Progress in neuro-psychopharmacology & biological psychiatry
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Prog. Neuropsychopharmacol. Biol. Psychiatry · Nov 2009
Temporally anticorrelated brain networks during working memory performance reveal aberrant prefrontal and hippocampal connectivity in patients with schizophrenia.
Functional neuroimaging studies on cognitive dysfunction in schizophrenia have suggested regional brain activation changes in the dorsolateral prefrontal cortex and the medial temporal lobe. However, less is known about the functional coupling of these areas during cognitive performance. In this study, we used functional magnetic resonance imaging, a verbal working memory (WM) task and multivariate statistical techniques to investigate the functional coupling of temporally anticorrelated neural networks during cognitive processing in patients with schizophrenia (n=16) compared to healthy controls (n=16). ⋯ In addition, aberrant functional coupling of the hippocampal cortex in patients with schizophrenia was detected within a "task-negative" medial frontotemporal network. In patients with schizophrenia, functional connectivity indices in the left dorsolateral prefrontal cortex and the right hippocampal cortex were positively correlated with accuracy during the WM task, while the connectivity strength in the right dorsolateral prefrontal cortex was negatively correlated with measures of symptom severity. These data suggest that within two temporally anticorrelated network states, patients with schizophrenia exhibit increased and persistent dorsolateral prefrontal and hippocampal connectivity during WM performance.
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Prog. Neuropsychopharmacol. Biol. Psychiatry · Nov 2009
Involvement of NO-cGMP pathway in anti-anxiety effect of aminoguanidine in stressed mice.
In the present study, effect of aminoguanidine (12.5, 25 and 50mg/kg, i.p.), a selective inhibitor of inducible nitric oxide synthase, was evaluated for its anti-anxiety activity in stressed mice employing elevated plus maze, open field test, light/dark test and social interaction test. Restraint stress induced by immobilizing for 6h enhanced an anxiety-like behavior and increased plasma nitrite levels in mice. Only the highest dose (50mg/kg) employed of aminoguanidine attenuated the stress-induced anxiety-like behavior and decreased plasma nitrite levels. ⋯ Aminoguanidine (50mg/kg) attenuated the anxiogenic effect of sildenafil. Aminoguanidine and sildenafil per se and in combination did not affect the locomotor activity of stressed and unstressed mice as compared to their respective control groups. Thus, aminoguanidine produced anti-anxiety activity in stressed mice through iNOS-NO-cGMP pathway.