• Development and Reproduction
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• v.26 no.2
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• pp.37-47
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• 2022

Photoperiod has well been established to regulate testicular activities in golden hamsters. These animals breed actively around summer but become infertile in winter. In males, testicles are full of multistep germ cells including spermatozoa in summer. But in winter only fundamental cells consisting of the testicles are detected. The testicular degeneration is accompanied by the reduced levels of blood gonadotropins and testosterone. In this study, the expressions of gonadotropin subunit genes were investigated in the reproductive active and inactive testicles. And parts of sequences of the gonadotropin subunits were identified and compared with those of other rodents. As results, common gonadotropin alpha (CGa), follicle-stimulating hormone (FSH) β, and luteinizing hormone (LH) β genes were equivalently detected in pituitaries of both sexually active and inactive animals. In considering low concentrations of gonadotropin hormones determined in pituitary, the present findings imply that the processes involved in translation and/or formation of functional hormones could be impeded in the sexually inactive hamsters. All the nucleotide sequences of gonadotropin subunits identified in this study were same as those reported previously except for one base in CGa. An unsure amino acid deduced from the CGa sequence was confirmed from mRNA sequencing. The outcomes mentioned above suggest that animals with regressed testes prepare for the sexually active period forthcoming in the future.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.3
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• pp.219-224
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• 2009

Objective: Hypogonadotropic hypogonadism (HH) is an uncommon cause of male infertility. We investigated the outcome of gonadotropin therapy for restoring fertility and pregnancy outcomes in patients with HH. Methods: Medical charts of 10 infertile male patients with HH treated with gonadotropin were reviewed. Initial testicular volume were estimated. Semen analysis parameters (semen volume, sperm counts, motility), serum leutenizing hormone (LH), follicle stimulating hormone (FSH), total testosterone were determined before and after human chorionic gonadotropin/human menopausal gonadotropin (hCG/hMG) treatment. Differences were analyzed statistically. Results: Of 10 patients, 7 (70%) succeed at pregnancy (nature pregnancy in 4). Semen analysis parameters, serum FSH, and testosterone were increased significantly after treatment. The population was stratified according to initial testicular volume into a small testis subset (testicular volume less than 10 cc in 4) and a large testis subset (testicular volume 10 cc or greater in 6). Semen analysis parameters and serum testosterone were increased significantly after treatment in large testis subset. Conclusion: Infertile men with HH initiate and maintain spermatogenesis with gonadotropin (hCG/hMG alone or combined) therapy, thus gonadotropin therapy is good choice in infertile men with HH.

• The Korean Journal of Pharmacology
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• v.23 no.2
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• pp.57-75
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• 1987

Two modalities of gonadotropin secretion, pulsatile gonadotropin and preovulatory gonadotropin surge, have been identified in the mammals. Pulsatile gonadotropin secretion is modulated by the pulsatile pattern of GnRH release and complex ovarian steroid feedback actions. The neural mechansim that regulates the pulsatile release of GnRH in the hypothalamus is called "GnRH pulse generator". Ovarian steroids, estradiol and progesterone, appear to exert thier feedback effects both directly on the pituitary to modulate gonadotropin release and on a hypothalamic site to modulate GnRH release; estradiol primarily affects the amplitude while progesterone decreases the frequency of the pulsatile GnRH. Steroid hormones are known to affect catecholamine transmission in brain. MBH-POA is richly innervated by NE systems and close apposition of NE terminals and GnRH cell bodies occurs in the MBH as well as in the POA. NE normally facilitates pulsatile LH release by acting through ${\alpha}-receptor$ mechanism. However, precise nature of facilitative role of NE transmission in maintaining pulsatile LH has not been clearly understood. Close apposition of DA and GnRH terminals in ME might permit DA to influence GnRH release. Action of DA transmission probably is mediated by axo-axonic contacts between GnRH and DA fibers in the ME. Dopamine transmission does not normally regulate pulsatile LH release, but under certain conditions, increased DA transmission inhibit LH pulse. Endogenous opioid acts to suppress the secretion of GnRH into hypophysial portal circulation, thereby inhibiting gonadotropin secretion. However, an interaction between endogenenous opioid peptides and gonadotropin release is a complex one which involves ovarian hormones as well. LH secretion appears to be most suppressed by endogenenous opioids during the luteal phase, at a time of elevated progesterone secretion. The arcuate nucleus contains not only cell bodies for GnRH and ${\beta}-endorphin$ but also a dense aborization of fibers suggesting that GnRH release is changed by the interactions between GnRH and ${\beta}-endorphin$ cell bodies within the arcuate nucleus. The frequency and amplitude of pulsatile LH release seem to be increased during the preovulatory gonadotropin surge. Estradiol exerts positive feedback action on the hypothalamo-pituitary axis to trigger preovulatory LH surge. GnRH is also crucial hormonal stimulus for preovulatory LH surge. It is unlikely, however, that increased secretion of GnRH during the preovulatory gonadotropin surge represents an obligatory neural signal for generation of the LH discharge in primates including human. Modulation of preovulatory LH surge by catecholamines has been studied almost exclusively in rats. NE and E may be involved in distinct way to accumulate GnRH in the MBH and its release into the hypophysial portal system during the critical period for LH surge on proestrus in rats. However, the mechanisms whereby augmented adrenergic transmission may facilitate the formation and accumulation of GnRH in the ME-ARC nerve terminals before the LH surge have not been clearly understood.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.427-428
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• 2002

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.08a
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• pp.230.2-231
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• 2002

• Clinical and Experimental Pediatrics
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• v.53 no.3
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• pp.294-299
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• 2010

Although the increasing incidence of central precocious puberty (CPP) in Korea has recently raised public concerns about health and growth problems, there are many areas of uncertainty regarding the pathogenesis, diagnosis, and management of CPP. In this paper, we review the definition of precocity, the assessment of CPP, and the hormonal abnormalities that support the diagnosis. In addition, we review the practical guidelines regarding the clinical use of gonadotropin-releasing hormone analogs in children with CPP. Indications for treatment, determination of dosage, monitoring during treatment, and discontinuation of therapy are discussed.

• Clinical and Experimental Reproductive Medicine
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• v.28 no.1
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• pp.73-77
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• 2001

Objective: To report the pregnancy which was made by in vitro fertilization using recombinant follicle stimulating hormone and gonadotropin releasing hormone antagonist. Material and Method: Case report. Results: Six oocytes were retrieved and all were fertilized by intracytoplasmic sperm injection. Six embryos were transferred and the pregnancy was confirmed. Conclusion: It is envisaged that the availability of recombinant gonadotropins and gonadotropin releasing hormone antagonists will ultimately lead to shorter, cheaper and safer treatments, using reduced dosages.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.1
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• pp.1-5
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• 1991

Responsiveness of the testis to pregnant mare's serum gonadotropin (PMSG) was studied in immature Nili-Ravi buffalo bulls. Four month old bull calves weighing between 66 to 100 kg raised under uniform condition, were treated with 1000 IU PMSG or vehicle, daily, for six days. PMSG induced an increase in the size of the testis, enlargement of the seminiferous tubules and activation of the spermatogonia. The number of differentiated Leydig cells in the testis of gonadotropin treated animals increased considerably over that of the control testes. A significant increase in plasma testosterone concentrations was observed 24 h following the first injection of PMSG and the levels continued to increase until day 6. In vehicle treated animals plasma testosterone levels remained more or less at pretreatment values. The data suggest that buffalo bull testis is functionally responsive to gonadotropin at an early stage of prepubertal development.

• Clinical and Experimental Reproductive Medicine
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• v.14 no.2
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• pp.119-126
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• 1987

Exponential rise rate(ERR) of serum estradiol concentrations during active follicular phase was calculated for 49 ovulation induction cycles by human menopausal gonadotropin to know the ovulation induction outcome according to ERR classified into 3 groups with low, moderate and high ERR values(Group I${\leqq}$0.3, 0.3${\leqq}$0.6，Group III>0.6). The results were summarised as follows : 1. No significant difference in the dosage of human menopausal gonadotropin was identified in each group. 2. The mean serum estradiol concentration at the day of human chorionic gonadotropin injection in Group II and Group ill was significantly higher than that in Group I . 3. The mean diameter of leading follicles at the day of human chorionic gonadotropin injection showed no significant difference in each group. 4. No significant difference in the ovulation rate was observed in relation to ERR. How ever, 20% and 20.8% of pregnancy rate in Group I and Group II were achieved while no pregnancy was occurred in Group III. 5. The ovarian hyperstimulation frequency was significantly higher in Group ill that in Group I and Group II. In conclusion, the study suggests that exponential rise rate of serum estradiol is a useful tool in HMG ovulation induction by preventing ovarian hyperstimulation without reducing pregnancy success rate.

• Journal of Aquaculture
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• v.9 no.1
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• pp.3-10
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• 1996

Ovulation of maturing female yellow puffer, Takifugu obscrus, was induced by using single injection of human chorionic gonadotropin (HCG) or gonadotropin releasing hormone-analogue (GnRH-A) $des-Gly^{10}[D-Ala^6]$ GnRH-ethylamide plus pimozide. The response was evaluated using the fertilization and embryo-formation rate after insemination and the gonadotropin (GTH) level in blood plasma using radioimmunoassay. In the fertilization and embryo-formation, maximal effects were recorded by using 1,000 IU/kg HCG or $10\;{mu}g/kg$ GnRH-A plus 5 mg/kr pimozide. Pimozide (1, 5 mg/kg) or GnRH-A treatment alone was not effective in elevation of GTH level, however combinations of these treatments were particularly effective. Injection of dopamine blocked the rapid elevation of plasma GTH levels of blood. These data suggest that yellow puffer secrete GnRH and gonadotropin-releasing-inhibiting factor during the spawning or the other period.