Early Embryonic Exposure of Freshwater Gastropods to Pharmaceutical 5-Alpha-Reductase Inhibitors Results in a Surprising Open-Coiled 'Banana-Shaped' Shell

In the study, freshwater gastropods (Biomphalaria glabrata and Physella acuta) were exposed to pharmaceutical 5α-reductase inhibitors, which in vertebrates convert testosterone to a more potent androgen. This exposure resulted in a consistent and reproducible abnormal shell morphology, where the gastropods developed elongated, open-coiled "banana-shaped" shells with unattached whorls. The inhibitor dutasteride was found to be approximately 10 times more potent in causing this phenotype than finasteride, mirroring its greater efficacy in humans. The specificity of the response was confirmed as other enzyme inhibitors did not induce the same shell deformation. These findings indicate that gastropods may have novel substrates for 5α-reductase, suggesting a fundamental difference between molluscan and vertebrate endocrinology, as molluscs appear to lack the enzymes and receptors for traditional steroidogenesis and androgen function.