Male preputium eversion in Biomphalaria alexandrina caused by SSRI's

Lam Hoi-ka, Edwin ten Winkel, bbPharma
Abstract. Eversion of the male preputium is an initial step in the copulatory behavior of several species of freshwater snails. Serotonergic mechanisms are involved in eversion in Biomphalaria glabrata snails as methiothepin, a serotonin receptor antagonist, has been shown to cause long-lasting dose-dependent eversion.
A number of selective serotonin reuptake inhibitors (SSRI's) were tested for their ability to induce preputium eversion in B. alexandrina in order to clarify the physiological mechanism of eversion. Methioheptin and serotonin were added as controls. Results were as follows: (SSRI's) fluoxetine (=Prozac®, 10–100 μM; p<0.0001), fluvoxamine (=Fluvox®, 10-50μM; p<0.0001), paroxetine (=Seroxat®, 10-50μM; p<0.0001). The receptor antagonist methiothepin (1 -10 μM; <0.0001). Serotonin did not induce eversion and did not block methiothepin-induced eversion. This suggests that the SSRI's are not acting as SSRI, but possibly as a receptor ligand.