Reversibility of apical dendritic retraction in the rat medial prefrontal cortex following repeated stress

Abstract

Apical dendritic retraction and axospinous synapse loss in the medial prefrontal cortex (PFC) are structural alterations that result from repeated restraint stress. Such changes in this brain region may be associated with impaired working memory, altered emotionality, and inability to regulate hypothalamic-pituitary adrenal activity, which in turn may underlie stress-related mental illnesses. In the present study, we examined the persistence of these stress-induced dendritic alterations in the medial PFC following the cessation of stress. Animals received either daily restraint stress for a 3-week period and were then allowed to recover for another 3 weeks, restraint stress for 3 or 6 weeks, or no restraint. Following perfusion and fixation, intracellular iontophoretic injections of Lucifer Yellow were performed in layer II/III pyramidal neurons in slices from the medial PFC, and apical and basal dendritic arbors were reconstructed in three dimensions. We observed a significant reduction in apical dendritic length and branch number following 3 or 6 weeks of repeated stress compared to 3-week stress/3-week recovery. These results suggest that stress-induced dendritic plasticity in the medial PFC is reversible and may have implications for the functional recovery of medial PFC function following prolonged psychological stress.