Weight and vaginal opening in the albino rat

Edwards, Dorothy Farrar; Kay, R M

doi:10.1530/jrf.0.0730001

Cited by 3 publications

(1 citation statement)

References 9 publications

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“…In the context of evaluating potential estrogenicity in rat pubertal development, slight advancement of the time of vaginal opening, e.g. 0.5 day, is not strong evidence of potential estrogenicity, whereas a three-day advance would be (Edwards & Kay 1985). Evaluation of response magnitude requires an appreciation of the variability inherent to the parameter in control test systems or species.…”

Section: Scorementioning

confidence: 99%

Weight-of-the-evidence evaluation of 2,4-D potential for interactions with the estrogen, androgen and thyroid pathways and steroidogenesis

Neal

Marty

Coady

et al. 2017

Critical Reviews in Toxicology

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A comprehensive weight-of-the-evidence evaluation of 2,4-dichlorophenoxyacetic acid (2,4-D) was conducted for potential interactions with the estrogen, androgen and thyroid pathways and with steroidogenesis. This assessment was based on an extensive database of high quality in vitro, in vivo ecotoxicological and in vivo mammalian toxicological studies. Epidemiological studies were also considered. Toxicokinetic data provided the basis for determining rational cutoffs above which exposures were considered irrelevant to humans based on exceeding thresholds for saturation of renal clearance (TSRC); extensive human exposure and biomonitoring data support that these boundaries far exceed human exposures and provide ample margins of exposure. 2,4-D showed no evidence of interacting with the estrogen or androgen pathways. 2,4-D interacts with the thyroid axis in rats through displacement of thyroxine from plasma binding sites only at high doses exceeding the TSRC in mammals. 2,4-D effects on steroidogenesis parameters are likely related to high-dose specific systemic toxicity at doses exceeding the TSRC and are not likely to be endocrine mediated. No studies, including high quality studies in the published literature, predict significant endocrine-related toxicity or functional decrements in any species at environmentally relevant concentrations, or, in mammals, at doses below the TSRC that are relevant for human hazard and risk assessment. Overall, there is no basis for concern regarding potential interactions of 2,4-D with endocrine pathways or axes (estrogen, androgen, steroidogenesis or thyroid), and thus 2,4-D is unlikely to pose a threat from endocrine disruption to wildlife or humans under conditions of real-world exposures.ARTICLE HISTORY

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Section: Scorementioning

confidence: 99%

Weight-of-the-evidence evaluation of 2,4-D potential for interactions with the estrogen, androgen and thyroid pathways and steroidogenesis

Neal

Marty

Coady

et al. 2017

Critical Reviews in Toxicology

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Effect of Dimethoate Administration Schedules on Compensatory Ovarian Hypertrophy, Follicular Dynamics, and Estrous Cycle in Hemicastrated Mice

Mahadevaswami¹,

Kaliwal²

2002

Journal of Basic and Clinical Physiology and Pharmacology

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Dimethoate, a widely used organophosphate insecticide, was administered orally (28 mg/kg body weight) to hemicastrated (HC) virgin mice on day 1 and for 5, 10, and 15 days. Hemicastrated untreated control mice showed a significant increase in relative ovarian weight, with 42.74% hypertrophy and an increase in healthy and atretic follicles when compared with those of sham-operated control animals. The HC mice treated for 1 day or for 5 days showed no significant change in ovarian weight (36.64% and 25.19% hypertrophy, respectively) or in healthy and atretic follicles, when compared with HC-control mice. Treatment with dimethoate for 10 or 15 days, however, resulted in a significant decrease in ovarian weight (19.84% and 0.76% hypertrophy, respectively), a significant decrease in the number of healthy follicles, and a concomitant significant increase in the number of atretic follicles when compared with those in HC control animals. No significant change occurred in the number of estrous cycles or duration of each phase of the estrous cycle in HC mice treated with dimethoate for either 1 or 5 days. In HC mice treated with dimethoate for 10 or 15 days, however, a significant decrease in the number of estrous cycles, duration of proestrus, estrus, and metestrus, a concomitant significant increase in the diestrus phase, when compared with HC control animals. In mice receiving dimethoate for 15 days (but not for 1, 5, or 10 days) a significant decrease occurred in body weight and in the weights of the uterus, kidney, spleen, and liver when compared with the parallel weights in HC control animals. The overall findings suggest that following dimethoate treatment, a significant decrease in ovarian weight with a concomitant increase in compensatory ovarian hypertrophy and in the number of healthy follicles, with a concomitant increase in the number of atretic follicles and interrupted estrous cycles, may be due to the direct effect on the ovary or may be due to a hormonal imbalance in any stage of the hypothalamo-hypophysial ovarian axis.

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Effect of Edifenphos on Compensatory Ovarian Hypertrophy, Follicular Kinetics and Estrous Cycle in Hemicastrated Rats

Nanda

Kaliwal²

2003

Journal of Basic and Clinical Physiology and Pharmacology

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Edifenphos, an organophosphate fungicide, was administered to hemicastrated albino rats intraperitoneally for 15 consecutive days in graded doses of 2 to 8 mg/kg body weight. In the oil-treated hemicastrated control group, ovarian weight and total number of healthy and atretic follicles were significantly higher than the same parameters in sham-operated control animals, and the estrous cycle was normal. Treatment with 2, 4, 6, or 8 mg/kg/d edifenphos significantly decreased ovarian weight (-6.75, -9.79, -18.71, and -34.13 percent, respectively) below that of the controls. Although treatment with 2 or 4 mg/kg/d edifenphos did not change the number of healthy and atretic follicles, a dosage of 4 mg/kg/d significantly decreased the number and duration of estrous cycles. Treatment with 6 or 8 mg/kg/d, however, significantly decreased the number and duration of different phases of the estrous cycle as well. In all treated groups, the weights of the thymus and uterus were significantly reduced when compared with those of hemicastrated oil-treated control animals.

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Weight and vaginal opening in the albino rat

Abstract: Summary. The body weight of rats at spontaneous vaginal opening (Wvo) was related to the weight at weaning (Ww)

Cited by 3 publications

References 9 publications

Weight-of-the-evidence evaluation of 2,4-D potential for interactions with the estrogen, androgen and thyroid pathways and steroidogenesis

Weight-of-the-evidence evaluation of 2,4-D potential for interactions with the estrogen, androgen and thyroid pathways and steroidogenesis

Effect of Dimethoate Administration Schedules on Compensatory Ovarian Hypertrophy, Follicular Dynamics, and Estrous Cycle in Hemicastrated Mice

Effect of Edifenphos on Compensatory Ovarian Hypertrophy, Follicular Kinetics and Estrous Cycle in Hemicastrated Rats

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