Midazolam-treated rats show less helping behavior than those receiving saline or no injection
TUESDAY, July 5, 2016 (HealthDay News) — In an experimental study, rats given midazolam were less likely to free trapped companions, presumably due to decreased empathy. The study findings were published online June 8 in Frontiers in Psychology.
In an effort to examine the roots of pro-sociality in mammals, Inbal Ben-Ami Bartal, Ph.D., from the University of Chicago, and colleagues established the helping behavior test in which rats are faced with a conspecific trapped in a restrainer that can only be opened from outside. Rats learn to open the door to the restrainer over the course of repeated test sessions. To assess whether an affective response motivates door opening, rats were treated with a benzodiazepine anxiolytic, midazolam.
The researchers found that, compared with saline-treated rats or rats receiving no injection, midazolam-treated rats showed less helping behavior. However, midazolam-treated rats opened a restrainer containing chocolate, indicating the socially specific effects of midazolam. Helping was not affected by administration of the peripherally restricted beta-adrenergic receptor antagonist nadolol. There was a correlation between corticosterone response of rats exposed to a trapped cage-mate with helping behavior; rats with the greatest corticosterone responses showed the least helping behavior. Behavior in one session influenced that in the next session; helping a trapped rat had greater motivational value than 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,” the authors write.
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