AUTHOR=Yang Yanan , Lin Dongdong , Bao Chenchang , Huang Huiyang , Ye Haihui 

TITLE=Serotonergic Mechanisms of Oocyte Germinal Vesicle Breakdown in the Mud Crab, Scylla paramamosain

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00797

DOI=10.3389/fphys.2019.00797

ISSN=1664-042X

ABSTRACT=<p>The mechanism of serotonin (5-HT)-induced oocyte germinal vesicle breakdown (GVBD) in the mud crab, <italic>Scylla paramamosain</italic>, was investigated in this study. Histological staining showed that there were two meiotic arrests in oocyte, appearing at prophase I and metaphase I. This result indicated that meiosis I arrest at prophase I in <italic>S. paramamosain</italic> was similar to that of vertebrates, but meiosis II arrest at metaphase I was different from that of vertebrates. Resumption of oocytes arrest at meiosis prophase I could be induced by 5-HT rapidly within 5 min in <italic>S. paramamosain</italic>. We obtained the sequence of the 5-HT receptor type 1A (<italic>5-HTR<sub>1A</sub></italic>) from the NCBI database, and found that <italic>5-HTR<sub>1A</sub></italic> was expressed in oocytes and follicle cells. In addition, we found that an agonist 8-OH-DPAT which binds <italic>5-HTR<sub>1A</sub></italic> induced GVBD and an antagonist WAY100635 which inhibited 5-HT induced GVBD in <italic>S. paramamosain</italic>. This result showed that <italic>5-HTR<sub>1A</sub></italic> mediated the regulation of oocyte GVBD by 5-HT. To explore the functional mechanism of 5-HT in inducing oocyte GVBD, forskolin, a cAMP agonist was used. Results showed that, forskolin significantly blocked 5-HT-induced GVBD, and there was a negative correlation between GVBD rate and cAMP level. Our data indicate that there are two meiotic arrests in <italic>S. paramamosain</italic>, and the resumption of prophase I arrest can be induced by 5-HT, which binds to <italic>5-HTR<sub>1A</sub></italic>, and this process is mediated by cAMP, which acts as negative regulator via cAMP signaling pathway.</p>