• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.347-355
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• 1996

We examined the effects of EGTA and verapamil on phorbol ester-and forskolin-stimulated LH releases and $LH{\beta}$ subunit mRNA levels in order to verify the role of extracellular $Ca^{++}$ on PKC- or cAMP-induced increases in LH release and $LH{\beta}$ subunit mRNA levels in cultured anterior pituitary cells of rat. Forskolin-stimulated $LH{\beta}$ subunit mRNA levels as well as LH release were all suppressed by prevention of $Ca^{++}$ mobilization from extracellular environment, after the treatment of EGTA as a $Ca^{++}$ chelator or verapamil as a $Ca^{++}$ channel blocker. PMA-stimulated $LH{\beta}$ subunit mRNA levels were also suppressed by the treatment of EGTA and verapamil, while PMA-induced LH release was not affected. From the present study, it is, therefore, suggested that PKC activation and cAMP elevation all stimulate $LH{\beta}$ subunit mRNA levels and these are extracellular $Ca^{++}$-dependent. However, LH releases by PKC activation and cAMP increase seem to be different each other. LH release by PKC activation is thought to be independent of extracellular $Ca^{++}$. On the other hand, cAMP stimulated-LH release is thought to be dependent on the entry of extracellular $Ca^{++}$.

• The Korean Journal of Pharmacology
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• v.29 no.2
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• pp.225-235
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• 1993

Pituitary LH release has been known to be regulated by the hypothalamic gonadotropin releasing hormone (GnRH) and the gonadal steroid hormones. In addition, neurotransmitters and neuropeptides are actively involved in the control of LH secretion. The alteration in LH release might reflect changes in biosynthesis and/or posttranslational processing of LH. However, little is known about the mechanism by which biosynthesis of LH subunits is regulated, especially at the level of transcription. In order to investigate if ovarian steroid hormones regulate the LH subunit gene expression, ${\alpha}\;and\;LH{\beta}$ steady state mRNA levels were determined in anterior pituitaries of ovariectomized rats. Serum LH concentrations and pituitary LH concentrations were increased markedly with time after ovariectomy. ${\alpha}\;and\;LH{\beta}$ subunit mRNA levels after ovariectomy were increased in a parallel manner with serum LH concentrations and pituitary LH contents, the rise in $LH{\beta}$ subunit mRNA levels being more prominent than the rise in ${\alpha}\;subunit$ mRNA. ${\alpha}\;and\;LH{\beta}$ subunit mRNA levels in ovariectomized rats were negatively regulated by the continuous treatment of ovarian steriod hormones for $1{\sim}4\;days$ and $LH{\beta}\;subunit$ mRNA seemed to be more sensitive to negative feedback of estradiol than progesterone. Treatment of estrogen antagonist, LY117018 or progesterone antagonist, RU486 significantly restroed LH subunit mRNA levels as well as LH release which were suppressed by estradiol or progesterone treatment. These results suggest that ovarian steroids negatively regulate the LH synthesis at the pretranslational level by modulating the steady state levels of ${\alpha}\;and\;LH{\beta}\;subunit$ mRNA and $LH{\beta}\;subunit$ mRNA seemed to be more sensitive to negative feedback action of estradiol than progesterone.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.19-28
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• 1994

The effects of gonadoropin-releasing hormone (GnRH) and ovarian steroid hormones on the release of luteinizing hormone (LH) and its subunit mRNA levels were investigated in anterior pituitary cells in culture. LH concentration was measured by a specific radioimmunoassay and mRNA levels of u and $LH{\beta}$ subunits by RNA slot blot hybridization assay. GnRH stimulated LH release in a dose-dependent manner from cultured pituitary cells. However, the basal LH release in the absence of GnRH was not changed during the course of 24h culture, strongly suggesting that release of LH is directly controlled by GnRH. The treatment of the pituitary cells with GnRH increased $LH{\beta}$ subunit mRNA levels in a dose-dependent manner, reaching the maximum with $2\;{\times}\;10^{-10}M$ GnRH while no significant increase in ${\alpha}$ subunit mRNA levels was observed after GnRH treatment. Estradiol did not augment GnRH-induced LH release while progesterone augmented GnRH-induced LH release in a dose-dependent manner at the level of pituitary. However, estradiol and progesterone increased basal and GnRH-induced $LH{\beta}$ subunit mRNA levels in a dose-dependent manner. The treatment of estrogen antagonist, LYI17018 blocked the effect of estradiol on GnRH-induced $LH{\beta}$ subunit mRNA levels in a dose-dependent manner while progesterone antagonist, Ru486 tended to block the effect of progesterone on GnRH-induced $LH{\beta}$ subunit mRNA levels. It is therefore suggested that GnRH Playa a major role in LH release and subunit biosynthesis by influencing the steady state $LH{\beta}$ subunit mRNA loves and ovarian steroid hormones modulate subunit biosynthesis via directly acting on pituitary gonadotropes.

• Development and Reproduction
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• v.4 no.1
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• pp.87-93
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• 2000

Equine chorionic gonadotropin (eCG) consists of highly glycosylated noncovalently linked $\alpha$- and $\beta$-subunits and belongs to the glycoprotein hormone family that includes lutropin (LH), follitropin (FSH), and thyrotropin (FSH). eCG is a unique member of the gonadotropin family because it elicits response characteristics of both FSH and LH in other species than the hone. eCG is synthesized and secreted by trophoblastic cells of the endometial cups between 40 and 130 days of gestation. In the present study, mRNA expression ratio of eCG, eLH and eFSH $\alpha$- and $\beta$-subunints was investigated in the placenta and pituitary. mRNA was extracted from equine placenta on day 70 of gestation and from pituitary of male horse (27 month-old). When the expression of both subunit mRNAs of eCG in the equine placenta was compared by Northern blotting, the expression of the $\beta$ -subunit mRNA was relatively greater than that of the $\alpha$-subunit. And mRNA expression of $\alpha$-, LH $\beta$- and FSH $\beta$-subunits was analysed in the equine pituitary. An $\alpha$-subunit was revealed with a size of approximately 0.8 kb. FSH $\beta$-subunit mRNA also was detected out 1.8 kb. It is the same size of the FSH $\beta$ -subunit mRNA cloned. The intensity of $\alpha$-subunit mRNA was greater than that of the $\beta$-subunit suggesting that the expression of $\alpha$ -subunit was dominant in the equine anterior pituitary. Thus, 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 equine placenta and pituitary.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.2
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• pp.199-205
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• 1998

The present study was performed to analyze the expression of LH genes in the rat ovary. Expression of LH subunit genes in the rat ovary was demonstrated by amplification of ovarian RNA by RT-PCR. The ovarian $LH_\beta$ transcripts contained at least two parts of the published cDNA structure, the pituitary exons 1, 2 and 3 and the part of testicular ex on 1 in the major trancripts form in rat testis. Using RIA, significant amount of LH-like molecules were detected in crude ovarian extracts, and the competition curves with increasing amount of tissue extracts were parallel with those of standard peptide, indicating that the ovarian immunoreactive LH-like material is similar to authentic pituitary LH molecule. The administration of PMSG to immature rats resulted in a sharp decrease of the ovarian LH contents after 24 h post-injection. In conclusion, these findings demonstrate that genes for LH subunits are expressed in the rat ovary, and suggest that LH can playa central role in regulation of female reproduction with both endocrine (by pituitary LH) and auto- and/or para-crine (by ovarian LH) manner.

• Journal of Aquaculture
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• v.18 no.4
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• pp.293-298
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• 2005

We examined the effects of GnRHa on expression of the gonadotropin subunit gene in the pituitary and on syn-thesis of the plasma sex steroids (testosterone and 17$\beta$-estradiol) in protandrous black porgy. Fish were injected intraperitoneally with 0.2g GnRHa/g and then both the pituitary and the plasma were sampled 0, 6, 12, 24 and 48 hours after injection. The mRNA level of the FSH subunit increased at 6 hours post-injection, while the LH mRNA levels expressed are same with or without GnRHa treatment. Also, GnRHa stimulation caused a significant increase of the plasma testosterone (T) and 17$\beta$-estradiol ($E_2$) after 24 hours. The homologies of black porgy FSH to red seabream, Pagrus majoy FSH, snakehead fish, Channa maculata FSH and striped bass, Morone saxatilis FSH were $83.3\%,\;79.2\%$ and $76.0\%$ respectively. Amino acid homology analysis using the GenBank and EMBL general searches indicated that black porgy FSH has a high homology with yellowfin seabream, Acanthopagrus latus LH ($97.7\%$ identity) and red seabream LH ($83.3\%$ identity).

• The Korean Journal of Zoology
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• v.37 no.3
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• pp.377-384
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• 1994

The present study examines the inhibitow effect of progesterone (P) on luteinizing hormone $(LH)\beta$ subunit gene expression in anterior pituitary of ovariectomized, estradiol-treated adult rats. A single injection of P (1mg) further decreased the estradiol-Induced decrease in $LH\beta$ mRNA levels in ovariectomTzed rats in a time-dependent manner. p suppressed UIP mRNA levels at lower doses (0.1 and 1mg), but increased $LH\beta$ mRNA levels 81 a high dose (toms). The inhibitor action of P on $Uf\beta$ mRNA was restored when Ru486, a P receptor antagonist, was administered 1h before P treatment. These data clearly indicate that P inhibits gene expression of $LH\beta$ in the rift pituitary in a swersic manner with estrogen.

• Development and Reproduction
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• v.21 no.3
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• pp.327-333
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• 2017

Gonadotropins are heterodimers consisting an alpha chain ($Cg{\alpha}$) and a beta chain. Interestingly, presence of complicated $LH-{\beta}$ transcripts in rat testis was accidently found; testicular $LH-{\beta}$ transcripts were confined in seminiferous tubules to spermatids, and the translated products were localized in the elongated spermatids. We hypothesized that mouse testis has potential to produce the tissue specific $LH-{\beta}$ with similar structure to the rat testicular forms. To verify our hypothesis, we examined the adult mouse (ICR) testis using RT-PCR and immunohistochemistry. The PCR revealed the presence of the identical products in the reactions for three LH subunit types. The expected product sizes for mouse $Cg{\alpha}$ and $LH-{\beta}$ known as pituitary type were 224 bp and 503 bp, respectively. The testicular type $LH-{\beta}$ products were produced by a primer set based on the rat sequences, with unexpected size of 800 bp. Sequencing revealed that the proximal and distal parts (2-82 and 661- 773 bp, respectively) were homologous to rat testicular $LH-{\beta}$ cDNA, and middle part (83-660 bp) was a unique mouse-specific region. Both $Cg{\alpha}$ and $LH-{\beta}$ positive signals were in the round and elongated spermatids and mature sperms, and the $LH-{\beta}$ signals were more intense. In conclusion, our study demonstrated that the presence and localization of the LH subunits in mouse testis. Further studies will be needed to understand the precise structure and function of mouse testicular LH.

• Development and Reproduction
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• v.4 no.2
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• pp.231-236
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• 2000

Recent studies have clearly shown that the expression of genes for gonadotropin-releasing hormone (GnRH) and its receptor in the rat reproductive organs including ovary, testis, placenta uterus and mammary gland. Moreover, luteinizing hormone (LH) classically known to be a main target product of GnRH in anterior pituitary has been found in rat gonads. These findings suggested the presence of local circuit composed of GnRH and LH in the rat gonads. The present study was undertaken to elucidate whether the genes for LH and its receptor are expressed in rat mammary gland. Expression of LH and its receptor genes in the rat mammary gland was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) and specific LH radioimmunoassay (RIA). The LH${\beta}$ transcripts in the mammary gland from cycling rats contained the pituitary type of LH${\beta}$ exons 1~3 encoding the entire LH${\beta}$ polypeptide but lacked the rat testis-specific LH${\beta}$ exon(s). Presence of ${\alpha}$ -subunit transcripts in the rat mammary gland were determined by RT-PCR. The cDNA fragments encoding exons 2~7 of rat LH receptor transcripts were amplified in both rat ovary and mammary gland samples. We could detect the GnRH expression in mammary gland from cycling virgin rats, and this result disagreed with previous report that mammary GnRH expression is occured in lactating rats only. Considerable amounts of immunoreactive LH molecules with good RIA parallelism in standard curve were detected in crude extracts from the rat mammary gland, indicating that the immunoreactive LH materials in the gland might be identical to authentic pituitary LH. To our knowledge, the present study demonstrated for the first time the expression of LH subunits and LH receptor in the rat mammary gland. Our findings suggested that the mammary gland might be the novel source and target of LH and the mammary LH could be act as a local regulator with auto-and/or paracrine manner under the regulation of local GnRH.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.377-381
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• 1999

Objectives: Recent studies, including our own, demonstrated that the novel expression of LH gene in rat gonads and uterus, indicating that the local production and action of the LH-like molecule. In the present study, we investigated whether human uterus also expresses the LH gene. Design: Reverse transcription-polymerase chain reaction (RT-PCR) amplified the cDNA fragments coding $LH_{\beta}$ polypeptide from human endometrium but not from myometrium. Presence of the transcripts for the ${\alpha}$-subunit in human endometrium was also confirmed by RT-PCR. Results: Transcripts for $LH_{\beta}$ subunit were detected in endometrial samples from women with endometriosis. The gene for LH/hCG receptor was expressed in both endometrium and myometrium, showing good agreement with previous studies. Increased level of $LH_{\beta}$ transcript was determined in the endometrium from follicular phase compared to that from luteal phase. Conclusion: Taken together, our findings demonstrated that 1) the genes for LH subunits and LH/hCG receptor are expressed in human uterus, 2) the uterine LH expression was changed during menstrual cycle, suggesting that the uterine LH may playa local role in the control of uterine physiology and function(s).