Structural and functional damage to the retina and skeletal muscle in Xenopus laevis embryos exposed to the commonly used psychotropic benzodiazepine delorazepam

Benzodiazepines, psychotropic drugs, are among the most frequently found pharmaceuticals in aquatic matrices. An increasing number of studies are reporting their harmful effects on adults' behaviour and physiology, while little information is available regarding developing organisms exposed since early stages. Improper activation of GABA receptors during embryonic development is likely to induce relevant consequences on the morphogenesis and, at later stages, on behaviour. This study investigated the negative effects of three increasing concentrations of delorazepam on Xenopus laevis retinal and skeletal muscle morphogenesis. Morphological and ultrastructural investigations were correlated with gene expression, while Raman spectroscopy highlighted the main biochemical components affected. Conventional phototactic response and orientation in the magnetic field were assessed as indicators of proper interaction between sensory organs and the nervous system. Results confirm the profound impact of delorazepam on development and return an alarming picture of the amphibians’ survival potentialities in a benzodiazepine-contaminated environment.