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    ABSTRACT: Hippocampal atrophy is reported in several neuropathological disorders. The hippocampal dentate gyrus (DG) is a brain region where adult neurogenesis constitutively occurs. There are some reports suggesting the ability of endogenous neurogenesis to initiate neuronal repair in the hippocampus in response to neuropathological conditions, but its capacity to compensate for neuronal loss is limited. Among strategies to enhance adult hippocampal neurogenesis are enriched environment and lithium. This study aimed to assess whether both strategies could interact to potentiate the generation of new cells in the adult DG. Healthy adult male C57BL/6 mice were divided into four treatment groups for 28 days: control, lithium, enriched environment, enriched environment plus lithium. The animals were injected with BrdU (cell proliferation marker) shortly before the start of the treatments and killed 28 days later for analysis of newly generated cells. Two-way ANOVA followed by post hoc test revealed a significant synergistic interaction between enriched environment and lithium in the total number of BrdU(+) cells in the entire DG (p = 0.019), a trend towards significant synergistic interaction in the dorsal DG (p = 0.075), and a significant additive effect in the ventral DG (p = 0.001). These findings indicate that the combination of enriched environment and lithium has both synergistic and additive effects on the generation of new cells in the healthy adult DG (these effects being possibly segregated along the dorso-ventral axis of the hippocampus), and suggest that it might be worth investigating whether this combination would have a similar effect in neuropathological conditions.
    Journal of Neural Transmission 02/2014; 121(7). · 2.87 Impact Factor
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    ABSTRACT: An enduring question is unity vs. separability of executive deficits resulting from impaired frontal lobe function. In previous studies, we have asked how executive deficits link to a conventional measure of fluid intelligence, obtained either by standard tests of novel problem-solving, or by averaging performance in a battery of novel tasks. For some classical executive tasks, such as the Wisconsin Card Sorting Test (WCST), Verbal Fluency, and Trail Making Test B (TMTB), frontal deficits are entirely explained by fluid intelligence. However, on a second set of executive tasks, including tests of multitasking and decision making, deficits exceed those predicted by fluid intelligence loss. In this paper we discuss how these results shed light on the diverse clinical phenomenology observed in frontal dysfunction, and present new data on a group of 15 schizophrenic patients and 14 controls. Subjects were assessed with a range of executive tests and with a general cognitive battery used to derive a measure of fluid intelligence. Group performance was compared and fluid intelligence was introduced as a covariate. In line with our previous results, significant patient-control differences in classical executive tests were removed when fluid intelligence was introduced as a covariate. However, for tests of multitasking and decision making, deficits remained. We relate our findings to those of previous factor analytic studies describing a single principal component, which accounts for much of the variance of schizophrenic patients' cognitive performance. We propose that this general factor reflects low fluid intelligence capacity, which accounts for much but not all cognitive impairment in this patient group. Partialling out the general effects of fluid intelligence, we propose, may clarify the role of additional, more specific cognitive impairments in conditions such as schizophrenia.
    Frontiers in Behavioral Neuroscience 01/2014; 8:46. · 4.16 Impact Factor
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    ABSTRACT: Perinatal immune challenge leads to neurodevelopmental dysfunction, permanent immune dysregulation and abnormal behaviour, which have been shown to have translational validity to findings in human neuropsychiatric disorders (e.g. schizophrenia, mood and anxiety disorders, autism, Parkinson's disease and Alzheimer's disease). The aim of this animal study was to elucidate the influence of early immune stimulation triggered by systemic postnatal lipopolysaccharide administration on biochemical, histopathological and morphological measures, which may be relevant to the neurobiology of human psychopathology. In the present study of adult male Wistar rats we examined the brain and plasma levels of monoamines (dopamine, serotonin), their metabolites, the levels of the main excitatory and inhibitory neurotransmitters glutamate and γ-aminobutyric acid and the levels of tryptophan and its metabolites from the kynurenine catabolic pathway. Further, we focused on histopathological and morphological markers related to pathogenesis of brain diseases - glial cell activation, neurodegeneration, hippocampal volume reduction and dopaminergic synthesis in the substantia nigra. Our results show that early immune stimulation in adult animals alters the levels of neurotransmitters and their metabolites, activates the kynurenine pathway of tryptophan metabolism and leads to astrogliosis, hippocampal volume reduction and a decrease of tyrosine hydroxylase immunoreactivity in the substantia nigra. These findings support the crucial pathophysiological role of early immune stimulation in the above mentioned neuropsychiatric disorders.
    PLoS ONE 01/2015; 10(1):e0115439. · 3.53 Impact Factor