Rapid eye movement sleep deprivation induces a decrease in neuronal nuclear volume in the locus coeruleus, hippocampus and cingulated cortex of the rat

Background: Literature findings have suggested that brain morphological changes may underlie behavioral disturbances such as depression. In depressed patients, alteration in the volume of some brain regions were described and in laboratory animals antidepressant treatments change neuronal nuclei volume and axon densities in some brain regions. Rapid eye movement (REM) sleep deprivation has antidepressant effect in humans and in animals models of depression; moreover it induces changes in brain neurotransmission similar to those obtained after chronic antidepressant drug treatment (i.e., down-regulation of beta-adrenergic receptors and decreased synthesis of noradrenaline-stimulated cAMP). Objective and methods: The aim of this work was to determine if REM sleep deprivation would induce morphological changes in the brains of rats. The effects of REM sleep deprivation on the nuclear volume of neurons from the locus coeruleus, the main noradrenergic nucleus in the brain, hippocampus (area CA1) and cingulate cortex, two brain areas innervated by locus coeruleus, were studied. Results: The results obtained showed that REM sleep deprivation significantly decreased the nuclear volume of neurons in the locus coeruleus and in cingulate cortex and hippocampus, whereas stress significantly decreased the mean nuclear volume of neurons only from the hippocampus. Conclusion: A change in cell nuclear volume suggests a change in its metabolic activity, therefore, our data provide an anatomical basis for further studies of neuron’s morphology in brain structures after REM sleep deprivation.