A serotonin receptor antagonist induces oocyte maturation in both frogs and mice: Evidence that the same G protein-coupled receptor is responsible for maintaining meiosis arrest in both species
✍ Scribed by Yinglun Sheng; Ling Wang; X. Shawn Liu; Véronique Montplaisir; Mario Tiberi; Jay M. Baltz; Dr. X. Johné Liu
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 407 KB
- Volume
- 202
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Abstract
Accumulating evidence has indicated that vertebrate oocytes are arrested at late prophase (G2 arrest) by a G protein coupled receptor (GpCR) that activates adenylyl cyclases. However, the identity of this GpCR or its regulation in G2 oocytes is unknown. We demonstrated that ritanserin (RIT), a potent antagonist of serotonin receptors 5‐HT~2~R and 5‐HT~7~R, released G2 arrest in denuded frog oocytes, as well as in follicle‐enclosed mouse oocytes. In contrast to RIT, several other serotonin receptor antagonists (mesulergine, methiothepine, and risperidone) had no effect on oocyte maturation. The unique ability of RIT, among serotonergic antagonists, to induce GVBD did not match the antagonist profile of any known serotonin receptors including Xenopus 5‐HT~7~R, the only known G~s~‐coupled serotonin receptor cloned so far in this species. Unexpectedly, injection of x5‐HT~7~R mRNA in frog oocytes resulted in hormone‐independent frog oocyte maturation. The addition of exogenous serotonin abolished x5‐HT~7~R‐induced oocyte maturation. Furthermore, the combination of x5‐HT~7~R and exogenous serotonin potently inhibited progesterone‐induced oocyte maturation. These results provide the first evidence that a G‐protein coupled receptor related to 5‐HT~7~R may play a pivotal role in maintaining G2 arrest in vertebrate oocytes. © 2004 Wiley‐Liss, Inc.