• Korean Journal of Animal Reproduction
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• v.17 no.4
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• pp.325-329
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• 1994

Seasonal and diurnal variation in serum testosterone was measured by radioimmunossary in 3 mature Korean native male goats. Blood was collected at 3-h intervals for 24h in each season. Mean levels of 4 seasons ranged from 0.82 to 2.06ng/ml and no difference was among seasons, although level in fall and winter was slightly higher. Diurnal level tended to increase at daytime in all season and when diurnal variation in level was compared to daily mean of each season, level of daytime greatly(P<0.05) increased in summer. However, variation between light and dark period in other seasons did not show significant difference. Daytime increase of testosterone was found 3 to 4 after dawn and level increased 1 to 2h ahead in summer and fall than that in others. These results in serum testosterone suggest that there was no great seasonal variation in endocrine function of goat testis.

• YAKHAK HOEJI
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• v.45 no.6
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• pp.694-700
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• 2001

Synthetic pyrethroids are analysis of a natural chemical moiety, pyrethrin derived from the pyrethrum plant Chrysanthemum. The natural pyrethrin structure has been modified to be highly lipophilic and photostable, creating an effective pesticide and resulting in an increased presence in the environment. Worldwide, they are commonly used insecticides against ticks, mites, mosquitoes, and as treatment for human head lice and scabies. Therefore, human exposure to their compounds in extensive. Several studies on the effects of pyrethroids on thyroid hormone regulation, estrogen and androgen function have been reported and yet little has been done try assess their potential hormonal activities. Among humans, a pyrethroid compound was suggested to be the causal agent for gynecomastia in a group of Haitian men. The reports suggest that some pyrethroid compounds are capable of disrupting endocrine function. Therefore, we examined estrogenic/antiestrogenic potential of three pyrethroid insecticides, that is permethrin, allethrin and fenvalerate in human breast cancer cell and action mechanism mediated by the estrogen receptor. Fenvalerate showed weak estrogenic activity but aallethrin and permethrin showed no effect. In combination with high levels (10$^{-10}$ M, 10$^{-11}$ M) of 17$\beta$-estradiol and three synthetic pyrethroids inhibited cert proliferations in MCF7-BUS cell by 17$\beta$-estradiol. Whereas, fenvalerate increased cell proliferative activity at lower level of estradiol (10$^{-12}$ M, 10$^{-13}$ M). The relative affinities to the estrogen receptor were observed by allethrin and permethrin treatment, but not by fenvalerate. These results indicated that some of pyrethroid insecticides may modulate estrogen functions in human breast cancer cell. The action mechanisms of estrogen receptor mediated antiestrogenicity by allethrin and permethrin were postulated.

• Toxicological Research
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• v.35 no.1
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• pp.9-12
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• 2019

One of the major challenges in methadone maintenance therapy (MMT) for drug dependence is the physiological side effects on endocrine hormones. Because of the key role of the thyroid gland in the normal functioning of the human body and brain, this study examined the effect of MMT on thyroid function. Thyroid hormones (T3, T4, and thyroid-stimulating hormone (TSH)) were evaluated in normal and user treated with MMT who were referred to the Province Clinical & Pathology Center of Urmia, Iran. The study was conducted for three months using the Case Series method. A total of 270 samples were collected, 215 were from individuals who were not treated, whereas 55 were from men treated with methadone. Average levels of T3 and T4 in non-treated sample of men are $1.34{\pm}0.02ng/mL$ and $90.96{\pm}1.38ng/mL$ while the corresponding values for patients treated with methadone are $1.39{\pm}0.04ng/mL$ for T3 and $94.57{\pm}2.72ng/mL$ for T4. Mean TSH levels of the non-treated group and the methadone consuming group were $1.75{\pm}0.08{\mu}IU/mL$ and $3.17{\pm}0.45{\mu}IU/mL$, respectively. These results indicate that although men treated with methadone had higher levels of T3, T4, and TSH than normal individuals, only the difference in TSH level was significant. The importance of this difference among individuals on methadone maintenance programs should be investigated in larger samples over long periods of time. Additionally, the effects of methadone treatment on women should be examined.

• Biomolecules & Therapeutics
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• v.15 no.1
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• pp.58-64
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• 2007

The previous study reported the biological effect of magnetic field exerted by acting on endocrine and anti-oxidant system. The present study aims to study whether ELF-MF (extremely low frequency magnetic field) affects the physiological endocrine systems such as thyroid and whether ELF-MF affects the defense system against oxidative stress when it alters the function of thyroid. Finally, we correlate the effects of MF on oxidative stress, and adrenal and thyroid with an environmental stress factor. We exposed sham or MF to rats for 5 or 25 days. After the exposure, we determined pain sensitivity, level of TSH, $T_3$ and free $T_4$ in plasma. We also assayed in whole brain, lipid peroxidation, the activity of enzymatic anti-oxidant defense including superoxide dismutase(SOD) and glutathione peroxidase (GPx), and non enzymatic defense such as reduced or oxidized glutathione contents. MF induced the hypersensitivity to thermal stimuli with the reduction of latency. $T_3$ and $T_4$ levels were also increased by the exposure of MF. In addition, we observed the rise of MDA level in rat brain by MF although the MF did not change superoxide dismutase and glutathione peroxidase activity. The effect of MF on both reduced and oxidized glutathione results in decrease in reduced or oxidized glutathione in whole brain. In every experiment, there was no significant difference in MF influence between short term (5 days) and long term (25 days) exposure. Taken together, MF exposure affects the thyroid hormonal control in brain. The elevated thyroid hormone acts on brain, leading to hyper-utilization of oxygen. This phenomenon may be correlated with oxidative stress resulting from MF exposure. In conclusion, we suggest that MF exposure may be an environmental stress by exerting oxidative stress.

• Development and Reproduction
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• v.15 no.2
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• pp.159-166
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• 2011

Simazine (6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine) is a triazine herbicide that has been applied worldwide including Korea for agricultural purposes. Simazine is the second most commonly detected pesticide in surfaceand ground-water in the United States, Europe and Australia. It has been shown that simazine is a potent endocrine disruptor in wildlife and laboratory animals. Although many endocrine disruptors can induce apoptosis in various types of cells, the effects of simazine on apoptosis and on the expression of Bcl-2 family genes are not known. Also it is unknown the effect of simazine on the expression of steroidogenesis-regulating genes in testicular cells. In this study, we investigated the effect of simazine on the expression levels of apoptosis- and steroidogenesis-regulating genes in testicular cells. We found that a low concentration of simazine can alter the mRNA expression levels of steroidogenesis-related genes and Bcl-2 family genes in mouse Sertoli cells and rat Leydig cells. Thus, our results suggest that simazine can disturb normal testicular development and reproductive function by altering the expression of genes that are critical for the regulation of apoptosis and steroidogenesis.

• Development and Reproduction
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• v.11 no.3
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• pp.179-185
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• 2007

The estrogens and estrogenic endocrine disrupting chemicals(EDCs) function through a steroid nuclear receptor-mediated process and subsequently regulate the transcription of mRNA for a number of target proteins. The estrogen receptor-related receptors(ERRs), which are structurally similar to estrogen receptors, are members of orphan nuclear receptor in the nuclear receptor superfamily and their functions are known to be involved in the formation of extra-embryonic ectoderm. To investigate effects of EDCs on early embryogenesis and ERR gene expression in marine invertebrates, we examined morphological changes and the mRNA expression of $ERR{\beta}$ like 1 in sea urchin Strongylocentrotus nudus exposed to estradiol-$17{\beta}(E_2)$ or nonylphenol(NP). The $E_2$ and NP-exposed embryos showed a delayed development compared to control embryos. Furthermore, they showed abnormal embryonic developments at late stages, i.e., blastular, gastrula and plutei stages. The mRNA level of $ERR{\beta}$ like 1 at the gastrula stage was significantly lower in $E_2$ and NP-exposed embryos than those of control group. These results suggest that NP and $E_2$ are potent chemicals causing abnormal embryonic development of S. nudus through at least in part down-regulated $ERR{\beta}$ like 1.

• Korean Journal of Environmental Biology
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• v.32 no.4
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• pp.271-285
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• 2014

Aluminum flows into the river from the abandoned mine leachate, industrial wastewater, and sewage and is responsible for acute toxicity in aquatic organisms. Recently, the number of reports have indicated the increased toxicity in a variety of aquatic organisms' due to the aluminum toxicity. In this study, we reviewed the toxicity of aluminum on aquatic invertebrates, fishes and amphibians and suggested the guideline for management of aluminum residues in aquatic environment and strategies for aluminum toxicity evaluation. In aquatic animals aluminum complexes evoke gill dysfunction primarily, the cytotoxicity, genotoxicity, oxidative stress, disruption of endocrine function, reproductive success, metabolism and homeostasis. Notably, at environmentally relevant concentration, aluminum complex can alter the hormone levels in fish in acidic condition. Further, since the solubility of aluminum is higher in the acidic and basic conditions, thus it is likely that the toxic effects of aluminum may not only occur in acidic water near the abandoned mines but also in lakes and rivers, where pH is raised by algal bloom.

• Clinical and Experimental Reproductive Medicine
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• v.35 no.3
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• pp.181-191
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• 2008

Objective: Environmental chemicals alter reproduction, growth, and survival by changing the normal function of the endocrine system. Bisphenol A (BPA), one of the endocrine disruptors, is known to be an estrogen receptor agonist. Therefore, we hypothesized that BPA may affect male reproduction including spermatogenesis in the mouse testis. Methods: We used 7-week-old ICR mice. The first experiment group received BPA in sesame oil (vehicle, 1 mg/kg, 10 mg/kg, and 100 mg/kg) by i.p. injection and mice were sacrificed 24 hr later. The second experiment group received BPA (vehicle, 10 ${\mu}g/kg$, 1 mg/kg, and 100 mg/kg) daily for 14 days by subcutaneous injection. Expression of cell type-specific marker genes in the testis was evaluated by RT-PCR. Histological analysis, immunofluorescence staining, and TUNEL staining were also performed. Results: RT-PCR analyses showed that expression of luteinizing hormone receptor (LHR), a marker gene for the Leydig cell, was notably decreased in the testes of high dose-exposed mice. No obvious difference in the histology of testes was noted among treatment groups. Immunostaining of LHR in the first experiment group did not show noticeable difference in LHR protein expression in Leydig cells. Immunohistochemistry also revealed heightened expression of the immunoreactive Bax in the treatment group, and this was accompanied by positive TUNEL staining in the interstitial area within testis where Leydig cells reside. Conclusions: Our result suggests that BPA affects Leydig cell functions by altering gene expression and by increasing apoptosis in the mouse testis.

• Korean Journal of Poultry Science
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• v.27 no.2
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• pp.115-132
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• 2000

Eggshell strength and eggshell pigmentation are described in this paper since these are needed for quality egg production. A strong eggshell is determined by the components of the shell (cuticle, true shell and membranes) as well as the proper function of the gastrointestinal tract, the shell gland, the Kidneys and the endocrine system. When the puller reaches sexual maturity, the medullary bone must be ready for the laying hen at the peak egg shell formation. The amount of calcium in the layer diet, sources of calcium feed, the ratio of calcium and phosphorus in the layer diet, adequate levels of vitamin D and the dietary mineral (electrolyte) balance in the body fluid are important factors along with the levels of other nutrients. Biological, environmental and managerial factors such as the age of laying flock, temperature and humidity of the hen house, bird strain, disease, egg collection through transportation and others and influence the shell breakage at various stages of movement of the eggs from the producer to the consumer. The pigments present in eggshells are protoporphyrin-Ⅸ, biliverdin-Ⅸ and its zinc chelate and occasional traces of coproporphyrin-Ⅲ. However, there are several causes of changes in eggshell pigmentation such as the age of hen, disease, drugs and surface defects due to abnormal post-cuticular deposits.

• Journal of Food Hygiene and Safety
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• v.21 no.2
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• pp.118-128
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• 2006

This study was conducted to determination of the endocrine distruptor function of 'Parabens' by dosing ethyl paraben, propyl paraben, isopropyl paraben, butyl paraben and isobutyl paraben to the immature SD rats. 18 groups were given vehicle control group, negative control group (Dibutyl phthalate), postive control group ($1'7-{\alpha}$ Ethynylestrdiol) and each paraben groups involved 3 dose level. Rats were injected with 62.5, 250 and 1,000mg/kg from postnatal day 19 till 21 once a day in subcutaneous and a total 3, times. There was no treatment related death. but, subcutaneous nodule, edema, alopecia and scrub formation on injection site was observed. These signs was become worse in high dose level. these signs was cause from physical stimulation by test substance which parabens were mix with com oil as vehicle. In the analysis of organ weights, absolute and relative weights of brain, spleen, liver, thymus, heart, kidneys, adrenals, ovaries and vagina were no difference with control group. but, wet and blotted weight of uterus was increased in every high dose parabens treat group. Especially, all dose level of isobutyl paraben was showed increment of uterus weight. uterus dilatation of parabens treated group was observed in gross anatomic pathology and these result was agree with wet and blotted weight of uterus. In the result of this study, estrogenic effect as endocrine distruptor was observed in ethyl paraben, propyl paraben, isopropyl paraben, butyl paraben and isobutyl paraben. and it was considered isobutyl paraben has highest estrogrnic effect under the condition of this study.