Pharmacological characterization of serotonin receptor in the oocyte membrane of bivalve molluscs and its formation during oogenesis
✍ Scribed by Osada, Makoto; Nakata, Ayumi; Matsumoto, Toshie; Mori, Katsuyoshi
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 235 KB
- Volume
- 281
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Serotonin (5-hydroxytryptamine, 5-HT) is a major neurotransmitter that triggers the spawning of bivalve molluscs and oocyte germinal vesicle breakdown (GVBD) of oocytes. The present study employed [ 3 H] 5-HT binding assay to characterize a putative receptor on oocyte membranes prepared from scallops and oysters. Results demonstrated a profile of hormone control of 5-HT receptor formation during oocyte growth. The dissociation constants for 5-HT on the surfaces of scallop and oyster oocytes were estimated to be 2.64 µM and 2.01 µM, respectively, and the maximal binding capacity of the oocyte surface was 152 pmol/mg protein in scallops and 529 pmol/mg protein in oysters. The inhibition of [ 3 H] 5-HT bound by various agonists and antagonists provided pharmacological evidence for a 5-HT receptor in each oocyte, a mixed profile of 5-HT 1 /5-HT 2 in scallops and a single profile of 5-HT 1 in oyster. Formation of 5-HT receptor on the surface of the scallop oocyte was induced by estradiol-17β(E 2 ), which was suggested as a primary promoter of the effect of E 2 on sensitivity to 5-HT, resulting in the induction of spawning. This formation occurred during oocyte growth controlled by E 2 .