Peripubertal stress increases play fighting at adolescence and modulates nucleus accumbens CB1 receptor expression and mitochondrial function in the amygdala

Summary & key facts

In a study with rats, researchers found that stress around puberty (peripubertal stress) made adolescent rats play-fight more. The rats that showed the highest levels of play fighting later showed abnormal aggressive behaviors as adults. Those high play-fighting rats also showed faster reduction (habituation) of their stress hormone response to repeated stress and had higher mitochondrial (cell-energy) function in the amygdala. Rats with low play fighting had higher levels of the CB1 cannabinoid receptor in the nucleus accumbens shell. The authors say this points to adolescence as an important time when altered play can be linked to later aggression and that brain energy metabolism during ad

Key facts:

• Peripubertal stress (stress around puberty) made rats show more play fighting during adolescence.
• Rats with the highest adolescent play fighting after peripubertal stress were the ones that developed abnormal forms of aggression as adults.
• High play-fighting rats showed faster habituation of their corticosterone (stress hormone) response when exposed repeatedly to stress during peripuberty.
• High play-fighting rats had increased mitochondrial function in the amygdala when tested ex vivo; this increase was not seen in the nucleus accumbens.
• Rats with low levels of play fighting (not the high players) showed increased expression of the CB1 cannabinoid receptor in the nucleus accumbens shell.
• The authors suggest adolescence may be a critical period linking altered play behavior to adult aggression and that brain energy metabolism during adolescence could be a possible target to prevent adult aggression.
• These findings come from a rat model, so they do not automatically apply to humans.

Abstract

Play fighting is a highly rewarding behavior that helps individuals to develop social skills. Early-life stress has been shown to alter play fighting in rats and hamsters as well as to increase aggressive behaviors at adulthood. However, it is not known whether individual differences in stress-induced play fighting are related to differential developmental trajectories towards adult aggression. To address this question, we used a rat model of peripubertal stress (PPS)-induced psychopathology that involves increased aggression at adulthood. We report that, indeed, PPS leads to enhanced play fighting at adolescence. Using a stratification approach, we identify individuals with heightened levels of play fighting as the ones that show abnormal forms of aggression at adulthood. These animals showed as well a rapid habituation of their corticosterone responsiveness to repeated stressor exposure at peripuberty. They also showed a striking increase in mitochondrial function in the amygdala-but not nucleus accumbens-when tested ex vivo. Conversely, low, but not high players, displayed increased expression of the CB1 cannabinoid receptor in the nucleus accumbens shell. Our results highlight adolescence as a potential critical period in which aberrant play fighting is linked to the emergence of adult aggression. They also point at brain energy metabolism during adolescence as a possible target to prevent adult aggression.

Topics

Neuroendocrine regulation and behavior Stress Responses and Cortisol Tryptophan and brain disorders

Categories

Behavioral Neuroscience Life Sciences Neuroscience

Tags

Aggression Amygdala Central nervous system Clinical psychology Developmental psychology Extended amygdala Habituation Neuroscience Nucleus accumbens Psychology Psychopathology Stressor Stria terminalis