Neuroscience letters
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Neuroscience letters · Jan 2011
Failure of NMDA receptor hypofunction to induce a pathological reduction in PV-positive GABAergic cell markers.
Reduction in cortical presynaptic markers, notably parvalbumin (PV), for the chandelier subtype of inhibitory γ-amino-butyric acid (GABA) interneurons is a highly replicated post-mortem finding in schizophrenia. Evidence from genetic and pharmacological studies implicates hypofunction of N-methyl-d-aspartate receptor (NMDAR)-mediated glutamatergic signaling as a critical component of the pathophysiology of schizophrenia. Serine racemase (SR) produces the endogenous NMDAR co-agonist d-serine, and disruption of the SR gene results in reduced NMDAR signaling. ⋯ To control for these surprising results, we investigated PV expression in mice and rats following subchronic phencyclidine or ketamine treatments in adulthood. PV expression was not affected by drug these treatment in either species, failing to reproduce previously published findings. Our findings challenge the hypothesis that pathological deficits in PV expression are simply a consequence of NMDAR hypofunction.
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Neuroscience letters · Jan 2011
Sustained increase in adult neurogenesis in the rat hippocampal dentate gyrus after transient brain ischemia.
It is known that the number of newly generated neurons is increased in the young and adult rodent subventricular zone (SVZ) and dentate gyrus (DG) after transient brain ischemia. However, it remains unclear whether increase in neurogenesis in the adult DG induced by ischemic stroke is transient or sustained. We here reported that from 2 weeks to 6 months after transient middle cerebral artery occlusion (MCAO), there were more doublecortin positive (DCX+) cells in the ipsilateral compared to the sham-control and contralateral DG of the adult rat. ⋯ These BrdU-labeled neurons survived for at least 6 months. When BrdU was injected 6 weeks after injury, there were still more newly generated neuroblasts differentiated into mature neurons in the ipsilateral DG. Altogether, our data indicate that transient brain ischemia initiates a prolonged increase in neurogenesis and promotes the normal development of the newly generated neurons in the adult DG.
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Neuroscience letters · Jan 2011
Simvastatin treatment improves functional recovery after experimental spinal cord injury by upregulating the expression of BDNF and GDNF.
The aim of this study was to determine the therapeutic efficacy of simvastatin treatment starting 1 day after spinal cord injury (SCI) in rat and to investigate the underlying mechanism. Spinal cord injury was induced in adult female Sprague-Dawley rats after laminectomy at T9-T10. Then additionally with sham group (laminectomy only) the SCI animals were randomly divided into 3 groups: vehicle-treated group; 5-mg/kg simvastatin-treated group; and 10-mg/kg simvastatin-treated group. ⋯ Results show that the simvastatin-treated animals showed significantly better locomotor function recovery, better electrophysiological outcome, less myelin loss, and higher expression of BDNF and GDNF. These findings suggest that simvastatin treatment starting 1 day after SCI can significantly improve locomotor recovery, and this neuroprotective effect may be related to the upregulation of BDNF and GDNF. Therefore, simvastatin may be useful as a promising therapeutic agent for SCI.
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Neuroscience letters · Jan 2011
Comparative StudyChanges in intramuscular cytokine levels during masseter inflammation in male and female rats.
The present study was conducted to examine cytokine profiles in the masseter muscle before and after complete Freund's adjuvant (CFA)-induced inflammation and possible sex differences in the cytokine levels. Age matched male and female Sprague Dawley rats were injected with CFA in the mid-region of the masseter muscle. Muscle tissue surrounding the injection site was extracted 6h, 1, 3 and 7 days after the injection to measure TNF-α, IL-1β, IL-6 and IL-4 levels with Luminex multi-analyte profiling (xMAP) technology. ⋯ The level of IL-4 was slightly, but significantly, reduced in both sexes at 6h and 3 days after CFA-induced inflammation. No significant sex differences were observed in the levels of IL-1β, IL-6 or IL-4. The results provided novel information about distinct cytokine profiles during CFA-induced muscle inflammation, and the basis for further pursuing contributions of each cytokine in pain processing and analgesic responses in both sexes.
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Neuroscience letters · Jan 2011
Spatial coding of touch at the fingers: Insights from double simultaneous stimulation within and between hands.
We studied the effect of tactile double simultaneous stimulation (DSS) within and between hands to examine spatial coding of touch at the fingers. Participants performed a go/no-go task to detect a tactile stimulus delivered to one target finger (e.g., right index), stimulated alone or with a concurrent non-target finger, either on the same hand (e.g., right middle finger) or on the other hand (e.g., left index finger=homologous; left middle finger=non-homologous). Across blocks we also changed the unseen hands posture (both hands palm down, or one hand rotated palm-up). ⋯ Taken together, these findings provide behavioral evidence in humans for multiple spatial coding of touch during tactile DSS at the fingers. In particular, they confirm the existence of representational stages of touch that distinguish between body-regions more than body-sides. Moreover, they show that the availability of tactile stimulation side becomes prominent when postural update is required.