Homer1a and 1bc levels in the rat somatosensory cortex vary with the time of day and sleep loss

Homer protein expression is dependent in part on neuronal activity and sleep. Homer1a differs in function from Homer1bc although both are involved in synaptic scaffolding. The effects of sleep loss, time of day and afferent activity on these molecules were investigated. Rats were sacrificed at the midpoint of either their activity or sleep phases and RNA was prepared from somatosensory cortex samples. Homer1a and Ibc mRNA levels were determined by real time PCR. There were greater amounts of both Homerla and Ibc in night time samples. In controls, there was more Homer1bc than 1a both day and night. Sleep loss upregulated Homer1a in the morning but not at night. Homer1bc was much less affected by manipulations of sleep. Thus, Homer1a may be a state- and activity-dependent synaptic scaling factor. (C) 2004 Elsevier Ireland Ltd. All rights reserved.