Sreedharan Sajikumar, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore

Mood disorders affect the lives and functioning of millions each year. A greater understanding of the neuronal circuits underlying mood in both normal and abnormal affective states has been identified as one of the critical needs in the field of mood disorders. Stress, particularly when uncontrollable, excessive and/or prolonged, can produce a myriad of emotional and cognitive alterations facilitating both adaptive and maladaptive changes that control the way in which neurons are wired that eventually affect behavior. Regulation of synaptic transmission, intracellular signal transduction, gene expression and even structural alterations are some of the mechanisms underlying these changes. The fact that the effects of stress is long lasting even long after the elimination of the actual stressors, places a special emphasis on the regulation of transcription factors and patterns of gene expression that could underlie these changes. In our studies, the effects of stress during juvenility brings about depressive-like behavior in adulthood affecting emotional and cognitive aspects. Our preliminary gene expression profile has provided us insights on the activation and a heightened expression of epigenetic factors in these stress models, especially on the factors such as G9a/GLP. Electrophysiology results also prove that there is an altered long-term potentiation in juvenile stressed rats and the modulation of this epigenetic complex on the slices from these rats showed alleviation of long term potentiation. Thus, our studies investigate the differential mechanisms behind the regulation of stress in learning and memory models.