A 5-HT1A-like receptor is involved in the regulation of the embryonic rotation of Lymnaea stagnalis L

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology Vol. 152; no. 1; pp. 57 - 61
• Main Authors: Hiripi, László, Elekes, Károly
• Format: Journal Article
• Language: English
• Published: United States 01.06.2010
• Subjects: Animals; Body Patterning - drug effects; Body Patterning - physiology; Dose-Response Relationship, Drug; Embryo, Nonmammalian - drug effects; Embryo, Nonmammalian - metabolism; Lymnaea - drug effects; Lymnaea - growth & development; Lymnaea - metabolism; Receptor, Serotonin, 5-HT1A - physiology; Rotation; Serotonin - toxicity; Serotonin Receptor Agonists - toxicity
• ISSN: 1532-0456
• DOI: 10.1016/j.cbpc.2010.02.012

Cilia driven rotation of the pond snail Lymnaea stagnalis embryos is regulated by serotonin (5-HT). In the present study, physiological and biochemical assays were used to identify the 5-HT receptor type involved in rotation. The 5-HTergic agonists applied stimulated the rotation by 180-400% and their rank order potency was as follows: LSD>5-HT>8-OH-DPAT>WB4101>>5-CT. The applied antagonists, spiperone, propranalol and mianserin inhibited the 5-HT or 8-OH-DPAT stimulated rotation of the embryos by 50-70%. (3)H-5-HT was bound specifically to the washed pellet of the embryo homogenates. The specific binding of (3)H-5-HT was saturable and showed a single, high affinity binding site with K(d) 7.36 nM and B(max) 221 fmol/mg pellet values. This is the first report demonstrating the high affinity binding of (3)H-5-HT to the native receptor in molluscs. All of the pharmacons that stimulated the rotation or inhibited the 5-HT or 8-OH-DPAT evoked stimulation displaced effectively the binding of (3)H-5-HT. 5-HT resulted in the inhibition of forskolin stimulated cAMP accumulation, showing that 5-HT is negatively coupled to adenylate cyclase. Our results suggest that in the 5-HTergic regulation of the embryonic rotation in L. stagnalis a 5-HT(1A)-like receptor of the vertebrate type is involved.