Abstract # 2407:

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Anterior hippocampal volume is reduced in behaviorally depressed female Macaca fascicularis living in social groups

S. L. Willard1, E. J. Glover1, D. P. Friedman2, C. K. Henkel3 and C. A. Shively4
1Wake Forest University School of Medicine, Interdisciplinary Graduate Program in Neuroscience, Medical Center Boulevard, Winston-Salem, NC 27157, USA, 2Physiology & Pharmacology, Wake Forest University School of Medicine, 3Neurobiology & Anatomy, Wake Forest University School of Medicine, 4Comparative Medicine, Wake Forest University School of Medicine
     Alterations in hippocampal (HC) volume have been implicated in the pathophysiology of depression. Reduced HC volume has been observed in depressed humans, although the effect is not always significant. Rodent studies indicate that anterior HC is associated with emotional and anxiety-related behavioral functioning. Using unbiased stereology, we measured whole, anterior, and posterior HC volumes in a matched sample of adult female cynomolgus macaques characterized for behavioral depression (n=6 depressed, 6 nondepressed). HC tissue was serially sectioned, slide mounted, and Nissl-stained. Using Neurolucida software, every tenth serial section along the anterior-posterior HC axis was traced and used to reconstruct a 3-D model by which volumes were determined. Structures included in quantitative volume analyses were the cornu ammonis (CA1-CA3), dentate gyrus, subiculum, alveus, and fimbria. Anterior and posterior HC were delineated by the presence of the uncus at the point at which the HC head is separate from the body. Volumes were log transformed to reduce variability and ANOVA was used to determine group differences. No significant differences were found between depressed and nondepressed monkeys for whole or posterior HC volume. Anterior HC volumes were significantly smaller [F(1,10)=6.16, p=0.03] in depressed compared to nondepressed monkeys. These results indicate that reduced volume in the anterior HC, an area previously implicated in emotional functioning, may be associated with depressive behavior in female cynomolgus macaques.