di(2-ethylhexyl) phthalate (DEHP) (0.0, 0.01, or 0.3%). Both male and female CD-1 mice were dosed for 7 days prior to and during a 98-day cohabitation period. Reproductive function was evaluated during the cohabitation period by measuring the numbers of litters per pair and of live pups per litter, pup weight, and offspring survival. There was no apparent effect on reproductive function in the animals exposed to DEP, despite significant effects on body weight gain and liver weight. DBP exposure resulted in a reduction in the numbers of litters per pair and of live pups per litter and in the proportion of pups born alive at the 1.0% amount, but not at lower dose levels. A crossover mating trial demonstrated that female mice, but not males, were affected by DBP, as shown by significant decreases in the percentage of fertile pairs, the number of live pups per litter, the proportion of pups born alive, and live pup weight. DHP in the diet resulted in dose-related adverse effects on the numbers of litters per pair and of live pups per litter and proportion of pups born alive at 0.3, 0.6, and 1.2% DHP in the diet. A crossover mating study demonstrated that both sexes were affected. DEHP (at 0.1 and 0.3%) caused dose-dependent decreases in fertility and in the number and the proportion of pups born alive. A crossover mating trial showed that both sexes were affected by exposure to DEHP. These data demonstrate the ability of the continuous breeding protocol to discriminate the qualitative and quantitative reproductive effects of the more and less active congeners as well as the large differences in reproductive toxicity attributable to subtle changes in the alkyl substitution of phthalate esters.

Evaluation of a New Reproductive Toxicology Protocol Using Diethylstilbestrol (DES) as a Positive Control Compound

A new National Toxicology Program (NTP) reproductive toxicology assay designated Fertility Assessment by Continuous Breeding was evaluated using trans-diethylstilbestrol (DES) as a positive control compound. The testing scheme employs young adult CD-1 male and female mice and is comprised of 5 possible tasks: task 1, 14-day dose-finding (repeated or continuous dosing); task 2, continuous breeding; task 3, determination of affected sex; task 4, offspring assessment; task 5, hormone patterns. Only tasks 2 and 3 were performed in the present study. Task 2 employed dietary levels of 0, 1, 10, and 50 ppb DES (99% pure). Task 3 used the control and high dose parental mice from task 2 in a crossover mating trial (control x treated) to determine whether one or both sexes in the F0 generation were adversely affected. Continuous exposure of F0 mice to 50 ppb DES in the diet during task 2 significantly decreased (P &lt; 0.01) the proportion of pairs that produced at least 1 litter as compared to pairs continuously exposed to dietary levels of 0, 1, and 10 ppb DES. In addition, continuous exposure to 50 ppb DES in the diet had a cumulative adverse effect on the production and viability of litters. Thus, the pairs fed 50 ppb DES produced significantly fewer litters (P &lt; 0.01), had fewer live pups per litter (P &lt; 0.01), and tended toward a lower proportion of pups born alive per litter than did pairs in the 0, 1, and 10 ppb DES groups. In the crossover mating trial (task 3) the proportion of F0 females that mated (number with copulatory plugs/number cohabited) and that were fecund (number delivering litters/number with copulatory plugs) did not differ significantly among the 3 different combinations of paired mice. It was noted, however, that the proportion of cohabited F0 females delivering litters (number delivering litters/number cohabited) was significantly reduced (P &lt; 0.05) in the control male x 50 ppb DES female group vs. the control male x control female group. The proportion of cohabited F0 females delivering litters in the 50 ppb DES male x control female group did not differ significantly from either of the above groups. Further, the number of live pups per litter and the proportion of pups born alive were significantly lower (P &lt; 0.01) in the F0 control male x 50 ppb DES female group than in the other 2 groups. The proportion of male pups born alive (males/total) and the live pup weights, however, did not differ significantly among the 3 combinations of paired mice. Collectively, these results indicated that DES interfered with ovulation, conception, pre- and postimplantational processes in female mice. Thus, this new assay readily discriminated DES as a reproductive toxicant in CD-1 mice.

Effects of Exercise on Fetal-Placental Growth and Uteroplacental Blood Flow in the Rat

The effects of daily maternal exercise on fetal-placental growth and development and the associated changes in uteroplacental blood flow were studied in pregnant rats. Pregnant females were exercised for 1 h (0% grade at 28 m/min) daily between either days 1 and 12, 1 and 18, 1 and 22, 12 and 18, or 12 and 22 of gestation and compared with nonexercised controls. Exercise between days 1 and 12 of pregnancy had no effect on fetal-placental parameters (i.e., fetal weight or gestation length) relative to controls. In contrast, exercise between days 1 and 22 and 12 and 22 resulted in a lower number of live pups born, an increase in gestational length, and an increased birth weight of the live pups relative to controls. Exercise between days 1 and 18 or 12 and 18 induced a significant (p less than or equal to 0.05) suppression of uteroplacental blood flow, the number of viable fetuses, and placental weights as compared with controls. Daily exercise had no effect on ovarian function as indicated by the comparable serum progesterone levels in all groups. These data indicate that an exercised-induced depression of uteroplacental blood flow is related to impaired fetal-placental growth and development during pregnancy in the rat.

Results of Testing Fifteen Glycol Ethers in a Short-Term in Vivo Reproductive Toxicity Assay

Fifteen glycol ethers were investigated for their potential to cause adverse reproductive toxic effects using an in vivo mouse screening bioassay. Pregnant mice were orally dosed once per day on days 7 through 14 of gestation at concentrations causing 0 to 41% maternal mortality. Reproductive endpoints included pup survival in utero (percent of live litters/pregnant survivors), pup perinatal and postnatal survival (number of live pups per litter, number of dead pups per litter, and pup survival to 2.5 days of age), and pup body weight statistics (weight at birth and weight at 2.5 days of age). The study was conducted in two phases: a dose range-finding phase using nonpregnant female mice, and a definitive reproductive phase using time-mated mice. The range-finding phase sought to identify, for each chemical, the maternal LD10 as the target dose. However, based upon reproductive phase results, such an exact dose was impractical to achieve. Thus, a range from the LD5 to the LD20 was considered a sufficient challenge dose that would not affect results due to high mortality, i.e., greater than the LD20. Glycol ethers were assigned to groups having different priorities for further testing based upon whether a sufficient challenge dose was administered and the degree of effects recorded for each chemical.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of testing fifteen glycol ethers in a short-term in vivo reproductive toxicity assay.

Fifteen glycol ethers were investigated for their potential to cause adverse reproductive toxic effects using an in vivo mouse screening bioassay. Pregnant mice were orally dosed once per day on days 7 through 14 of gestation at concentrations causing 0 to 41% maternal mortality. Reproductive endpoints included pup survival in utero (percent of live litters/pregnant survivors), pup perinatal and postnatal survival (number of live pups per litter, number of dead pups per litter, and pup survival to 2.5 days of age), and pup body weight statistics (weight at birth and weight at 2.5 days of age). The study was conducted in two phases: a dose range-finding phase using nonpregnant female mice, and a definitive reproductive phase using time-mated mice. The range-finding phase sought to identify, for each chemical, the maternal LD10 as the target dose. However, based upon reproductive phase results, such an exact dose was impractical to achieve. Thus, a range from the LD5 to the LD20 was considered a sufficient challenge dose that would not affect results due to high mortality, i.e., greater than the LD20. Glycol ethers were assigned to groups having different priorities for further testing based upon whether a sufficient challenge dose was administered and the degree of effects recorded for each chemical.(ABSTRACT TRUNCATED AT 250 WORDS)

Vomitoxin (4-deoxynivalenol): effects on reproduction of mice and rats

Weanling male and female mice (F o) were fed daily diets containing 4-deoxynivalenol (DON) at concentrations that resulted in a dose of 0 or 2.0 mg/kg body wt in Experiment I and 0, 0.375, 0.75, or 1.5 mg/kg body wt in Experiment II. The test diets were continuously fed to the F o parents and their progeny for the entire duration of these two experiments, which were similar in design. After 30 days of dietary feeding, the mice were allowed to mate within experimental groups for a maximum of three 5-day trials. Females found to have mated successfully were allowed to litter normally. The F 1a progeny from 10 dams of each control and 1.5-mg DON/kg groups were cross-fostered at birth, whereas all of the remaining F 1a progeny were reared by their natural dams. The progeny were examined until 21 days of age and discarded. The F o mice were rebred. The females bred to produce the F 1b litters were killed on Day 19 of gestation and their fetuses were examined for gross, visceral, and skeletal malformations. Reductions were observed in feed and water intakes and body weight of F o male and female mice, the number of live pups and postnatal survivors, postnatal body weight of F 1a progeny, number of live fetuses, and mean fetal weight of F 1b fetuses. No adverse effects on fertility of F 0 male and female mice and no major malformations in F 1b fetuses were found. Cross-fostering offspring between control dams and 1.5-mg DON/kg-treated dams revealed that both postnatal survival and body weight were adversely affected by prenatal exposure as well as by a combined pre- and postnatal exposure. Male and female Sprague-Dawley rats were fed diets containing DON so as to deliver daily doses of 0.25, 0.5, or 1.0 mg/kg body wt. After 6 weeks of feeding, the rats were bred within groups and the males were then discarded. The mated females, maintained on their respective diets for the entire period of pregnancy, were killed on the last day of pregnancy and fetuses evaluated for effects on prenatal development. Except for dilation of renal pelvis and urinary bladder, the significance of which remains undetermined, no other adverse effect was observed.

Hepatic Insulin Binding Following In Utero Exposure to Ethanol

Insulin binding to liver membranes has been studied in term fetuses of rats fed ethanol-containing liquid diet during pregnancy . Pair-fed and ad libitum-fed controls received liquid diet in which maltose-dextrins were substituted isocalorically for ethanol. Food consumption and body weigh gain of ethanol- imbibing dams were 35% and 70% less than their ad libitum counterparts respectively. Ethanol-fed rats also exhibited less gain in body weight than pair-fed controls despite isocalorically equivalent food intake. The number of live pups was not different among the various groups; however, liver weight of fetuses exposed to ethanol in utero was 47% less than those of the pups of ad libitum control dams and 28% less than those of the offspring of pair-fed control rats. Insulin binding to liver membranes of fetuses exposed to ethanol in utero was lower than that of ad libitum controls but was not significantly different from that of the pair-fed control animals. Average affinity profiles showed a reduction in K at all levels of receptor occupancy in the fetuses of ethanol-fed rats. For fetuses of the pair-fed group, K was reduced only at fractional occupancy below 20% but not at higher fractional occupancy. Because of the similarity of insulin binding in the fetuses of the ethanol-fed rats and their pair-fed counterparts, effects of ethanol on insulin binding cannot account for the reduced hepatic glycogen stores previously reported in term fetuses.

Vitamin A Deficiency and Fetal Growth and Development in the Rat

Studies were conducted to examine in detail the effects of vitamin A deficiency on fetal growth and development in the rat. The gradations of deficiency were examined in two studies. The first included total vitamin A depletion followed by retinoic acid supplements, and the second included three different levels of restricted intake of retinyl acetate (42, 16, or 8 mug of retinol equivalents/day/kg of body weight) in vitamin A-depleted rats. In the first study, extensive fetal resorption and death were observed in retinoic acid-fed females after day 14 of gestation. These findings confirmed the morphological studies of Thompson and associates (Proc. Roy. Soc. London, Ser. B 159, 510-535, 1964) who found the earliest Detectable histological lesions to be in the placentas at days 15-16 of pregnancy. Analyses were carried out of the total weight, the DNA, RNA, and protein contents of fetuses and placentas of different gestational ages in retinyl ester-fed and retinoic acid-fed females. Biochemical changes indicative of a reduced rate of cell division were observed in both fetus and placenta by day 14 in the retinoic acid-fed rats. The few live fetuses in this group maintained a growth rate of only 60-70% of that of the fetuses of retinyl ester-fed dams after day 14. By contrast, the growth rate of the placentas (of live fetuses) after day 14 of gestation was not as consistently affected by retinol deficiency. Restriction of retinyl acetate intake (in the second study) significantly reduced both the total litter size and the number of live pups per litter. Most of the females in the retinyl acetate-restricted groups delivered pups that had normal body weight and appeared normal on visual inspection. Significant differences from normal controls were seen only in the neonates from dams given 8 mug of retinol equivalents (per kg of body weight per day), which had smaller livers and kidneys than the control neonates. In contrast, the weights of the brains of the neonates in all three retinyl acetate-restricted groups showed no differences from control values. Vitamin A assays on maternal and neonatal sera and livers indicated that the transport of vitamin A across the placenta was well regulated, and suggested that this transport is maintained with high priority in the presence of maternal deficiency. The effects of vitamin A deficiency on fetal growth and development might reflect primary effects on the placenta, with secondary effects on the fetus, or primary direct effects on the fetus itself. The mechanisms of the observed effects remain to be explained.

Effects of progesterone injections administered during late pregnancy on lactation and nursing behavior in the rat.

SummarySubcutaneous doses of 2-mg progesterone in 0.1 ml sesame oil twice daily on Day 23 of gestation significantly depressed litter growth, particularly on postpartal Days 4-5, and markedly reduced the number of live pups. Like doses of progesterone on Day 18 had no such effects. Because the latency and duration of crouching behavior remained at least normal, the depressed litter growth in the Day 23 group could not be due to poor nursing behavior. It implicates lactation alone.