GABAergic control of novelty stress-responsive epigenetic and gene expression mechanisms in the rat dentate gyrus.

The activity of dentate gyrus granule neurons is under a strong GABAergic tonic inhibitory control which contributes to the sparse activation pattern of these neurons after environmental stimuli. Previously, we reported that in sparse dentate gyrus neurons such stimuli evoke Ser-10 (S10) phosphorylation and Lys-14 (K14) acetylation in the nucleosomal protein histone H3 (H3S10p-K14ac) resulting in the induction of c-Fos. We hypothesized that GABA is an important modulator of novelty stress-evoked epigenomic mechanisms in rat dentate neurons.

Exercise improves cognitive responses to psychological stress through enhancement of epigenetic mechanisms and gene expression in the dentate gyrus.

Background: We have shown previously that exercise benefits stress resistance and stress coping capabilities. Furthermore, we reported recently that epigenetic changes related to gene transcription are involved in memory formation of stressful events. In view of the enhanced coping capabilities in exercised subjects we investigated epigenetic, gene expression and behavioral changes in 4-weeks voluntarily exercised rats.

The forced swimming-induced behavioural immobility response involves histone H3 phospho-acetylation and c-Fos induction in dentate gyrus granule neurons via activation of the N-methyl-D-aspartate/extracellular signal-regulated kinase/mitogen- and stress-activated kinase signalling pathway.

The hippocampus is involved in learning and memory. Previously, we have shown that the acquisition of the behavioural immobility response after a forced swim experience is associated with chromatin modifications and transcriptional induction in dentate gyrus granule neurons. Given that both N-methyl-D-aspartate (NMDA) receptors and the extracellular signal-regulated kinases (ERK) 1/2 signalling pathway are involved in neuroplasticity processes underlying learning and memory, we investigated in rats and mice whether these signalling pathways regulate chromatin modifications and transcriptional events participating in the acquisition of the immobility response.

Epigenetic mechanisms in stress-related memory formation.

Coping with stressful events is part of everyone's daily life. The organism's response to stress is a complex array of physiological and behavioral changes aimed at the preservation/protection of the organism during the stressful event as well as at stimulating adaptive and mnemonic processes in case the event would re-occur in the future. The hippocampus including its 'gate', the dentate gyrus, is highly involved in these processes.

Voluntary exercise impacts on the rat hypothalamic-pituitary-adrenocortical axis mainly at the adrenal level.

Introduction: Evidence is accumulating that the regular performance of exercise is beneficial for stress coping. However, the hypothalamic-pituitary-adrenocortical (HPA) axis of voluntarily exercising rats has never been comprehensively investigated.

Methods: Therefore, male Sprague-Dawley rats were given access to a running wheel in their home cage for 4 weeks in which they ran 4-7 km per night.

Novelty stress induces phospho-acetylation of histone H3 in rat dentate gyrus granule neurons through coincident signalling via the N-methyl-D-aspartate receptor and the glucocorticoid receptor: relevance for c-fos induction.

The hippocampus plays an important role in novelty detection, stress-related adaptation and learning and memory. However, it is unknown whether the response to novelty in the hippocampus involves induction of chromatin remodelling events known to be associated with transcriptional regulation. Here, we examined whether exposure to a novel environment, a mild psychological stressor, would affect the number of phospho-acetylated histone H3-positive [P(Ser10)-Ac(Lys14)-H3+] neurons in the rat hippocampus.

Psychological stress increases histone H3 phosphorylation in adult dentate gyrus granule neurons: involvement in a glucocorticoid receptor-dependent behavioural response.

Chromatin remodelling associated with transcriptional activation of silent genes involves phosphorylation at Serine-10 and acetylation at Lysine-14 in the N-terminal tails of the nucleosomal protein histone H3. We have identified neurons predominantly in the dentate gyrus showing a speckled nuclear immunoreactivity pattern for phosphorylated histone H3 [i.e.