• 한국가축번식학회지
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• 제24권4호
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• pp.357-364
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• 2000

Members of the glycoprotein family, which includes CG, LH, FSH and TSH, comprise two noncovalently linked $\alpha$- and $\beta$-subunits. Equine chorionic gonadotropin (eCG), known as PMSG, has a number of interesting and unique characteristics since it appears to be a single molecule that possesses both LH- and FSH-like activities in other species than the horse. This dual activity of eCG in heterologous species is of fundamental interest to the study of the structure-function relationships of gonadotropins and their receptors. CG and LH $\beta$ genes are different in primates. In horse, however, a single gene encodes both eCG and eLH $\beta$ -subunits. The subunit mRNA levels seem to be independently regulated and their imbalance may account for differences in the quantities of $\alpha$ - and $\beta$-subunits in the placenta and pituitary. The dual activities of eCG could be separated by removal of the N-linked oligosaccharide on the $\alpha$-subunit Asn 56 or CTP-associated O-linked oligosaccharides. The tethered-eCG was efficiently secreted and showed similar LH-like activity to the dimeric eCG. Interestingly, the FSH-like activity of the tethered-eCG was increased markedly in comparison with the native and wild type eCG. These results also suggest that this molecular can implay particular models of FSH-like activity not LH-like activity in the eCG/indicate that the constructs of tethered molecule will be useful in the study of mutants that affect subunit association and/or secretion. A single-chain analog can also be constructed to include additional hormone-specific bioactive generating potentially efficacious compounds that have only FSH-like activity. The LH/CG receptor (LH/CGR), a membrane glycoprotein that is present on testicular Leydig cells and ovarian theca, granulosa, luteal, and interstitial cells, plays a pivotal role in the regulation of gonadal development and function in males as well as in nonpregnant and pregnant females. The LH/CGR is a member of the family of G protein-coupled receptors and its structure is predicted to of a large extracellular domain connected to a bundle of seven membrane-spanning a-helices. The LH/CGR phosphorylation can be induced with a phorbol ester, but not with a calcium ionophore. The truncated form of LHR also was down-regulated normally in response to hCG stimulation. In contrast, the cell lines expressing LHR-t631 or LHR-628, the two phosphorylation-negative receptor mutant, showed a delay in the early phase of hCG-induced desensitization, a complete loss of PMA-induced desensitization, and an increase in the rate of hCG-induced receptor down-regulation. These results clearly show that residues 632~653 in the C-terminal tail of the LHR are involved in PMA-induced desensitization, hCG-induced desensitization, and hCG-induced down-regulation. Recently, constitutively activating mutations of the receptor have been identified that are associated with familial male-precocious puberty. Cells expressing LHR-D556Y bind hCG with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. This mutation enhances the internalization of the free and agoinst-occupied receptors ~2- and ~17- fold, respectively. We conclude that the state of activation of the LHR 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 LHR-L435R is due to the fast rate of internalization of the bound hCG. This statement is supported by the finding that hCG responsiveness is restored when the cells are lysed and signal transduction is measured in a subcellular fraction (membranes) that cannot internalize the bound hormone.

• 한국가축번식학회지
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• 제16권2호
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• pp.149-155
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• 1992

The present study was conducted to find out the changes of progesterone and 20$\alpha$-dihydroprogesterone(20$\alpha$-OHP) levels before and after parturition, 4 pluriparous goats were offered for this experiment. Blood samples were taken from jugular vein on Days, 5, 3, 2 and 1 before parturition, the day of parturition, 1, 3, 5, 7 and 9 after parturition. The blood samples were centraifuged and stored at -2$0^{\circ}C$ until hormone assay. The serum levels of progesterone and 20$\alpha$-OHP were measrued by radioimmunoassay. The changes of serum progesterone level during peripartum period were characterized as a remarkable decrease. The progesterone level was 4.05$\pm$0.52ng/ml on 56 days before parturition and decreased to 2.24$\pm$0.38ng/ml on 1 day before parturition and 0.79$\pm$0.09ng/ml on the day of parturition and the basal level was maintained through 9 days of postpartum period. The serum level of 20$\alpha$-OHP during the peripartum period was 1.25$\pm$0.21ng/ml on 5 days before paturition and increased to 1.32$\pm$0.25 on 3 days and 1.59$\pm$0.24ng/ml on 1 day before parturition, and reached a peak level of 1.78$\pm$0.25ng/ml just prior to parturition and then decreased greatly to 0.31$\pm$0.03ng/ml on 1 day postpartum and the basal level was remained until 9 days postpartum. The high serum level of 20$\alpha$-OHP, which was peak just prior to parturition, was maintained for 2 days following the onset of remarkable decrease in the serum level of progesterone. From the above results, it was concluded that the enzyme 20$\alpha$-hydroxysteroid dehydrogenase (20$\alpha$-HSD) catalyzing the conversion of progesterone to a biologically inactive steroid, 20$\alpha$-OHP was active properly in the luteal cells in Korean native goats.

• 한국임상수의학회지
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• 제31권5호
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• pp.394-402
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• 2014

본 연구의 목적은 예측 불가능한 만성적인 스트레스가 생식기능과 황체형성호르몬 수용체의 발현에 미치는 영향을 알아보는 것이다. 9 주령 암컷 C57BL/6 마우스를 무작위로 선택하여 대조군과 스트레스군의 두 집단으로 분류하였다. 스트레스군은 35일 동안 하루에 두 번씩 12가지의 서로 다른 스트레스를 무작위로 선택하여 스트레스를 주었다. 대조군에 비하여 스트레스군에서 불안과 관련된 행동들이 유의성 있게 증가하였으며(P < 0.05), 스트레스를 받는 동안의 증체율 또한 유의성 있게 감소하였다(P < 0.01). 그리고 평균 산자수도 대조군에 비하여 스트레스 군에서 유의하게 감소함을 관찰 하였다(P < 0.01). 조직학적인 검사에서 일차, 이차 및 초기 성숙 난포의 비율이 대조군에 비해 스트레스 군에서 유의하게 감소한 반면(P < 0.05) 폐쇄 난포의 비율은 유의하게 증가하였다(P < 0.01). 면역조직화학적 검사를 통해 과립막세포와 황체세포의 황체형성호르몬 수용체 발현을 관찰한 결과, 대조군에 비해 스트레스군에서 그 발현이 감소하였고, 웨스턴 블롯을 통해 난소 내 황체형성호르몬 수용체의 단백질 양을 측정한 결과 또한 대조군에 비하여 스트레스군에서 유의하게 감소하였다(P < 0.05). 본 연구를 통해 난소의 황체형성호르몬 수용체는 예측 불가능한 스트레스에 의해 영향을 받으며, 변화된 황체형성호르몬 수용체가 난자의 난포 발육 불량과 생식기능의 이상에 영향을 미친다는 것을 실험적으로 증명하였다.