1Center for Molecular Medicine and Genetics, Wayne State University, 2Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, 3Department of Anatomy, Howard University College of Medicine
Friday 16, 200DE
The Energy Trade-off Hypothesis (ETOH; Aiello and Wheeler, 1995) argues that brain tissue is metabolically costly and that increasing the relative mass of the brain would increase the overall metabolic requirements needed to sustain an animal. The ETOH proposes that species can maintain a balanced metabolic budget by reducing the mass of other metabolically costly tissues (e.g., gut), or altering diet, behavior, and/or life history. Benington and Heller (1995) suggest that sleep functions to replenish energy stores in the brain that have been depleted during wakefulness. Variation in sleep and wake cycles across primates (including humans) and mammals may be one behavioral mechanism by which taxa with relatively large brains may maintain a viable energy budget. A wide variety of evolutionarily conserved molecular pathways support the energy hypothesis of sleep (e.g., adenosine and glycogen metabolism, unfolded protein response, electron transport chain, circadian rhythm regulators, AMP activated protein kinase, astrocyte to neuron lactate shuttle, oxidative stress, and uncoupling proteins). These molecular and physiological responses to depletion of energy stores in the brain resulting from wakefulness may provide additional mechanisms by which animals can meet metabolic demands. Exploring the molecular pathways of sleeps may provide new insights on primate and human evolution.
This research was funded by the National Science Foundation grant BCS0827546.