• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.427-428
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• 2002

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.08a
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• pp.230.2-231
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• 2002

• Development and Reproduction
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• v.26 no.2
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• pp.37-47
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• 2022

Photoperiod has well been established to regulate testicular activities in golden hamsters. These animals breed actively around summer but become infertile in winter. In males, testicles are full of multistep germ cells including spermatozoa in summer. But in winter only fundamental cells consisting of the testicles are detected. The testicular degeneration is accompanied by the reduced levels of blood gonadotropins and testosterone. In this study, the expressions of gonadotropin subunit genes were investigated in the reproductive active and inactive testicles. And parts of sequences of the gonadotropin subunits were identified and compared with those of other rodents. As results, common gonadotropin alpha (CGa), follicle-stimulating hormone (FSH) β, and luteinizing hormone (LH) β genes were equivalently detected in pituitaries of both sexually active and inactive animals. In considering low concentrations of gonadotropin hormones determined in pituitary, the present findings imply that the processes involved in translation and/or formation of functional hormones could be impeded in the sexually inactive hamsters. All the nucleotide sequences of gonadotropin subunits identified in this study were same as those reported previously except for one base in CGa. An unsure amino acid deduced from the CGa sequence was confirmed from mRNA sequencing. The outcomes mentioned above suggest that animals with regressed testes prepare for the sexually active period forthcoming in the future.

• Fisheries and Aquatic Sciences
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• v.18 no.2
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• pp.211-220
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• 2015

We investigated the differences in the expression of the neurohormones kisspeptin (Kiss) and gonadotropin-inhibitory hormone (GnIH) and cytochrome P450 aromatase (P450arom), gonadotropin hormones (GTHs), and sex steroids in the goldfish Carassius auratus exposed to light-emitting diodes (LEDs). The expression levels of Kiss1, Kiss2, G-protein-coupled receptor 54 (GPR54), GTHs, GnIH, and P450arom were compared between the control (white light) and LED-treated goldfish. Furthermore, we measured the plasma levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The levels of Kiss1 mRNA and protein; Kiss2, GPR54, and $GTH{\alpha}$ protein; GTH mRNA; and plasma FSH and LH in the hypothalamus and cultured hypothalamus cells were significantly higher in the green and purple LED treatment groups than in the other groups. These results suggested that red LEDs inhibit the sex maturation hormones, Kiss, GPR54, GTHs, and P450arom, and that GnIH plays a role in the negative regulation of reproductive function in goldfish.

• The Korean Journal of Pharmacology
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• v.23 no.2
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• pp.57-75
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• 1987

Two modalities of gonadotropin secretion, pulsatile gonadotropin and preovulatory gonadotropin surge, have been identified in the mammals. Pulsatile gonadotropin secretion is modulated by the pulsatile pattern of GnRH release and complex ovarian steroid feedback actions. The neural mechansim that regulates the pulsatile release of GnRH in the hypothalamus is called "GnRH pulse generator". Ovarian steroids, estradiol and progesterone, appear to exert thier feedback effects both directly on the pituitary to modulate gonadotropin release and on a hypothalamic site to modulate GnRH release; estradiol primarily affects the amplitude while progesterone decreases the frequency of the pulsatile GnRH. Steroid hormones are known to affect catecholamine transmission in brain. MBH-POA is richly innervated by NE systems and close apposition of NE terminals and GnRH cell bodies occurs in the MBH as well as in the POA. NE normally facilitates pulsatile LH release by acting through ${\alpha}-receptor$ mechanism. However, precise nature of facilitative role of NE transmission in maintaining pulsatile LH has not been clearly understood. Close apposition of DA and GnRH terminals in ME might permit DA to influence GnRH release. Action of DA transmission probably is mediated by axo-axonic contacts between GnRH and DA fibers in the ME. Dopamine transmission does not normally regulate pulsatile LH release, but under certain conditions, increased DA transmission inhibit LH pulse. Endogenous opioid acts to suppress the secretion of GnRH into hypophysial portal circulation, thereby inhibiting gonadotropin secretion. However, an interaction between endogenenous opioid peptides and gonadotropin release is a complex one which involves ovarian hormones as well. LH secretion appears to be most suppressed by endogenenous opioids during the luteal phase, at a time of elevated progesterone secretion. The arcuate nucleus contains not only cell bodies for GnRH and ${\beta}-endorphin$ but also a dense aborization of fibers suggesting that GnRH release is changed by the interactions between GnRH and ${\beta}-endorphin$ cell bodies within the arcuate nucleus. The frequency and amplitude of pulsatile LH release seem to be increased during the preovulatory gonadotropin surge. Estradiol exerts positive feedback action on the hypothalamo-pituitary axis to trigger preovulatory LH surge. GnRH is also crucial hormonal stimulus for preovulatory LH surge. It is unlikely, however, that increased secretion of GnRH during the preovulatory gonadotropin surge represents an obligatory neural signal for generation of the LH discharge in primates including human. Modulation of preovulatory LH surge by catecholamines has been studied almost exclusively in rats. NE and E may be involved in distinct way to accumulate GnRH in the MBH and its release into the hypophysial portal system during the critical period for LH surge on proestrus in rats. However, the mechanisms whereby augmented adrenergic transmission may facilitate the formation and accumulation of GnRH in the ME-ARC nerve terminals before the LH surge have not been clearly understood.

• Journal of Aquaculture
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• v.11 no.4
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• pp.513-519
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• 1998

Ovulation of maturing femal mandarin fish, Siniperca scherzeri was induced using single injection of human chorionic gonadotropin (HCG) or gonadotropin releasing hormone-analogue (GnRH-a), GnRH-a plus prostaglandin F2 (PG$F_2$) or GnRH-a plus pimozide. The response was evaluated by fertilization, embryo-formation and hatching rate after insemination. Those rates were generally higher in GnRH-a group than in HCG group. The higher hatching rat of above 89% was achived using a dosage of 5,000 IU/kg HCG plus 10 ${\mu}$g/kg GnRH-a, 10${\mu}$g/kg GnRH-a plus 500 ng/kg PGF2, and 10 ug/kg GnRH-a plus 1-5 mg/kg pimozide. Ovulation was induced in all female injected with sex-maturation hormones and stimulator, but blocked in female injected with HCG plus GnRH-a plus dopamine combination, and GnRH-a plus PGF2 plus indometacin combination. These results show that the mandarin fish in spawning period secrete a sex-mutruation assosiated hormones and gonadotropin-releasing -inhibiting factor(GRIF).

• BMB Reports
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• v.32 no.5
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• pp.474-479
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• 1999

Using a hybridoma technique, spleen cells of Balb/c mice immunized with human chorionic gonadotropin (hCG) were fused with NS-1 mouse myeloma cells. Two hybrid cell lines, clones KS-8 and KS-19, secreting monoclonal antibodies to hCG, were isolated. KS-8 and KS-19 belong to the immunoglobulin $G_1$ subclass. With the aid of a double-antibody radioimmunoassay, it was established that the KS-8 monoclonal antibody recognizes an immunodeterminant of the $\beta$-subunit of hCG, whereas the KS-19 monoclonal antibody recognizes an epitope present on the $\alpha$-subunit of hCG. The KS-8 monoclonal antibody specifically reacts with human chorionic gonadotropin and shows cross-reactivity of less than 0.3% to other related human glycoprotein hormones. On the other hand, using a hemagglutination test based on antibody-induced agglutination of sheep red blood cells coated with hCG, It was shown that only the KS-19 monoclonal antibody was capable of inducing a positive reaction, although both monoclonal antibodies had similar binding capacity to the coated cells. The results from the dual screening procedures demonstrate that KS-8 and KS-19 monoclonal antibodies show high sensitivity in two different assays, and are hence useful for the qualitative and quantitative determination of hCG by both radioimmunoassay and hemagglutination inhibition tests.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.1
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• pp.17-22
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• 2022

Successful reproduction in vertebrates necessitates complex interactions along the brain-pituitary-gonad axis, it is determined by gonadotropin releasing hormone produced in the hypothalamus of the brain, gonadotropin synthesized in the pituitary gland, and sex hormone secreted by the gonads. The goal of this study was to secure and test technology for controlling (inhibiting) sexual maturation hormones such as maturation hormones through hormone regulation. We studied the effect on sexual maturation of zebrafish Danio rerio by tamoxifen, anastrozole, exemestane and dopamine 4 kinds of sexual maturation inhibitors to feed and after administration. As a result, 4 kinds of sexual maturation inducing substances were mixed with zebrafish feed, it could be concluded that all of them were effective in inhibiting sexual maturation by reducing mRNA levels of genetic materials related to sexual maturation.

• Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.12-19
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• 2022

In the present study, we investigated the effects of recombinant eel gonadotropins (rec-GTHs) on maturation induction in immature ovarian culture in vitro and sex steroid hormones in vivo in the Japanese eel Anguilla japonica. To study the in vitro effects of rec-GTHs on estradiol-17β (E2) production in immature ovarian tissues, ovarian tissues were incubated with different doses of rec-follicle-stimulating hormone (rec-FSH) or rec-luteinizing hormone (rec-LH). The results revealed that the E2 levels in the rec-FSH (0.1, 0.5, or 1 ㎍/mL)- and rec-LH (0.1 or 0.5 ㎍/mL)-treated groups were significantly higher than those in the female eels from the control group. Furthermore, to investigate the in vivo effects of rec-GTHs on the gonadosomatic index (GSI) and plasma sex steroid hormone levels, the eels were injected intraperitoneally with eel's ringer (control), salmon pituitary extract (SPE; for female eels), human chorionic gonadotropin (hCG; for male eels), rec-FSH, rec-LH, and rec-FSH + rec-LH once a week. The results revealed that except for the SPE and the hCG groups, none of the groups exhibited a significant difference in GSI values. However, in vivo plasma E2 levels increased at the end of 4 weeks after rec-FSH treatment in female eels. Based on these results, it is suggested that rec-GTHs may have a positive effect on sexual maturation in female eels; however, further studies on complementary rec-protein production systems and additional glycosylation of rec-hormones are needed to elucidate hormone bioactivity in vivo and in vitro.

• Development and Reproduction
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• v.1 no.2
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• pp.165-172
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• 1997

the pupose of this study was to investigate the effects of gonadotropin and nitric oxide (NO) on the expression of mouse follicular bad and bax genes that are known induce apoptosis. Large and midium size follicles of immature mice were obtained at 0, 24, and 48 hours time intervals after Pregnant Mare's Serum gonadotropins(PMSG, 5 I.U.) injection. Preovulatory follicles collected at 24 hrs after PMSG injection were cultured with or without various chemicals such as gonadotropin, gonadotropin Releasing hormone(GnRH), testosterone, Sodium nitroprusside (SNP) for 24 hrs at $37^{\circ}C$. After 24 hrs culture, the culture media was used for nitrite assay and total RNA was extracted, subjected to RT-PCT for the analyses of bad and bax expression. We found that expression of bad and bax genes in follicles was markedly reduced before and after in vivo priming with hCG. When the preovulatory follicles were cultured for 24 hrs in culture media with PMSG and hCG, the expression of bad and bax genes was decreased. Moreover, SNP (NO generating agent) can significantly suppress the expression of bad and bax genes in follicles when apoptosis was induced by GnRH agonist and testosterone. At the same time, nitrite production of culture media was increased in GnRH agonist + SNP, testosterone + SNP and SNP treated groups than control group. These data demonstrated for the first time that peptide hormones and NO may play important roles in the regulation of mouse follicular differentiation and may prevent apoptosis via supressing the expression of bad and bax genes.