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Arch Hellen Med, 32(3), May-June 2015, 280-294


The hippocampus, neuronal plasticity and stress exposure

J. Anastasiades, G. Garyfallos
Second Department of Psychiatry, Aristotle University of Thessaloniki, Psychiatric Hospital, Thessaloniki, Greece

The hippocampus is a special area of convergence between the organic substrate and environmental effects for many physiological functions (e.g., memory, emotion), and also for pathological processes occurring in psychiatric diseases. Current research focuses on neuronal plasticity, the mechanism through which recent memory records are stored and new behavioral patterns are developed. This is a review of the role of neuronal plasticity in the hippocampus, as this is the area in which neuronal plasticity has been studied extensively. Long term potentiation (LTP) constitutes a mechanism by which synaptic functionality is implemented, making the transmission of information more efficient, and thus the neuronal circuits involved in learning and behavioral procedures are facilitated. "Stress" is a non-specific term referring to situations affecting homeostasis. Glucocorticoid receptors are abundant in the hippocampus, resulting in a vulnerability of this area to stress. Stress exposure induces a decrease in hippocampal volume and a reduction in its functionality, with loss and shrinkage of neurons detected microscopically. Disturbance in LTP constitutes the subtle mechanism of the functional consequences of stress exposure in the hippocampus. The disturbance in LTP results not only in a decrease in functionality, but also in a decrease in volume secondary to reduced production of neurotrophic factors and inhibition of neurogenesis. The mechanism of LTP between neurons is not yet fully understood, but its disclosure will provide new understanding of the pathophysiology of many diseases and the potential for novel therapeutic strategy.

Key words: Hippocampus, Long term potentiation (LTP), Neuronal plasticity, Stress.

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