Teratogenicity and maternal effects of Lactobacillus brevis KB290 in rats and rabbits.

Lactobacillus brevis KB290 (KB290), a plant-derived probiotic lactic acid bacterium, improves gut health and stimulates immune function. Here we extensively investigated the teratogenicity of KB290 in rats and rabbits. We observed no adverse maternal or fetal effects and concluded that the no observable adverse effect level for maternal general toxicity, maintenance of pregnancy, and teratogenicity should be ≥ 10(10) cfu/kg/day. Our results suggest that KB290 would be safe for pregnant females and their offspring.

Late preconditioning in rat retina: involvement of adenosine and ATP-sensitive K(+) channel.

To determine whether stimulation of adenosine receptors and opening of ATP-sensitive K(+) channels were involved in the protective effect of late preconditioning in the rat retina, rats were subjected to 60 min of retinal ischemia, and ischemic preconditioning was achieved by applying 5 min of ischemia 24 h before 60 min of ischemia. In non-preconditioned rats, cell loss in the ganglion cell layer and thinning of the inner plexiform and inner nuclear layer were observed 7 days after 60 min of ischemia. Ischemic preconditioning completely prevented the retinal tissue damage and 8-phenyltheophylline or 5-hydroxydecanoate reduced the protective effect of ischemic preconditioning. Therefore, stimulation of adenosine receptors and opening of ATP-sensitive K(+) channels might be involved in the mechanism of histological protection by late preconditioning in the retina.

Effects of prenatal and postnatal exposure to styrene dimers and trimers on reproductive function in rats.

Styrene dimers and trimers (SDT) were evaluated for reproductive toxicity in Sprague-Dawley rats. SDT was administered orally to rats at doses of 0, 0.04, 0.2, and 1.0 mg/kg from day 6 of gestation through day 21 after delivery. Clinical signs, including pregnancy and lactation, and changes in body weight and food consumption were assessed. All dams underwent a gross necropsy examination. The brain, liver, kidney, ovary, uterus, thyroid gland, and pituitary were weighed. Offspring were evaluated for the effects of the test compound on viability, growth, anogenital distance, preputial separation and vaginal opening, behavioral function, estrous cycling, mating, and fertility. There were no test compound-related clinical signs or effects on body weight or food consumption in dams during any phase of the study. In addition, no abnormalities in delivery or lactation, including gestation length, were noted in any dam. No dose-dependent changes were observed in pup viability or growth. There were no adverse effects of SDT on any developmental landmark, learning, memory, or estrous cycling in offspring. The number of days to inseminations in the 0.2 mg/kg group was significantly greater than that in the control group, but was independent of dose. No test compound-related necropsy findings were seen in either the dams or the offspring. No compound-related histopathologic findings were noted in the reproductive tissues of either the male or female offspring. No compound-related alterations in sperm motion or density were detected in the offspring. Thyroid stimulating hormone levels in the male offspring of the 0.2 mg/kg and 1.0 mg/kg groups were significantly higher than those in the controls, whereas thyroid hormone (T(3), T(4)) levels in these groups were comparable to the controls. In addition, the thyroid glands of males in all groups were similar histologically. These results indicate that SDT administered at doses as high as 1.0 mg/kg (1000 times the estimated human daily intake) did not produce reproductive toxicity in dams or offspring.

Reproductive function in rats exposed neonatally to bisphenol A and estradiol benzoate.

The reproductive function in rats treated subcutaneously (s.c.) with 300 microg/g bisphenol A or 2 microg/g estradiol benzoate from postnatal Day 1 to 5 was examined after puberty as well as histolopathogic changes in reproductive organs. All male and female rats treated postnatally with estradiol benzoate showed poor reproductive capability, including adverse effects on masculine sexual behavior, and marked histopathologic alterations of the reproductive organs. In addition, estradiol benzoate markedly reduced the volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in males. On the other hand, all male and female rats treated postnatally with bisphenol A showed normal reproductive function and no histopathologic abnormalities of reproductive organs. Bisphenol A did not affect the volume of the SDN-POA. These results indicated that neonatal exposure to estradiol benzoate affects reproductive function in male and female rats, and treatment with bisphenol A at a fairly high dose was ineffective if given postnatally to male and female rats.

Behavior and reproductive function of rat male offspring treated prenatally with 5-bromo-2'-deoxyuridine.

5-Bromo-2'-deoxyuridine (BrdU) was administered intraperitoneally to Sprague-Dawley rats at doses of 50 mg/kg/d on Days 9 through 15 and at 100 mg/kg/d on Days 16 through 20 of gestation. Dams were allowed to deliver naturally. Male offspring were subjected to a variety of pre- and postweaning behavioral tests: surface righting, negative geotaxis, open field test, Biel maze test, wheel cage test, and shuttlebox avoidance test. After puberty, masculine sexual behavior was observed. Male offspring of dams treated with BrdU on Days 9 through 15 of gestation showed an accelerated negative geotaxis reflex and increased ambulation and rearing in open field, while those of dams treated on Days 16 through 20 of gestation showed normal activity. Offspring of dams treated on Days 9 through 15 of gestation showed a higher activity level in the wheel cage than offspring of dams treated on Days 16 through 20 of gestation. In the Biel maze, offspring of dams treated on Days 9 through 15 of gestation showed impaired learning and memory. In the shuttlebox avoidance response, offspring of dams treated on Days 9 through 15 of gestation moved significantly more than offspring of dams treated on Days 16 through 20 of gestation. Masculine sexual behavior was markedly reduced in male offspring of dams treated on Days 9 through 15 of gestation. However, no significant differences between groups in blood pressure nor heart rate were noted. We conclude that male offspring of dams treated with BrdU on Days 9 through 15 of gestation are hyperactive without hypertension and that these offspring show an impairment of masculine sexual behavior, i.e., hyposexuality.

Effects of prenatal exposure to 5-fluoro-2'-deoxyuridine on developing central nervous system and reproductive function in male offspring of mice.

The effect of 5-fluoro-2'-deoxyuridine (FrdU) on the developing brain and postpubertal reproductive function of male mouse offspring treated prenatally was investigated. FrdU was administered intraperitoneally to pregnant ICR mice at 1.5, 3, 6, 12.5, 25, and 50 mg/kg/day on days 8 through 13 of gestation or 12.5, 25, and 50 mg/kg/day on days 14 through 18 of gestation. Dams were allowed to deliver spontaneously. Dams treated with FrdU at 12.5, 25, and 50 mg/kg/day on days 8 through 13 of gestation did not deliver because of entire intrauterine death of embryos. Male offspring were aged for 10 or 15 weeks and then cohabited with untreated female mice for assessment of reproductive performance. Histological examination of the testis, epididymis, prostate, and seminal vesicle of offspring at 12 weeks of age, and sperm analysis of offspring at 12 or 17 weeks of age were performed. Dose-dependent decreases in body weight gain were noticed throughout the life of offspring. A marked decrease in the copulation rate was noted in the group treated with FrdU at 6 mg/kg/day on days 8 through 13 of gestation. However, neither histological examination of testes and sex-accessory glands nor sperm analysis revealed adverse effects of FrdU on the reproductive function in the male offspring of dams treated with FrdU at 6 mg/kg/day on days 8 through 13 of gestation. There were no significant differences in the relative weight of testes and epididymides between the group treated with FrdU at 6 mg/kg/day on days 8 through 13 of gestation and the control group. Absolute brain weight in the groups treated with FrdU on days 8 through 13 of gestation significantly decreased, while relative brain weight increased in the group treated at 6 mg/kg/day on days 8 through 13, and at 25 and 50 mg/kg/day on days 14 through 18 of gestation. Dilatation of the lateral and third ventricles was observed in all of the male offspring of dams treated with FrdU at 6 mg/kg/day on days 8 through 13 of gestation, when inspected at 12 and 17 weeks of age. In the subsequent study, ICR mice were treated intraperitoneally with FrdU at 6.25-100 mg/kg on day 12 of gestation, and the fetuses obtained 24 h after treatment. Histological observation was performed in the ventricular zone of telencephalon, and in the ependymal and mantle layers of diencephalon in the fetal brain. The incidence of pyknotic cells in these areas was increased linearly with increasing FrdU dose. From these results and our previous findings, we suggest that damage to the central nervous system, a substantial neuronal deficit, resulting from excessive cell death in the developing brain may lead to reproductive dysfunction after puberty.

Effects of prenatal exposure to 5-bromo-2'-deoxyuridine on the developing brain and reproductive function in male mouse offspring.

The effect of prenatal exposure to 5-bromo-2'-deoxyuridine (BrdU) on the brain and reproduction in mice was studied. ICR mice were treated intraperitoneally (i.p.) with BrdU at 200 mg/kg on Day 10, 13, or 15 of gestation, or with BrdU at various doses (100 to 800 mg/kg) on Day 10 of gestation. In both experiments, dams were allowed to deliver, and male offspring were aged for 10 weeks and then cohabited with untreated females. In the phase-specificity study, the copulation rate was significantly decreased in the group treated on Day 10 of gestation, while the rate in the groups treated on Day 13 or 15 was comparable to the control level. In the dose-dependency study, copulation rates in the groups treated with BrdU at 200, 400, and 800 mg/kg were significantly lower than the control level, while the rate in the group treated with BrdU at 100 mg/kg was comparable to the control level. Masculine sexual behavior in the group treated with BrdU at 800 mg/kg was markedly impaired. Neither histopathologic changes of testis and sex-accessory glands nor alterations of sperm motility and concentration were observed in the offspring of the highest dose group. Dilatation of the third ventricles was observed in the highest dose group, whereas the relative brain weight in this group was comparable to that in the control group. In the subsequent study, ICR mice were treated i.p. with BrdU at various doses (25 to 800 mg/kg) on Day 10 of gestation, and the embryos were obtained 24 h after treatment. Histopathologic evaluation was performed in the ventricular zone of the telencephalon as well as ependymal and mantle layers of diencephalon (hypothalamus). The incidence of pyknotic cells in these areas was increased linearly with increasing BrdU dose and the incidence in the ependymal and mantle layers of the diencephalon was higher than that in the ventricular zone of the telencephalon. From these results, we conclude that damage to the central nervous system resulting from excessive cell death in the developing brain, particularly in the ependymal and mantle layers of the diencephalon (hypothalamus) may lead to reproductive dysfunction in postpubertal male offspring.

A comparison of the in vivo and in vitro response of rat embryos to 5-fluorouracil.

This study serves to further define the capabilities of the whole embryo culture system using the well-known teratogen, 5-fluorouracil (5-FU), an antineoplastic agent. An initial in vivo study was performed whereby pregnant rats were injected intraperitoneally with 10-30 mg/kg 5-FU on day 9 of gestation. On day 20 of gestation, the effects of this drug on the growth and development of embryos were evaluated. The number of externally malformed fetuses increased in a dose-related manner, and the most common defect was micro-/anophthalmos in fetuses of dams treated with 5-FU. Growth retardation was also noted in the 5-FU treated groups. An in vitro study was performed in which drug concentrations were varied (0.15-0.30 microg/ml). Externally abnormal embryos were observed in whole embryo culture system from embryonic day 9 to 11. The most common defect was hypoplastic optic vesicles. In the whole embryo culture system, crown-rump length, somite number, protein contents, and morphological score were decreased in a dose-dependent fashion. Finally, histological evaluation and observation of the pattern of cell death of the optic vesicle of 11-day-old embryos in in vivo and in vitro were performed. These parameters revealed no differences in response between in vivo and in vitro embryos treated with 5-FU, suggesting that the whole embryo culture system was an appropriate model for developmental toxicity studies of 5-FU.

Effects of prenatal exposure to 5-bromo-2'-deoxyuridine on reproductive function in male mouse offspring.

The effect of the halogenated pyrimidine analog 5-bromo-2'-deoxyuridine (BrdU), on reproductive functions of male mouse offspring treated prenatally was studied. BrdU was administered intraperitoneally to pregnant ICR mice at 100 mg/kg/d on days 8 through 13 of gestation, and at 100 or 200 mg/kg/d on days 14 through 18 of gestation. Dams were allowed to deliver naturally. Male offspring were aged for 10 weeks and then cohabited with untreated female mice for assessment of reproductive performance. Histopathologic examination of the testes and pituitary, sperm analysis, and determination of plasma testosterone concentrations of offspring at 12 weeks of age were performed. In the subsequent study, pregnant ICR mice were treated with 200 mg BrdU/kg on day 10, 13, or 15 of gestation. The embryos or fetuses were obtained from mothers from 6 to 48 h after treatment, and pyknotic cells in the ventricular zone of the telencephalon were counted. There was a significant decrease in body weight gain of offspring in all of the BrdU-treated groups. A marked decrease in copulation rate was noted in the male offspring of dams treated on days 8 through 13 of gestation, whereas no significant decreases in copulation and fertility rates were found in the male offspring of dams treated on days 14 through 18 of gestation. Neither histopathologic examination of testes nor sperm analyses revealed adverse effects of this compound, whereas cysts in the pars distalis of the pituitary were observed in the male offspring treated on days 8 through 13 of gestation. Dilatation of the lateral ventricles was also observed in male offspring at 12 weeks of age in the group treated on days 8 through 13 of gestation. The incidence of pyknotic cells in the ventricular zone of embryos was markedly increased 24 h after treatment on day 10 of gestation. These results indicate that the impaired fertility of the male offspring of dams treated with BrdU on days 8 through 13 of gestation may be due to the effects of BrdU exposure on central nervous system function that result in loss of libido rather than to the direct effects of this compound on the male reproductive organs.