• 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.

• 한국발생생물학회지:발생과생식
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• 제13권4호
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• pp.353-362
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• 2009

GnRH는 국부적으로 난소에서 합성되며, 난소내 과립 및 황체세포에 직접적으로 작용하여 난소의 기능을 조절하는 것으로 알려져 있으며, 특히, GnRH는 난소내 과립-황체화 세포의 세포자연사를 유도하는 것으로 보고하고 있다. 그러나 GnRH에 의한 세포자연사가 FSH에 의해 회복될 수 있는지는 명확히 밝혀져 있지 않다. 따라서 본 실험에서 난자 채취시 획득한 사람 과립-황체화 세포를 배양한 후 5, 50, 100 ng/$m\ell$ GnRH와 1 IU/$m\ell$ FSH를 처리하고 세포의 세포자연사 여부와 분비된 progesterone$(P_4)$과 estradiol$(E_2)$ 양의 변화를 조사하였다. DNA 분절화 분석과 TUNEL 방법으로 세포자연사를 평가한 결과, GnRH는 농도 의존적으로 과립-황체화 세포의 세포자연사를 증가시켰고, 특히 100 ng/$m\ell$ GnRH을 처리한 군에서 유의한 차이를 보이며 세포자연사 비율이 증가하였다. 또한 GnRH에 의한 세포자연사의 증가는 FSH에 의해 억제되는 것을 확인할 수 있었다. 화학발광면역 측정법을 이용하여 배양내 $P_4$와 $E_2$의 양을 측정한 결과, GnRH을 처리한 후 $E_2$의 양은 변화가 없었던 반면 $P_4$의 양은 감소하였다. 이러한 GnRH의 $P_4$ 합성 억제 효과는 세포자연사 결과 마찬가지로 FSH에 의해 회복되는 것을 확인할 수 있었다. 이상의 결과는 체외수정 및 배아이식 시술시 사용되고 있는 GnRH 작용제가 난소의 기능을 억제시킬 수 있을 것으로 보이나, 다량으로 투여되는 FSH에 의해 회복될 수 있음을 보여주고 있다. 이러한 실험 결과는 난소에 대한 GnRH의 생리적 기전을 이해하고 향후 새로운 과배란 유도 방법을 개발하는데 필요한 기초 자료로 사용될 수 있을 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제11권1호
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• pp.78-83
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• 1998

The objective of this study was to investigate the responsiveness of hypophysis and gonads to synthetic GnRH among prepubertal buffalo heifers at 12 months of age. Peripheral plasma FSH, LH, estradiol and progesterone level were measured in blood samples collected at 1 hr before and up to 18 days subsequent to the administration of $200{\mu}g$ GnRH (n=6) or saline (n=6) in Murrah buffalo heifers. The pretreatment peripheral plasma FSH, LH, estradiol and progesterone among GnRH treated heifers were $7.35{\pm}0.45ng/ml$, $1.08{\pm}0.3ng/ml$, $22.93{\pm}1.06pg/ml$ and $0.27{\pm}0.04ng/ml$ respectively. A quick elevation (p < 0.01) of FSH and LH within five min of GnRH administration was observed in all geifers. Although the peak FSH $(89.57{\pm}23.43ng/ml)$ and LH $(7.52{\pm}3.08ng/ml)$ reached by 10 min of GnRH administration, yet the animals differed both in terms of their amplitude response of FSH and LH release as well as in terms of time which animals took to exhiit maximum response to GnRH administration. The GnRH administration did not cause alteration in plasma estradiol and progesterone level. The present study suggests that the pituitary of 12 month buffalo heifers has capacity to synthesize and store of gonadotropin and have developed receptors for GnRH for a spike of gonadotropin release.

• Clinical and Experimental Reproductive Medicine
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• 제32권4호
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• pp.315-324
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• 2005

Objectives: To compare the efficacy of GnRH antagonist multiple dose protocol (MDP) with that of GnRH agonist long protocol (LP) in controlled ovarian hyperstimulation for in vitro fertilization in patients with high basal FSH (follicle stimulating hormone) level or old age, a retrospective analysis was done. Methods: Two hundred ninety four infertile women (328 cycles) who were older than 41 years of age or had elevated basal FSH level (> 8.5 mIU/mL) were enrolled in this study. The patients had undergone IVF-ET after controlled ovarian hyperstimulation using GnRH antagonist multiple dose protocol (n=108, 118 cycles) or GnRH agonist long protocol (n=186, 210 cycles). The main outcome measurements were cycle cancellation rate, consumption of gonadotropins, the number of follicles recruited and total oocytes retrieved. The number of fertilized oocytes and transferred embryos, the clinical pregnancy rates, and the implantation rates were also reviewed. And enrolled patients were divided into three groups according to their age and basal FSH levels; Group A - those who were older than 41 years of age, Group B - those with elevated basal FSH level (> 8.5 mIU/mL) and Group C - those who were older than 41 years of age and with elevated basal FSH level (> 8.5 mIU/mL). Poor responders were classified as patients who had less than 4 retrieved oocytes, or those with $E_2$ level <500 pg/mL on the day of hCG injection or those who required more than 45 ampules of exogenous gonadotropin for stimulation. Results: The cancellation rate was lower in the GnRH antagonist group than in GnRH agonist group, but not statistically significant (6.8% vs. 9.5%, p=NS). The amount of used gonadotropins was significantly lower in GnRH antagonist group than in agonist group ($34.8{\pm}11.3$ ampules vs. $44.1{\pm}13.4$ ampules, p<0.001). The number of follicles > 14 mm in diameter was significantly higher in agonist group than in antagonist group ($6.7{\pm}4.6$ vs. $5.0{\pm}3.4$, p<0.01). But, there were no significant differences in clinical pregnancy rate (24.5% in antagonist group vs. 27.4% in agonist group, p=NS) and implantation rate (11.4% in antagonist group vs. 12.0% in agonist group, p=NS) between two groups. Mean number of retrieved oocytes was significantly higher in GnRH agonist LP group than in GnRH antagonist MDP group ($5.4{\pm}3.5$ vs. $6.6{\pm}5.0$, p<0.0001). But, the number of mature and fertilized oocytes, and the number of good quality (grade I and II) and transferred embryos were not different between two groups. In each group A, B, and C, the rate of poor response did not differ according to stimulation protocols. Conclusions: In conclusion, for infertile women expected poor ovarian response such as who are old age or has elevated basal FSH level, a protocol including a controlled ovarian hyperstimulation using GnRH antagonist appears at least as effective as that using a GnRH agonist, and may offer the advantage of reducing gonadotropin consumption and treatment period. However, much work remains to be done in optimizing the GnRH antagonist protocols and individualizing these to different cycle characteristics.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• 제11권4호
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• pp.416-421
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• 1998

The objective of this study was to investigate the responsiveness of hypophysis and gonads to synthetic GnRH among noncycling Murrah buffalo heifers at 24 months of age. The plasma FSH, LH, estradiol and progesterone levels were measured in blood samples collected at 1 hour before and upto 18th day subsequent to the administration of GnRH ($(200 {\mu}g)$) or saline (2 ml). The pretreatment levels of plasma FSH, LH estradiol and progesterone among GnRH treated heifers (N = 6) were $11.55{\pm}0.57ng/ml$, $0.68{\pm}0.06ng/ml$, $19.84{\pm}0.82pg/ml$ and $0.45{\pm}0.07ng/ml$ respectively. A quick elevation of FSH (p < 0.01) and LH (p < 0.05) within 5 min of GnRH administration was observed in all the heifers. The peak FSH ($74.97{\pm}18.63ng/ml$) and LH ($3.09{\pm}0.54ng/ml$) level was obtained at 30 min of GnRH administration. The elevated level of plasma estradiol on 5th to 18th day, FSH on 7th to 9th day (n = 3) and the progesterone on 13th to 18th day (n = 2) of GnRH injection was obtained. The study indicates that gonads of buffalo heifers at 24 months of age are responsive of GnRH induced gonadotropin release for folliculogenesis and luteal tissue formation

• Animal cells and systems
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• 제1권4호
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• pp.595-602
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• 1997

Treatment of newborn female rats with gonadal steroids induces permanent sterility in adulthood. We investigated the alteration in expression patterns of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) in neonatally estrogenized sterile rats (ESR). Newborn female rats received daily injections of 17${\beta}$-estradiol (E, 10 ${\mu}$g) from the day of birth (day 1) to postnatal day 5. Controls were subjected to vehicles over the same period. All animals were sacrificed on week 7 after birth. Hypothalamic GnRH mANA levels were markedly higher in all ESR than in controls, while hypothalamic GnRH contents in ESR increased in proportion to the frequency of daily administration of E. However, both pituitary LH6 mRNA and serum LH levels were inversely decreased by the same treatment. The data indicate that neonatal exposure of E equally elevates the expression of GnRH gene, but reduces the secretion of GnRH, accordingly leading to attenuation of LH6 gene expression and circulating LH levels. The temporal effect of E and/or progesterone (P) on GnRH and LH6 mRNA levels was also examined in ESR. Newborn female rats were daily injected with E (10 ${\mu}$g) or vehicle for five successive days from day 1 and ovariectomized at week 5. They were implanted with E (235 ${\mu}$g/ml) two days prior to week 7, injected with P (1 mg) 42 h later, and sacrificed 7 h after P administration. In ovariectomized controls, hypothalamic GnRH mRNA levels were dropped to half by treatment of E and restored by subsequent treatment of P. The negative feedback action of E on GnRH mRNA levels observed in ovariectomized rats was completely blocked by neonatal exposure of E. The change in pituitary LH mRNA levels was similar to that in hypothalamic GnRH mRNA levels. Taken together, the results suggest that neonatal treatment of E alters the synthesis and release of GnRH in adulthood and furthermore blocks the negative feedback regulation of E which occurs normally after ovariectomy.

• Clinical and Experimental Reproductive Medicine
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• 제34권2호
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• pp.125-131
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• 2007

목 적: 난소 반응이 저하된 환자에서 GnRH agonist flare up protocol과 GnRH antagonist protocol의 효용성을 비교하고자 하였다. 연구방법: 2003년 1월부터 2005년 8월까지 체외수정시술을 받은 환자들 가운데 이전의 체외수정시술 주기에서 5개 이하의 난자가 채취되고 기저 FSH 농도가 12 mIU/ml 이상인 총 144명 가운데 73명은 GnRH agonist flare up요법을 사용하였고 71명은 GnRH antagonist 요법을 사용하였다. 양군간에 주기의 취소율, 채취된 난자수, 양질의 수정란의 수, 착상율, 임신율, 출산율을 비교하였다. 결 과: 각 군간에 나이는 평균 37.4세와 38.1세로 antagonist group에서 높았으나 통계학적 유의성은 없었다. 그 외에 기저 FSH 농도와 이전 주기의 취소율도 통계학적 유의성은 없었다. GnRH agonist flare up 주기와 GnRH antagonist 주기에서 취소율은 각각 30.1%, 53.5%로 GnRH antagonist protocol에서 유의 있게 높게 나타났다. 채취된 난자수도 각각 4.18개와 2.16개로 차이를 보였으며 난소 과자극 기간은 각각 10.5일과 9.2일로 antagonist protocol에서 약간 낮은 모습을 보였다. 최고 혈중 E$_2$의 농도와 good embryo 개수도 GnRH agonist flare up요법에서 유의 있게 높게 나타났다. 각 군에서의 착상율, 이식 주기당 임신율, 이식 주기당 출생율은 GnRH agonist flare up요법에서 약간 높은 경향을 보이기는 하였으나 통계학적인 유의성은 없었다. 결 론: 두 군간의 비교에서 GnRH agonist flare up 요법이 시작 주기당 임신율, 출산율에서 높은 경향을 보였으나 통계학적 의의는 없었다. 하지만 난소기능이 저하된 환자에서 난자의 채취 개수는 GnRH agonist flare up 요법이 GnRH antagonist를 사용한 주기보다 의의있게 높게 나타났다. 이러한 연구 결과로 볼 때 저 반응군에 있어서 GnRH antagonist flare up요법이 저 반응군에 있어 향상된 난소 반응을 기대할 가능성이 높을 것으로 생각된다.

• Clinical and Experimental Pediatrics
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• 제53권9호
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• pp.845-851
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• 2010

Purpose: Recombinant human growth hormone (rhGH) has been widely used to treat short stature. However, there are some concerns that growth hormone treatment may induce skeletal maturation and early onset of puberty. In this study, we investigated whether rhGH can directly affect the neuronal activities of of gonadotropin-releasing hormone (GnRH). Methods: We performed brain slice gramicidin-perforated current clamp recording to examine the direct membrane effects of rhGH on GnRH neurons, and a whole-cell voltage-clamp recording to examine the effects of rhGH on spontaneous postsynaptic events and holding currents in immature (postnatal days 13-21) and adult (postnatal days 42-73) mice. Results: In immature mice, all 5 GnRH neurons recorded in gramicidin-perforated current clamp mode showed no membrane potential changes on application of rhGH (0.4, $1{\mu}g/mL$). In adult GnRH neurons, 7 (78%) of 9 neurons tested showed no response to rhGH ($0.2-1{\mu}g/mL$) and 2 neurons showed slight depolarization. In 9 (90%) of 10 immature neurons tested, rhGH did not induce any membrane holding current changes or spontaneous postsynaptic currents (sPSCs). There was no change in sPSCs and holding current in 4 of 5 adult GnRH neurons. Conclusion: These findings demonstrate that rhGH does not directly affect the GnRH neuronal activities in our experimental model.

• Clinical and Experimental Pediatrics
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• 제55권9호
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• pp.337-343
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• 2012

Purpose: Leptin has been considered a link between metabolic state and reproductive activity. Defective reproductive function can occur in leptin-deficient and leptin-excessive conditions. The aim of this study was to examine the effects of centrally injected leptin on the hypothalamic KiSS-1 system in relation to gonadotropin-releasing hormone (GnRH) action in the initial stage of puberty. Methods: Leptin (1 ${\mu}g$) was injected directly into the ventricle of pubertal female mice. The resultant gene expressions of hypothalamic GnRH and KiSS-1 and pituitary LH, 2 and 4 hours after injection, were compared with those of saline-injected control mice. The changes in the gene expressions after blocking the GnRH action were also analyzed. Results: The basal expression levels of KiSS-1, GnRH, and LH were significantly higher in the pubertal mice than in the prepubertal mice. The 1-${\mu}g$ leptin dose significantly decreased the mRNA expression levels of KiSS-1, GnRH, and LH in the pubertal mice. A GnRH antagonist significantly increased the KiSS-1 and GnRH mRNA expression levels, and the additional leptin injection decreased the gene expression levels compared with those in the control group. Conclusion: The excess leptin might have suppressed the central reproductive axis in the pubertal mice by inhibiting the KiSS-1 expression, and this mechanism is independent of the GnRH-LH-estradiol feedback loop.