• Fisheries and Aquatic Sciences
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• 제3권1호
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• pp.37-43
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• 2000

We used a mammalian GnRH antagonist, $[Ac-3,4-dehydro-Pro^1,\;D-p-F-Phe^2,\;D-Trp^{3.6}]$-GnRH, to examine the details of the salmon type gonadotropin-releasing hormone (sGnRH) and GnRH agonist analog $(Des-Gly^{10}$[d-Ala^6]-ethylamide GnRH; GnRHa) functions in the control of maturational gonadotropin (GTH II) secretion, in precocious male rainbow trout, in both in vivo and in vitro experiments. In the in vivo study, plasma GTH II levels increased by sGnRH or GnRHa treatment, but the response was more rapid and stronger in the GnRHa treatment group. The increase in GTH II was significantly suppressed by the GnRH antagonist, while the antagonist had no effect on basal GTH II levels in both groups. The GnRH antagonist showed stronger suppression of GTH II levels in the sGnRH treatment fish than in the GnRHa treatment fish. In addition, plasma androgenic steroid hormones (testosterone and 11-ketotestosterone) increased by the sGnRH or GnRHa treatment. The GnRH antagonist significantly inhibited the increases in plasma androgenic steroid hormone levels stimulated by the sGnRH or GnRHa, while the antagonist had no effect on basal androgenic steroid hormone levels in both groups. In the in vitro study, treatment with sGnRH or GnRHa increased GTH II release from the cultured dispersed pituitary cells, but the response was stronger in the GnRHa treatment group. The increase in GTH II release by GnRH was suppressed by adding the GnRH antagonist, dose­dependently. On the other hand, basal release of GTH II did not decrease by the GnRH antagonist treatment in both groups. These results suggest that the GnRH antagonist, $[Ac-3,4-dehydro-Pro^1,\;D-p-F-Phe^2,\;D-Trp^{3.6}]-GnRH$, used in this study is effective in blocking the action of GnRH-induced GTH II release from the pituitary gland both in vivo and in vitro.

• 한국발생생물학회지:발생과생식
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• 제6권2호
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• pp.131-139
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• 2002

최근 난포에서 GnRH와 그 수용체의 발현이 확인되면서 GnRH가 국소적으로 난소의 기능을 조절하고,특 히 과립세포의 세포자연사(apoptosis)를 유도하는 것으로 보고되고 있다. 그러나 황체에서 GnRH와 그 수용체의 발현과 기능에 대해서는 잘 알려져 있지 않다. 따라서 본 연구는 임신한 흰쥐의 황체세포에서 GnRH와 그 수용체가 발현되는지를 확인하고, 또한 GnRH가 황체세포의 세포자연사를 직접적으로 유발시킬 수 있는지를 알아보고자 시행하였다. 임신된 흰쥐로부터 황체세포를 획득하여 배양한 후 면역조직화학적 염색과 Western blot 방법으로 GnRH와 그 수용체의 발현을 확인한 결과 배양된 황체세포에서 GnRH와 그 수용체가 강하게 발현되는 것을 관찰할 수 있었다. GnRH가 배양된 황체세포의 세포자연사에 미치는 영향을 조사하기 위하여, $10^{-6}$ GnRH-agonist(GnRH-Ag)를 처리한 후 3, 8, 12시간에 TUNEL 방법과 DNA 분절화 검증 방법으로 세포자연사를 조사하였다. TUNEL 결과 세포자연사를 보이는 황체세포는 처리 후 12 시간에 GnRH-Ag 처리군에서 유의하게 증가하였다(p<0.05). 또한 DNA 분절화를 조사한 결과에서도 TUNEL 결과와 유사하게 GnRH-Ag처리 후 12 시간에 DNA 분절화가 유의하게 증가하였다(p<0.05). 이러한 세포자연사의 증가가 cytochrome c 방출과 연관이 있는지를 알아보고자 미토콘드리아로부터 방출된 cytochrome c를 Western blot 방법으로 정량한 결과, GnRH-Ag 처리 후 12 시간에 cytochrome c가 미토콘드리아로부터 세포질쪽으로 방출된 것을 확인할 수 있었다. 결론적으로 임신된 흰쥐의 황체세포에서 GnRH와 그 수용체 단백질이 발현되며 GnRH-Ag가 GnRH 수용체에 결합함으로써 cytochrome c가 미토콘드리아로부터 방출되고, 이로 인해 황체세포가 세포자연사하는 것을 알 수 있었다. 이러한 결과들은 국소적으로 분비되는 GnRH가 미토콘드리아로부터 cytochrome c의 방출을 유발시켜 황체세포의 세포자연사를 유도할 수 있다는 것을 제시하고 있다.

• Clinical and Experimental Reproductive Medicine
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• 제21권1호
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• pp.121-130
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• 1994

Expression of gonadotropin releasing hormone(GnRH) has been described in the rat ovary. It remains, however, unkown whether GnRH is synthesized as a prohormone. Therefore, this study was performed to verify the expression of pro-GnRH by in situ hybridization and further to investigate the effect of gonadotropin on GnRH or GnRH mRNA in rat ovary by immunohistochemical and in situ hybridization techniques. Adult female Sprague-Dawely rats were used and the estrous cycle was synchronized by intraperitoneal injection of pregnant mare's serum gonadotropin(PMSG). Ovaries were fixed with 4% paraformaldehyde and embedded with G.C.T. compound and cut by cryostat. For immunohistochemistry, avidin-biotin peroxidase complex(ABS) method was employed and for in situ hybridization, $^{35}S$-end labeled oligonucleotide was used and followed by autoradiography. By in situ hybridization using GnRH oligomer and GAP(GnRH associated protein) oligomer, GnRH mRNA and GAP mRNA were co-localized in the fullicular cells, luteal cells, interstitial cells and theca cells. GnRH or GnRH mRNA signals in the ovary increased by human chorionic gonadotropin(hCG) injection. At the 3 and 6 hrs after hCG injection, the number of GnRH and GnRH mRNA containing cells increased rapidly and the density of GnRH and GnRH mRHA culminated at 9 hrs after heG injection. With the follicular development, the high expression of GnRH and GnRH mRNA was also observed within the follicles. After ovulation, the density of GnRH or GnRH mRNA decreased in the follicles but increased in the corpus lutea.

• 한국임상수의학회지
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• 제19권3호
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• pp.322-327
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• 2002

The effect of GnRH alone and concomitant with PMSG on the prevention of implantation. termination of pregnancy, and concentration of plasma progesterone were studied in pregnant rats. GnRH 50, 100 or 200 ug alone and concomitant with PMSG 25 or 50 IU were administered once on day 2 or 9 of gestation, respectively. Rats were autopsied on days 7 or 20. Administration of GnRH on day 2 did not result in the prevention of implantation and termination of pregnancy but resulted in termination of pregnancy administering on day 9. Administration of GnRM concomitant with PMSG on day 2 or 9 resulted in prevention of implantation and termination of pregnancy, but injection of GnRH 50 ug concomitant with PMSG 25 IU on day 9 had only one live fetus. Administration of GnRH alone and concomitant with PMSG on day 2 had no effect on the concentration of plasma progesterone determining on day 7. Administration of GnRH concomitant with PMSG on day 2 resulted in decrease of progesterone level determining on day 20 but GnRH alone was normal level. Administration of GnRH alone and concomitant with PMSG on day 9 resulted in decrease of the concentration of progesterone but was normal concentration administering GnRH 50 ug concomitant with PMSG 25 IU.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.379-388
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• 2011

The mechanism by which gonadotropin-releasing hormone (GnRH) and dopamine (DA) control gonadotropin (GTH) release was studied in male and female rainbow trout using cultured pituitary cells obtained at different reproductive stages. The mechanisms of follicle-stimulating hormone (FSH) release by GnRH and DA could not be determined yet. However, basal and salmon-type GnRH (sGnRH)- or chicken-II-type GnRH (cGnRH-II)- induced luteinizing hormone (LH) release increased with gonadal maturation in both sexes. LH release activity was higher after sGnRH stimulation than cGnRH-II stimulation at maturing stages in both sexes. The GnRH antagonist ([Ac-3, 4-dehydro-$Pro^1$, D-p-F-$Phe^2$, D-$Trp^{3,6}$] GnRH) suppressed LH release by sGnRH stimulation in a dose-dependent manner, although the effect was weak in maturing fish. The role of DA as a GTH-release inhibitory factor differs during the reproductive cycle: the inhibition of sGnRH-stimulated LH release by DA was stronger in immature fish than in maturing, ovulating, or spermiated fish. DA did not completely inhibit sGnRH-stimulated LH release, and DA alone did not alter basal LH release. Relatively high doses ($10^{-6}$ or $10^{-5}M$) of domperidone (DOM, a DA D2 antagonist) increased LH release, which did not change with reproductive stage in either sex. The potency of DOM to enhance sGnRH-stimulated LH release was higher in maturing and ovulated fish than in immature fish. These data suggest that LH release from the pituitary gland is controlled by dual neuroendocrine mechanisms by GnRH and DA in rainbow trout, as has been reported in other teleosts. The mechanism of control of FSH release, however, remains unknown.

• 한국동물학회:뉴스레터
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• 제16권1호
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• pp.17-50
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• 1999

시상하부에 극히 적은 수로 존재하는 신경분비세포인 성선자극호르몬-방출호르몬(gonadotropin-releasing hormone; GnRH) 뉴런은인간을 포함한 포유동물의 생식과 발생 과정에 있어 중요한 역할을 담당하고 있다. GnRH 뉴런은 배아 발생과정 중에 후판에서 유래하여 시상하부의 여러 영역으로 이동하며, 생후와 사춘기를 거치면서 분화를 계속한다. GnRH 뉴런에서 합성, 분비되는 10개의 아미노산으로 이루어진 작은 신경호르몬인 GnRH는 맥동적으로 분비되어 뇌하수체 성선자극 세포막에 존재하는 GnRH 수용체와 결합한 후 일련의 신호전달과정을 거쳐 성선자극호르몬의 합성과 분비를 제어하게 된다. GnRH의 합성과 분비는 글루탐산, 노르에피네프린, GABA와 같은 각종 신경입력과 스테로이드 호르몬에 의한 액성 피드백 신호에 의해 조절되나 이들의 GnRH 유전자 발현에 미치는 영향은 최근에 연구되고 있는 실정이다. GnRH 뉴런의 분화와 발생에는 다양한 신경영양인자들이 영향을 미치나 그 분자생물학적 기작은 아직 밝혀져 있지 않다. 본 논단에서는 신경호르몬인 GnRH와 그 수용체에 관하여 최근 연구성과를 중심으로 살펴보고자 한다.

• Animal cells and systems
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• 제11권2호
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• pp.93-98
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• 2007

Gonadotropin-releasing hormone (GnRH), synthesized in the hypothalamus, plays a pivotal role in the regulation of vertebrate reproduction. Since molecular isoforms of GnRH and their receptors (GnRHR) have been isolated in a broad range of vertebrate species, GnRH and GnRHR provide an excellent model for understanding the molecular co-evolution of a peptide ligand-receptor pair. Vertebrate species possess multiple forms of GnRH, which have been created through evolutionary mechanisms such as gene/chromosome duplication, gene deletion and modification. Similar to GnRHs, GnRH receptors (GnRHR) have also been diversified evolutionarily. Comparative ligand-receptor interaction studies for non-mammalian and mammalian GnRHRs combined with mutational mapping studies of GnRHRs have aided the identification of domains or motifs responsible for ligand binding and receptor activation. Here we discuss the molecular basis of GnRH-GnRHR co-evolution, particularly the structure-function relationship regarding ligand selectivity and signal transduction of mammalian and non-mammalian GnRHRs.

• 한국동물학회지
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• 제34권4호
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• pp.491-499
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• 1991

The present experiment was carried out 1) to study the developmental topography of GnRH neuronal system and 2) to characterize the cellular localization of GnRH neurons in the prenatal brain development of the rat. At embryonic day (I) 14.5, immunoreactive cell bodies of GnRH were first seen in the nasal septum and in the ganglion terminate located in the ventral protion of the caudal olfactory bulb. Two days later (E 16.5), GnRH-containing neurons were observed at the level of olfactory tubercle and diagonal band of Broca, which is the first appearance in the intracerebral region. From 118.5, the topographic pattern of immunoreactive GnRH perikarya was similar to that of adult rats. The present data suggest that GnRH neurons were originated from the nasal septum and gradually extended to the hvpothalamic regions with increasing fetal age.

• 한국동물학회지
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• 제37권3호
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• pp.304-310
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• 1994

Using in situ hybridization, we have mapped the anatomical localization of perikarya containing myNA that codes for sonadotropin releasing hormone (GnRH) in the brains of female frogs, R. dybowskii. DNA olisomers, with sequences complementary to the GnRH portion of pro-GnRH myNA sequence, were synthesized and hybridized to paraformaldehvde-fixed, sagittal sections of the whole brain stem. The distribution of the GnRH mRNA containing cell bodies was similar to that described for GnRH peptide by immunohistochemistrv. That is, cells containing GnRH mRNA were observed in the medial septal area, anterior preoptic area, ventromedial hvpothalamus and infundibular regions. However, another cell groups which contains GnRH mRNAs were also detected by in situ hybridization in the bed nucleus of hippocampal commissure, preoptic area, nucleus infundibularis dorsalis, mesencephalic nuclei and intermediolateral cell column of spinal cord areas. These results demonstrate the feasibility of using in situ hybridization as a strategy to study the distribution of GnRH neurons and the detection of GnRH gene expression in the vertebrates.

• 한국수정란이식학회지
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• 제24권1호
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• pp.1-14
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• 2009

Ovarian cancer is a significant cause of cancer-related death in women, but the main biological causes remain open questions. Hormonal factors have been considered to be an important determinant causing ovarian cancer. Recent studies have shown that gonadotropin-releasing hormone (GnRH)-I and its analogs have clinically therapeutic value in the treatment of ovarian cancer. In addition, numerous studies have shown that the potential of GnRH-II in normal reproductive system or reproductive disorder. GnRH-I receptors have been detected in approximately 80% of ovarian cancer biopsy specimens as well as normal ovarian epithelial cells and immortalized ovarian surface epithelium cells. GnRH-II receptors have also been found to be more widely expressed than GnRH-I receptors in mammals, suggesting that GnRH receptors may have additional functions in reproductive system including ovarian cancer. The signal transduction pathway following the binding of GnRH to GnRH receptor has been extensively studied. The activation of protein kinase A/C (PKA/PKC) pathway is involved in the GnRH-I induced anti-proliferative effect in ovarian cancer cells. In addition, GnRH-I induced mitogen-activated protein kinase (MAPK) activation plays a role in anti-proliferative effect and apoptosis in ovarian cancer cells and the activation of transcriptional factors related to cellular responses. However, the role of GnRH-I and II receptors, there are discrepancies between previous reports. In this review, the role of GnRH in ovarian cancer and the mechanisms to induce anti-proliferation were evaluated.