Meeting Abstract
To better understand the genetic underpinnings of inter-individual difference in fear-induced freezing, it is essential to identify key modulators that are differently expressed in the targeted brain regions. We used newborn domestic chicks to isolate differently expressed genes (DEGs) between individuals with high and low sensitivity to novel fear stimuli. The tonic immobility test was employed to measure the duration of immobilization as an indicator of innate fear response. RNA sequencing technique was used for the rapid identification of up- and down-regulated genes in the amygdala of high-fear chicks as compared with the other brain regions such as the hippocampus and striatum. The top and bottom 10 DEGs included important neurotransmitter-related genes, e.g., mesotocin/oxytocin receptor and arginine-vasotocin/ arginine-vasopressin (AVT/AVP). Finally, experimental validation revealed that the relative mRNA expressions of AVT/AVP are significantly different between behavioral groups that showed extreme responses to fear-inducting stimuli. AVT/AVP mRNA expression was significantly higher in chicks with short freezing duration, suggesting different types of coping strategies in response to acute stress between rodents and birds. Our results suggest that AVT/AVP may play a critical role in modulating fear responses by lowering the threshold of risk-taking behavior, as it represents one of the alternative strategies for survival.
