• Toxicological Research
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• v.26 no.4
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• pp.301-313
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• 2010

Growth promoters including hormonal substances and antibiotics are used legally and illegally in food producing animals for the growth promotion of livestock animals. Hormonal substances still under debate in terms of their human health impacts are estradiol-$17\beta$, progesterone, testosterone, zeranol, trenbolone, and melengestrol acetate (MGA). Many of the risk assessment results of natural steroid hormones have presented negligible impacts when they are used under good veterinary practices. For synthetic hormonelike substances, ADIs and MRLs have been established for food safety along with the approval of animal treatment. Small amounts of antibiotics added to feedstuff present growth promotion effects via the prevention of infectious diseases at doses lower than therapeutic dose. The induction of antimicrobial resistant bacteria and the disruption of normal human intestinal flora are major concerns in terms of human health impact. Regulatory guidance such as ADIs and MRLs fully reflect the impact on human gastrointestinal microflora. However, before deciding on any risk management options, risk assessments of antimicrobial resistance require large-scale evidence regarding the relationship between antimicrobial use in food-producing animals and the occurrence of antimicrobial resistance in human pathogens. In this article, the risk profiles of hormonal and antibacterial growth promoters are provided based on recent toxicity and human exposure information, and recommendations for risk management to prevent human health impacts by the use of growth promoters are also presented.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.882-887
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• 2014

We studied oocyte steroidogenesis in blacktip grouper Epinephelus fasciatus ovarian follicles during vitellogenesis. Vitellogenic oocytes with average diameters of 0.45, 0.48 and 0.50 mm were incubated in vitro in the presence of $[^3H]17{\alpha}$-hydroxyprogesterone as a precursor. The steroid metabolites were analyzed using thin layer chromatography (TLC), high performance liquid chromatography (HPLC), and gas chromatography-mass spectrometry (GC/MS). The major metabolites in the vitellogenic oocytes were androstenedione ($A_4$), testosterone (T), estradiol-$17{\beta}$ ($E_2$), and estrone ($E_1$). The metabolites of androgen ($A_4$ and T) were higher in the 0.50-mm oocytes than in the 0.45- and 0.48-mm oocytes, while the estrogen metabolites (E2 and E1) were lower in the 0.50-mm oocytes. These results suggest that 0.50-mm oocytes are fully vitellogenic following initiation of the maturation process.

• Journal of Aquaculture
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• v.20 no.3
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• pp.154-159
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• 2007

Manchurian trout (Brachymystax lenok) is an endangered fish species in East Asia including the Korean peninsula. To establish a method for artificial propagation and to improve our understanding of the reproduction in the species, we have produced recombinant gonadotropins, follicle-stimulating hormone (r-mtFSH) and luteinizing hormone (r-mtLH), which may play central roles in reproductive activities. In the present study, the biological activities of the recombinant hormones were analyzed by gonadosomatic index (GSI), ovarian follicle diameter, and sex steroid levels in mature rainbow trout (Oncorhynchus mykiss). In the 6th day post-injection, FSH-injected fish were slightly decreased in the GSI value, although there were no significant differences among those of control, r-mtFSH, and r-mtLH treatments. Injection of the r-mtFSH increased follicle diameters significantly as compared with those of control- and r-mtLH-injected fish. The plasma steroid levels showed wide differences in the groups at 1, 3, or 6th day post-injection. Despite the variable steroid levels, three individuals receiving either r-mtFSH or r-mtLH showed a great increase in a maturation-inducing steroid, $17{\alpha},20{beta}$-dihydroxy-4-pregnen-3-one, at 3 and 6 days. Taken together, these results suggest that biological efficacies of the recombinant FSH and LH should be further studied in the Manchurian trout.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2004.07a
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• pp.30-30
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• 2004

• 대한생식의학회:학술대회논문집
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• 2003.12a
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• pp.149-150
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• 2003

• Journal of Aquaculture
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• v.9 no.3
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• pp.279-285
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• 1996

The effects of various concentrations of $17{\beta}-methyltestosterone$ (MT) or $17{\beta}-estradiol\;(E_2)$ on sex reversal, survival and growth rates of olive flounder, Paralichthys olivaceus were investigated. MT and $E_2$ were treated to juvenile flounder for 60 days from 30 (total length : 14.5 mm) to 90 (TL : $10.41\~11.17$ mm) days after hatching. Fish were treated with 0, 1, 10 and 100 ppb of MT or $E_2$ in the rearing water for 2 hours per day. At the time of 200 days after hatching, fish were sampled to examine sex ratio. One hundred pub of MT produced $100\%$ male, however 1 and 10 ppm MT produced 72.5 and $87.2\%$ males. One, 10 and 100 ppb of $E_2$ produced 75.5, 91.9 and $97.2\%$ females, respectively. Survival and growth rates of each experimental group at the end treatment were not significantly different from those of the control (P>0.05).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.3
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• pp.153-159
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• 2007

We studied oocyte steroidogenesis in relation to oocyte development in the greenling, Hexagrammos otakii, a marine multiple spawner. Vitellogenic and mature oocytes were incubated in vitro in the presence or absence of $[^3H]-17\;{\alpha}-hydroxyprogesterone$ as a precursor. The major metabolites were androgens [androstenedione $(A)_4)$ and testosterone (T)] and estrogens [$17\;{\beta}-estradiol\;(E_2)$ and estrone ($E_1$)] in vitellogenic oocytes. The metabolic rate of T was lower in 1.08 to 12-mm oocytes, while that of $E_2$ increased with oocyte size. The endogenous productions of T, $E_2$ and 17 ${\alpha}-hydroxy$, 20 ${\beta}-dihydroprogesterone\;(17{\alpha}20{\beta}OHP)$ were quantified using a radioimmunoassay in the non-precursor group. The endogenous levels of T and $E_2$ were highest in 1.08 to 12-mm oocytes and $17{\alpha}20{\beta}OHP$ was produced only in 1.90 to 95-mm oocytes. The relationship between oocyte size and steroidogenesis showed that 1.08 to 12-mm oocytes are full vitellogenic following induction of the maturation process. Moreover, $17{\alpha}20{\beta}OHP$ acts as a maturation inducing hormone in H. otakii.

• Journal of Embryo Transfer
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• v.3 no.1
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• pp.13-23
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• 1988

These studies were undertaken to examine the interaction of tamoxifen with sex steroid hormones in rat uterine activity. The uterine wet weights of the immature Tat uterus were examined after the administration of estradiol-l7$\beta$(1$\mu$g), tamoxifen(50$\mu$g), progesterone(lmg). The uterotropic activity in immature ovariectomized rats was observed under various treatment conditions following pretreatment with above drugs. The results obtained were as follows:1) Tamoxifen produced significant increase (p <0.01) in uterine wet weight compared with control group, although the increase was not as great as that seen with estradiol-17$\beta$. Administration of estradiol-17$\beta$ together with tamoxifen inhibited significantly the increase of uterine wet weight by estradiol-17$\beta$ (p < 0.01). Coadministration of progresterone with tamoxifen partly blocked the increase of tamoxifen-induced uterine wet weights by progesterone. 2) Estradiol-17$\beta$after the estradiol-17$\beta$ pretreatment discontinued the declining uterine wet weights due to the absence of estrogen support, but uteri continued to increase in weight if daily estradiol-17 $\beta$ was maintained. Administration of tamoxifen on the fourth day of estradiol-17$\beta$ treatment reduced uterine wet weights within 24 hours, and the weights continued to decline with additional tamoxifen. 3) The modest growth of the uterus induced by three daily injections of 5Opg tamoxifen remained stable for five days, with or without additional tamoxifen treatment. Coadministration of tamoxifen with estradiol17$\beta$ increased slightly the increase of uterine wet weight by tamoxifen. Coadministration of tamoxifen with progesterone inhibited the increase of uterine wet weight by tamoxifen. 4) The modest growth of the uterus induced by three daily injections of lmg progesterone reduced uterine wet weight to the control level for five days. Commencement of tamoxifen or estadiol-17 $\beta$ injections on the fourth day of progesterone treatment rapidly elevated uterine wet weight.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.6
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• pp.1003-1012
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• 2012

The gonadosomatic index (GSI), sex steroid hormones and gonadal development of roughscale sole Clidoderma asperrimum cultured in indoor tank were investigated to evaluate its sexual maturation and reproductive cycle. The highest GSI values of female and male were $6.91{\pm}4.03$ (May) and $0.16{\pm}0.08$ (August), respectively. The reproductive cycle would be classified into four successive developmental stages: growing stage (December to February), maturation stage (March to April), ripe and spawning stage (May to June), recovery and resting stage (July to November). The highest plasma testosterone (T) and estradiol-$17{\beta}$ ($E_2$) levels of female were $259.4{\pm}76.8$ and $633.3{\pm}182.5$ pg/mL, respectively in May. Also $17{\alpha}$, $20{\beta}$-dihydroxy-4-pregen-3-one ($17{\alpha}$, $20{\beta}$-OHP) levels of female peaked in April before spawning season ($244.2{\pm}42.5$ pg/mL). The highest plasma testosterone (T) and 11-ketotestosterone levels of male were $231.0{\pm}46.0$ and $273.9{\pm}54.5$ pg/mL, respectively in April. But there was no significant difference in $17{\alpha}$, $20{\beta}$-OHP.

• International Journal of Oral Biology
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• v.36 no.2
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• pp.103-108
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• 2011

Measurement of estrogen concentration in bio-samples are very important for differential diagnosis of various disease or evaluation of health status. However, it is difficult to collect immediate data of estrogen concentration because they are measured by radioimmunoassay or chromatography which need time- and cost-consuming sample pre-treatment. This study was performed for development of new estrogen biosensor employing taste principles, and for evaluation of cross reactivity between various steroid hormones. Gene sequence of ligand binding domain of ${\alpha}$-human estrogen receptor (amino acid 302-553; hER-LBD) was cloned from human breast cancer cell line. The proteins of hER-LBD were produced by T7-E.coli expression system, and isolated by chromatography. hER-LBD were coated on the gold plated quartz crystal (AT-cut 9MHz), and resonance frequencies were measured by universal frequency counter. Estradiol, progesterone, testosterone, and aldosterone were used for cross reactivity of the hER-LBD. We also monitored influences of pH change in resonance frequency. The resonance frequencies of hER-LBD coated quartz crystal were decreased during increase of estrogen concentration from $15 \;{\mu}g/mL$ to $50\;{\mu}g/mL$. However, similar steroid hormones, progesterone and aldosterone, did not elicit the change in resonance frequency. Testosterone evoke weak change in resonance frequency. The new estrogen biosensor was more sensitive in pH 7.2 than in pH 7.6. These results suggest that hER-LBD coated quartz crystal biosensor is a probable estrogen biosensor.