'One night' sleep deprivation stimulates hippocampal neurogenesis

Neurogenesis in the adult hippocampus can be up- or downregulated in response to a variety of physiological and pathological conditions. Among these, dysregulation of hippocampal neurogenesis has been recently implicated in the pathogenesis of depression. In addition, in animal models of depression, a variety of antidepressant treatments reverse that condition by increasing neurogenesis. As one night sleep deprivation is known to improve mood in depressed patients for at least 1 day, we investigated whether a comparable treatment may affect hippocampal neurogenesis in adult rats. Accordingly, rats were sleep-deprived by gentle handling for 12 h during their physiological period of rest, and were injected with bromodeoxyuridine 4 h and 2 h before the end of sleep deprivation. They were then perfused immediately thereafter, or after 15 days and 30 days. We found that 12h sleep deprivation significantly increased cell proliferation and the total number of surviving cells in the hippocampal dentate gyrus soon after sleep deprivation, as well as 15 days and 30 days later, in comparison to control rats allowed to sleep. No changes were instead found in the subventricular zone of the lateral ventricles, indicating that 12 h sleep deprivation selectively triggers neurogenic signals to the hippocampus. The present data include acute sleep deprivation among the conditions which upregulate hippocampal neurogenesis and raise the possibility that such response could be implicated in the beneficial effects elicited in depressed patients by one night sleep deprivation. Thus, the findings could contribute to the understanding of the intriguing relationship between depression and neurogenesis in the adult brain. (c) 2006 Elsevier Inc. All rights reserved.