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Inhibition of protein kinase C signaling protects prefrontal cortex dendritic spines and cognition from the effects of chronic stress.

ABSTRACT: The prefrontal cortex r regulates behavior, cognition, and emotion by using working memory. Prefrontal functions are impaired by stress exposure. Acute, stress-induced deficits arise from excessive protein kinase C (PKC) signaling, which diminishes prefrontal neuronal firing. Chronic stress additionally produces architectural changes, reducing dendritic complexity and spine density of cortico-cortical pyramidal neurons, thereby disrupting excitatory working memory networks. In vitro studies have found that sustained PKC activity leads to spine loss from hippocampal-cultured neurons, suggesting that PKC may contribute to spine loss during chronic stress exposure. The present study tested whether inhibition of PKC with chelerythrine before daily stress would protect prefrontal spines and working memory. We found that inhibition of PKC rescued working memory impairments and reversed distal apical dendritic spine loss in layer II/III pyramidal neurons of rat prelimbic cortex. Greater spine density predicted better cognitive performance, the first direct correlation between pyramidal cell structure and working memory abilities. These findings suggest that PKC inhibitors may be neuroprotective in disorders with dysregulated PKC signaling such as bipolar disorder, schizophrenia, post-traumatic stress disorder, and lead poisoning--conditions characterized by impoverished prefrontal structural and functional integrity.

SUBMITTER: Hains AB

PROVIDER: S-EPMC2742406 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature

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Inhibition of protein kinase C signaling protects prefrontal cortex dendritic spines and cognition from the effects of chronic stress.

Hains Avis Brennan AB Vu Mai Anh T MA Maciejewski Paul K PK van Dyck Christopher H CH Gottron Melissa M Arnsten Amy F T AF

Proceedings of the National Academy of Sciences of the United States of America 20090911 42

The prefrontal cortex r regulates behavior, cognition, and emotion by using working memory. Prefrontal functions are impaired by stress exposure. Acute, stress-induced deficits arise from excessive protein kinase C (PKC) signaling, which diminishes prefrontal neuronal firing. Chronic stress additionally produces architectural changes, reducing dendritic complexity and spine density of cortico-cortical pyramidal neurons, thereby disrupting excitatory working memory networks. In vitro studies have ...[more]

PMID: 19805148

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Project description:BackgroundMultiple neuropsychiatric disorders, e.g., depression, are linked to imbalances in excitatory and inhibitory neurotransmission and prefrontal cortical dysfunction, and are concomitant with chronic stress.MethodsWe used electrophysiologic (n = 5-6 animals, 21-25 cells/group), neuroanatomic (n = 6-8/group), and behavioral (n = 12/group) techniques to test the hypothesis that chronic stress increases inhibition of medial prefrontal cortex (mPFC) glutamatergic output neurons.ResultsUsing patch clamp recordings from infralimbic mPFC pyramidal neurons, we found that chronic stress selectively increases the frequency of miniature inhibitory postsynaptic currents with no effect on amplitude, which suggests that chronic stress increases presynaptic gamma-aminobutyric acid release. Elevated gamma-aminobutyric acid release under chronic stress is accompanied by increased inhibitory appositions and terminals onto glutamatergic cells, as assessed by both immunohistochemistry and electron microscopy. Furthermore, chronic stress decreases glucocorticoid receptor immunoreactivity specifically in a subset of inhibitory neurons, which suggests that increased inhibitory tone in the mPFC after chronic stress may be caused by loss of a glucocorticoid receptor-mediated brake on interneuron activity. These neuroanatomic and functional changes are associated with impairment of a prefrontal-mediated behavior. During chronic stress, rats initially make significantly more errors in the delayed spatial win-shift task, an mPFC-mediated behavior, which suggests a diminished impact of the mPFC on decision making.ConclusionsTaken together, the data suggest that chronic stress increases synaptic inhibition onto prefrontal glutamatergic output neurons, limiting the influence of the prefrontal cortex in control of stress reactivity and behavior. Thus, these data provide a mechanistic link among chronic stress, prefrontal cortical hypofunction, and behavioral dysfunction.

Dataset Information

Inhibition of protein kinase C signaling protects prefrontal cortex dendritic spines and cognition from the effects of chronic stress.

Publications

Inhibition of protein kinase C signaling protects prefrontal cortex dendritic spines and cognition from the effects of chronic stress.

Similar Datasets

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