Biomedical subjects

Kanji Yamasaki

Publications and source records attributed to Kanji Yamasaki.

At least 19 recordsLinked to original sources

PubMed2006

Subacute oral toxicity study of di(2-ethylhexyl)adipate based on the draft protocol for the "Enhanced OECD Test Guideline no. 407".

We performed a 28-day repeated-dose toxicity study of di(2-ethylhexyl)adipate (DEHA) based on the draft protocol of the "Enhanced OECD Test Guideline 407" to investigate whether it has endocrine-mediated properties according to this assay. DEHA was orally administered to SD rats at doses of 0, 40, 200 and 1,000 mg/kg/day for at least 28 days, and disturbance of the estrous cycle and increased ovarian follicle atresia were detected in the 1,000 mg/kg group.

Adipates↗

PubMed2005

OECD validation of the Hershberger assay in Japan: Phase 3. Blind study using coded chemicals.

The Organization for Economic Co-operation and Development (OECD) has initiated the development of new guidelines for the screening and testing of potential endocrine disrupters. The Hershberger assay is one of the assays selected for validation based on the need for in vivo screening to detect androgen agonists or antagonists by measuring the response of five sex accessory organs and tissues of castrated juvenile male rats: the ventral prostate, the seminal vesicles with coagulating glands, the levator ani and bulbocavernosus muscle complex (LABC), Cowper's glands, and the glans penis. The Phase 1 feasibility demonstration stage of the Hershberger validation program has been successfully completed with a single androgen agonist and a single antagonist as reference substances. The Phase 2 validation study was performed, employing a range of additional androgen agonists and antagonists. Recently, the Phase 3 validation study was conducted and performed in several International laboratories. Three Japanese laboratories have contributed to the blind study using coded materials of Phase 3 validation. Four coded test substances in the agonistic version and seven substances in the antagonistic version were orally administered by gavage for 10 consecutive days, respectively. In the antagonist version of the assay, 0.2mg/kg/day of testosterone propionate (TP) was coadministered by subcutaneous injection. All five accessory sex reproductive organs and tissues consistently responded with statistically significant changes in weight within a narrow window in both versions. Therefore, the Japanese studies support the Hershberger assay as a reliable and reproducible screening assay for the detection of androgen agonistic and antagonistic effects.

Androgen Antagonists↗

PubMed2005

Subacute oral toxicity study of diethylphthalate based on the draft protocol for "Enhanced OECD Test Guideline no. 407".

We performed a 28-day repeated-dose toxicity study of diethylphthalate based on the draft protocol of the "Enhanced OECD Test Guideline 407" to investigate whether it has endocrine-mediated properties according to this assay. Diethylphthalate was orally administered to SD rats at doses of 0, 40, 200, and 1,000 mg/kg/day for at least 28 days, but no endocrine-mediated effects were detected based on any of the parameters examined, suggesting that diethylphthalate does not possess endocrine properties according to this assay.

Administration, Oral↗

PubMed2005

Ability of the Hershberger assay protocol to detect thyroid function modulators.

In vivo screening methods for detection of thyroid function modulators are now under development in many research laboratories. We assessed the applicability of the Hershberger assay protocol to screen for thyroid function modulators. In experiment 1, castrated male BrlHan WIST@Jcl (GALAS) rats were administered a potent thyroid peroxidase inhibitor, 3-amino-1,2,4-triazole (AT), in doses of 0, 40, 200, and 1,000 mg/kg/day with gravimetric endpoint, and in experiment 2, castrated and intact male rats were administered in doses of 0, 40, and 200 mg/kg/day, with quantification of the extent of hypertrophy of the thyroid epithelium, to assess the effects of castration, by gavage to 8-week-old for 10 consecutive days. At necropsy of both experiments, the thyroid glands and hypophysis were collected and fixed with 10% neutral-buffered formalin. To avoid crushing during weighing because of their fragility, the thyroid glands and hypophysis were weighed approximately 24 h after fixation with 10% neutral-buffered formalin. All animals were sacrificed approximately 24 h after the final dose. In experiment 2, the thyroid glands of all animals were stained with hematoxylin and eosin for histological examination and morphometry of follicular epithelial height. In experiment 1, absolute and relative thyroid weights in all of the AT groups were statistically increased in a dose-dependent manner, regardless of the testosterone propionate (TP)-injection. In experiment 2, the results showed a significant increase in thyroid weight in the 200 mg/kg groups of both castrated and intact rats. Hypophyseal weight was unaltered by AT, but comparison of vehicle-treated groups showed that the hypophyseal weight of the castrated rats was greater than that of the intact rats. Enlarged thyroid glands were observed in the AT-treated rats at necropsy. Histological examination of the thyroid glands of all the AT-treated animals showed hypertrophy and hyperplasia of the follicular epithelial cells, and the height of follicular epithelium of the thyroid glands increased in a dose-dependent manner in both the castrated and intact rats. In experiment 1, assessment of the (anti-) androgenic action of AT in seminal vesicle weight revealed a significant increase in the 200 and 1,000 mg/kg + TP groups in a dose-dependent manner. These results suggest that the effect of AT can be detected by the Hershberger assay 10-day administration protocol and may be useful for screening for thyroid function modulators regardless of whether the animals have been castrated.

Amitrole↗

PubMed2005

Preliminary evaluation of an in utero-lactation assay using 6-n-propyl-2-thiouracil.

In this preliminary study, the potential of an in utero-lactation assay to detect thyroid effectors was evaluated by treating three dams/group with 6-n-propyl-2-thiouracil (PTU), a known thyroid antagonist, by oral gavage at doses of 0, 0.0032, 0.016, 0.08 and 0.4 mg/kg/day during fetal organogenesis and lactation. Hearing disturbances and an elevated relative thyroid weight were observed in offspring of both sexes in the 0.4 mg/kg/day group. The Biel-type water T-maze test showed an increase in the number of errors made by females in the 0.4 mg/kg/day group. Histopathologically, flattening of follicular epithelium, a decrease in resorptive colloid droplets, degeneration of follicular epithelium, and hyperplasia of follicular epithelium were observed in males belonging to the 0.4 mg/kg/day group. Histopathological abnormalities were also observed in some offspring belonging to the 0.08 mg/kg/day group. In the dams, hypertrophy of the follicular epithelium of the thyroid was observed in the 0.4 mg/kg/day group. Although we could not explain the mechanism for the difference in the effects seen in the offspring and the dams, the effect of PTU in utero through lactational exposure is apparently different from that resulting from exposure in homeostatically mature rats. Most reports studying PTU have involved administration in water or in food, and reports on the oral gavage of PTU during the fetal organogenesis and lactation period are very rare. This assumes that dosages >0.4 mg/kg/day would also produce clear anti-thyroid effects by oral gavage and, possibly, emphasizes that dosages <0.4 mg/kg/day did not have a noticeable effect. Based on the present results, a study to determine the reproducibility of the data in a much larger number of dams will be performed to confirm the findings in the present study, and to evaluate other endpoints, such as hormonal evaluation of dams and their offspring, sexual developmental landmarks, and fertility of the offspring.

Animals↗

PubMed2005

Effects of in utero and lactational exposure to flutamide in SD rats: comparison of the effects of administration periods.

Pregnant CD(SD) IGS rats were given flutamide (FLUT) orally at doses of 0.4, 2, or 10 mg/kg/day from gestational day 6 to postnatal day (PND) 20, and the effects of FLUT exposure on male offspring were examined 10 weeks after birth, and compared to the effects in offspring treated after weaning and in offspring untreated after weaning. Although the body weight of the dams treated with FLUT remained normal, two dams in the 10 mg/kg/day group were killed because of abnormal parturition periods and loss of all the pups. The number of stillborns and dead newborns at birth was significantly higher in the 10 mg/kg/day group than in the control groups. No abnormalities in the reproductive parameters of the other dams treated with FLUT were detected. The body weights of the male offspring in each group remained normal from birth until the end of the study. The ano-genital distance was significantly shortened in 2 and 10 mg/kg/day groups. Changes in the organ weights and gross findings were detected in the 2 and/or 10 mg/kg/day groups with or without the continuous administration of FLUT after weaning; these changes were more appreciable in groups treated with FLUT after weaning than in groups untreated after weaning. The prolongation of preputial separation was observed in the 0.4 and 2 mg/kg/day groups treated with FLUT after weaning, but this change was not detected in the same dose groups untreated after weaning. The testosterone levels were higher in the 10 mg/kg/day group treated with FLUT after weaning. The present data demonstrated that the endocrine-mediated effects on rats were more appreciable in offspring treated with FLUT after weaning than in offspring untreated after weaning.

Abnormalities, Drug-Induced↗

PubMed2005

Effects of in utero and lactational exposure to tamoxifen in SD rats.

Pregnant CD (SD) IGS rats were given tamoxifen (TMX) orally at doses of 0.12, 0.6, or 3 microg/kg/day from gestational day 6 to postnatal day 21, and the effects of TMX exposure on all offspring were examined 10 weeks after birth; the reproductive performance of the offspring was also evaluated. Although the body weights of the dams treated with TMX remained normal from gestational day 6 until the day of autopsy (postnatal day 21), three dams in the 3 microg/kg/day group died during the pregnancy or partum periods. These deaths were regarded as the toxicological effects of TMX. No changes were detected in the reproductive parameters of all the TMX groups except for a decrease in the number of newborns/live newborns in the 3 microg/kg/day group. No abnormal clinical signs, body weight change, ano-genital distance, vaginal opening, or organ weight changes were detected in any of TMX groups, but the day of preputial separation was prolonged in the male offspring of all TMX groups and cleft phallus was detected in the female offspring of the 0.6 and 3 microg/kg/day groups. No abnormalities were detected in the reproductive performance of the male and female offspring.

Administration, Oral↗

PubMed2005

Two-generation reproductive toxicity studies in rats with extra parameters for detecting endocrine disrupting activity: introductory overview of results for nine chemicals.

Two-generation reproductive toxicity studies using rats of benzophenone, n-butylbenzene, butyl benzyl phthalate, 2,4-dichlorophenol, dicychlohexyl phthalate, diethyl phthalate, 4-nitrotoluene, lindane and vinclozolin, were performed to investigate whether these chemicals have endocrine-mediated effects with the support of the Ministry of Economy, Trade and Industry and the Ministry of the Environment. Benzophenone exposure was via the diet at concentrations of 0, 100, 450 or 2000 ppm, n-butylbenzene was administered orally by gavage at dose levels of 0, 30, 100 or 300 mg/kg/day, butyl benzyl phthalate was administered orally by gavage at dose levels of 0, 100, 200, or 400 mg/kg/day, 2,4-dichlorophenol was administered in the diet at concentrations of 0, 500, 2000 or 8000 ppm, dicyclohexyl phthalate was given in the diet at concentrations of 0, 240, 1200 or 6000 ppm, diethyl phthalate was administered in the diet at concentrations of 0, 600, 3000 or 15000 ppm, 4-nitrotoluene was administered orally by gavage at doses of 0, 40, 80, or 160 mg/kg/day, lindane exposure was in the diet at concentrations of 0, 10, 60, or 300 ppm, and vinclozolin treatment was by feeding diet at concentrations of 0, 40, 200 or 1000 ppm.

Administration, Oral↗

PubMed2004

Comparison of the Hershberger assay and androgen receptor binding assay of twelve chemicals.

We performed the Hershberger assay of 12 chemicals based on the OECD draft protocol. The chemicals tested by the Hershberger assay were phthalic acid di-n-hexyl ester, phthalic acid di-n-amyl ester, phthalic acid di-n-propyl ester, diethylstilbestrol, 17beta-estradiol, tamoxifen, 5alpha-dihydrotestosterone, dichlorodiphenyldichloroethane, cyproterone acetate, 6alpha-methyl-17alpha-hydroxy-progesterone, atrazine, and spironolactone. Phthalic acid di-n-hexyl ester, phthalic acid di-n-amyl ester, and phthalic acid di-n-propyl ester are phthalates; diethylstilbestrol and 17beta-estradiol are estrogenic chemicals; tamoxifen is partial estrogen receptor antagonist with mainly estrogenic properties; 5alpha-dihydrotestosterone is an androgen derivatives; dichlorodiphenyldichloroethane is a reference androgen antagonistic chemical; cyproterone acetate, 6alpha-methyl-17alpha-hydroxy-progesterone, and spironolactone have an androgenic steroid structure and are known as androgen antagonistic chemicals; and atrazine is a reference endocrine disruptor. We also subjected these chemicals to the receptor binding assay for androgen. A clear androgen agonistic effect was detected in 5alpha-dihydrotestosterone, and an androgen antagonistic effect was observed in five chemicals: cyproterone acetate, spironolactone, 6alpha-methyl-17alpha-hydroxy-progesterone, phthalic acid di-n-amyl ester, and dichlorodiphenyldichloroethane. By contrast, diethylstilbestrol, 17beta-estradiol, tamoxifen, 5alpha-dihydrotestosterone, dichlorodiphenyldichloroethane, cyproterone acetate, 6alpha-methyl-17alpha-hydroxy-progesterone, and spironolactone were positive in the receptor binding assay for androgen. Three estrogenic chemicals, diethylstilbestrol, 17beta-estradiol, and tamoxifen, were negative in the Hershberger assay with receptor binding affinity. On the other hand, the Hershberger assays of three phthalates were performed at the same dosages, and the results showed androgen antagonistic affinity only in the assay of phthalic acid di-n-amyl ester without receptor binding affinity.

Administration, Oral↗

PubMed2004

Comparative study of the uterotrophic potency of 14 chemicals in a uterotrophic assay and their receptor-binding affinity.

We performed an immature rat uterotrophic assay of 14 chemicals having various receptor-binding affinities in order to assess the relationship between their uterotrophic potency and receptor-binding affinity. The chemicals tested were phthalic acid di-n-hexyl ester, phthalic acid di-n-amyl ester, phthalic acid di-n-propyl ester, 2-ethylhexyl-p-hydroxybenzoate, 4,4'-biphenol, 4,4'-sulfonyldiphenol, 4,4'-dihydroxydiphenylmethane, 2,4-dihydroxybenzophenone, 4,4'-cyclohexylidenebisphenol, 4-t-butylpyrocatechol, clomiphene citrate, 4,4'-(1,3-phenylenediisopropylidene)bisphenol, p-t-butylphenol, and diallylterephthlate. Two of the 14 chemicals, phthalic acid di-n-propyl ester and diallylterephthlate, exhibited no receptor-binding affinity, and the receptor-binding affinity of phthalic acid di-n-hexyl ester and phthalic acid di-n-amyl ester was lower than that of the other chemicals. Ten of the chemicals showed uterotrophic potency, the exceptions being phthalic acid di-n-propyl ester, diallylterephthlate, phthalic acid di-n-hexyl ester, and phthalic acid di-n-amyl ester. The results of the present study demonstrate that the affinity of the chemicals in the receptor-binding assay correlated well with their potency in the uterotrophic assay except for a few chemicals with very low receptor-binding affinity.

Animals↗

PubMed2004

Differences in responsiveness of mouse strain against p-benzoquinone as assessed by non-radioisotopic murine local lymph node assay.

The non-radioisotopic modification of murine local lymph node assay (LLNA) by using 5-bromo-2'-deoxyuridine (BrdU) was conducted to investigate the strain-related difference of the responsiveness of mice to p-benzoquinone (PBQ) with BALB/cAnN, CBA/JN and CD-1 mouse strains. Strain and dose related differences were analyzed by two-way analysis of variance (two-way ANOVA). CBA/JN was considered to be the highest responsive strain to PBQ, and interaction was detected between CD-1 and each of the other inbred strains. These results support the recommendation in the OECD test guideline 429 and the skin sensitization test guideline of US-EPA with regard to the selection of mouse strain for LLNA.

Analysis of Variance↗

PubMed2003

Assessment of statistic analysis in non-radioisotopic local lymph node assay (non-RI-LLNA) with alpha-hexylcinnamic aldehyde as an example.

The murine local lymph node assay (LLNA) is used for the identification of chemicals that have the potential to cause skin sensitization. However, it requires specific facility and handling procedures to accommodate a radioisotopic (RI) endpoint. We have developed non-radioisotopic (non-RI) endpoint of LLNA based on BrdU incorporation to avoid a use of RI. Although this alternative method appears viable in principle, it is somewhat less sensitive than the standard assay. In this study, we report investigations to determine the use of statistical analysis to improve the sensitivity of a non-RI LLNA procedure with alpha-hexylcinnamic aldehyde (HCA) in two separate experiments. Consequently, the alternative non-RI method required HCA concentrations of greater than 25% to elicit a positive response based on the criterion for classification as a skin sensitizer in the standard LLNA. Nevertheless, dose responses to HCA in the alternative method were consistent in both experiments and we examined whether the use of an endpoint based upon the statistical significance of induced changes in LNC turnover, rather than an SI of 3 or greater, might provide for additional sensitivity. The results reported here demonstrate that with HCA at least significant responses were, in each of two experiments, recorded following exposure of mice to 25% of HCA. These data suggest that this approach may be more satisfactory-at least when BrdU incorporation is measured. However, this modification of the LLNA is rather less sensitive than the standard method if employing statistical endpoint. Taken together the data reported here suggest that a modified LLNA in which BrdU is used in place of radioisotope incorporation shows some promise, but that in its present form, even with the use of a statistical endpoint, lacks some of the sensitivity of the standard method. The challenge is to develop strategies for further refinement of this approach.

Acrolein↗

PubMed2003

In utero through lactational exposure to ethinyl estradiol induces cleft phallus and delayed ovarian dysfunction in the offspring.

Most of the attention currently focused on endocrine-active chemicals is directed to their effects on the development of offspring exposed to them in utero or during the neonatal period. Pregnant Crj:CD(SD)IGS rats were given ethinyl estradiol (EE) orally in doses of 0.5-50 microg/kg/day from gestational day 7 to postnatal day 18, and their offspring were examined for its effects. Our previous study according to a similar protocol demonstrated the occurrence of cleft phallus in the female offspring exposed to 50 microg/kg of EE in utero and during the lactation period. The present study was designed to assess (1) the reproducibility of the induction of cleft phallus, (2) the fertility of female rats with cleft phallus, and (3) whether any delayed effects, possibly delayed anovulation, were induced. At 50 microg/kg cleft phallus was observed in almost all of the female offspring, and slight retardation of body weight gain was detected in both sexes. At 15-17 weeks of age the animals with cleft phallus could copulate and had fertility comparable to the control group. At 6 months of age, on the other hand, 6/8 of the female offspring at 50 microg/kg exhibited abnormal cyclicity, including persistent estrus, and histological examination revealed follicular cysts and absence of corpora lutea in the ovaries of the rats with persistent estrus. These findings are consistent with delayed anovulation syndrome. The results suggest that observation of cyclicity at 6 months old is able to detect possible delayed ovarian dysfunction induced by perinatal exposure to chemicals.

Abnormalities, Drug-Induced↗

PubMed2003

Comparison of the reporter gene assay for ER-alpha antagonists with the immature rat uterotrophic assay of 10 chemicals.

We performed a reporter gene assay for estrogen receptor (ER)-alpha agonists and antagonists of 10 chemicals that showed both estrogen agonistic and reduced the estrogenic effect of ethinyl estradiol in a rat uterotrophic assay. The chemicals tested by the immature uterotrophic assay were p-(tert-pentyl)phenol, 4,4'-thiobis-phenol, 4,4'-(hexafluoroisopropylidene)diphenol, 2,2-bis(4-hydroxyphenyl)-4-methyl-n-pentane, 4,4'-(octahydro-4,7-methano-5H-inden-5-ylidene)bisphenol, 4-(phenylmethyl)phenol, 4,4'-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-hydroxybenzophenone and 2,4,4'-trihydroxybenzophenone. Although all chemicals examined in this study were positive in the reporter gene assay for ER-alpha agonists, 4,4'-(octahydro-4,7-methano-5H-inden-5-ylidene)bisphenol was only positive in the reporter gene assay for ER-alpha antagonists. These findings demonstrate that results of the reporter gene assay for ER-alpha agonists correlated well with those of the uterotrophic assay, but antagonistic change of 9 of 10 chemicals in the uterotrophic assay was not detected by the reporter gene assay for ER-alpha antagonists.

Animals↗

PubMed2003

Development of a high-performance reporter plasmid for detection of chemicals with androgenic activity.

A number of chemicals are present in the environment, and some synthetic chemicals may disrupt endocrine function of wild animals and humans. An effective procedure to screen chemicals for endocrine modulating activity has been needed to ensure the safety of chemicals, and the reporter gene assay technique may provide a powerful tool for screening endocrine-disrupting chemicals. We have developed a high-performance reporter plasmid that can trigger high androgen-dependent induction with high selectivity by using mouse mammary tumor virus (MMTV) androgen-responsive elements and a partial fragment of the rat alpha(2u)-globulin promoter region. This new type plasmid can induce higher transcriptional activation than a commercial PGV-P-based construct bearing the SV40 promoter fragment, and the basal induction level of this plasmid is much lower than that of the PGV-P-based construct. Moreover, only androgen derivatives could selectively induce a high response in the reporter gene assay with the new reporter plasmid. This new type of reporter plasmid, ARE-AUG- Luc+, should be of value in endocrine research and in screening to identify endocrine-modulating chemicals.

Alpha-Globulins↗

PubMed2003

Immature rat uterotrophic assay of 18 chemicals and Hershberger assay of 30 chemicals.

We performed an immature rat uterotrophic assay of 18 chemicals and Hershberger assay of 30 chemicals to assess the relationship between the results of two assays. The chemicals tested by the uterotopic assay were 4-n-amylphenol, p-dodecyl-phenol, p-(tert-pentyl)phenol, 4-cyclohexylphenol, 4-(1-adamantyl)phenol, 4,4'-thiobis-phenol, diphenyl-p-phenylenediamine, 4-hydroxyazobenzene, 4-(phenylmethyl)phenol, 4,4'-(hexafluoroisopropylidene)diphenol, 2,2-bis(4-hydroxyphenyl)-4-methyl-n-pentane, 4,4'-(octahydro-4,7-methano-5H-inden-5-ylidene)bisphenol, 4,4'-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-hydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, testosterone enanthate, and methyltestosterone. The chemicals tested by the Hershberger assay were the 18 chemicals tested in the uterotrophic assay plus the following: 17 alpha estradiol, estrone, equilin, norethindrone, norgestrel, ethynyl estradiol, bisphenol A, bisphenol B, bisphenol F, 4-tert-octylphenol, p-cumyl phenol, and nonylphenol. All chemicals examined in this study were positive in a reporter gene assay for ER-alpha. In the immature rat uterotrophic assay, all chemicals induced uterotrophy and p-(tert-pentyl)phenol, 4,4'-thiobis-phenol, 4-(phenylmethyl)phenol, 4,4'-(hexafluoroisopropylidene)diphenol, 2,2-bis(4-hydroxyphenyl)-4-methyl-n-pentane, 4,4'-(octahydro-4,7-methano-5H-inden-5-ylidene)bisphenol, 4,4'-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-hydroxybenzophenone, and 2,4,4'-trihydroxybenzophenone exerted both estrogen agonistic effect and reduced the estrogenic effect of ethynylestradiol. In the Hershberger assay, a clear androgen agonistic effect was detected in the androgen derivatives testosterone enanthate and methyltestosterone.

Androgen Antagonists↗

PubMed2003

OECD validation of the Hershberger assay in Japan: phase 2 dose response of methyltestosterone, vinclozolin, and p,p'-DDE.

The Organisation for Economic Co-operation and Development has initiated the development of new guidelines for the screening and testing of potential endocrine disruptors. The Hershberger assay is one of the assays selected for validation based on the need for in vivo screening to detect androgen agonists or antagonists by measuring the response of five sex accessory organs and tissues of castrated juvenile male rats: the ventral prostate, the seminal vesicles with coagulating glands, the levator ani and bulbocavernosus muscle complex, the Cowper's glands, and the glans penis. The phase 1 feasibility demonstration stage of the Hershberger validation program has been successfully completed with a single androgen agonist and a single antagonist as reference substances. The phase 2 validation program employs a range of additional androgen agonists and antagonists as well as 5alpha-reductase inhibitors. Seven Japanese laboratories have contributed phase 2 validation studies of the Hershberger assay using methyltestosterone, vinclozolin, and 2,2-bis (4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE). The methyltestosterone doses were 0, 0.05, 0.5, 5, and 50 mg/kg/day, and the vinclozolin and p,p'-DDE doses were 0, 3, 10, 30, and 100 mg/kg/day. All chemicals were orally administered by gavage for 10 consecutive days. In the antagonist version of the assay using vinclozolin and p,p'-DDE, 0.2 mg/kg/day of testosterone propionate was coadministered by subcutaneous injection. All five accessory sex preproductive organs and tissues consistently responded with statistically significant changes in weight within a narrow window. Therefore, the Japanese studies support the Hershberger assay as a reliable and reproducible screening assay for the detection of androgen agonistic and antagonistic effects.

Androgen Antagonists↗

PubMed2002

Immature uterotrophic assay of estrogenic compounds in rats given diets of different phytoestrogen content and the ovarian changes with ICI 182,780 or antide.

To investigate the influence of phyotestrogens in the diet, an immature uterotrophic assay of ethinylestradiol, bisphenol A, 4-nonylphenol or genistein was performed in rats given the formula MF diet, modified NIH-07 open formula diet, or modified NIH-07 phytoestrogen-lowered-diet (study 1). The chemicals were administered subcutaneously from 20 days of age for 3 days. Doses of ethinylestradiol, bisphenol A, 4-nonylphenol or genistein were 0.06-0.6 micro g/kg per day, 1-10 mg/kg per day, 10-100 mg/kg per day or 1-20 mg/kg per day, respectively. In another study, an immature uterotrophic assay of genistein and ethinylestradiol together with ICI 182,780 or antide was performed to compare the ovarian changes with these chemicals (study 2). Doses of genistein or ethinylestradiol were 30 mg/kg per day or 0.6 micro g/kg per day, respectively, and these chemicals were injected subcutaneously from 20 days of age for 3 days. In study 1, there were no essential differences in the uterus weights among the various phytoestrogen-content diets. In study 2, the ovary weights in rats given genistein were significantly higher than in the controls, whereas the ovary weights in rats given ethinylestradiol were lower than in the controls. The ovary weights in the ICI 182,780 plus genistein group were significantly higher than in the genistein group, but decrease of the ovary weights was detected in the antide plus genistein group. There was no significant difference in ovary weights between the ICI 182,780 plus ethinylestradiol group and the ethinylestradiol group, but decrease of ovary weights was detected in antide plus ethinylestradiol group. In a histological examination of the ovary, fluid-filled follicles in the genistein group were more numerous than in other groups and increase of granulosa cell fragmentation was seen in the ethinylestradiol and other groups with the exception of the genistein group. The present findings demonstrate that the sensitivity of the immature rat uterotrophic assay is not influenced by the relatively low level of phytoestrogen in diets and that the ovarian changes occurring with genistein and ethinylestradiol are different.

Animals↗