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  1. Article: Neuronal mechanisms underlying attention deficit hyperactivity disorder: the influence of arousal on prefrontal cortical function.

    Brennan, Avis R / Arnsten, Amy F T

    Annals of the New York Academy of Sciences

    2008  Volume 1129, Page(s) 236–245

    Abstract: Neuropsychological and imaging studies indicate that attention deficit hyperactivity disorder (ADHD) is associated with alterations in prefrontal cortex (PFC) and its connections to striatum and cerebellum. Research in animals, in combination with ... ...

    Abstract Neuropsychological and imaging studies indicate that attention deficit hyperactivity disorder (ADHD) is associated with alterations in prefrontal cortex (PFC) and its connections to striatum and cerebellum. Research in animals, in combination with observations of patients with cortical lesions, has shown that the PFC is critical for the regulation of behavior, attention, and affect using representational knowledge. The PFC is important for sustaining attention over a delay, inhibiting distraction, and dividing attention, while more posterior cortical areas are essential for perception and the allocation of attentional resources. The PFC in the right hemisphere is especially important for behavioral inhibition. Lesions to the PFC produce a profile of distractibility, forgetfulness, impulsivity, poor planning, and locomotor hyperactivity. The PFC is very sensitive to its neurochemical environment, and either too little (drowsiness) or too much (stress) catecholamine release in PFC weakens cognitive control of behavior and attention. Recent electrophysiological studies in animals suggest that norepinephrine enhances "signals" through postsynaptic alpha2A adrenoceptors in PFC, while dopamine decreases "noise" through modest levels of D1 receptor stimulation. alpha2A-Adrenoceptor stimulation strengthens the functional connectivity of PFC networks, while blockade of alpha2 receptors in the monkey PFC recreates the symptoms of ADHD, resulting in impaired working memory, increased impulsivity, and locomotor hyperactivity. Genetic alterations in catecholamine pathways may contribute to dysregulation of PFC circuits in this disorder. Medications may have many of their therapeutic effects by optimizing stimulation of alpha2A adrenoceptors and D1 receptors in the PFC, thus strengthening PFC regulation of behavior and attention.
    MeSH term(s) Arousal/physiology ; Attention Deficit Disorder with Hyperactivity/drug therapy ; Attention Deficit Disorder with Hyperactivity/genetics ; Attention Deficit Disorder with Hyperactivity/physiopathology ; Catecholamines/metabolism ; Environment ; Humans ; Neurons/physiology ; Prefrontal Cortex/physiopathology
    Chemical Substances Catecholamines
    Language English
    Publishing date 2008-06-30
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Review
    ZDB-ID 211003-9
    ISSN 1749-6632 ; 0077-8923
    ISSN (online) 1749-6632
    ISSN 0077-8923
    DOI 10.1196/annals.1417.007
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Blockade of IP3-mediated SK channel signaling in the rat medial prefrontal cortex improves spatial working memory.

    Brennan, Avis R / Dolinsky, Beth / Vu, Mai-Anh T / Stanley, Marion / Yeckel, Mark F / Arnsten, Amy F T

    Learning & memory (Cold Spring Harbor, N.Y.)

    2008  Volume 15, Issue 3, Page(s) 93–96

    Abstract: Planning and directing thought and behavior require the working memory (WM) functions of prefrontal cortex. WM is compromised by stress, which activates phosphatidylinositol (PI)-mediated IP3-PKC intracellular signaling. PKC overactivation impairs WM ... ...

    Abstract Planning and directing thought and behavior require the working memory (WM) functions of prefrontal cortex. WM is compromised by stress, which activates phosphatidylinositol (PI)-mediated IP3-PKC intracellular signaling. PKC overactivation impairs WM operations and in vitro studies indicate that IP3 receptor (IP3R)-evoked calcium release results in SK channel-dependent hyperpolarization of prefrontal neurons. However, the effects of IP3R signaling on prefrontal function have not been investigated. The present findings demonstrate that blockade of IP3R or SK channels in the prefrontal cortex enhances WM performance in rats, suggesting that both arms of the PI cascade influence prefrontal cognitive function.
    MeSH term(s) Animals ; Apamin/administration & dosage ; Apamin/pharmacology ; Boron Compounds/administration & dosage ; Boron Compounds/pharmacology ; Injections ; Inositol 1,4,5-Trisphosphate Receptors/metabolism ; Macrocyclic Compounds/administration & dosage ; Macrocyclic Compounds/pharmacology ; Male ; Maze Learning/physiology ; Memory/drug effects ; Memory/physiology ; Oxazoles/administration & dosage ; Oxazoles/pharmacology ; Prefrontal Cortex/drug effects ; Prefrontal Cortex/metabolism ; Rats ; Rats, Sprague-Dawley ; Signal Transduction/drug effects ; Signal Transduction/physiology ; Small-Conductance Calcium-Activated Potassium Channels/metabolism
    Chemical Substances Boron Compounds ; Inositol 1,4,5-Trisphosphate Receptors ; Macrocyclic Compounds ; Oxazoles ; Small-Conductance Calcium-Activated Potassium Channels ; xestospongin C ; Apamin (24345-16-2) ; 2-aminoethoxydiphenyl borate (E4ES684O93)
    Language English
    Publishing date 2008-02-19
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1204777-6
    ISSN 1549-5485 ; 1072-0502
    ISSN (online) 1549-5485
    ISSN 1072-0502
    DOI 10.1101/lm.767408
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Protein kinase C activity is associated with prefrontal cortical decline in aging.

    Brennan, Avis R / Yuan, Peixiong / Dickstein, Dara L / Rocher, Anne B / Hof, Patrick R / Manji, Husseini / Arnsten, Amy F T

    Neurobiology of aging

    2007  Volume 30, Issue 5, Page(s) 782–792

    Abstract: Aging is associated with deficiencies in the prefrontal cortex, including working memory impairment and compromised integrity of neuronal dendrites. Although protein kinase C (PKC) is implicated in structural plasticity, and overactivation of PKC results ...

    Abstract Aging is associated with deficiencies in the prefrontal cortex, including working memory impairment and compromised integrity of neuronal dendrites. Although protein kinase C (PKC) is implicated in structural plasticity, and overactivation of PKC results in working memory impairments in young animals, the role of PKC in prefrontal cortical impairments in the aged has not been examined. This study provides the first evidence that PKC activity is associated with prefrontal cortical dysfunction in aging. Pharmacological inhibition of PKC with chelerythrine rescued working memory impairments in aged rats and enhanced working memory in aged rhesus monkeys. Improvement correlated with age, with older monkeys demonstrating a greater degree of improvement following PKC inhibition. Furthermore, PKC activity within the prefrontal cortex was inversely correlated with the length of basal dendrites of prefrontal cortical neurons, as well as with working memory performance in aged rats. Together these findings indicate that PKC is dysregulated in aged animals and that PKC inhibitors may be useful in the treatment of cognitive deficits in the elderly.
    MeSH term(s) Aging/metabolism ; Aging/pathology ; Aging/psychology ; Animals ; Atrophy/enzymology ; Atrophy/pathology ; Atrophy/physiopathology ; Benzophenanthridines/pharmacology ; Cognition Disorders/enzymology ; Cognition Disorders/pathology ; Cognition Disorders/physiopathology ; Dendrites/enzymology ; Dendrites/pathology ; Dendritic Spines/enzymology ; Dendritic Spines/pathology ; Disease Models, Animal ; Enzyme Inhibitors/pharmacology ; Female ; Macaca mulatta ; Male ; Nerve Degeneration/enzymology ; Nerve Degeneration/pathology ; Neurons/enzymology ; Neurons/pathology ; Neuropsychological Tests ; Prefrontal Cortex/enzymology ; Prefrontal Cortex/pathology ; Prefrontal Cortex/physiopathology ; Protein Kinase C/antagonists & inhibitors ; Protein Kinase C/metabolism ; Rats ; Rats, Sprague-Dawley
    Chemical Substances Benzophenanthridines ; Enzyme Inhibitors ; chelerythrine (E3B045W6X0) ; Protein Kinase C (EC 2.7.11.13)
    Language English
    Publishing date 2007-10-04
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 604505-4
    ISSN 1558-1497 ; 0197-4580
    ISSN (online) 1558-1497
    ISSN 0197-4580
    DOI 10.1016/j.neurobiolaging.2007.08.020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: A sexually dimorphic ratio of orbitofrontal to amygdala volume is altered in schizophrenia.

    Gur, Raquel E / Kohler, Christian / Turetsky, Bruce I / Siegel, Steven J / Kanes, Stephen J / Bilker, Warren B / Brennan, Avis R / Gur, Ruben C

    Biological psychiatry

    2004  Volume 55, Issue 5, Page(s) 512–517

    Abstract: Background: Neuroanatomic sexual dimorphisms have been correlated with behavioral differences between healthy men and women. We have reported higher orbitofrontal cortex to amygdala ratio (OAR) in women than men. Although gender differences in ... ...

    Abstract Background: Neuroanatomic sexual dimorphisms have been correlated with behavioral differences between healthy men and women. We have reported higher orbitofrontal cortex to amygdala ratio (OAR) in women than men. Although gender differences in schizophrenia are evident clinically and correlate with neuroanatomic measures, their relationship to OAR has not been examined.
    Methods: Magnetic resonance imaging was performed in 31 neuroleptic-naïve schizophrenic patients (16 men) and 80 healthy volunteers (34 men), aged less than 50 years. An automated tissue segmentation procedure was combined with expert-guided parcellation of orbitofrontal and amygdala volumes.
    Results: Men with schizophrenia had increased OAR relative to healthy men, whereas women had decreased OAR. Increased OAR in men with schizophrenia reflected abnormally low amygdala volumes, whereas decreased OAR in women reflected abnormally low orbitofrontal volumes. Less severe negative symptoms were associated with increased OAR in men but with decreased OAR in women. In men, increased amygdala volume was associated with greater symptom severity, whereas in women higher volumes of both amygdala and orbitofrontal regions were associated with lesser severity of negative symptoms.
    Conclusions: These opposite OAR abnormalities, whereby men show feminization and women masculinization, suggest gender-mediated effects of the underlying neuropathologic processes. The correlations with symptom severity suggest that neuroanatomic abnormalities in OAR reflect compensatory brain changes.
    MeSH term(s) Adult ; Affective Symptoms/diagnosis ; Affective Symptoms/etiology ; Amygdala/pathology ; Amygdala/physiopathology ; Anthropometry ; Female ; Frontal Lobe/pathology ; Frontal Lobe/physiopathology ; Humans ; Magnetic Resonance Imaging/statistics & numerical data ; Male ; Psychiatric Status Rating Scales/statistics & numerical data ; Schizophrenia/complications ; Schizophrenia/diagnosis ; Schizophrenia/pathology ; Severity of Illness Index ; Sex Characteristics
    Language English
    Publishing date 2004-03-01
    Publishing country United States
    Document type Clinical Trial ; Controlled Clinical Trial ; Journal Article ; Research Support, U.S. Gov't, P.H.S.
    ZDB-ID 209434-4
    ISSN 1873-2402 ; 0006-3223
    ISSN (online) 1873-2402
    ISSN 0006-3223
    DOI 10.1016/j.biopsych.2003.10.009
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Role of hippocampal sodium channel Nav1.6 in kindling epileptogenesis.

    Blumenfeld, Hal / Lampert, Angelika / Klein, Joshua P / Mission, John / Chen, Michael C / Rivera, Maritza / Dib-Hajj, Sulayman / Brennan, Avis R / Hains, Bryan C / Waxman, Stephen G

    Epilepsia

    2008  Volume 50, Issue 1, Page(s) 44–55

    Abstract: Purpose: Central nervous system plasticity is essential for normal function, but can also reinforce abnormal network behavior, leading to epilepsy and other disorders. The role of altered ion channel expression in abnormal plasticity has not been ... ...

    Abstract Purpose: Central nervous system plasticity is essential for normal function, but can also reinforce abnormal network behavior, leading to epilepsy and other disorders. The role of altered ion channel expression in abnormal plasticity has not been thoroughly investigated. Nav1.6 is the most abundantly expressed sodium channel in the nervous system. Because of its distribution in the cell body and axon initial segment, Nav1.6 is crucial for action potential generation. The goal of the present study was to investigate the possible role of changes in Nav1.6 expression in abnormal, activity-dependent plasticity of hippocampal circuits.
    Methods: We studied kindling, a form of abnormal activity-dependent facilitation. We investigated: (1) sodium channel protein expression by immunocytochemistry and sodium channel messenger RNA (mRNA) by in situ hybridization, (2) sodium current by patch clamp recordings, and (3) rate of kindling by analysis of seizure behavior. The initiation, development, and expression of kindling in wild-type mice were compared to Nav1.6 +/-med(tg) mice, which have reduced expression of Nav1.6.
    Results: We found that kindling was associated with increased expression of Nav1.6 protein and mRNA, which occurred selectively in hippocampal CA3 neurons. Hippocampal CA3 neurons also showed increased persistent sodium current in kindled animals compared to sham-kindled controls. Conversely, Nav1.6 +/-med(tg) mice resisted the initiation and development of kindling.
    Discussion: These findings suggest an important mechanism for enhanced excitability, in which Nav1.6 may participate in a self-reinforcing cycle of activity-dependent facilitation in the hippocampus. This mechanism could contribute to both normal hippocampal function and to epilepsy and other common nervous system disorders.
    MeSH term(s) Animals ; Disease Progression ; Epilepsy/genetics ; Epilepsy/physiopathology ; Hippocampus/metabolism ; Immunohistochemistry ; In Situ Hybridization ; Kindling, Neurologic/genetics ; NAV1.6 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins/genetics ; Nerve Tissue Proteins/metabolism ; Patch-Clamp Techniques ; RNA, Messenger/genetics ; Rats ; Rats, Sprague-Dawley ; Sodium Channels/genetics ; Sodium Channels/metabolism
    Chemical Substances NAV1.6 Voltage-Gated Sodium Channel ; Nerve Tissue Proteins ; RNA, Messenger ; SCN8A protein, human ; Sodium Channels
    Language English
    Publishing date 2008-07-14
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 216382-2
    ISSN 1528-1167 ; 0013-9580
    ISSN (online) 1528-1167
    ISSN 0013-9580
    DOI 10.1111/j.1528-1167.2008.01710.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: The effects of sex and hormonal status on restraint-stress-induced working memory impairment

    Brennan Avis / Rubinow Katya / Shansky Rebecca M / Arnsten Amy FT

    Behavioral and Brain Functions, Vol 2, Iss 1, p

    2006  Volume 8

    Abstract: Abstract Background Restraint stress has been shown to elicit numerous effects on hippocampal function and neuronal morphology, as well as to induce dendritic remodeling in the prefrontal cortex (PFC). However, the effects of acute restraint stress on ... ...

    Abstract Abstract Background Restraint stress has been shown to elicit numerous effects on hippocampal function and neuronal morphology, as well as to induce dendritic remodeling in the prefrontal cortex (PFC). However, the effects of acute restraint stress on PFC cognitive function have not been investigated, despite substantial evidence that the PFC malfunctions in many stress-related disorders. Methods The present study examined the effects of restraint stress on PFC function in both male rats and cycling female rats in either the proestrus (high estrogen) or estrus (low estrogen) phase of the estrus cycle. Animals were restrained for 60 or 120 minutes and then tested on spatial delayed alternation, a PFC-mediated task. Performance after stress was compared to performance on a different day under no-stress conditions, and analyzed using analysis of variance (ANOVA). Results Sixty minutes of restraint impaired only females in proestrus, while 120 minutes of restraint produced significant impairments in all animals. Increases in task completion times did not affect performance. Conclusion These results demonstrate an interaction between hormonal status and cognitive response to stress in female rats, with high estrogen levels being associated with amplified sensitivity to stress. This effect has been previously observed after administration of a pharmacological stressor (the benzodiazepine inverse agonist FG7142), and results from both studies may be relevant to the increased prevalence of stress-related disorders, such as major depressive disorder, in cycling women. Overall, the results show that restraint stress has important effects on the cognitive functions of the PFC, and that hormonal influences in the PFC are an important area for future research.
    Keywords Neurology. Diseases of the nervous system ; RC346-429 ; Neurosciences. Biological psychiatry. Neuropsychiatry ; RC321-571 ; Internal medicine ; RC31-1245 ; Medicine ; R ; DOAJ:Neurology ; DOAJ:Medicine (General) ; DOAJ:Health Sciences
    Subject code 150
    Language English
    Publishing date 2006-03-01T00:00:00Z
    Publisher BioMed Central
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Inhibition of protein kinase C signaling protects prefrontal cortex dendritic spines and cognition from the effects of chronic stress.

    Hains, Avis Brennan / Vu, Mai Anh T / Maciejewski, Paul K / van Dyck, Christopher H / Gottron, Melissa / Arnsten, Amy F T

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

    2009  Volume 106, Issue 42, Page(s) 17957–17962

    Abstract: The prefrontal cortex r regulates behavior, cognition, and emotion by using working memory ...

    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.
    MeSH term(s) Animals ; Atrophy ; Benzophenanthridines/pharmacology ; Cognition/drug effects ; Cognition/physiology ; Dendritic Spines/drug effects ; Dendritic Spines/enzymology ; Dendritic Spines/physiology ; Dendritic Spines/ultrastructure ; Disease Models, Animal ; Humans ; Male ; Memory/drug effects ; Memory/physiology ; Models, Neurological ; Prefrontal Cortex/drug effects ; Prefrontal Cortex/enzymology ; Prefrontal Cortex/physiology ; Protein Kinase C/antagonists & inhibitors ; Protein Kinase C/physiology ; Protein Kinase Inhibitors/pharmacology ; Rats ; Rats, Sprague-Dawley ; Signal Transduction/drug effects ; Signal Transduction/physiology ; Stress, Physiological/drug effects ; Stress, Physiological/physiology ; Stress, Psychological/drug therapy ; Stress, Psychological/enzymology ; Stress, Psychological/pathology ; Stress, Psychological/physiopathology
    Chemical Substances Benzophenanthridines ; Protein Kinase Inhibitors ; chelerythrine (E3B045W6X0) ; Protein Kinase C (EC 2.7.11.13)
    Language English
    Publishing date 2009-09-11
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.0908563106
    Database MEDical Literature Analysis and Retrieval System OnLINE

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

    Hains, Avis Brennan / Vu, Mai Anh T / Maciejewski, Paul K / van Dyck, Christopher H / Gottron, Melissa / Arnsten, Amy F.T

    Proceedings of the National Academy of Sciences of the United States of America. 2009 Oct. 20, v. 106, no. 42

    2009  

    Abstract: The prefrontal cortex r regulates behavior, cognition, and emotion by using working memory ...

    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.
    Keywords cell structures ; cognition ; cortex ; in vitro studies ; lead poisoning ; long term effects ; memory ; neurons ; protein kinase C ; rats ; schizophrenia
    Language English
    Dates of publication 2009-1020
    Size p. 17957-17962.
    Publishing place National Academy of Sciences
    Document type Article
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.0908563106
    Database NAL-Catalogue (AGRICOLA)

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