Brief embryonic exposure to Prozac® is correlated with alterations in embryonic synaptic gene expression and larval behavioral changes in Danio rerio

Abstract

Prozac®, a widely prescribed drug of the selective serotonin reuptake inhibitor class, is used to treat a number of disorders, including depression, panic attacks, obsessive compulsive disorder, and some eating disorders. Its widespread use raises concerns regarding the potentially harmful effects of embryonic exposure to the drug, and research on the relationship between embryonic exposure to pharmaceuticals and long-term behavioral disorders in adolescents or adults remains relatively sparse. A zebrafish model was utilized to study the effects of Prozac® on the developing nervous system.  Here we specifically focused on embryonic synaptic remodeling events and the later-staged adolescent behavioral changes resulting from a brief window of embryonic exposure to the drug. To that end, experimental embryos were exposed to Prozac® for 48, 72, and 96 hours and compared to control siblings of the same age. While no morphological differences between experimental and control embryos were observed, reverse transcriptase polymerase chain reaction analysis indicated that at the molecular level, exposure to Prozac® induced changes in the expression of genes involved in synaptic transmission, including those for serotonin and dopamine transporters. To determine whether these gene expression changes resulted in later-staged adolescent behavioral effects, larval zebrafish behavior was analyzed using DanioVision ® tracking software by Noldus. Zebrafish exposed to Prozac® for 72 hours after fertilization were released from drug treatment and raised under normal conditions in standard fish water until two weeks of age. Drug-treated fish showed significant changes in swimming behavior, including decreased total distance moved, time spent mobile, velocity, and time spent in an inner zone in the testing well. Prozac®-treated embryos also exhibited changes in learning responses in a simple non-threatening habituation assay compared with controls. Using the zebrafish model, we demonstrate that a brief period of embryonic exposure to Prozac® alters the expression of genes involved in embryonic synaptic transmission and is associated with changes in later-staged adolescent behavior.