• Clinical and Experimental Reproductive Medicine
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• v.37 no.3
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• pp.239-244
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• 2010

Objective: The objective of this retrospective study was to compare the in vitro fertilization (IVF) outcomes of gonadotropinreleasing hormone (GnRH) agonist and GnRH antagonist protocols in poor responders. Methods: A total of 172 cycles in subjects with less than 5 oocytes retrieved treated with either GnRH agonist long protocols or antagonist protocols were included. The outcome variables such as numbers of growing follicles and retrieved oocytes, and the fertilization rate were evaluated as the main outcome measures. Results: There was no difference in regard to the numbers of growing follicles and oocytes, and fertilization rate between the two groups. $E_2$ level on Day 7/8, mean gonadotropin dose, and the days of stimulation were shown to be statistically different (p<0.01, respectively). Conclusion: Considering that similar results were observed with less time and gonadotropin dose, GnRH antagonist protocol may be considered as a preferable choice over GnRH agonist protocols in poor responders.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.96-96
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• 2002

We examined the role of SR 144528 (N-[-(1S-endo-1,3,,3-trimethyl-bicycle[2, 2, 1 ] heptan-2-y1]-5-(-4-chloro-3-mothyl-phenyl)-(4-methylbenzyl)-pyrazole-3- carboxamide) in the modulation of certain AC isoforms in transiently transfected COS-7 cells. We found that CB2 in COS cells has a constitutive activity, and thus leading to inhibition of AC-V activity even in the absence of agonist. In addition, this constitutive modulation of AC is reversed by SR144528. It is now well established that several G protein-coupled receptors can signal without agonist stimulation(constitutive receptors). Inverse agonists have been shown to inhibit the activity of such constitutive G protein-coupled receptor signaling. Agonist activation of the G$\_$i/o/-coupled peripheral cannabinoid receptor CB2 normally inhibits adenylyl cyclase type V and stimulates adenylyl cyclase type II. Using transfected COS cells, we show here that application of SR144528, an inverse agonist of CB2, leads to a reverse action (stimulation of adenylyl cyclase V and inhibition of adenylyl cyclase II). This inverse agonism of SR144528 is dependent on the temperature, as well as on the concentration of the cDNA of CB2 transfected. Pertussis toxin blocked the regulation of adenylyl cyclase activity by SR 144528.

• Molecular & Cellular Toxicology
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• v.4 no.1
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• pp.72-77
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• 2008

The present study was undertaken to determine whether pioglitazone treatment influences on the agonist-induced vascular smooth muscle contraction and, if so, to investigate the related mechanism. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Pioglitazone decreased Rho-kinase activating agonist-induced contraction but not phorbol ester-induced contraction suggesting the least involvement of $Ca^{2+}$-independent thin filament regulation of contractility. Furthermore, pioglitazone decreased thromboxane $A_2$ mimeticinduced phosphorylation of MYPT1 at Thr855, the newly-highlighted site, instead of Thr696. In conclusion, this study provides the evidence and possible related mechanism concerning the vasorelaxing effect of pioglitazone as an antihypertensive on the agonist-induced contraction in rat aortic rings regardless of endothelial function.

• Korean Journal of Veterinary Service
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• v.40 no.1
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• pp.79-82
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• 2017

We investigated the residues of ${\beta}-agonist$ (zilpaterol, ractopamine and clenbuterol) using LC-MS/MS in raw meat in Seoul. The recoveries ranged between 76.7~89.9% in beef respectively. The limits of detection were $0.01{\sim}0.09{\mu}g/kg$ and the limits of quantification were $0.03{\sim}0.28{\mu}g/kg$ respectively. Residues of ${\beta}-agonist$ drugs which exceeded maximum residue limits (MRL) were not exceed in any of the 267 samples.

• Journal of Korean Neurosurgical Society
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• v.42 no.6
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• pp.455-461
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• 2007

Objective : It was hypothesized that dopamine agonist administration and subthalamic nucleus (STN) lesion in the rat might have a synergistic effect on the neuronal activities of substantia nigra pars reticulata (SNpr) as observed in patients with Parkinson's disease. The effects of SKF38393 (a $D_1$ receptor agonist) and Quinpirole (a $D_2$ receptor agonist) were compared in parkinsonian rat models with 6- hydroxydopamine (6-OHDA) after STN lesion. Methods : SKF38393 and Quinpirole were consecutively injected intrastriatally. SNpr was microrecorded to ascertain the activity of the basal ganglia output structure. The effect of SKF38393 or Quinpirole injection on the firing rate and firing patterns of SNpr was investigated in medial forebrain bundle (MFB) lesioned rats and in MFB+STN lesioned rats. Results : The administration of SKF38393 decreased SNpr neuronal firing rates and the percentage of burst neurons in the MFB lesioned rats, but did not alter them in MFB+STN lesioned rats. The administration of Quinpirole significantly decreased the spontaneous firing rate in the MFB lesioned rats. However, after an additional STN lesion, it increased the percentage of burst neurons. Conclusion : This study demonstrated that dopamine agonists and STN lesion decreased the hyperactive firing rate and the percentage of burst neurons of SNpr neurons in 6-OHDA lesioned rats, respectively. Quinpirole with STN lesion increased a percentage of burst neurons. To clear the exact interactive mechanism of $D_1$ and $D_2$ agonist and the corresponding location, it should be followed a study using a nonselective dopamine agonist and $D_1$, $D_2$ selective antagonist.

• Clinical and Experimental Reproductive Medicine
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• v.32 no.4
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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.

• Clinical and Experimental Reproductive Medicine
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• v.39 no.1
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• pp.22-27
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• 2012

Objective: To evaluate the effectiveness of GnRH antagonist multiple dose protocol applied during early and late follicular phase (MDP-EL) in comparison with standard GnRH agonist luteal long protocol (LP) in each non-obese and obese polycystic ovary syndrome (PCOS) women undergoing IVF. Methods: Two hundred eleven infertile women with PCOS were recruited and randomized to undergo either GnRH antagonist MDP-EL (antagonist group) or standard GnRH agonist luteal LP (agonist group). IVF cycle outcomes were compared between the two groups. Results: Total dose and days of recombinant human follicle stimulating hormone (rhFSH) administered were significantly fewer in the antagonist group than in the agonist group. Incidence of severe ovarian hyperstimulation syndrome was significantly lower in the antagonist group. However, IVF and pregnancy outcomes were similar in the two groups. When all subjects were divided into non-obese and obese subgroups, in non-obese PCOS subgroup, IVF and pregnancy outcomes were comparable in the antagonist and agonist groups but total dose and days of rhFSH were also significantly fewer in the antagonist group. Similar findings were also observed in obese PCOS subgroup. Conclusion: GnRH antagonist MDP-EL is at least as effective as GnRH agonist LP and may be a more patient-friendly alternative in controlled ovarian stimulation for PCOS patients undergoing IVF, independent of body mass index.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.83-83
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• 2003

The lutropin/choriogonadotropin receptor (LHR) is a member of the rhodopsin-like subfamily of G protein coupled receptor (GPCRs), that has been shown to mediate the internalization of its two naturally occurring agonist, lutropin and choriogonadotropin (CG). The clustered agonist-receptor complex is internalized by a dynamin-dependent pathway and traverses the endosomal compartment without agonist dissociation Dissociation of the agonist-receptor complex occurs in the lysosomes, where both the agonist and receptor are degrade. Recently, constitutively activating mutations of the receptor have been identified that are associated with familial male-precocious puberty (FMPP). A FMPP is a form of sexual precocious puberty in boys in which testosterone levels are elevated independent of changes in luteinizing hormone-releasing hormone and serum luteinizing hormone levels, We have now analyzed two naturally occurring, constitutively active mutants of the human LHR. These mutations were introduced into the rat LHR (rLHR) and are designated L435R and D556Y. Cells expressing rLHR-D556Y bind human choriogonadotropin (hCG) with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. Cells expressing rLHR-L435R also bind hCG with normal affinity, exhibit a 47-fold increase in basal cAMP, and do not respond to hCG with a further increase in cAMP accumulation. This mutation enhances the internalization of the free and agonist-occupied receptors ~2- and ~17- fold, respectively We conclude that the state of activation of the rLHR can modulate its basal and/or agonist-stimulated internalization. Since the internalization of hCG is involved in the termination of hCG actions, we suggest that the lack of responsiveness detected in cells expressing rLHR-L435R is due to the fast rate of internalization of the bound hCG. The finding that membranes expressing rLHR-L435R respond to hCG with an increase in adenylyl cyclase activity supports this suggestion. Autonomous Leydig cell activity in FMPP is caused by a constitutively activating LH/CGR.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.157-157
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• 2005

• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.48.2-48.2
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• 2007

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