The serotonin 5-HT1B agonist sumatriptan increases aggressive behaviors in adult male rats in a neutral cage setting

Abstract: Aggressive behavior is defined as that in which an individual aims to harm another person, with the intent to physically or psychologically wound or kill. Aggression – whether unprimed or primed – is thus a trait of interest in both criminal behavior and every day mood management. Previous research (using the established intruder-scenario model) has reported high levels of serotonin and dopamine in the nucleus accumbens of adult male rats, both during and after aggressive bouts. Since the intruder-scenario could have a priming effect on aggression, this study for the first time investigated aggression in a neutral cage, only “priming” with the serotonergic agonist sumatriptan in an attempt to establish a potential connection between levels of nucleus accumbens serotonin and aggressive behavior. Thus, a total of eight male rats were randomly split into four pairs and tested for aggressive behaviors in a single 30-minute session. The pairs each consisted of one saline-infused rat versus one sumatriptan-infused rat. While the results showed non-significant effects of sumatriptan for some aggressive behaviors, sumatriptan-infused rats showed significantly higher occurrences of chasing and clinch attacking as compared to saline controls. Interestingly, both of these behaviors occur towards the beginning of an aggressive bout, suggesting that sumatriptan may influence the initiation of aggressive behavior. More research is necessary to confirm and expand these initial findings.

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