CNFA 2004 SfN Abstracts

CHRONIC BEHAVIORAL STRESS DECREASES APICAL DENDRITIC SPINE DENSITY IN THE MEDIAL PREFRONTAL CORTEX
J.J.Radley1,2*; A.B.Rocher2; J.Hao2; T.McCall1,3; A.Wang1,3; P.R.Hof1,2; B.S.McEwen1,3; J.H.Morrison1,2
1. NIMH Ctr. for Fear and Anxiety, New York, NY, USA 2. Neurosci., Mount Sinai Sch. of Med., New York, NY, USA 3. Lab. of Neuroendocrinology, Rockefeller Univ., New York, NY, USA
The medial prefrontal cortex (mPFC) plays an important role in the negative feedback regulation of hypothalamic-pituitary-adrenal (HPA) activity during physiologic and behavioral stress. In addition, chronic behavioral stress is known to affect the morphology of layer II/III pyramidal neurons in the rat mPFC, by reducing the total length and branch number in apical dendrites by 20% (Radley et al., Neuroscience, 2004). In the current study, we investigated the effects of chronic behavioral stress on dendritic spine density in layer II/III pyramidal neurons of the mPFC. Rats were perfused after receiving 21 d of daily restraint stress, and intracellular iontophoretic injections of Lucifer Yellow were carried out in layer II/III pyramidal neurons in the anterior cingulate and prelimbic cortices. In order to reveal spines in all angles of orientation, deconvolved optical image stacks of randomly chosen dendritic segments were analyzed by digitally superimposing the sections in 3-D. We observed a significant reduction (25%) in total spine density in apical dendrites following 21 d of daily restraint stress. Since these same neurons underwent a 20% reduction in total apical dendritic length, these results suggest that total spine numbers on apical dendrites may be reduced by as much as 40% following chronic stress. We suggest that these cellular morphologic changes may impair the capacity of the mPFC to suppress HPA activity under stressful conditions. Synapse loss and apical dendritic atrophy may be important cellular features of stress-related psychiatric disorders where the mPFC is functionally impaired, such as post-traumatic stress disorder. Support Contributed By: MH58911
Program No. 208.1 Poster presentation:Sunday, Oct. 24, 8:00 AM - 9:00 AM Location:NN16