• Asian-Australasian Journal of Animal Sciences
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• v.9 no.6
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• pp.711-714
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• 1996

The present study investigated the hypophysial responsiveness in terms of GnRH induced LH and FSH release in cycling buffalo during the tropical summer and winter climatic conditions (seasons). Peripheral plasma LH and FSH levels were measured at 1 hour before and 6 hours subsequent to the administration of GnRH (1 ug/kg body weight) or saline on Day 14 of oestrous cycle in 2 groups of buffalo (n = 6 each) during summer and winter seasons. Although GnRH induced LH peak concentrations did not differ during the two seasons, time to attain LH peak concentration was shorter (p < 0.05) and the area under LH peak was 39% higher (p < 0.05) during winter season in comparison to summer season. However, season had no effect on GnRH induced peak FSH concentration, time to attain peak FSH concentration and the area under FSH peak. Pretreatment basal LH and FSH levels did not differ during the two seasons. The present study suggests that the summer season adversely affects the GnRH stimulated release of LH in buffalo.

• Korean Journal of Animal Reproduction
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• v.25 no.1
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• pp.29-33
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• 2001

This study was conducted to investigate the effects of various estrus synchronization and seasonal breeding in Hanwoo. Delivery interval and number of service per conception were 412.9 and 1.76 in the annual breeding and 376.59 and 1.48 in the seasonal breeding, respectively. The percentage of cows exhibiting estrus in PG $F_{2{\alpha}}$, PRID, CIDR and CnRH-PG $F_{2{\alpha}}$-GnRH were 68.1%(141/207), 71.42%(15/20), 56.8%(33/38) and 93.1%(216/232), respectively. A greater percentage of GnRH-PG $F_{ 2{\alpha}}$-GnRH treatment became pregnant(91.1%) than across all treatments(75.0%, 81.0%, 89.6%). The results show that GnRH-PG $F_{2{\alpha}}$-GnRH treatment f3r pregnant in Hanwoo seems to be more effective than the others.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.3
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• pp.191-200
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• 2004

Objective: To compare the clinical efficacy of double intrauterine insemination with single intrauterine insemination in GnRH antagonist combined ovarian hyperstimulation (Mild ovarian hyperstimulation) Materials and Methods: From Jan. 2001 to Jul. 2004, a retrospective clinical analysis was done of a total of 295 cycles in 170 patients who underwent ovarian hyperstimulation for ART (assisted reproductive technique). Subjects were divided into three groups; only clomiphene citrate ovarian hyperstimulation (n=55, 95cycles), GnRH antagonist combined ovarian hyperstimulation (soft ovarian hyperstimulation) (n=66 99cycles), and GnRH agonist combined ovarian hyperstimulation (short protocol) (n=49, 101cycles) Each group were randomly devided into two subgroups. One group underwent single IUI and the other group underwent double IUI. Results: GnRH antagonist group and GnRH agonist group had similar pregnancy rate. In GnRH antagonist Group, pregnancy rate was 36.1% in single IUI subgroup and was 36.6% in double IUI subgroup. These finding were not statistically significant. And Pregnancy rate was 20.8% in single IUI subgroup and was 19.3% in double IUI subgroup in single clomiphene citrate group, and 36.3% in single IUI subgroup and was 33.3% in double IUI subgroup in GnRH agonist group. These finding were not statistically significant, too. Conclusion: Pregnancy rate of GnRH antagonist was high and complication rate such as OHSS and multiple pregnancy was lower. In GnRH antagonist group, to compare with single IUI and double IUI, the result do not statistically differ. So GnRH antagonist single injection with single IUI was relatively comparable ART in infertiliry patient.

• Korean Journal of Veterinary Research
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• v.21 no.1
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• pp.59-64
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• 1981

Holstein-Friesian cows(n=284) were given $100{\mu}g$ of gonadotropin-releasing hormone(GnRH) or saline solution by intramuscular injection at 10 to 22 days after parturition, and were investigated their reproductive performance and frequency of ovarian cysts. Among them 28 cystic cows were injected with $150{\mu}g$ of GnRH intramuscularly and examined the recovery rate. The results obtained in this study were summarized as follows: 1. The interval from calving to 1st ovulation was reduced from 28.2 days in controls to 16.5 days for cows given GnRH (p<0.01). 2. The intervals from calving to 1st estrus and from calving to conception were extended significantly in control group (p<0.05). 3. Inseminations per conception and conception rate at 1st insemination did not reveal difference between two groups. 4. Frequency of ovarian cysts was reduced from 14.0% in control to 4.20% for cows given GnRH (p<0.05). 5. Of the 28 cystic cows receiving $150{\mu}g$ of GnRH, 23(82.1%) responded to 1st treatment and returned to estrus $24.2{\pm}4.3$ days after treatment. 6. These data provide evidence for reduction in infertility and reproductive disorders in early postpartum dairy cows given GnRH as a prophylactic.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.8
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• pp.1059-1062
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• 2000

The objective of the investigation was to study the effect of intramuscular $PGF_2\;{\alpha}$ and GnRH on estrus behavior and ovarian response in Murrah buffalo heifers. Twelve Murrah buffalo heifers at 32 months of age that had not exhibited behavioral estrus symptom were included in the experiment. Out of 12,4 heifers were in follicular phase (plasma estradiol $57.05{\pm}12.52pg/ml$), another 4 heifers were in luteal phase (Plasma progesterone $2.24{\pm}0.25ng/ml$) while the ovaries of remaining four heifers were inactive (estradiol $23.70{\pm}1.66pg/ml$and progesterone $0.32{\pm}0.06ng/ml$). $PGF_2\;{\alpha}$ (25 mg, Lutalyse, im) and GnRH (200 ug, Fertagyl, iv) was administered to each heifer at interval of 10 days. The plasma progesterone concentration decreased within 48 hrs after $PGF_2\;{\alpha}$ injection and followed thereafter with follicular growth, estrus and ovulation. GnRH administration induced follicular growth, elevation of plasma estradiol concentration with subsequent exhibition of behavioral estrus in 2 out of 4 heifers having inactive ovary. The observation reveals that Murrah buffalo heifers at 32 months of age have developed receptors for $PGF_2\;{\alpha}$ and GnRH on ovarian and pituitary tissue respectively and response the single injection of $PGF_2\;{\alpha}$ and GnRH similar to the mature cycling animals.

• Korean Journal of Animal Reproduction
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• v.13 no.2
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• pp.79-84
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• 1989

This study was carried out to investigate the effect of LH-RH and Gn-RH treatment in Holstein cows with ovarian quiescence and follicular cystic ovaries. The cows with ovarian quiescence and follicular cystic ovaries injected intramuscularly with 100$\mu\textrm{g}$, 200$\mu\textrm{g}$ and 400$\mu\textrm{g}$ of LH-RH and 200$\mu\textrm{g}$ and 400$\mu\textrm{g}$ of Gn-RH respectively. The cows was diagnosed by repeated rectal palpation. The plasma progesterone and estradiol-17$\beta$ concentrations were assayed by radioimmunoassay methods. The resutls of this study were summarized as follows : 1. Ovulations were induced after treatment of LH-RH and Gn-RH. The concentrations of progesterone reached small peak level at luteal phase and estradiol-17$\beta$ reached obvious peak level with the development and maturation of the follicle during the periods of degeneration of the corpus luteum, and normal ovarian cycle activity started subsequently. 2. The cows with ovarian quiescence and follicular cystic ovaries were induced ovulation at 38.9$\pm$5.3 hrs. after treatment of LH-RH in 66.7% cows and at 52.7$\pm$7.9 hrs after treatment of Gn-RH in 60.0% cows respectively. 3. The good ovarian responses were indicated in treatment with 200$\mu\textrm{g}$ to 400$\mu\textrm{g}$ of LH-RH than those treated with 100$\mu\textrm{g}$ in cows with ovarian quiescence, and did not show difference of ovarian responses between treatments with 200$\mu\textrm{g}$ to 400$\mu\textrm{g}$ of Gn-RH in cows with follicular cystic ovaries.

• Journal of Aquaculture
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• v.9 no.3
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• pp.205-213
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• 1996

Experiments were carried out to investigate the effect of GnRH-analogue (GnRH-a) on the induction of ovulation in catfish, S. asotus. Fully matured female catfish ($250\~600\;g$) received a single intraperitoneal injection of GnRH-a ($50\~200\;{\mu}g/kg{\cdot}body$ weight) showed the successful induction of ovulation. More than $86\%$ of treated females were ovulated after injection of GnRH-a ($90\;{\mu}g/kg$) at $25{\pm}1^{\circ}C$. The majority of spawning took place within 22 to 25 hours after the injection. The gonadosomatic index (GSI) and pseudo-GSI in the group treated with $120\;{\mu}g/kg$ GnRH-a were $23-30\%$ and $18-21\%$, respectively. Average fertilization and hatching rates were $94\%\;and\;81\%$, respectively. Electron microscopically, gonadotrophs of maturing female catfish were characterized by the presence of numerous small, electron-dense granules of approximately $150\~300$ nm in diameter and a few larger, less electron-dense granules of approximately $800\~1000$ nm in size in their cytoplasm. Gonadotrophs of GnRH-a treated catfish showed that their was a distinct decrease in number of small and large granules. The rough endoplasmic reticulum was composed of numerous cisternae conspicuosly dilated to various degrees.

• Clinical and Experimental Pediatrics
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• v.53 no.9
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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.

• Korean Journal of Veterinary Research
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• v.63 no.2
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• pp.14.1-14.4
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• 2023

This study evaluated the effect of resynchronization programs on pregnancies in dairy cows. Of 1,342 cows confirmed not pregnant after their first artificial insemination (AI), those with a corpus luteum (CL) were resynchronized using Ovsynch or PG-GnRH-Ovsynch and those without a CL were resynchronized using GnRH-Ovsynch or modified Double-Ovsynch. There were no differences (p > 0.05) in the pregnancies per AI either between the Ovsynch (31.3%) and PG-GnRH-Ovsynch (34.0%) or between the GnRH-Ovsynch (38.7%) and modified Double-Ovsynch (39.5%). In conclusion, Ovsynch and GnRH-Ovsynch programs could be preferred to resynchronize cows with and without a CL, respectively, from the perspective of reducing costs and labor.

• Clinical and Experimental Reproductive Medicine
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• v.18 no.1
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• pp.1-11
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• 1991