Neuroscience letters
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Neuroscience letters · May 2010
Enriched environment increases spinophilin mRNA expression and spinophilin immunoreactive dendritic spines in hippocampus and cortex.
Housing rodents in an enriched environment (EE) induces structural and functional plasticity in the adult brain, including increased dendritic sprouting and number of dendritic spines. However, the molecular mechanisms behind EE-induced brain plasticity remain largely unknown. Circadian rhythm plays an important role in memory processing but the neurobiological mechanisms of how circadian rhythm affects memory and brain plasticity remain controversial. ⋯ Increased spinophilin expression was found during the light phase of the diurnal cycle, but not the dark phase. Thus, enriched housing altered the diurnal variation in spinophilin mRNA expression, suggesting that circadian modulation is likely to be important for experience dependent plasticity. The current results suggest a possible role for spinophilin in neuronal plasticity induced by environmental enrichment, but further studies are needed to establish a cause-effect relation.
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Neuroscience letters · May 2010
Heterotopically transplanted CVO neural stem cells generate neurons and migrate with SVZ cells in the adult mouse brain.
Production of new neurons throughout adulthood has been well characterized in two brain regions, the subventricular zone (SVZ) of the anterolateral ventricle and the subgranular zone (SGZ) of the hippocampus. The neurons produced from these regions arise from neural stem cells (NSCs) found in highly regulated stem cell niches. We recently showed that midline structures called circumventricular organs (CVOs) also contain NSCs capable of neurogenesis and/or astrogliogenesis in vitro and in situ (Bennett et al.). ⋯ CVO-derived BrdU(+) cells ultimately reach the olfactory bulb where they express early (PSA-NCAM) and mature (NeuN) neuronal markers. Collectively, these data suggest that although NSCs derived from the ME and OVLT CVOs are astrogliogenic in situ, they produce cells phenotypic of neurons in vivo when placed in a neurogenic environment. These findings may have implications for neural repair in the adult brain.
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Neuroscience letters · Apr 2010
PER2 rhythms in the amygdala and bed nucleus of the stria terminalis of the diurnal grass rat (Arvicanthis niloticus).
The suprachiasmatic nucleus (SCN) of the hypothalamus is the central pacemaker that controls circadian rhythms in mammals. In diurnal grass rats (Arvicanthis niloticus), many functional aspects of the SCN are similar to those of nocturnal rodents, making it likely that the difference in the circadian system of diurnal and nocturnal animals lies downstream from the SCN. Rhythms in clock genes expression occur in several brain regions outside the SCN that may function as extra-SCN oscillators. ⋯ In the BLA, PER2 expression was relatively low for most of the 24-h cycle, but showed an acute elevation late in the light period (ZT10). This pattern is also different from that of nocturnal rodents that show elevated PER2 expression in the mid to late night and into the early day. These results are consistent with the hypothesis that diurnal behavior is associated with a phase change between the SCN and extra-SCN oscillators.
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Neuroscience letters · Apr 2010
Behavioral evidence of thermal hyperalgesia and mechanical allodynia induced by intradermal cinnamaldehyde in rats.
TRPA1 agonists cinnamaldehyde (CA) and mustard oil (allyl isothiocyanate=AITC) induce heat hyperalgesia and mechanical allodynia in human skin, and sensitize responses of spinal and trigeminal dorsal horn neurons to noxious skin heating in rats. TRPA1 is also implicated in cold nociception. We presently used behavioral methods to investigate if CA affects sensitivity to thermal and mechanical stimuli in rats. ⋯ CA significantly reduced mechanical withdrawal thresholds of the injected paw that peaked sooner (3 min) and was more profound (44.4% of baseline), with no effect contralaterally. Bilateral intraplantar injections of CA resulted in a significant cold hyperalgesia (cold plate test) and a weak enhancement of innocuous cold avoidance (thermal preference test). The data are consistent with roles for TRPA1 in thermal (hot and cold) hyperalgesia and mechanical allodynia.
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Neuroscience letters · Apr 2010
Catechol-O-methyltransferase (COMT) inhibition reduces spinal nociceptive activity.
Several variants of the catechol-O-methyltransferase (COMT) gene have recently been linked to pain sensitivity. In the present study, electrophysiological field potential recordings from the dorsal horn in rats were used to examine the spinal effect of reduced COMT activity. ⋯ HFS+OR 486). Our findings suggest that low COMT activity may have an antinociceptive effect in the spinal cord.