POSSIBLE PATHOPHYSIOLOGICAL MECHANISMS REGULATING FOOD-INTAKE IN SEASONAL AFFECTIVE-DISORDER

Noradrenaline, estrogen, neuropeptide Y and galanin are all involved i n regulation of eating behaviour. Based on a recent case report on sea sonal affective disorder (SAD), there is evidence of decreased insulin sensitivity. Reduced insulin sensitivity may increase the transcripti onal activity of the neuropeptide Y gene in the medial basal hypothala mus and subsequent ingestion of food. Decreased availability of estrog en may also increase the levels of neuropeptide Y, leading to decrease d release of noradrenaline from the ventromedial hypothalamus. The inc reased noradrenaline content may increase the concentration of galanin , which will decrease the circulating levels of insulin and increase t he pace of transcription of the neuropeptide Y gene. Among some SAD pa tients, it is possible that the sustained ingestion of high-fat diet w ill rather activate the transcription of the neuropeptide Y gene than deactivate it, indicating a defect in macronutrient selection.