Dynamic Expression and Regulation of Urotensin I and Corticotropin-Releasing Hormone Receptors in Ovary of Olive Flounder Paralichthys olivaceus

Abstract

Urotensin I (UI), a fish corticotropin-releasing hormone (CRH) like peptide, has been found throughout vertebrate species that has great effects on adaptive physiology comprising stress-related responses, and osmotic regulation by binding with CRH type I receptor (CRHR1) and CRH type II receptor (CRHR2) in fish. Dynamic expression and regulation of UI and CRH receptors in the olive flounder ovarian follicle were studied so as to make further efforts to understand the role of UI in the development of teleost ovary. The results showed that stage-specific change in UI mRNA levels in ovarian follicles of olive flounder. UI and CRHR1 mRNA levels were higher in stage III follicles (300∼500 μm diameter) compared to stage II (90∼300 μm diameter) and IV (500∼800 μm diameter) follicles, however, the levels of CRHR2 mRNA were decreased in line with the ovarian development from stage II to stage IV. A strong signal of UI protein was observed in the follicular cells and oocyte in stage III and IV follicles by immunohistochemistry. In vitro treatment of olive flounder ovarian follicles with human chorionic gonadotropin (hCG) showed that the mRNA expression of UI increased significantly at low concentration and decreased at high concentration at 6 h, but the CRHR1 and CRHR2 mRNA did not change obviously. In addition, the results of incubation with 17α, 20β-dihydroxy-4-oregnen-3-one (DHP) show that UI and CRHR1 mRNA expression were elevated with increasing concentrations at 9 h. All above results indicated that UI and CRH receptors may have a vital effect on olive flounder ovarian development.

Reproductive endocrine variation in female olive flounder with different stress coping styles during the breeding season

“…We followed the histological procedures reported in previous studies (Zhou et al, 2019). To be briefly, ovarian tissues were placed into Bouin's fixative for 24 h, after dehydrated in ascending concentration of alcohol, cleared in xylene, the ovarian tissues were embedded in paraffin.…”

Functional characterization of two corticotropin-releasing hormone receptors in Larimichthys crocea

“…CRHR expressions changed during ovarian development in the olive flounder (Zhou et al, 2019) and in the zebrafish (Zhou et al, 2021). In addition, treatment with 17 a, 20 b-dihydroxy-4-pregnen-3-one (DHP) increases CRHR1 mRNA expression in ovarian follicles from olive flounder (Zhou et al, 2019), and the two CRH identified in the zebrafish, decrease estradiol release from primary cultures of follicular cells in this species (Zhou et al, 2021). These data suggest a potential involvement of CRH system in teleost reproduction.…”

“…Therefore, a deep understanding of the signaling and functional mechanisms of the CRH/CRHR1 system needs to be developed in teleosts. Scientists have elucidated the molecular properties of CRHR1 in teleost fish, such as the gene structural characters of the receptor in Cyprinus carpio (Huising, 2004;Manuel et al, 2014), protein structure and functions of the receptor in Astatotilapia burtoni (Chen and Fernald, 2008), and distribution profiles of the receptor in the ovary of Paralichthys olivaceus (Zhou et al, 2019), Fugu (Cardoso et al, 2003), and chum salmon (Pohl et al, 2001). CRHR expressions changed during ovarian development in the olive flounder (Zhou et al, 2019) and in the zebrafish (Zhou et al, 2021).…”

“…Scientists have elucidated the molecular properties of CRHR1 in teleost fish, such as the gene structural characters of the receptor in Cyprinus carpio (Huising, 2004;Manuel et al, 2014), protein structure and functions of the receptor in Astatotilapia burtoni (Chen and Fernald, 2008), and distribution profiles of the receptor in the ovary of Paralichthys olivaceus (Zhou et al, 2019), Fugu (Cardoso et al, 2003), and chum salmon (Pohl et al, 2001). CRHR expressions changed during ovarian development in the olive flounder (Zhou et al, 2019) and in the zebrafish (Zhou et al, 2021). In addition, treatment with 17 a, 20 b-dihydroxy-4-pregnen-3-one (DHP) increases CRHR1 mRNA expression in ovarian follicles from olive flounder (Zhou et al, 2019), and the two CRH identified in the zebrafish, decrease estradiol release from primary cultures of follicular cells in this species (Zhou et al, 2021).…”