Anxiolytic Treatment Impairs Helping Behavior in Rats

Abstract

Despite decades of research with humans, the biological mechanisms that motivate an individual to help others remain poorly understood. In order to investigate the roots of pro-sociality in mammals, we established the helping behavior test, a paradigm in which rats are faced with a conspecific trapped in a restrainer that can only be opened from the outside. Over the course of repeated test sessions, rats exposed to a trapped cagemate learn to open the door to the restrainer, thereby helping the trapped rat to escape (Ben-Ami Bartal et al., 2011). The discovery of this natural behavior provides a unique opportunity to probe the motivation of rodent helping behavior, leading to a deeper understanding of biological influences on human pro-sociality. To determine if an affective response motivates door-opening, rats receiving midazolam, a benzodiazepine anxiolytic, were tested in the helping behavior test. Midazolam-treated rats showed less helping behavior than saline-treated rats or rats receiving no injection. Yet, midazolam-treated rats opened a restrainer containing chocolate, highlighting the socially specific effects of the anxiolytic. To determine if midazolam interferes with helping through a sympatholytic effect, the peripherally restricted beta-adrenergic receptor antagonist nadolol was administered; nadolol did not interfere with helping. The corticosterone response of rats exposed to a trapped cagemate was measured and compared to the rats’ subsequent helping behavior. Rats with the greatest corticosterone responses showed the least helping behavior and those with the smallest responses showed the most consistent helping at the shortest latency. These results are discussed in terms of their implications for the interaction between stress and pro-social behavior. Finally, we observed that door-opening appeared to be reinforcing. A novel analytical tool was designed to interrogate the pattern of door-opening for signs that a rat’s behavior on one session influenced his behavior on the next session. Results suggest that helping a trapped rat has a greater motivational value than does chocolate. In sum, this series of experiments clearly demonstrates the fundamental role of affect in motivating pro-social behavior in rodents and the need for a helper to resonate with the affect of a victim.

Are There Multiple Motivators for Helping Behavior in Rats?

“…In conclusion, there are multiple factors involved in the motivation to the opening behavior in the protocol proposed by Ben-Ami Bartal et al (2011) and used in the present study. This outcome is relevant as there is an increasing number of studies that used the original or modified versions of the releasing task with the purpose of studying empathy or prosocial behavior in rodents ( Ben-Ami Bartal et al, 2014 , 2016 ; Silberberg et al, 2014 ; Hachiga et al, 2018 ; Kandis et al, 2018 ; Karakilic et al, 2018 ; Fontes-Dutra et al, 2019 ; Yamagishi et al, 2019 ). Our study provided data that ruled out the desire for social contact or the exploration of the restraint box as key motivators, at least under our experimental conditions.…”

Pet dogs (Canis lupus familiaris) release their trapped and distressed owners: Individual variation and evidence of emotional contagion

“…Specifically, free rats made more alarm calls when their cage-mate was restrained than when the apparatus was empty or contained a toy rat [45]. In addition, anxiolytic treatment impaired rescue behavior in rats indicating that this behavior was motivated by an affective state of anxiety elicited by the distress of the trapped conspecific [33].…”

“…Prosocial helping paradigms have typically employed an 'out-of-reach task' in which potential donor individuals can choose to retrieve and transfer an item to a recipient individual, for whom this item is otherwise out of reach (e.g., [32]). The current study adopted an alternative test for helping that has been used to successfully demonstrate prosocial rescue behavior in rats [33] and ants [8]. In this paradigm, a potential rescuer is free to move about a testing arena while a conspecific in the same arena is either trapped inside a restrainer apparatus that can only be opened from the outside (rats), or partially buried in sand and tied down by a nylon thread (ants).…”

Empathy as a Concept from Bench to Bedside: A Translational Challenge

“…Intranasal oxytocin was shown to improve empathy in PTSD patients (106). Ben-Ami Bartal et al showed that administration of a benzodiazepine (midazolam) impaired helping behavior in rats (107). Benzodiazepines are known to downregulate oxytocin transmission, which is linked to empathy, and reducing anxiety is also linked to deactivating HPA axis and sympathetic system.…”