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Elena Timofeeva

Elena Timofeeva

Laval University,Canada

Title: The neuronal mechanisms of overeating of sweet palatable food

Biography

Elena Timofeeva is an Associate Professor at the Laval University, Department of Psychiatry and Neuroscience. After receiving a bachelor’s degree from the Odessa State University, Ukraine, she has completed her master’s (1997) and PhD (2001) degrees in the Department of Anatomy and Physiology at the Laval University, Quebec, Canada. Dr. Timofeeva performed her post-doctoral studies from 2001 to 2005 at the Mental Health University Institute of Quebec, Canada. Dr Timofeeva has published 4 book chapters and 35 research papers. Her laboratory investigates the molecular and neuronal mechanisms of the interactive effects of stress and diets on food intake regulation.

Abstract

Our research is focused on the brain mechanisms triggering overeating of palatable sweet foods and the neuronal and metabolic consequences of this overeating. To investigate the molecular, neuronal and metabolic aspects of sweet diets, we use the rat models subjected to the diets containing palatable sweet ingredients. Our experiments show that intake of the sweet palatable food by rats exponentially increases in spite of detrimental metabolic consequences which include accumulation of fat and development of obesity. In the brain, repeated consumption of sucrose displaced the neuronal pre-prandial activity from the medial hypothalamic region, the dorsomedial hypothalamic nucleus (DMH) and the paraventricular hypothalamic nucleus (PVN), to the brain arias involved in reward, the nucleus accumbens (Acb) and the prefrontal cortex (PF). Suppression of activity of the medial hypothalamus by sucrose was confirmed in the experiments testing the effects of consumption of sucrose on the reaction to restraint stress in rats. The animals with a given choice to consume sucrose along with rat chow provided ad libitum showed lower expression of the mRNA of a stress neurohormone, corticotropin-releasing factor, in the PVN and lower levels of plasma corticosterone in response to 1-h stress session. Therefore, consumption of sucrose may dampen the neuronal and hormonal response to stress that explains why sweets may be consumed as ‘comforting’ food. On the other hand, displacement of neuronal pre-prandial activity from the medial hypothalamus to the reward areas by sucrose suggests that regulation of sucrose intake may escape from the homeostatic control.