Long-lasting, sex-specific inhibition of serotonin-induced spawning by methiothepin in the zebra mussel,Dreissena polymorpha (Pallas)

✍ Scribed by Fong, Peter P. ;Hardege, Jorg D. ;Ram, Jeffrey L.

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 708 KB
• Volume: 270
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402700310

✦ Synopsis

Abstract

Zebra mussels (Dreissena polymorpha) can be stimulated to spawn with external application of serotonin. Inhibition of serotonin‐elicited spawning by methiothepin, a serotonin receptor ligand, was investigated. Methiothepin, which inhibits both male and female spawning when present concomitantly with serotonin (Fong et al. [1994a]) was demonstrated to cause long‐lasting inhibition of spawning in females for up to 12 days after its application. Mussels were exposed to various concentrations of methiothepin for 5 hours, rinsed with fresh water, and then tested with 10^−3^ M serotonin on the next day. Spawning in females that had been exposed to 10^−5^ M methiothepin was completely blocked, with little effect on male spawning. At methiothepin concentrations as low as 10^−8^ M, spawning latency in response to serotonin was significantly increased in females; higher concentrations also increased spawning latency in males. Exposure to 10^−5^ M methiothepin for as little as 30 minutes was sufficient to completely inhibit spawning in females, but not in males. A 21‐hour exposure to either 10^−6^ or 10^−5^ M methiothepin also significantly inhibited female spawning, with much smaller effects on males. Percent spawning in different groups of animals tested 1,2,4,8, and 12 days after a 5‐hour exposure to 10^−5^ M methiothepin was significantly reduced for females on all test days, but not for males. The mechanisms of this sex‐specific and long‐lasting inhibition of serotonin‐induced spawning are discussed with reference to receptor binding, retention, toxicity, and partial agonist properties of methiothepin. © 1994 Wiley‐Liss, Inc.