Sucralose: lack of effects on sperm glycolysis and reproduction in the rat.

Certain chlorine-substituted sugars with chemical similarities to sucralose have been demonstrated previously to diminish or inhibit sperm glycolysis and fertility in the rat ([Ford]). In order to investigate this potential for sucralose, epididymal spermatozoa were recovered from rats exposed in vivo to oral doses of one of three of these substituted sugars: 6-chloroglucose (6-CG, 24mg/kg/day, positive control), sucralose (500mg/kg/day, over 300 times the expected human daily intake), or a 6'-substituted isomer of sucralose, trichloro de-oxy sucrose (TCDS, 100mg/kg/day, a potential trace impurity in commercial sucralose); distilled water served as the negative control. After incubation of the spermatozoa with D-[U-(14)C] glucose, measurements of (14)CO(2) and of ATP content showed no impairment of the glycolytic ability of spermatozoa in any of the groups except for a marked inhibition for those exposed to 6-CG, the positive control. In order to determine whether other parameters of reproduction and fertility could be affected, reproductive endpoints were examined following oral exposure of male and female rats to sucralose. Sucralose was fed in the diet at concentrations of 0, 0.3, 1.0 and 3.0% (approx. 100, 365 and 1150 times the EDI) to groups of 30 male and 30 female rats for 10 weeks prior to mating, and continued through two subsequent generations until weaning of the F(2) pups. Two litters were produced per generation. Food consumption and weight gain in the F(0) and F(1) generations were depressed in all sucralose groups before mating and in all four litters prior to weaning. The decrease in initial average weight for newborn pups probably reflects the increased litter sizes noted for sucralose-treated groups and the reduced food consumption of the dams during gestation and lactation. The latter is a result primarily of the unpalatability of sucralose to rats ([McNeil,]). Caecal enlargement (a common animal response to large doses of indigestible material) occurred in both the F(0) and F(1) parents. Increased kidney weights, possibly associated with increased water intake, were observed primarily among animals receiving 3% sucralose (no renal histopathology has been detected). Decreased thymus weights occurred in F(1) males and in both F(1) and F(2) females at the 3% level. Subsequent studies specifically designed to investigate the potential for adverse immune system effects of sucralose ([McNeil,]) showed no adverse effects. These findings are consistent with investigations by others showing that decreases in thymus weights occur in young rats in response to stressful conditions associated with reductions in weight gain. All reproductive indices (oestrous cycles, mating behaviour, fertility, gestation, maternal and foetal viability, foetal development, parturition, pup maturation and lactation) were comparable between the control and sucralose-treated groups. We conclude from these results that sucralose has no effect on sperm glycolysis or on male or female reproductive performance in the rat.

Sucralose: assessment of teratogenic potential in the rat and the rabbit.

The teratogenic potential of sucralose was examined following gavage administration to pregnant rats and rabbits during organogenesis. Groups of 20 mated rats were dosed on days 6-15 of gestation inclusive at 500, 1000 or 2000mg/kg/day; groups of 16 to 18 inseminated rabbits were dosed on days 6 to 19 of gestation inclusive at 175, 350 or 700mg/kg/day following preliminary studies at higher doses. Concurrent control groups received vehicle alone. Rats were killed on day 21 and rabbits on day 29 of gestation. Foetuses were evaluated at necropsy and after processing for possible soft tissue and skeletal alterations. There was no evidence of teratogenicity for either species. The only observed response to treatment in rats was a slight increase in water intake. Some adult rabbits receiving 700mg/kg/day exhibited marked gastrointestinal disturbance, also seen at higher doses in preliminary studies. Gastrointestinal effects such as these occur non-specifically in response to high doses of poorly absorbed compounds, and in the present study were considered to be responsible for two maternal deaths and four abortions. Full evaluation of rabbit foetuses in the main study (up to 700mg/kg/day) and necropsy of foetuses in a preliminary study with pregnant animals (up to 1000mg/kg/day) showed no evidence of adverse foetal response to sucralose. These teratology studies in both pregnant rodent and non-rodent animal models demonstrate that maternal consumption of high levels of sucralose during the period of organogenesis has no effect on normal foetal development in the rat or rabbit.

[Reproductive and developmental toxicity studies of lactitol (NS-4) (3)--Teratogenicity study in rabbits by oral administration].

Lactitol, a hepatic encephalopathy drug, was administered by oral gavage to pregnant New Zealand White rabbits during organogenesis from day 6 to day 18 of gestation inclusive, at dosages of 0, 0.25, 0.75 or 4.5 g/kg/day. On day 29 of gestation, females were killed to allow examination of their uterine contents. There was a slight reduction in food intake and faecal output among females receiving 4.5 g/kg. One female receiving 4.5 g/kg aborted following a prolonged period of weight loss. No adverse effects on litter parameters were recorded that could be attributed to treatment. Foetal morphogenesis was unaffected by treatment with lactitol. The results show that no-effect dose levels of lactitol are 0.75 g/kg in mother rabbits for general toxicity and for reproductive functions, and 4.5 g/kg for their fetuses.

Effects of female sex hormones in whole embryo culture.

Much work has been done in vivo on the effects of sex steroids on the developing foetus. Many genital anomalies have been reported; defects of other organ systems have been suggested. Synthetic oestrogens are considered to be developmental toxicants in vivo, while natural oestrogens are thought to present little or no risk. A small selection of hormones (17beta-oestradiol, 17alpha-ethynyloestradiol, diethylstilboestrol and progesterone) was tested using the rat whole embryo culture technique to see whether this difference could also be confirmed in vitro. Dysmorphogenic embryotoxic effects were evident with both natural and synthetic oestrogens, but at much higher concentrations than would be expected to circulate in humans after therapeutic use.

Absence of developmental effects in CF-1 mice exposed to aspartame in utero.

Aspartame (L-aspartyl-L-phenylalanine methyl ester) is a widely used high potency dipeptide sweetener. Developmental toxicology studies have been performed in several species documenting no effects of high doses of aspartame. Recently, a study by Mahalik and Gautieri [1984) Res. Commun. Psychol. Psychiatry Behav. 9, 385-403) reported a delay in the achievement age for the visual placing response in mice pups after maternal administration of high dosages of aspartame during late gestation. In the present study developmental parameters were determined in offspring of CF-1 mice after maternal administration of aspartame at 500, 1000, 2000, and 4000 mg/kg body wt by oral gavage. Aspartame was administered on Days 15 through 18 of gestation. Maternal body weight, food consumption, gestation length, reproductive indices, and litter size were not affected by aspartame treatment. In the pups, body weights, negative geotaxis, and surface and midair righting reflexes were not altered by treatment. There was no delay in the development of the visual placing response regardless of the method employed for assessment (grid or rope) or the manner by which the data were analyzed. There were also no changes in time of eye opening, reflex pupil closure, and ophthalmoscopic examination in the offspring. Thus, neither physical nor functional development was altered in mice after in utero exposure to extremely large dosages of aspartame. More specifically, in utero exposure to aspartame did not affect the development of the visual system in mice.

Reproductive studies of NY-198 in rats. I. Fertility study.

Lomefloxacin (NY-198), a new antibacterial agent, was administered daily by gavage to groups of 22 male and 22 female rats at dosages of 30, 100 or 300 mg/kg/day. Males were dosed for 71 days before pairing and then until termination, and females were dosed for 15 days before pairing, throughout mating and until Day 7 of gestation. Females were killed on Day 20 of gestation for examination of their uterine contents. Males were killed after approximately 14 weeks treatment and their reproductive organs were weighed and retained. At 300 mg/kg/day the majority of animals showed increased salivation, water intake was slightly increased throughout the treatment period in males and before pairing in females whereas food intake showed a slight, transient reduction during the first few days of treatment in both sexes. Body weight gain of males was marginally depressed during the first week of treatment, but no other signs of reaction to treatment were observed. At 30 and 100 mg/kg/day some animals exhibited increased salivation after being dosed. At all dosages, NY-198 was without adverse effects upon mating performance and fertility, or upon survival, growth and development in utero. On the basis of the above results it is considered that the no effect level with respect to reproduction and breeding performance of treated F0 animals and the in utero development of the foetuses was 300 mg/kg/day. A dosage of 100 mg/kg/day was considered to be the no effect level for somatic changes in the F0 animals, and even at the highest dosage of 300 mg/kg/day only slight effects were recorded on the F0 animals.

Reproductive studies of NY-198 in rats. II. Teratology study.

Lomefloxacin (NY-198), a new antibacterial agent, was administered daily by gavage to groups of 32 pregnant female rats of the CD strain at dosages of 30, 100 or 300 mg/kg/day from Day 7 to Day 17 of gestation. Twenty-one females in each group were killed on Day 20 of gestation for examination of their uterine contents. Eleven females in each group were allowed to deliver their litters and the offspring were examined for growth and functional development. At the highest dosage (300 mg/kg/day), there was a small reduction in maternal weight gain and a transient reduction in food intake during the treatment period. Foetal and placental weights were markedly reduced. However, survival, growth and development of F1 offspring were unaffected and, with the possible exception of a slight reduction in F2 foetal weight, their reproductive performance was unimpaired. At the intermediate level (100 mg/kg/day), maternal body weight gain and food intake during the treatment period were slightly reduced but, with this exception, the performance of F0 females and of the F1 generation was essentially similar to that of the vehicle controls. At the lowest dosage (30 mg/kg/day), no adverse effects were recorded on either the F0 females or the F1 generation. On the basis of the above results 30 mg/kg/day was considered to be the no effect level for the F0 females treated during gestation while 100 mg/kg/day administered during gestation to F0 females had no effect upon performance of the F1 generation.

Reproductive studies of NY-198 in rats. III. Perinatal and postnatal study.

Lomefloxacin (NY-198), a new antibacterial agent, was administered daily by gavage to groups of 22 pregnant female rats of the CD strain at dosages of 30, 100 or 300 mg/kg/day from Day 17 of gestation to Day 21 of lactation. Females were allowed to deliver their litters and the offspring were examined for growth and functional development. There was a slight maternal response at the highest dosage (300 mg/kg/day), including increased salivation after dosing, reduced food intake in the treated period of gestation and increased water intake during the lactation period. Gestation length was slightly increased, although remaining within the laboratory background control range; in consequence, body weight of F1 offspring at Day 1 post partum was slightly increased. At 100 mg/kg/day, a few females showed increased salivation after dosing and there was a slight increase in gestation length. Birth weight of F1 offspring was slightly increased at 30 and 100 mg/kg/day but all values were within laboratory background control ranges. The survival, functional responses and fertility of F1 offspring were essentially unaffected by NY-198. On the basis of the above results, 30 mg/kg/day was considered to be the no-effect level for the F0 females treated during late gestation and lactation whilst 300 mg/kg/day administered to the F0 females had no adverse effect upon their offspring.

Feeding of partially hydrogenated fish oils to rats in comparison with partially hydrogenated soybean oil and refined rapeseed oil: a combined chronic oral toxicity and carcinogenicity study with in utero phase.

Partially hydrogenated fish oils (PHFO) have been widely used in human food products for many years, particularly in Europe, North and South America and in South Africa. Animal studies, mainly with rapeseed oil, suggested that erucic acid might be responsible for morphological changes in the myocardium. It was suggested that other members of the docosenoic (22:1) family of fatty acids might produce similar effects to those ascribed to erucic acid. Certain PHFO can contain relatively high levels of these other isomers. Thus it was decided to evaluate PHFO of differing 22:1 levels in comparison with partially hydrogenated soybean oil (PHSBO) and refined rapeseed oil (LEAR) in a rat life span study, preceded by a breeding period in which the experimental lipids were fed to male and female parents. Two commercially produced PHFO were selected to represent the lower (PHFO-L) and upper (PHFO-U) range of 22:1 contents, 4.3 and 13.8%, respectively. A third test oil was prepared from a 50:50 blend of these (PHFO-M) to provide and intermediary 22:1 level. The control PHSBO and LEAR contained 0 and 1.0% 22:1, respectively. These experimental oils were included in semi-purified diets at 8 and 16%, respectively, in the breeding and life span periods of the study, together with 4% of oil mixtures providing essential fatty acids (EFA). Specific pathogen free (SPF). Wistar weanling rats, 200 of each sex, provided the subjects for the breeding period. Sufficient numbers of offspring were obtained in suitable condition from each treatment group to allow selection of a total of 555 weanlings for allocation to the five dietary treatments of the life span period of the study. For the life span period of the study, which was terminated after 107 to 110 weeks of treatment, 50 subjects were allocated to each of the PHSBO, PHFO-L and PHFO-U dietary groups, and 50 males to each of the LEAR and PHFO-M groups. The remaining subjects were allocated to sub-groups for sacrifice four days or 26 weeks after introduction of the life span period diets. All life span group subjects were weighed and had their food intakes recorded, and were subjected to clinical examination, routinely. At designated stages, ophthalmoscopic examination of all subjects was carried out, and samples of blood and urine were obtained from sub-groups for laboratory analysis. All decedent and terminated life span group subjects were subjected to post mortem examination, with weighing of 16 organs.(ABSTRACT TRUNCATED AT 400 WORDS)

The application of whole-embryo culture to new product development.

Whole-embryo culture is employed routinely in our laboratories as one aspect in the early toxicity screening of new compounds. More than 150 experimental compounds have been examined to date, in addition to a number of known teratogenic agents. The rationale and study design are discussed and results are presented for cyclophosphamide, retinoic acid, lithium, thalidomide and mercury, all of which demonstrate good correlation between effects in vitro and those reported in vivo. The system has proved to be a rapid, cost-effective screen with marked economies in the numbers of animals, amount of compound and time required; as yet, no false positive or false negative results have been observed. It is considered, therefore, that taken in conjunction with other aspects of biological activity, the results from embryo-culture studies can make a valuable contribution to the selection process of new product development.

Safety evaluation of Streptomyces murinus glucose isomerase.

A glucose isomerase enzyme, obtained from Streptomyces murinus, was produced by a fermentation process and subjected to a series of tests to investigate its safety in use and manufacture. It was not mutagenic (Ames test, using liquid culture) nor did it provoke chromosomal damage (rat bone marrow cytogenetics test). It did not contain (nor did the organism produce) antimicrobial activity or macrolidpolyene antibiotics. It had no teratogenic activity when administered to pregnant rats at 100,000 ppm in the diet. It was without effect upon rats when administered at this dietary concentration for 4 weeks. Dietary administration at 5000, 15,000 or 50,000 ppm to rats for 13 weeks resulted in nephrocalcinosis in females at all dosages (probably a physiological response to the altered calcium:phosphate ratio in the admixed diet) and status spongiosus in the brains of males receiving 50,000 ppm. As the finding of nephrocalcinosis in rats is generally agreed to be of no toxicological importance with regard to the use in man, the dietary concentration of 15,000 ppm was considered to be highest no-effect level. This level corresponds to an intake of some 1000 mg/kg/day, which represents approximately 8000 times the human intake based on a conservative estimation.

Agent-determined type of maternal influence on induced cleft palate in mice.

The maternal influence on induced cleft palate frequency, as revealed by reciprocal crosses, was investigated after treatment with triamcinolone or cortisone. Mouse blastocysts from the CBA and A/Jax strains were transferred to pseudopregnant A/Jax and CBA foster mothers and in addition CBA X A/Jax and A/Jax X CBA embryos were raised in pseudopregnant CBA foster mothers. According to the period of maximum sensitivity revealed by a time response study triamcinolone was injected as a single dose (2 mg/kg, i.m.) on day 11 at 8 a.m. when the precocious development of transferred fetuses had been taken into account. A predominant uterine factor slightly modified by the fetal genome was found. This was in contrast to the effect of the 4-day treatment with cortisone (62.5 mg/kg i.m.) where, as also previously has been shown, cytoplasmic factors in the embryos were accountable for the magnitude of the teratogenic response. An increased corticoid elimination from the resistant CBA fetuses might explain the maternal influence on triamcinolone treatment but would not be responsible for the influence on cortisone-induced cleft palate frequency.