Identification, functional characterization, and estrogen regulation on gonadotropin-releasing hormone in the spotted scat, Scatophagus argus

• Published in: Fish physiology and biochemistry Vol. 46; no. 5; pp. 1743 - 1757
• Main Authors: Chen, Hua-pu, Cui, Xue-fan, Wang, Yao-rong, Li, Zhi-yuan, Tian, Chang-xu, Jiang, Dong-neng, Zhu, Chun-Hua, Zhang, Yong, Li, Shui-sheng, Li, Guang-li
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2020; Springer Nature B.V
• Subjects: 17β-Estradiol; Amino Acid Sequence; Animal Anatomy; Animal Biochemistry; Animal Physiology; Animals; Biomedical and Life Sciences; Cloning; Cloning, Molecular; Desensitization; DNA, Complementary; Endocrinology; Estradiol; Estrogen receptors; Estrogens; Estrogens - metabolism; Female; Fish; Fisheries; Fishes - physiology; Fishing; Follicle Stimulating Hormone - metabolism; Follicle-stimulating hormone; Freshwater & Marine Ecology; Fulvestrant; Gene expression; Gene Expression Regulation, Developmental - drug effects; Gonadotropin-releasing hormone; Gonadotropin-Releasing Hormone - genetics; Gonadotropin-Releasing Hormone - metabolism; Gonadotropins; Gonads; Histology; Hormones; Hypothalamus; Laboratories; Life Sciences; Luteinizing hormone; Luteinizing Hormone - metabolism; Morphology; Oestrogens; Ovaries; Ovary - growth & development; Peptides; Phylogeny; Pituitary (anterior); Receptors, Estrogen - antagonists & inhibitors; Regulation; Reproductive system; Salmon; Scatophagus argus; Sex hormones; Steroids; Tissue; Transcription; Transcriptome - drug effects; Zoology; 17β-Estradiol; Feedback regulation; Reproduction; Gonadotropin-releasing hormone; Scatophagus argus
• ISSN: 0920-1742; 1573-5168
• DOI: 10.1007/s10695-020-00825-5

Gonadotropin-releasing hormone (GnRH) is a key neuropeptide of the reproductive system. However, little is known about the role of GnRH in the spotted scat ( Scatophagus argus ). Here, three GnRH subtypes (cGnRH-II, sGnRH, and sbGnRH) were identified in the spotted scat. cGnRH-II and sGnRH were only expressed in the brains and gonads of both male and female fish, exhibiting a tissue-specific expression pattern, while sbGnRH was expressed at different transcription levels in all examined tissues. During ovarian maturation, hypothalamus-associated sbGnRH was upregulated, while the expression of sGnRH was variable and cGnRH-II first increased and then decreased. In vivo experiments showed that sbGnRH significantly promoted the expression of fsh and lh genes in a dose-dependent manner and exhibited a desensitization effect on lh expression at high concentrations. For sGnRH and cGnRH-II, only high concentrations could induce fsh and lh expression. Furthermore, treatment with highly concentrated sbGnRH peptide also induced fsh and lh expression, whereas the sGnRH and cGnRH-II peptides only induced fsh expression in vitro. 17β-Estradiol (E 2 ) significantly inhibited the expression of sbGnRH mRNA in a dose-dependent manner and did not impact sGnRH and cGnRH-II mRNA levels in vivo or in vitro. The inhibitory effect of E 2 on sbGnRH expression was attenuated by the estrogen receptor (ER) broad-spectrum antagonist (fulvestrant) and the ERα-specific antagonist (methyl-piperidinopyrazole), respectively, implying that the feedback regulation on sbGnRH is mediated via ERα. This study provides a theoretical basis for the reproductive endocrinology of the spotted scat by studying GnRH.