Differences in Stress-Induced Changes in Extinction and Prefrontal Plasticity in Postweanling and Adult Animals

Stress and Fear Extinction

“…The situation may be more complex in adolescence, however. One recent study found that acute elevatedplatform stress in post-weaning rats facilitated extinction retrieval (Schayek and Maroun, 2014) which is distinct from the stress-impairing effect of stress in adults. However, in other studies that subject adolescents to repeated stressors (e.g., predator-odor, elevated-platform, social instability or footshock) elevated fear was evident during extinction training when the animals were later tested in young adulthood (Figure 4) Judo et al, 2010;McCormick et al, 2013;Toledo-Rodriguez et al, 2012).…”

“…While they have not yet been studied for their potential interaction with stress, variants in the Tolloid-Like 1 Gene (TLL1) (Xie et al, 2013), retinoid-related orphan receptor alpha gene (RORA) (Logue et al, 2013) and fatty acid amide hydrolase (FAAH) (Dincheva, 2015;Gunduz-Cinar et al, 2013b) genes have been recently associated with PTSD or PTSD-related personality traits, including fear extinction and stressreactivity. (c) Adolescent rats exposed to chronic stress typically show impaired extinction when tested as adults Judo et al, 2010;Toledo-Rodriguez et al, 2012), though there is preliminary evidence that acute stress in adolescence can facilitate extinction (Schayek et al, 2014). In the vmPFC, stress has been shown to cause excess glutamate and associated dendritic hypotrophy and downregulation of glutamate receptors.…”

“…Studies by Maroun and colleagues and others have demonstrated how extinction deficits produced by acute elevated-platform stress are tied to the disruption of synaptic plasticity (LTP) in the mPFC-BLA pathway (Maroun, 2006;Maroun et al, 2003;Richter-Levin and Maroun, 2010) (see also Rocher et al, 2004). Interestingly, the same stressor was recently found to enhance mPFC-BLA plasticity in adolescent rats, providing another example of how the neural consequences of stress differ as a function of age (Schayek et al, 2014). In adults, stress-induced plasticity changes in mPFC-BLA pathway are associated with multiple of molecular abnormalities in the mPFC.…”

PI3-kinase cascade has a differential role in acquisition and extinction of conditioned fear memory in juvenile and adult rats

“…We have recently shown that the function of the mPFC in juvenile prepubertal rats is affected differently by stress than in adult animals (Schayek and Maroun 2015). In adult animals stress resulted in impaired extinction and plasticity in the form of longterm potentiation in the mPFC (Maroun and Richter-Levin 2003;Rocher et al 2004;Markham et al 2007;Schayek and Maroun 2015), whereas in juvenile animals, a similar stressor was associated with enhanced extinction and enhanced mPFC plasticity (Schayek and Maroun 2015). The BLA, similarly to the mPFC, undergoes changes in juvenile rats (Markham et al 2007;Rubinow and Juraska 2009).…”

Preclinical studies of stress, extinction, and prefrontal cortex: intriguing leads and pressing questions

“…This pattern of results suggests that differences between stressed and unstressed rats during testing for extinction retrieval do indeed reflect deficits in the extinction memory. Subsequent studies have demonstrated that an acute platform stressor applied after acquisition of conditioned fear impairs extinction (Maroun et al 2013; Schayek and Maroun 2015). While these studies eliminate the possibility of stress-induced facilitation of acquisition, the experimental design, in which stress was applied immediately after a probe for fear retrieval, leaves open the possibility that stress strengthened memory reconsolidation, thus promoting fear during extinction training.…”