Cilia-driven rotational behavior in gastropod (Physa elliptica) embryos induced by serotonin and putative serotonin reuptake inhibitors (SSRIs)
✍ Scribed by Uhler, Gretchen C.; Huminski, Peter T.; Les, Frederick T.; Fong, Peter P.
- Book ID
- 101226967
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 147 KB
- Volume
- 286
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
We characterized the serotonin (5-hydroxytryptamine; 5-HT) receptor mediating cilia-driven rotational movement in embryos of the freshwater gastropod Physa elliptica. In addition, putative serotonin reuptake inhibitors (SSRIs), previously shown to induce other 5-HT-mediated processes in molluscs, were tested for their ability to induce rotation. As in previous studies with other freshwater gastropods, 5-HT induced a significant dose-dependent increase in rotation from 10 -6 to 10 -4 M. The 5-HT 1A agonist 8-OH-DPAT produced a similar dose-dependent increase in rotation. However, the 5-HT 2 agonist α-CH3-serotonin evoked a significant rotational response only at the highest concentration of 10 -4 M. The 5-HT 2 receptor antagonist mianserin not only blocked 5-HT-induced rotation, it reduced rotation rate below that of baseline. However, two other antagonists, cyproheptadine (5-HT 2 ) and propranolol (5-HT 1 ), caused similar responses that consisted of an initial rotational surge followed by reduced rotation. Thus, these drugs appear to act as partial agonists. The putative SSRI fluvoxamine exhibited a significant dose-dependent increase in positive rotation as that seen with 5-HT. The SSRIs paroxetine and fluoxetine both caused an increase in rotation at 10 -6 and 10 -5 M but reduced rotation rate below that of baseline at 10 -4 M. These results agree with other studies on aquatic molluscs, suggest a 5-HT receptor with a mixed 5-HT 1 /5-HT 2 pharmacological profile and add to a now growing body of literature on the pharmacology of molluscan 5-HT receptors. In addition, all the tested putative SSRIs induced cilia-driven rotation in Physa embryos, indicating either the presence of 5-HT reuptake transporters or that these compounds act as 5-HT receptor ligands.