• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.1
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• pp.13-16
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• 2001

Plasma levels of sex steroid hormones in rockfish, Sebastes inermis were examined monthly in relation to gonadosomatic index (GSI) under a controlled water temperature and photoperiod, The GSI of a control group (C) in female began to increase from November and reached a maximum in January, Sample fish under a controlled water temperature and photoperiod (Tr) were divided into a responded group (Tr-r) and a un-responded group (Tr-n) by the gonadal maturation condition and GSI. The GSI of females in Tr-r reached a maximum in March. But the female GSI in Tr-n kept lower than 1.2 during the experimental period. No differences in male GSI were noticed between C and Tr. The $estradiol-17\beta$ and testosterone levels of female plasma in Tr reached a maximum in October, later than those in C. In males, these was no difference in 11-ketotestosterone and testosterone between C and Tr. When rockfish was reared in September under the controlled water temperature and photoperiod which were equivalent to those in July, that is two months earlier, the maturation of females was delayed in comparison with C. This finding suggested that delayed maturation in ovary was caused by the secretion of sex steroid hormones in relation to the water temperature and photoperiod of the hypothalamus-pituitary-gonad axis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.373-377
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• 2000

This study Investigated the effects of $estradiol-l7{\beta} (E_2)$, $17{\alpha}-methyltestosterone$ (MT) and high temperature (WT) on gonadal sex differentiation in black rockfish, Sebastes srhlegeli. fish were reared to oral adminstration of E, at nominal concentrations of $20, 40 and 60 {\mu}g/g diet$, and MT at nominal concentration of 20 and $50 {\mu}g/g$ diet from 56 days to 77 days after parturition. In the treatment of WT, water temperature of the breeding tanks ranged $27.0{\pm}0.5^{\circ}C$ more than $10^{\circ}C$ approximately, in comparison to the control and other experimental group, In the process of sex differentiation until 56 days after parturition, gonads were composed of mostly gonia cells, sexually undifferentiated. In contrast, 128 dal's after parturition, the ovaries were composed of ovarian cavity and lamellae, and oogonia and perinucleolus oocytes were distributed in the lamellae of ovary, and the testes were composed of a number of seminiferous tubule, and spermatogonia were distributed in the seminiferous tubule, and also melanophore scattered in the matrix layer of testis. In the sex ratio, more females than male were observed from $E_2$. treatment groups when compared to the control, but more males than females were observed from MT and WT treatment groups when compared to the control. In the results of the present study, the concentration and kinds of the sex steroid hormones, and also the rearing high temperature caused to the factor of sex determination in the process of sex differentiation of black rockfish.

• Clinical and Experimental Reproductive Medicine
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• v.11 no.2
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• pp.17-25
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• 1984

Hypothalamic-pituitary function in patients of 6 selected groups of amenorrhea was evaluated by performing premarin test. Selected amenorrheic patients were divided into 6 groups of Turner's syndrome(5), adrenogenital syndrome(3), Sheehan's syndrome(4), moderate hyperprolactinemia(3), severe hyperprolactinemia(9) and functional oligoamenorrhea(9) the diagnoses of which were performed according to modified our own protocol for management of amenorrheic patients. As control 20 normally cycling women in mid follicular phase determined by their symptothermal charts during last 6 months designed by WHO were compared. The premarin test which is one of the tests evaluating the hypothalamic-pituitary function by the principle of negative and positive feed back effect's of estrogen was performed by injecting 20 mg of premarin in volus intravenously. The levels of serum LH before, 24, 48, 72, 96 and 120 hours after injection of premarin were measured by double antibody technique radioimmunoassay the reagents of which were supplied by WHO. The results were as follows: 1. Both negative and positive feed back effects by exogenous estrogen were well preserved even in the patients of gonadal dysgenesis although the baseline levels were much higher than normal. 2. In the patients of Sheehan's syndrome one could observe the minimal response of feed back effect in the case with minimal pituitary function. 3, Androgens in adrenogenital syndrome and prolactin in hyperprolactinemia may suppress mainly the positive feed back effect rather than the negative one. The suppressive effect can be abolished by proper treatments which can eliminate those suppressive hormones. 4. This premarin test may be beneficial for predicting the result of clomiphene in ovulation induction.

• Development and Reproduction
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• v.1 no.2
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• pp.189-202
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• 1997

The hypothalamic peptide GnRH plays a central role in the regulation of the mammalian reproductive axis. Recent studies suggested that GnRH stimulates or inhibits the ovarian steroidogenesis and gametogenesis directly. Our previous report indicated that GnRH gene is expressed in adult rat ovary as well as in hypothalamus and that the expressed GnRH may induce the follicular atresia and apoptosis of ovarian granulosa cells in rat. Therfore, we studied whether GnRH gene is expressed in the mouse fetal ovary, when the germ cells are degenerating by apoptosis during gonad diffeerentiation. Mouse fetal gonads were obtained on the 12, 15,18 and 20th day of gestation from the mother mice superovulated (10 IU PMSG and 10 IU hCG) and mated. The morphological changes of fetal ovaries were examined histochemically by hematoxylin-eosin staining. The fetal sex was confirmed by PCR methods for sexing. RT-PCR methods were used to examine the expression of GnRH gene and the sex steroid hormones were determined by conventional radioimmunoassays. The levels of estradiol (E) and progesterone (P) were increaseduntil 18th day of gestation and then E was decreased just before parturition. The morphological changes of fetal gonadal tissue sections showed the ovarian development and coincided with the result of PCR analysis for sexing using ovary- or testis- specific oligonucleotide primers. Immunoreactive GnRH in placenta was decreased gradually until the end of gestation but fetal brain and ovarian GnRH were increased. The level of GnRH gene expression was increased during fetal ovarian development from 12 till 18th day and decreased suddenly on 20th day just before birth. From these results, it is suggested that ovarian GnRh may play a regulatory role on the germ cell differentiation of fetal ovary.

• Development and Reproduction
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• v.14 no.1
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• pp.35-41
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• 2010

Mammalian reproduction is regulated by a feedback circuit of the key reproductive hormones such as GnRH, gonadotropin and sex steroids on the hypothalamic-pituitary-gonadal axis. In particular, the onset of female puberty is triggered by gain of a pulsatile pattern and increment of GnRH secretion from hypothalamus. Previous studies including our own clearly demonstrated that genistein (GS), a phytoestrogenic isoflavone, altered the timing of puberty onset in female rats. However, the brain-specific actions of GS in female rats has not been explored yet. The present study was performed to examine the changes in the activities of GnRH neurons and their neural circuits by GS in female rats. Concerning the drug delivery route, intracerebroventricular (ICV) injection technique was employed to eliminate the unwanted actions on the extrabrain tissues which can be occurred if the testing drug is systemically administered. Adult female rats (PND 100, 210-230 g BW) were anaesthetized, treated with single dose of GS ($3.4{\mu}g$/animal), and sacrificed at 3 hrs post-injection. To determine the transcriptional changes of reproductive hormone-related genes in hypothalamus, total RNAs were extracted and applied to the semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). ICV infusion of GS significantly raised the transcriptional activities of enhanced at puberty1 (EAP-1, p<0.05), glutamic acid decarboxylase (GAD67, p<0.01) which are known to modulate GnRH secretion in the hypothalamus. However, GS infusion could not change the mRNA level of nitric oxide synthase 2 (NOS-2). GS administration significantly increased the mRNA levels of KiSS-1 (p<0.001), GPR54 (p<0.001), and GnRH (p<0.01) in the hypothalami, but decreased the mRNA levels of LH-$\beta$ (p<0.01) and FSH-$\beta$ (p<0.05) in the pituitaries. Taken together, the present study indicated that the acute exposure to GS could directly activate the hypothalamic GnRH modulating system, suggesting the GS's disrupting effects such as the early onset of puberty in immature female rats might be derived from premature activation of key reproduction related genes in hypothalamus-pituitary neuroendocrine circuit.

• Korean Journal of Psychosomatic Medicine
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• v.4 no.1
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• pp.146-154
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• 1996

The impact of stress on immune function is known to be associated with the interactions among the central nervous system(CNS), neuroendocrine system, and immune system. The main pathways between stress and immune system are wiring of lymphoid organs and neuroendocrine system. Immune system also produces neuropeptides, which modulate immune system. Mediators of psychosocial influences on immune function are found to be peptides released by the pituitry, hormones, md autonomic nervous system. Hypothalamus integrates endocrine, neural and immune systems. Particularly, paraventricular nucleus appears to play a central role in this integration. On the other hand, endocrine system receives feedback from the immune system. The major regulatory pathways which pituitary modulates include the hypothalamic-pituitary-adrenal-thymic(HPAT) axis, hypothalamic-pituitary-gonadal-thymic(HPGT) axis, pineal-hypothalamic-pituitary(PHP) axis. Bidirectional pathways such as feedforward and feedback pathways are suggested in the interaction between stress and immune system. It suggests that psychosocial inputs affect immune function, but also that immunological inputs affect psychosocial function. Thus, prospective studies for elucidating the relationship between stress and immune function should incorporate measures of immune function as well as measures of endocrine, autonomic, and brain activities at the same time.

• Korean Journal of Ichthyology
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• v.13 no.4
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• pp.248-253
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• 2001

An histological study was conducted to determine the initial treatment time and treatment duration in the use of sex-reversal hormones in relation to gonadal development and sexual differentiation in the bagrid catfish, Leiocassis ussuriensis. The primordial germ cell, which could be recognized from one-day-old fry, began to protrude into the peritoneal cavity between the mesonephric duct and the gut. The primordial gonad with a genital ridge was developed at 5~10 days after hatching. Sex differentiation of the ovary was identified by the ovarian cavity and meiotic oocytes from 20-day-old larvae. Testicular differentiation was also identified by spermatogonial cells from 20-day-old larvae. It may therefore be concluded that this species belongs to the differentiated type of gonochoristic teleost.

• Advances in Traditional Medicine
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• v.10 no.2
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• pp.103-110
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• 2010

The seed powder of Abrus precatorius L. has traditionally been used as oral contraceptive agent by the women in some rural areas in Bangladesh. The present study aimed to examine the antifertility activity of A. precatorius seed extracts in experimental female rats. Finely ground seeds were extracted with aqueous acetone followed by successive partitioning with n-hexane, ethyl acetate (EtOAc), methanol (MeOH) and water. Water suspended crude seed powder, organic fractions of acetone extract and a standard contraceptive drug ($Nordette^{(R)}28$) were separately administered orally to the female rats for 30 days. n-Hexane, EtOAc and MeOH solubles at the doses of 2, 4 and 6 mg/rat/day, respectively and crude seed powder at 100 mg/rat/day exhibited 100% antifertility activity with lowest levels of serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and $17{\beta}$-estradiol. Histological study of ovary and uterus of these rats exhibited reduced number of developing follicles and increased number of atretic follicles in the ovary, and fewer uterine glands with shrunken morphology, reduced endometrial height, poor vascularity and compact stroma in uterus. However, the activities of serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase and the body weight of the rats remained almost unaffected in all the seed extract treated rats compared to control. These results suggest that A. precatorius seed extracts reduced the levels of serum FSH, LH and $17{\beta}$-estradiol probably by affecting hypothalamic-pituitary-gonadal axis. The reduced levels of these hormones might have affected the oestrous cycle, follicular development, and subsequently the establishment of pregnancy in treated rats.

• Ocean and Polar Research
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• v.38 no.1
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• pp.81-88
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• 2016

In many fish species, including Nile tilapia (Oreochromis niloticus), gonadal development occurs at the expense of stored energy and nutrients. Therefore, reproductive systems are inhibited by limited food supply. It has been well established that reproductive function is highly sensitive to both metabolic status and energy balance. Nothing is known about the possible mediated connection between energy balance and reproduction. Kisspeptin, a neuropeptide product of the Kiss gene has emerged as an essential gatekeeper of reproduction and may be possibly be linked to energy balance and reproduction in non-mammalians. Thus, in this study, the effect of fasting (10 days) on the expression of kisspeptin and the gonadotropin-releasing hormone (GnRH) gene were assessed in Nile tilapia (male and female) using qRT-PCR. In addition, plasma levels of estradiol-$17{\beta}$ ($E_2$) and 11-ketotestosterone (11-KT) in adult tilapia were measured by ELISA. In male tilapia, fasting reduced Kiss2 and GnRH I mRNA expression in the brain and 11-KT level in comparison with the fed tilapia (p < 0.05). In females, however, there were no significant differences in GnRH I mRNA expression and $E_2$ between fish subjected to fasting and those fed (p > 0.05). These data indicate the impact of nutritional states on kisspeptin as a potential regulatory mechanism for the control of reproduction in male Nile tilapia.

• Journal of Embryo Transfer
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• v.33 no.4
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• pp.305-311
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• 2018

Gonadotropin releasing hormone (GnRH) centrally plays a role in control of the hypothalamic-pituitary-gonadal axis-related hormone secretions in the reproductive neuroendocrine system. In addition, hormone receptors like luteinizing hormone receptor (LHR) are important element for hormones to take effect in target organ. However, ageing-dependent changes in terms of the distribution of GnRH neurons in the brain and LHR expression in the acyclic ovary have not been fully understood yet. Therefore, we comparatively investigated those ageing-dependent changes using young (1-5 months), middle (11-14 months) and old (21-27 months) aged female mice. Whereas a number of GnRH positive fibers and neurons with monopolar or bipolar morphology were abundantly observed in the brain of the young and middle aged mice, a few GnRH positive neurons with multiple dendrites were observed in the old aged mice. In addition, acyclic ovary without repeated development and degeneration of the follicles was shown in the old aged mice than others. LHR expression was localized in theca cells, granulosa cell, corpora lutea and atretic follicle in the ovaries from young and middle aged mice, in contrast, old aged mice had few positive LHR expression on the follicles due to acyclic ovary. However, the whole protein level of LHR was higher in the ovary of old aged mice than others. These results are expected to be used as an important basis on the relationship between GnRH and LHR in old aged animals as well as in further research for reproduction failure.