A Comparative Study of Puberty, and Plasma Gonadotropin and Testicular Hormone Levels in Two Inbred Strains of Hatano Rats.

Satô, Masako; Ohta, Ryo; Kojima, Kohichi; Shirota, Mariko; Koibuchi, Hiroshi; Asai, Sayaka; Watanabe, Gen; Taya, Kazuyoshi

doi:10.1262/jrd.48.111

Cited by 9 publications

(11 citation statements)

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“…As found in male Hatano rats (Sato et al 2002c), HAAs, which were born with a lighter weight but became heavier under biological dams, attained puberty at a younger age than LAAs. Fostering under SD dams gave an identical nursing condition to both lines of pups, and the fostered LAAs kept their body weight at a higher level than the fostered HAAs.…”

Section: Discussionsupporting

confidence: 54%

“…Since completion of ovarian maturation is essential for preovulatory gonadotropin discharge (reviewed by Ojeda & Urbanski 1994), the line difference in the timing of female puberty could be attributed to the difference in the timing of ovarian maturation. While the number of ovulable follicles, which have developed as a result of the treatment on day 22 after birth, (Sato et al 2002c). Since FSH promotes FSH receptor in the granulosa cells in vitro (Tilly et al 1992), endocrinological profiles during early life could be different between both lines of females.…”

Section: Discussionmentioning

confidence: 99%

“…Among these characteristics, the line differences in body weight at birth (Ohta et al 1998) and maternal care ) might be suitable characteristics for model animals used to study the effects of somatic growth on the timing of puberty under physiological conditions, since their postnatal growth can be modified by nursing dams (Ohta et al 1998). Furthermore, the fact that balanopreputial separation, one of the indices of male puberty, occurs at a younger age in HAAs than in LAAs (Sato et al 2002c) leads to the hypotheses that the line difference is also observed in the timing of female puberty and that somatic growth determines the timing of puberty under physiological conditions.…”

Section: Introductionmentioning

confidence: 99%

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Minor involvement of somatic growth in the onset of puberty of Hatano high- and low-avoidance rats

Shirota¹,

Satô²,

Kojima³

et al. 2004

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The present study was planned to examine the effects of somatic growth on the determination of timing of puberty using Hatano high-and low-avoidance rats (HAAs and LAAs); the rats were genetically selected from Sprague-Dawley (SD) rats for good or poor performance in a two-way active avoidance-learning test. Since these two lines were found to have different characteristics, such as body weight at birth, maternal care and timing of male puberty, the present study characterized female puberty in Hatano rats and then compared postnatal growth and timing of puberty between the two lines of rats when they were nursed by foster SD dams. When nursed under biological dams, HAAs became heavier, exhibited vaginal opening at a younger age and first ovulation was accompanied by more oocytes than LAAs. In all of the HAAs, but none of the LAAs, ovulation was induced by a single s.c. injection of 5 IU equine chorionic gonadotropin (eCG) on day 22 after birth. An additional treatment with 10 IU human CG revealed that, in the ovaries of LAAs, a small number of follicles had developed to an ovulable stage as a result of the treatment. The fostering improved somatic growth, and weights of LAAs were sustained at a heavier level than those of fostered HAAs. The fostering, however, did not eliminate the line difference in the timing of puberty of both sexes; it did accelerate the vaginal opening of LAAs but not the balanopreputial separation. Thus, there is a phenotypic difference in the timing of female puberty in Hatano rats exhibiting a different timing of ovarian development in response to gonadotropin. The present study indicates that postnatal somatic growth is not the predominant determinant in the onset of puberty in Hatano rats.

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Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Minor involvement of somatic growth in the onset of puberty of Hatano high- and low-avoidance rats

Shirota¹,

Satô²,

Kojima³

et al. 2004

Reproduction

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“…Spermatozoa are found in seminiferous tubules at the time of puberty, approximately 6 weeks of age in the rat, and it takes at least 10 or 15 days to reach the cauda epididymis (Sommer et al, 1996;Robaire et al, 2006). We have con--da epididymis at 56 days of age at the youngest in the Sprague-Dawley derived inbred rats, which attain puberty at a comparable range of ages to Sprague-Dawley rats (Sato et al, 2002). Since the compound was administered for 4 weeks in the 28-day study, from 5 weeks of age, for a short period.…”

Section: Discussionmentioning

confidence: 99%

Screening of toxicological properties of 4-methylbenzoic acid by oral administration to rats

et al. 2008

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-Oral toxicity of 4-methylbenzoic acid in male and female Sprague-Dawley rats was proreproductive/developmental toxicities (the reproduction/developmental study) conducted under Organisation for Economic Co-operation and Development (OECD) test guidelines. Daily administration of 4-methylbenzoic acid, at a dose level of 0, 100, 300 or 1,000 mg/kg, did not show any adverse effect on reproductive organs of animals in the 28-day study. In the reproductive/developmental study, however, 1,000 mg/kg/day of the compound reduced epididymal weights and increased incidence of cauda epididymal oligo/azoospermia. While the compound did not affect estrous cycle or mating performances, 1,000 mg/kg of the compound reduced fertility. Furthermore, 300 mg/kg or more of the compound increased pre-implantation loss, which resulted in a decrease in the number of offspring, and reduced body weight gain of the dams during the latter period of gestation. From these results, the no-observed-effect-level (NOEL) for reproductive/developmental toxicities is considered to be 100 mg/kg, whereas 1,000 mg/kg did not show any effect on neonates. In the 28-day study, NOEL is considered to be 300 mg/kg for male and female rats, since 1,000 mg/kg of the compound caused, in both sexes, a few minor changes, such as temporal salivation, a slight increase in food consumption and a moderate increase in blood aspartate aminotransferase (AST) activity. Thus, 4-methylbenzoic acid has the potential for reproductive toxicity, with diverse adverse effects on the epididymis, after repeated administration, observed in the two studies.Key words: 4-methylbenzoic acid, Epididymis, OECD test guideline, Reproductive toxicant, Repeated dose toxicity, RatsCorrespondence: Mariko Shirota (E-mail: shirota.m@fdsc.or.jp) Original ArticleThe Journal of Toxicological Sciences (J. Toxicol. Sci.) Vol.33, No.4, 431-445, 2008 Vol. 33 No. 4 431 MATERIALS AND METHODS Test substance4-Methylbenzoic acid (CAS No. 99-94-5, purity 98.95%) was supplied by Toray (Tokyo, Japan), and was kept at room temperature until use. To prepare dosing -pended in a 0.5% sodium carboxymethylcellulose solution, and each dose was adjusted to a constant volume of 5 ml/kg. The stability of the suspended compound in the vehicle and the content and uniformity of the compound -tute.The doses used in the studies were determined based on a preliminary, 7-day, repeated dose, oral toxicity study of the compound, in which a dose level of 1,000 mg/kg did not show any toxic effects. This was considered sufficient for the highest dose, and the doses used in the present studies were set at 0, 100, 300 and 1,000 mg/kg. AnimalsMale and female rats of the Sprague-Dawley (Crj: CD(SD)) strain were purchased from Charles River Japan (Atsugi Breeding Center, Atsugi, Kanagawa, Japan). For the 28-day study, the animals were purchased at 4 weeks of age, and after an 8-day quarantine period, the animals were divided into 4 groups of each sex according to a the day before initial dosing. For the reproduction/develo...

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“…One of the most interesting features resulting from the genetic selection of Hatano rats has been their stress response: HAA rats are generally more reactive to stress than LAA rats [15] with the notable exception of prolactin secretion [3]. In addition, compared to LAA rats, HAA rats show earlier physical, behavioral and sexual maturation [13,21,22].…”

Section: Introductionmentioning

confidence: 99%

Immunological Characteristics of Hatano High-and Low-Avoidance Rats

et al. 2006

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A Comparative Study of Puberty, and Plasma Gonadotropin and Testicular Hormone Levels in Two Inbred Strains of Hatano Rats.

Cited by 9 publications

References 31 publications

Minor involvement of somatic growth in the onset of puberty of Hatano high- and low-avoidance rats

Minor involvement of somatic growth in the onset of puberty of Hatano high- and low-avoidance rats

Screening of toxicological properties of 4-methylbenzoic acid by oral administration to rats

Immunological Characteristics of Hatano High-and Low-Avoidance Rats

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