Sleep deprivation but not a whisker trim increases nerve growth factor within barrel cortical neurons

Sleep is hypothesized to influence activity-driven changes in the brain mic rocircuitry. A change in the barrel cortex following the removal of the mys tacial whiskers in rats is a model fur synaptic plasticity. This model was combined with sleep deprivation and immunoreactivity for nerve growth facto r (NGF) was determined. Sleep deprivation for 6 h after light onset signifi cantly increased the number of NGF-immunoreactive pyramidal neurons in laye r V of the barrel cortex. However, unilateral trimming of mystacial whisker s did not affect NGF immunoreactivity in the contralateral or ipsilateral b arrel cortices when rats were allowed to sleep. if the rats: received a uni lateral whisker cut at light onset, and subsequently were deprived of sleep , increases in the NGF-immunoreactive neurons were only observed in the bar rel cortex on the side that received input from the remaining intact whiske rs. In contrast. NGF immunoreactivity on the side contralateral to the cut whiskers decreased in sleep-deprived animals to levels below those observed in the control animals that were allowed to sleep. These results suggest t hat NGF expression is influenced by the interaction of sleep, afferent inpu t and the nature of ongoing synaptic reorganization. Further, results are c onsistent with the hypothesis that growth factors, such as NGF, form part o f the mechanism responsible for sleep regulation and that they also form on e facet of sleep-related synaptic plasticity. (C) 2001 Elsevier Science B.V . All rights reserved.