• Korean Journal of Veterinary Research
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• v.34 no.4
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• pp.745-757
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• 1994

Superovulatory treatment with exogenous gonadotropins adversely affects the uterus through the disruption of the delicate balance of ovarian steroids (estrogens, progestins, androgens). To examine the uterine effects of this treatment, 189 rats were given 4IU, 20IU or 40IU pregnant mare',s serum gonadotropin(PMSG) at 28 days of age and sacrificed every 24h until day 10(D10) post injection. Long term uterine effects were examined in 12 rats treated with 4IU or 40IU PMSG and killed on D30. Adult rat uteri were examined to provide a reference for comparisons. Morphological and histological changes of control (4IU) uteri mimicked those of the adult on a comparable time-course form D2 to D5. Administration of superovulatory doses(20IU, 40IU) of PMSG produced stromal hypertrophy by D2 and focal papillary hyperplasia of the luminal epithelia by D3. Levels of $17{\beta}$-estradiol following 20IU and 40IU PMSG treatment were significantly(p<0.05, p<0.005) elevated above those of controls after D1. Androgen levels of both groups(20IU, 40IU) significantly p<0.05, p<005 increased from baseline on D1 and were maximum between D2 and D3. In the 20IU PMSG group, the hyperplasia gradually regressed after D3 and was absent by D10. The hyperplasia in the 40IU PMSG group, however, had become extensive by D6. It is suspected that preceding elevated levels of estrogen may be responsible for this progressive change. On D 4, the levels of $17{\beta}$-estradiol reached a maximum, which was significantly(p<0.001) greater than both the controls and 20IU PMSG-treated rats. Between D6 and D10, the hyperplasia in 40IU PMSG-treated rats partially regressed. Examination of uteri from D30 revealed no evidence of the hyperplasia. It is suggested that previous exposure to high levels of estrogen and androgens, secondary to superovulation, is possible cause for the observed hyperplasia.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.255-264
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• 1997

The purpose of this study was attempted to investigate the number changes of the growing and mature follicles in ovary following repeats of pregnant mare serum gonadotropin(PMSG) treatments for superovulation in nulliparous rats. Thirty two rats(Sprague-Dawely, about 200~250 gm) were randomized into 4 groups. Control group rats were sacrified at estrus phase confirmed by vaginal smear. PMSG-treated group 1 rats, PMSG-treated group 2 rats and PMSG-treated group 3 rats were sacrified at 48 hrs after injection once with PMSG 25 IU, after 2 repeated injection by a week interval, and 3 repeated injection, respectively. The uteri and ovaries of rats were removed and weighed and then were observed grossly and serial sections of all ovaries and some sections of uteri by paraffin embedding were stained with H-E. Number of ovarian follicles about 3 grades of small, middle and large follicles from seondary and follicles were investigated by LM photographies of ovary preparations. The criteria of the small, middle, and large follicles were based as small follicle with preantral follicles with 2~4 layers of granulosa cells surrounding the oocyte, as secondary follicles with more than 5 layers of granulosa cells and early signs of antral cavity or with small clefts on either side of the oocytes, and as tirtiary follicles with a single medium sized antral cavity or large well-formed antral cavity, respectively. In gross findings, the wall of the uteri in control group were thin, and those in 3 PMS-treated group were markedly thickened and some uterine lumen of those filled with fluid. In histological findings, the walls of the uteri from 3 PMSG-treated groups were hypertrophied and their blood and lymph vessels were dilated than those of control group. The ovaries fo 3 PMSG-treated groups were more increased in size and the cortexes were more developed and increased in width but there are no difference of development and changes in 3 PMSG-treated groups. The weight of the uteri and ovaries per rat in PMSG -treated group 1, 2 and 3 were a, pp.ared to be significantly increased 171.4$\pm$47.6%, 162.3$\pm$43.9%, 206.9$\pm$30.4%, respectively than those of control groups. The mean number of follicle per ovary in control group were a, pp.ared to be 17.1$\pm$3.5, 46.2$\pm$14.5, and 74.3$\pm$22.7 at large, middle and small follicles, respectively and total number of these 3 grade follicles per ovary were a, pp.ared to be 137.7$\pm$31.7. The mean number of follicle per ovary in PMSG-treated group 1 were a, pp.ared to be 25.6$\pm$7.3, 78.1$\pm$29.9, and 83.2$\pm$34.0, at large, middle and small follicles, respectively and total number of these 3 grade follicles were a, pp.ared to be 187.5$\pm$58.8. The mean number of follicle per ovary in PMS-treated group 2 were a, pp.ared to be 21.9$\pm$5.2, 67.8$\pm$16.8, and 68.0$\pm$14.9 at large, middle and small follicles, respectively and total number of these 3 grade follicles were a, pp.ared to be 157.7$\pm$26.2. The mean number of follicle per ovary in PMS-treated group 3 were a, pp.ared to be 21.7$\pm$4.8, 61.5$\pm$17.0, and 59.7$\pm$16.2 at large, middle and small follicles, respectively and total number of these 3 grade follicles were a, pp.ared to be 143.5$\pm$29.6. The number of follicles in PMSG-treated group 1 a, pp.ared to be more number than other 2 PMSG-treated gruops and tended to be decreased by frequency of PMSG-treatment.

• Korean Journal of Veterinary Research
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• v.32 no.1
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• pp.15-24
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• 1992

The effects of CC the ovulatory response, oocyte normality, ovarian steroidogenesis and subsequent embryo developmental potential were examined in PMSG-treated rats. On Days of 25~27 of age, immature female Sprague Dawley rats were treated with three different doses(0.05, 0.1 or 1.0mg /day) of clomiphene citrate or vehicle. The females subsequently received 4IU PMSG on Day 28 and/or 10IU hCG on Day 30, and were killed on Day 31. Some females given 0.1mg CC or vehicle with 4IU PMSG were then mated and killed on Days 2, 3, 4 and 5 of pregnancy. Compared to vehicle(control) group, by increasing the doses of CC, there were a significant decrease in the ovulatory response as judged by both the proportion of rats ovulating and the mean number of oocytes per rat and a marked reduction of ovarian weight. The increasing doses of CC substantially promoted the degeneration(%) of oocytes ovulating in a dose-dependent manner. The CC-mediated inhibitions of the ovulatory response and ovarian weight were oompletely overcome by a subsequent treatment of hCG. Increasing doses of CC resulted in a siginificant elevation of serum estradiol with the decreased levels of progesterone and androgens. The additive treatment with hCG was effective to reduce the elevation of estradiol and to increase the reduction of progesterone produced by high dose(1.0mg) of CC. The preimplantation embryos recovered from 0.1mg CC-treated pregnant rats demonstrated a progressive early loss from Day 3 of pregnancy with a significant increase in the percentage of degeneration during all periods examined, compared to controls. The rate of progressive embryo cleavage in the CC-treated rats were slower than that in controls from Day 3 of pregnancy. Additionally, the percentage of the cleaved embryos recovered from the CC-treated rats remained significantly lower consistently from Day 2 of pregnancy, compared to control regimen. These results demonstrate a possible mechanism of CC-mediated inhibition of ovulatory response in the rats which may include the attenuation or blockade of the endogenous secretion of gonadotropins and also suggest that its detrimental effects observed on oocyte normality and embryonic development may be caused by abnormal follicular steroidogenesis( especially elevated estradiol) preceding fertilization.

• Korean Journal of Veterinary Research
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• v.34 no.4
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• pp.735-744
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• 1994

Catheters were placed into the external jugular veins of immature female rats. On the following day (day 28 of age), the animals were injected subcutaneously with pregnant mare serm gonadotropin(PMSG): 4IU(control) or 20IU(superovulation). Each animal was sequentially bled at Ohr and 12hr and subsequently at 6hr intervals until sacrifice at 72hr after PMSG. The superovulatory dose of PMSG significantly(P<0.05) increased the ovulatory response by 4.0 fold above controls. On the other hand, superovulated oocytes displayed considerably different stages of meiotic maturation: prophase I (14.7%), anaphase I (36.2%), telophase I (10.3%), metaphase I/II (32.4%), while in control rats a majority of the oocytes examined(94.0%) consistently showed a metaphase II configuration. Serum luteinizing hormone(LH) levels were determined by RIA. Both groups exhibited a similar time relationship with two distinct peaks: an initial slight rise at 0-18hr and a second sharp rise at 54-60hr. However, there was a marked change in the magnitude of LH levels between the two groups. In superovulated animals, prior to the second peak, overall LH levels were significantly(P<0.001) higher than controls. In contrast, at the peak occurring at 60hr, LH concentrations were significantly(P<0.001) reduced by 54% below that of control. Additionally, a maximum increase of mean ${\Delta}LH$ between two peaks was much less in superovulated as compared to control rats. The initial prolonged elevation of serum LH before 54hr in superovulated rats was found to result from actual cross-reaction of the injected PMSG with LH antibody in the assay, while a precipitous second elevation between 54hr and 60hr resulted primarily from an endogenous LH surge. This study clearly defines time-course features of serum LH in PMSG-treated rats. The overall results indicate that, following superovulatory treatment with PMSG, the increased ovulatory response is primarily associated with PMSG-derived intrinsic gonadotropin, and that the recovery of immature or asynchronously mature oocytes at ovulation may reult from the circulatory alteration of LH activity characterized by an initial prolonged elevation of serum LH and its subsequent attenuation.

• Korean Journal of Animal Reproduction
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• v.20 no.4
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• pp.379-384
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• 1997

Superovulation with exogenous gonadotropins creates a spectrum of pre or periovulatory hormonal changes with subsequent detrimental effects on oocyte quality, fertilization, embryo development, implantation and maintenance of pregnancy. Our recent study determined potential roles for insulin-like growth factor-1 (IGF-1) in uterine environment regulation and preimplant tation in the rat. The evidence indicates that IGF-l may play an important role in the main tenance of a receptive uterine environment for embryonic development and the regulation of decidualization. Embryonic loss and failure of implantations following superovulation may be partially attributed to disturbances in uterine IGF-l action as observed in this study. We investigated the effects of superovulatory doses of gonadotropins on frequency of chromosomal a abnormalities of mouse embryos. Chromosome a analysis of mouse zygotes and 8- to 16-cell stage embryos from spontaneously ovulated, 5, 10, and l 15 lU pregnant mare serum gonadotropin (PMSG) superovulated mice was carried out. Aneuploidy, polyploidy and structural chrom- osomal abnormalities were detected among the four groups. However, only polyploidy was correlated with superovulation. In 10 and 15 IV PMSG treated groups, the rate of polypoidy was 2.9% and 10.5%, respectively. Furthermore, there was a dose reponse relationship between the PMSG dose and the incidence of embryonic p polyploidy (P

• Nutritional Sciences
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• v.4 no.1
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• pp.3-12
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• 2001

Long chain polyunsaturated fatty acids (LCPUFA) are important components of brain phospholipds and play important role (s) in brain function. In rats, the maximum brain growth occurs during the period of lactation even though it happens during the third trimester of gestation in human. Since milk contained docosahexaenoic acid (DHA) even through the maternal diet had no DHA and/or a very small amount of its precursor, $\alpha$-linolenic acid ($\alpha$-LnA), an emphasis was given to maternal adipose tissue as a reservoir of this fatty acid. We, therefore, investigated the mesenteric and subcutaneous adipose tissues for their fatty acid composition in dams reared with different fat diets. Diets containing various amounts of $\omega$6 and $\omega$3 fatty acids were given to adult female rats (200-250g) throughout the pregnancy and lactation periods. Diets were composed of 10% (wt/wt) corn oil (CO), soybean oil (SO), perilla seed oil (PO) containing about 60% $\alpha$-LnA, or fish oil (FO) rich in eicosapentaenoic acid (EPA) and DHA. The fatty acid ompositions of mesenteric and subcutaneous fat were measured and evaluated at Day-2 and Day-15 after parturition. In general, major characteristics of dietary fatty acid composition was reflected on the fatty acid composition of adipose tissues. Dietary fatty acid composition was reflected more on mesenteric fat as compared to subcutaneous fat. Mesenteric fat was found to contain less arachidonic acid (AA) and mesenteric fats of CO, SO and PO groups contained less DHA than did the subcutaneous fat. The P/M/S ratios of adipose tissues were similar between experimental groups while dietary P/M/S ratios differed significantly. It was noticeable that a small proportion of DHA was found in the adipose tissues of animals of CO, SO and PO groups (Day-2) and in SO and PO groups (Day-15), the groups which do not contain DHA in their diets. The percentage of DHA in mesenteric fat o CO, SO and PO groups decreased as lactation continues, while the proportion of DHA in FO group increased. Adipose tissues of FO group had higher DHA/EPA ratio as compared to the diet. Considering the fact that the body contains a large amount of adipose tissues, our present finding suggests that the adipose tissue can serve as a reservoir of DHA for pregnant and lactating rats.

• Reproductive and Developmental Biology
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• v.30 no.4
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• pp.247-253
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• 2006

Our previous research has identified granulin (grn) and p130 genes as sex steroid-inducible genes in the rat hypothalamus, which might be involved in sexual differentiation of the brain. Phthalate esters that are used as plasticizers and also found at low levels in foods such as dairy products are often mentioned as suspected endocrine disrupters. The purpose of the present study is to elucidate whether perinatal exposure to di-n-butyl phthalate (DBP), diisononyl phthalate (DINP) and di-2-ethylhexyl adipate (DEHA) affects hypothalamic sex steroid-inducible genes. The present study assessed the effects of perinatal exposure to DBP, DINP and DEHA on sex steroid hormones levels and hypothalamic gm and p130 mRNA expressions at postnatal day (PND) 3 and 7. Pregnant rats were fed a soy-free diet containing 20, 200, 2,000 and 10,000 ppm of DBP, 40, 400, 4,000 and 20,000 ppm of DINP, or 480, 2,400 and 12,000 ppm of DEHA from gestational day (GD) 15 to GD 3 or 7. At PND 3 and 7, perinatal exposure to these chemicals did not substantially affect serum concentrations of testosterone and estradiol. At PND 3, the expression of grn mRNA levels in males was decreased by DEHA, and that of p130 was decreased by DBP, DINP and DEHA, though the effects were not dose-dependent. At PND 7, the expression of gm gene in female pups was increased by higher doses of DBP and all the doses, except for 4,000 ppm, of DINP, while that in male pups decreased by 480 and 12,000 ppm of DEHA. Hypothalamic expression of p130 mRNA in males was increased by lower doses of DBP and all the doses of DINP, whereas that of females was decreased by 480 and 2,400 ppm of DEHA. These results suggest that these chemicals may affect the expression of gm and p130 genes by directly acting on the hypothalamus, thus leading to inappropriate expression of these genes.

• Clinical and Experimental Pediatrics
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• v.50 no.7
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• pp.686-693
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• 2007

Purpose : Mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF), is a potent inhibitor of inosine-monophosphate dehydrogenase (IMPDH), a new immunosuppressive drug used. It was reported that MPA protected neurons after excitotoxic injury, induced apoptosis in microglial cells. However, the effects of MPA on hypoxic-ischemic (HI) brain injury has not been yet evaluated. Therefore, we examined whether MPA could be neuroprotective in perinatal HI brain injury using Rice-Vannucci model (in vivo) and in rat brain cortical cell culture induced by hypoxia (in vitro). Methods : Cortical cells were cultured using a 18-day-pregnant Sprague-Dawley (SD) rats and incubated in 1% $O_2$ incubator for hypoxia. MPA ($10{\mu}g/mL$) before or after a HI insult was treated. Seven-day-old SD rat pups were subjected to left carotid occlusion followed by 2 hours of hypoxic exposure (8% $O_2$). MPA (10 mg/kg) before or after a HI insult were administrated intraperitoneally. Apoptosis was measured using western blot and real-time PCR for Bcl-2, Bax, caspase-3. Results : H&E stain revealed increased brain volume in the MPA-treated group in vivo animal model of neonatal HI brain injury. Western blot and real-time PCR showed the expression of caspase-3 and Bax/Bcl-2 were decreased in the MPA-treated group In in vitro and in vivo model of perinatal HI brain injury, Conclusion : These results may suggest that the administration of MPA before HI insult could significantly protect against perinatal HI brain injury via anti-apoptotic mechanisms, which offers the possibility of MPA application for the treatment of neonatal HI encephalopathy.

• Journal of Preventive Medicine and Public Health
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• v.38 no.3
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• pp.330-336
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• 2005

Objectives : The aim of this study was to investigate the effects of bisphenol A (BPA), an estrogen-like environmental endocrine disrupter, on the placental function and reproduction in rats. The mRNA levels of the placental prolactin-growth hormone(PRL-GH) gene family, placental trophoblast cell frequency and reproductive data were analyzed. Methods : The pregnancies of F344 Fisher rats ($160g{\pm}20g$) were detected by the presence of the copulatory plug or sperm in the vaginal smear, which marked Day 0 of pregnancy. Pregnant rats were divided into three groups. The control group was intraperitoneally injected with a sesame oil vehicle. The two remaining groups were injected with 50 or 500 mg/kg B.W/day of BPA, resuspended in sesame oil, on either days 7 to 11 or 16 to 20 of pregnancy, with the rats sacrificed on either day 11 or 20, respectively. The mRNA levels of PRL-GH and Pit-1a and b isotype genes were analyzed by Northern blot hybridization and reverse transcription-polymerase chain reaction. The hormone concentrations were analyzed by radioimmunoassay, and the frequency of the placental trophoblast cells observed by a histochemical study. Reproductive data, such as the placental weight and litter size, were surveyed on day 20. The fetal weight was surveyed for 4 weeks after birth. A statistical analysis was carried out using the SAS program (version 8.1). Results : The mRNA levels of the PRL-GH gene family, such as placental lactogen I, Iv and II, prolactin like protein A, C and Cv, and decidual prolactin-related protein were significantly reduced due to BPA exposure. The mRNA levels of the Pit-1a and b isotype genes, which induce the expression of the PRL-GH gene family in the rat placenta, were also reduced due to BPA exposure. The PL-Iv and PL-II concentrations were reduced in the BPA exposed group. During the middle to last stage of pregnancy (Days 11-20), a high dose of BPA exposure reduced the frequency of spongiotrophoblast cells, which are responsible for the secretion of the PRL-GH hormones. Reproductive data, such as the placental and fetal weights and the litter size, were reduced, but that of the pregnancy period was extended in the BPA exposed compared to the control group. Conclusions : BPA disrupts the placental functions in rats, which leads to reproductive disorders.

• Journal of Preventive Medicine and Public Health
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• v.37 no.2
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• pp.157-165
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• 2004

Objectives : This study aimed to investigate the toxic effects of chromium (VI) on the placental function and reproduction in rats. For the study, the placental prolactin-growth hormone (PRL-GH) gene expression, placental trophoblast cell differentiation and reproductive data were analyzed. Methods : The pregnancies of F344 Fisher rats were checked by the presence of a copulatory plug or sperm in the vaginal smear, which was defined as day 0 of the pregnancy. Pregnant rats were divided into the three groups. The control group was given tap water (chromium level < 0.001 ppm) and the remaining groups were given 250 or 750 ppm of chromium (VI) [as potassium dichromate], from day 7 to 19 of the pregnancy. Rats were sacrificed at days 11 and 20 of pregnancy. The mRNA levels of PRL-GH and Pit-1a and b isotype genes were analyzed by Northern blot hybridization and reverse transcription-polymerase chain reaction (RT-PCR). The hormonal concentration was analyzed by radioimmunoassay, and the differentiation of placental trophoblast cells were observed by histochemical studies. Reproductive data, such as placental and fetal weights, pregnancy period, and litter size, were surveyed at day 20 of pregnancy and after birth. A statistical analysis was carried out using the SAS program (version 8.1). Results : The mRNA levels of the prolactin-growth hormone (PRL-GH) family of genes were dose dependently reduced by chromium exposure. The mRNA levels of Pit-1a and b isotype genes that induce the expression of the PRL-GH family of genes were also reduced by chromium exposure. The PRL-GH hormonal concentration in the rat placenta, fetus and maternal blood were decreased by chromium exposure. In the middle stage of pregnancy (day 11), a high dose of chromium suppressed the differentiation of spongiotrophoblast cells that secret the PRLGH hormones. In the last stage of pregnancy (day 20), a high dose of chromium induced apoptosis of placental cells. Reproductive data, such as placental and fetal weights, litter size, were reduced, but the pregnancy period was extended in the group exposed to chromium compared with the controls. Conclusion : Chromium (VI) disrupts the ordered functions of the placenta, which leads to reproductive disorders in rats.