Age Effects Aggressive Behavior: RNA-Seq Analysis in Cattle with Implications for Studying Neoteny Under Domestication

Abstract

The reactive type of aggression is regulated mostly by the brain’s prefrontal cortex; however, the molecular changes underlying aggressiveness in adults have not been fully characterized. We used an RNA-seq approach to investigate diferential gene expression in the prefrontal cortex of bovines from the aggressive Lidia breed at diferent ages: young three-year old and adult four-year-old bulls. A total of 50 up and 193 down-regulated genes in the adult group were identifed. Furthermore, a cross-species comparative analysis retrieved 29 genes in common with previous studies on aggressive behaviors, representing an above-chance overlap with the diferentially expressed genes in adult bulls. We detected changes in the regulation of networks such as synaptogenesis, involved in maintenance and refnement of synapses, and the glutamate receptor pathway, which acts as excitatory driver in aggressive responses. The reduced reactive aggression typical of domestication has been proposed to form part of a retention of juvenile traits as adults (neoteny).