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PubMedDate not supplied

Toxicologic and reproductive effects of inhaled 1,2-dibromo-3-chloropropane in male rabbits.

Groups of 10 male New Zealand white rabbits were exposed by inhalation to 0, 0.1, 1.0 or 10 ppm of 1,2-dibromo-3-chloropropane (DBCP) vapor for 6 hours/day, 5 days/week for 14 weeks, except that the 10 ppm group was exposed for only 8 weeks due to mortality. The semen of rabbits was evaluated on a weekly basis during the exposure period and at periodic intervals during a recovery period (32 weeks for all groups except the 10 ppm groups which was for 38 weeks). In order to assess the fertility of the exposed rabbits, each male was allowed to mate with an unexposed female at the 14th and 41st week of the study. Exposure of rabbits to 1 and 10 ppm of DBCP by inhalation produced adverse reproductive effects as well as decreases in sperm count, motility and viability. Rabbits treated at 1 and 10 ppm had decreased sperm counts between the 8th and 14th weeks of the study. All of the 10 ppm rabbits were infertile when mated during the 14th week. The effects of DBCP on spermatogenesis were shown to be essentially reversible in rabbits exposed to 1 ppm; however, at 10 ppm, recovery was not complete under the conditions of the test. Rabbits exposed to 10 ppm had severe testicular alterations as early as 4 weeks into the study and these progressed to severe testicular atrophy by 8 weeks. Those exposed to 1 ppm for 14 weeks developed moderate testicular atrophy (approximately 50% reduction in size). Following the recovery period, the rabbits in the 10 ppm group had evidence of partial reversibility of the testicular atrophy. Electron microscopic evaluation of testicular tissue confirmed findings by light microscopy effects and also indicated increased numbers of abnormal sperm within the seminiferous tubules of rabbits at both the 10 and 1 ppm exposure levels. Those exposed to 0.1 ppm had an equivocal increase in abnormal sperm after the 14-week exposure period but not after the recovery period. Based on these results 0.1 ppm level of DBCP is considered as a no effect level for reproductive parameters.

Animals↗

PubMed1991

Comparing alternative approaches to establishing regulatory levels for reproductive toxicants: DBCP as a case study.

This paper compares four alternative approaches for deriving regulatory levels for reproductive toxicants by applying them to the available data on the human spermatotoxicant 1,2-dibromo-3-chloropropane (DBCP). The alternatives examined include the Proposition 65 approach (application of a mandatory 1000-fold uncertainty factor to a no-observed-adverse-effect level [NOAEL]), the Environmental Protection Agency (EPA) approach (application of flexible uncertainty factors to a NOAEL), the Benchmark Dose approach (application of flexible uncertainty factors to a dose associated with a known level of change in a reproductive parameter), and the Quantitative Risk Estimation approach (using low-dose linear extrapolation and a model of the relationship between sperm count and infertility). Applied to DBCP, these approaches do not produce substantially different estimates of allowable exposure levels. However, the approaches do have different data requirements and provide different amounts of information on reproductive hazards to risk managers and the public. Neither the Proposition 65 nor the EPA approach provides information about the extent of health risk remaining at a regulatory level. In contrast, the Benchmark Dose approach can provide estimates of the magnitude of sperm count reduction at a regulatory level, and the Quantitative Risk Estimation approach can provide estimates of exposure-induced infertility.

Animals↗

PubMed1984

The effect of Aroclor 1254 (PCB) on the physiology of reproduction in the female rat--I.

Daily oral exposure of rats to 30 mg/kg of Aroclor 1254 for 1 month caused deleterious effects on the reproductive process, which were reflected in a decrease in the reproductive potential. The following disturbances were observed: prolongation of the estrous cycle; decrease in sexual receptivity; delay in timing of copulation; vaginal bleeding during gestation; decrease in litter size and delay in the time of parturition. The offspring, whether exposed to PCBs either prenatally and/or postnatally, showed a slower rate of body weight gain than controls. This was accompanied by high mortality until weaning of treated pups. Vaginal opening in the PCB-treated (as young) females occurred precociously, while other reproductive parameters were not affected at adulthood. Discontinuance of PCB treatment reversed the above symptoms.

Animals↗

PubMed1989

The effects of uranium on reproduction, gestation, and postnatal survival in mice.

Uranyl acetate dihydrate was tested for its effects on reproduction, gestation, and postnatal survival in Swiss mice. Four groups of animals, each of which consisted of 25 males and 25 females, were administered 0, 5, 10, and 25 mg/kg/day of uranyl acetate dihydrate. Mature male mice were treated orally for 60 days prior to mating with mature virgin female mice treated orally for 14 days prior to mating. Treatment of the females continued throughout mating, gestation, parturition, and nursing of the litters. One-half of the dams in each group were sacrificed on Day 13 of gestation and the remaining dams were allowed to deliver and wean their offspring. Postnatal development was monitored after 0, 4, and 21 days of lactation. No adverse effects on fertility were evident at the doses employed in this study. Nevertheless, embryolethality could be observed in the 25 mg/kg/day group. Significant increases in the number of dead young per litter were seen at birth and at Day 4 of lactation in the 25 mg/kg/day group. The growth of the offspring was always significantly lower for the uranium-treated animals. However, the present results suggest that uranium does not cause any adverse effects on fertility, general reproductive parameters, or offspring survival at the concentrations usually ingested by man.

Animals↗

PubMed1986

Studies on reproduction in rats with pirmenol, an antiarrhythmic agent.

Fertility and perinatal-postnatal studies were performed in CD rats given pirmenol, an antiarrhythmic agent, at dosages of 0, 25, 50, and 100 mg/kg. The drug was administered orally as diet admixtures in all studies. In the male fertility study, mature male rats were treated for 61 days prior to mating with virgin, untreated female rats. In the female fertility study, mature virgin female rats were treated for 15 days prior to mating with untreated partners with treatment continuing throughout mating, pregnancy, parturition, and weaning of the litters. In both studies, one-half of the dams in each group were killed on Day 21 of pregnancy and the remaining dams were allowed to deliver and wean their offspring and postnatal development was monitored. At weaning, two males and two females were arbitrarily selected from each litter, allowed to mature on unmedicated diet, and then mated within treatment groups to produce the F2 generation. In the perinatal-postnatal study, pregnant females were treated continuously from Day 15 of pregnancy until weaning of the litters on Day 21 postbirth. No adverse effects on fertility, general reproductive parameters, or offspring survival and development were evident at doses employed in these studies.

Animals↗

PubMed1994

[Use of a body condition index (BCI) for the study of the reproduction in snakes].

A body condition index (BCI = actual body mass/optimal theoritical body mass of the studied animal) was estimated in females of 3 species of snake. From dissections of 88 Vipera aspis and 18 Coluber viridiflavus, strong relationships between body reserves (such as mass of fat bodies and liver) and BCI were found. Furthermore, BCI explained most of the variance in the mass of the fat bodies and in the mass of the liver; however BCI and body length together increased the percentage of variation explained. Thus, a satisfactory estimation of body reserves in relation to body length is possible in living snakes. We have studied reproductive parameters (clutch size and litter size) in Vipera aspis (Viperidae) and Elaphe longissima (Colubridae) during a 3 year period. In the two species positive relationships between maternal body length and number of offspring were found. At the beginning of vitellogenesis, litter size is related to the BCI level in V. aspis but not in E. longissima. In both species, BCI must exceed a threshold value for reproduction to take place. However this threshold value is much lower in E. longissima (0.55) than in V. aspis (0.70). This indicates that in the latter species, large body reserves are necessary for the induction of vitellogenesis. In E. longissima, maternal body length is an important determinant of reproductive success, body reserves playing a minor role. In contrast, in female V. aspis the reproductive success is related to BCI and to a lesser extent to body length.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1981

Photoperiodicity in the male albino laboratory rat.

Animals inhabiting areas where there are drastic changes in the environment often reproduce only during limited time periods to ensure that young are raised in optimal environmental conditions. The lack of a well defined breeding season in many domesticated animals, presumably because the selective pressures for seasonal breeding have been minimized, suggests that the neuroendocrine events controlling seasonal cyclicity have been bred out of these animals. Little is known about the underlying neuroendocrine changes which may occur during the evolution of a species from a seasonal to a nonseasonal breeder. Whereas the changing photoperiod is the primary environmental cue which initiates and/or terminates the reproductive season in many animals, this is not so in the albino rat Rattus norvegicus, a model nonseasonal breeder. Nevertheless, daylength can influence various reproductive parameters in laboratory rats, suggesting that some of the neuroendocrine components that controlled seasonal breeding previously are still extant in this species. To test this hypothesis, we investigated the effect of daylength on the responsiveness of the neuroendocrine--gonadal axis to the negative-feedback effects of testosterone. This paradigm was chosen because of the important role played by photic-induced changes in steroid feedback sensitivity in the control of seasonal reproduction. We report here that although daylength has very little effect on neuroendocrine--gonadal function in the intact male laboratory rat, it seems that some component(s) of a photoperiodic system involving the pineal gland has been preserved.

Animals↗

PubMed1983

Effects of room temperature on reproduction, body and organ weights, food and water intakes, and hematology in mice.

Two consecutive generations of mice were raised at graded room temperatures ranging from 12 to 32 degrees C at intervals of 2 degrees C. The delivery rate decreased at 30 and 32 degrees C, and the litter size and weaning rate decreased above 28 degrees C. No significant difference was demonstrated within the 12-26 degrees C range for any reproduction parameters observed. The body weights of the first-generation mice born at 22 degrees C and transferred to rooms at assigned temperature did not significantly differ within the 14-28 degrees C range after 8 and 16 weeks of exposure. The second-generation mice born and reared at various temperature levels did not show significant inter-group difference in weight within the 20-26 degrees C range at any age in the growth period. No significant inter-group difference was observed within the 20-26 degrees C range in respect of food and water intakes in the second-generation mice. Hematological values and organ weights in the first and second generation mice of both sexes did not significantly differ in any parameter within the 20-26 degrees C range. The results suggest the temperature range of 20-26 degrees C to be optimal for laboratory mouse rooms.

Animals↗

PubMed1989

Suitability of white-tailed deer as hosts for cattle fever ticks (Acari: Ixodidae).

White-tailed deer (Odocoileus virginianus L.) were evaluated as an alternate host for the cattle fever tick, Boophilus annulatus (Say). The total of adult female ticks recovered and associated reproductive parameters were compared between deer and bovine hosts. Significantly fewer ticks were recovered from deer than from cattle; this was attributed to the grooming behavior of the deer. The mean weight of ticks taken from deer (243.5 mg) was significantly less than that of ticks recovered from cattle (344.5 mg) with about 15% of the ticks from deer prematurely detached. Egg mass weight from the ticks recovered from deer (129.4 mg) was significantly less than that of ticks from cattle (172.1 mg). A significant difference was observed between the percentage hatch of the eggs of ticks from deer (63.1%) and ticks from cattle (76.7%). The index of reproduction was about 20 times greater for the ticks from the cattle than for the ticks from the deer. When the larval progeny of the ticks recovered from deer were reared on cattle, significantly fewer adult females were recovered than when larvae of ticks recovered from cattle were reared on cattle. This indicates a possible reduction in viability. All other parameters were comparable between the two groups. Thus, deer are biologically suitable hosts for B. annulatus, but significantly fewer ticks complete engorgement and those that complete engorgement have reduced fecundity.

Animals↗

PubMed1989

The deleterious effects of cortisol implantation on reproductive function in two species of trout, Salmo trutta L. and Salmo gairdneri Richardson.

Implantation of a cortisol-releasing pellet (60 mg kg-1 fish) into the peritoneal cavity of brown trout, Salmo trutta L. (sexually maturing males and females), and rainbow trout, Salmo gairdneri Richardson (maturing males and immature fish of both sexes), significantly elevated their plasma cortisol level. At 18 days postimplantation, cortisol-implanted sexually maturing male brown trout had smaller gonads, a lower plasma testosterone level, and less gonadotropin in their pituitary gland than control fish. Plasma levels of 11-ketotestosterone and gonadotropin were not significantly affected. Cortisol-implanted sexually maturing female brown trout had smaller gonads, reduced plasma levels of 17 beta-oestradiol, testosterone, and vitellogenin, and a lower pituitary gland gonadotropin content than control fish. The plasma gonadotropin level was unaffected. At 36 days post-implantation, cortisol treatment of maturing male rainbow trout significantly suppressed plasma gonadotropin levels. Plasma levels of testosterone, 11-ketotestosterone, and 17 alpha,20 beta-dihydroxy-4-pregnen-3-one, pituitary gonadotropin content, and gonad size were not significantly affected. In sexually immature female rainbow trout, cortisol administration suppressed the level of vitellogenin in the plasma, compared to control-implanted fish. The 17 beta-oestradiol level was not affected. Cortisol implantation did not affect the plasma testosterone level in sexually immature male trout. These results suggest that prolonged elevation of plasma cortisol, to levels well within physiological range, can affect a wide range of reproductive parameters in both brown and rainbow trout. Further, some effects are manifest in immature as well as in mature fish. These findings are discussed in relation to the effects of cortisol treatment on the state of health of the treated fish.

Animals↗

PubMed1984

Central effects of photoperiod on reproduction in the ram revealed by the use of a testosterone clamp.

Over a 3-year period eight adult Soay rams were exposed to an artificial lighting regimen of alternating 16-week periods of long days (16 h light: 8 h darkness; 16L : 8D) and short days (8L : 16D) to induce a seasonal cycle in reproduction and wool growth every 32 weeks. Early in the study the rams were castrated (four during long days and four during short days) and 48 weeks later the castrated animals were each given an s.c. implant of testosterone to increase the blood plasma concentration of testosterone to 14-20 nmol/l. The changes in the concentrations of LH, FSH and testosterone were measured in blood samples collected once or twice weekly while records were made of the changes in the size of the testes (before castration), the intensity of the sexual skin flush, the expression of aggressive and sexual behaviour and the rate of wool growth. The results showed that in the castrated rams there were only minor changes in the blood levels of LH, FSH and the expression of aggressive behaviour related to the 32-week light cycle, while the sexual skin flush was permanently absent. However, after the commencement of the constant testosterone therapy, there were major changes in all the reproductive parameters related to the lighting regimen with a similar temporal relationship as observed in the rams before castration. Cyclic variation in wool growth occurred throughout the study related to the changes in photoperiod but this was not markedly affected by castration and testosterone replacement.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗

PubMedDate not supplied

Testing strategies in behavioral teratology: I. Testing battery approach.

Female rats were given drinking water containing 1.5, 5 or 15 mg/l methylmercury chloride from two weeks prior to pairing until the end of the lactation period. The usual reproduction parameters were recorded. The morphological, functional and behavioral development of the offspring was assessed by subjecting them to a routine testing battery in accordance with the English and Japanese guidelines. Due to toxic effects in the high dose group only offspring of the mid and low dose groups were tested. In both groups some motor coordination and learning deficits as well as delayed sexual maturation were noted, although effects were small and varied considerably. Results demonstrated that a routine testing battery can detect behavioral effects in the offspring at a dose where no reproduction effects are observed.

Animals↗

PubMed1979

The effect of age on reproduction in repeatedly mated female rats.

The effects of age and repeated pregnancies on reproduction were studied in Long-Evans rats. Indices of reproduction measured included estrous cycles, successful mating, numbers of rats producing litters, average litter size, average pup weight and serum LH-from a 4 pm proestrous blood sample. There were no differences in these reproductive parameters between rats with serial pregnancies initiated at 2 or 9 mo of age. The percentage of rats producing normal litters was reduced much faster than the percentage of successfully mated rats with normal ovarian cycles. Although 60% of the rats still had normal ovarian cycles and were mated at 17 mo of age, only one rat (4%) produced a litter. Increasing age and multiple pregnancies did not significantly affect the LH concentration of the proestrous blood sample or the average litter size or pup weight of the rats with successful pregnancies. These data suggest post-ovulatory loss of reproduction in the aging rat.

Animals↗

PubMed1995

Early lactation responses of Holstein cows fed a rumen-inert fat prepartum, postpartum, or both.

Primiparous (n = 22) and multiparous (n = 41) cows were randomly assigned by calving date and parity to one of four dietary sequences of supplemental fat from 14 d prepartum to 151 d postpartum. Partially hydrogenated tallow was added to diets at 0% prepartum and postpartum (control); 1% prepartum and 2% postpartum; 0% prepartum and 2% postpartum; and 0% prepartum, 0% from 1 to 34 d postpartum, and 2% from 35 to 151 d postpartum. Inclusion of partially hydrogenated tallow did not influence yields of milk or 3.5% FCM, milk composition, or DMI during the first 151 d postpartum. During the first 35 d postpartum, cows receiving partially hydrogenated tallow starting at parturition yielded milk with a higher fat content than those receiving fat prepartum and postpartum. Addition of partially hydrogenated tallow to diets starting 35 d postpartum resulted in cows being more persistent in yields of milk and 3.5% FCM from 60 to 151 d postpartum. Reproduction parameters measured were unaffected by time of fat addition to diets. Our data suggest that delaying the addition of partially hydrogenated tallow to diets until 35 d postpartum may improve the persistency of lactation.

Animals↗

PubMed1994

Alterations in the ontogeny of rat pup ultrasonic vocalization produced by prenatal exposure to nitrogen dioxide.

Wistar female rats were exposed to low concentrations of nitrogen dioxide, NO2 (1.5 and 3 ppm) from day 0 to day 20 of pregnancy. The results show that prenatal exposure to this oxidant gas produced significant changes in the duration pattern of ultrasonic vocalizations emitted by male pups removed from their nest. In particular, a significant decrease in the length of ultrasonic calls was found in both 10- and 15-day-old rats exposed to NO2 (3 ppm) during gestation. These alterations were found at dose levels which did not significantly affect reproduction parameters, body weight gain and motor activity development. These findings suggest that gestational exposure to NO2, at concentrations below those associated with overt signs of toxicity, induces in rat offspring subtle behavioral changes characterized by altered ontogeny of ultrasonic emission.

Aging↗

PubMedDate not supplied

Ethylene glycol monomethyl ether II. Reproductive and dominant lethal studies in rats.

Groups of male and female Sprague-Dawley (CD) rats were exposed to 0, 30, 100, or 300 ppm ethylene glycol monomethyl ether (EGME) vapor 6 hours/day, 5 days/week for 13 weeks. The 0 and 30 ppm groups each contained 30 rats/sex and the 100 and 300 ppm groups each had 20 rats/sex. Following the exposure period, males were bred to unexposed females to evaluate reproductive capability and dominant lethality. Additional matings of control and 300 ppm exposed males were performed during the post-exposure period in order to evaluate the recovery of fertility. Exposed females were bred with unexposed males to assess reproductive parameters. Results of the present study indicate a potential for inhaled EGME to completely suppress fertility in male rats at the 300 ppm level. Fertility of these rats was partially restored at 13 weeks post-exposure. Body weights of animals in the 300 ppm group were reduced as a result of the exposures. No dominant lethal effect or impaired fertility was observed in male rats exposed to 30 or 100 ppm EGME. Treatment-related pathologic alterations were observed only in male rats at the 300 ppm level and induced decreased testicular size and atrophic seminiferous tubules. Female rats tolerated up to 300 ppm EGME without any adverse reproductive effects. Based on these results, it was concluded that the no-adverse effect level of EGME for fertility and reproduction was 100 ppm in rats.

Animals↗

PubMed1984

Reproductive performance of broiler breeders exposed to cycling high temperatures from 17 to 20 weeks of age.

Forty male and 240 female broiler breeders were placed in cages within environmental chambers (20 males or 40 females per chamber) at 14 weeks of age. Chamber temperatures were maintained at 21.3 +/- 2.5 C, and relative humidity (RH) ranged from 40 to 50%. Ventilation rate was approximately 47.2 liters/sec per chamber, and light was provided from 0600 to 1800 hr. Feed was restricted daily according to industry recommendations, and water was provided ad libitum. From 17 to 20 weeks of age, control (C) chambers were kept at constant 21.0 +/- 1.4 C with 45 +/- 5% RH, and heat-treated (HT) chambers were cycled from 24.4 +/- 5.5 C (45 +/- 5% RH) during 1800 to 0800 hr to 36.0 +/- 2.8 C (15 +/- 5% RH) during 0800 to 1800 hr. Body weights were recorded at biweekly intervals. At 18 and 20 weeks of age, blood samples and rectal body temperatures were obtained randomly from five fasted birds per chamber at 0800 and 1400 hr. From 20 to 60 weeks of age, all birds were kept in individual cages in a conventional fan-ventilated house. Maximum temperature never exceeded 30 C, and average RH was 65.0%. Reproductive parameters were monitored and body weights were obtained at 4-week intervals. There were no significant treatment effects for body weight, body temperature, or differential leukocyte counts. Hematocrits were significantly lower for HT females than controls, and heat treatment did not result in consistent changes in plasma glucose or total proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1995

Retrospective evaluation of production characteristics in Sinclair miniature swine--44 years later.

Three hundred seventy-one litter records collected between 1985 and 1993 from 156 Sinclair S-1 miniature sows, a Hormel-derived strain of miniature swine, were retrospectively analyzed and compared with published records for 1950 to 1952 and 1963 to 1965. The effect of several variables such as season and month of parturition, age of sow, parity, and litter size on reproductive parameters of the Sinclair miniature swine were evaluated. The mean and standard error of the mean for litter size, number of liveborn, number of stillborn, and litter size at weaning of the Sinclair S-1 miniature swine were 7.20 +/- 0.12, 6.57 +/- 0.12, 0.63 +/- 0.06, and 5.75 +/- 0.12 piglets respectively. From a total of 2,436 liveborn piglets, 2,133 (87.56%) were weaned. The litter size at birth was similar to that previously reported for this strain of swine, whereas the litter size at weaning increased (P < 0.001) from 4.7 piglets during 1963 to 1965 to 5.8 piglets in our study. The average birth weight decreased (P < 0.001) from 0.90 kg in 1950 to 1952 and 0.72 kg in 1963 to 1965 to 0.59 kg in our study. Reproductive variables that had a considerable effect on the miniswine reproduction included month of parturition, age of sow, parity, and litter size. Primiparous sows had the smallest litter size and lowest number of weaned piglets. Sows during their second and third parity or sows between 2 and 4 years old had the best reproductive performances. Litter size and number of stillborn increased with parity and age of sow, resulting in fewer piglets weaned in older sows.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗