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Aggression is almost a universal behavior, common to almost all species. Although aggression is often looked at in terms of environmental factors, new research is examining aggressive behavior from a genetic point of view. It is important to examine the influence of gene regulation in aggression in order to understand social interactions, particularly in human society where aggression has effects on violent crime rates, suicide rates, and can be an indicator of other clinical conditions such as depression.
In order to treat depression, anxiety and personality disorders, selective serotonin reuptake inhibitors (SSRIs) are often used as an antidepressant medication. Over the past few decades, conflicting evidence regarding a possible link between SSRIs and aggression has surfaced. Some studies suggest SSRIs increase aggression; other studies find SSRI treatment reduces aggressive behavior. The current study evaluated the effect of SSRI treatment on gene regulation of aggression in the model organism; Danio rerio (Zebrafish). D. rerio are suitable model organisms as they display stereotypical aggressive behavior. Two strains of fish were used; Scientific Hatcheries (SH) and AB. SH is a relatively non aggressive wild type strain. The AB is the aggressive strain. Quantitative Polymerase Chain Reaction (qPCR) was used to assess and quantify the expression of 10 genes in the brain selected from the literature.
There were no significant differences between the fluoxetine treated fish and the biological control fish in either strain. However, two genes, avpl and oxtl, had a marginally significant difference between treatment groups in the SH strain. Fluoxetine treated fish had higher avpl and oxtl gene expressions than in the biological control fish. Furthermore, oxtl was higher in fluoxetine treated SH fish than AB fish. The gene expression level of avpl was marginally significantly higher in SH than AB fish. No other gene of interest was statistically different between strains.
The current study evaluated the effect that SSRI treatment, specifically fluoxetine, had on gene regulation in an aggressive adult male strain of D. rerio compared to a passive strain of D. rerio. Given the small sample size, this study serves as the basis for further investigation to determine the link between aggression and SSRI treatment and gene regulation. More research is needed to understand the genetics of aggression. The study contributes to understanding gene regulation and the serotonergic system, and highlights the hypothalamo-neurohypophysial-system (HNS) as a key neurological pathway in aggressive behavior in different strains of D. rerio.
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Naidoo, Megan, "The Genetics of Aggression in Danio rerio: Measuring the Regulation of Genes in Different Strains of Danio rerio in Response to SSRI Treatment" (2012). Senior Projects Fall 2012. 29.