Neuroscience letters
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Neuroscience letters · Sep 2016
Blockade of Cannabinoid CB1 receptor attenuates the acquisition of morphine-induced conditioned place preference along with a downregulation of ERK, CREB phosphorylation, and BDNF expression in the nucleus accumbens and hippocampus.
Cannabinoid CB1 receptor (CB1R) is highly expressed in the mesocorticolimbic system and associated with drug craving and relapse. Clinical trials suggest that CB1R antagonists may represent new therapies for drug addiction. However, the downstream signaling of CB1R is not fully elucidated. ⋯ Both morphine CPP and NO-CPP induced an upregulation of ERK, CREB phosphorylation and BDNF expression. Furthermore, pretreatment with AM251 before morphine attenuated the CPP acquisition and CB1R expression as well as the activation of ERK-CREB-BDNF cascade. Collectively, these findings demonstrate that (1) Repeated morphine with context exposures but not merely the pharmacological effects of morphine increased CB1R expression both in the NAc and hippocampus. (2) CB1R antagonist mediated blockade of ERK-CREB-BDNF signaling activation in the NAc and hippocampus may be an important mechanism underlying the attenuation of morphine CPP.
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Neuroscience letters · Aug 2016
Regional homogeneity changes in amnestic mild cognitive impairment patients.
Regional Homogeneity (ReHo) measures the local coherence of spontaneous brain activity, and it is sensitive to detect aberrant local functional connectivity of brain region. We tried to explore the activity of brain network by ReHo method in amnestic mild cognitive impairment (aMCI) patients and examine the impact of regional brain atrophy on the functional results. ⋯ Our study indicated that aMCI patients showed significant abnormal local coherence of biological activity in resting state and ReHo could serve as a sensitive biomarker in functional imaging studies of aMCI.
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Neuroscience letters · Aug 2016
Effects of the swimming exercise on the consolidation and persistence of auditory and contextual fear memory.
Exposure to negative environmental events triggers defensive behavior and leads to the formation of aversive associative memory. Cellular and molecular changes in the central nervous system underlie this memory formation, as well as the associated behavioral changes. In general, memory process is established in distinct phases such as acquisition, consolidation, evocation, persistence, and extinction of the acquired information. ⋯ In addition, rats submitted to swimming exercise over six weeks showed an improved performance in the test of auditory-cued fear memory persistence, but not in the test of contextual fear memory persistence. Moreover, no significant effect from swimming exercise was observed on consolidation of both contextual and auditory fear memory. So, our study, revealing the effect of the swimming exercise on different stages of implicit memory of tone/foot shock conditioning, contributes to and complements the current knowledge about the environmental modulation of memory process.
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Neuroscience letters · Aug 2016
L-DOPA treatment in MPTP-mouse model of Parkinson's disease potentiates homocysteine accumulation in substantia nigra.
One of the intermediates of methionine cycle, the homocysteine (Hcy), elevates in plasma of Parkinson's disease (PD) patients undergoing L-DOPA (3,4-dihydroxyphenylalanine) therapy and has been regarded as a risk factor of the disease. Several evidences pointed out that Hcy causes degeneration of dopaminergic neurons. In rodent, elevated level of Hcy in brain or infusion of the same directly into the substantia nigra (SN) potentiates dopaminergic neurodegeneration. ⋯ Interestingly, L-DOPA treatment significantly elevates Hcy level in nigra but not in striatum of parkinsonian mice, when compared with L-DOPA naïve group. However, there is no significant decrease in the number of dopaminergic neurons in SN region in the parkinsonian mice given L-DOPA treatment. Thus, the present study demonstrates that L-DOPA treatment potentiates the level of Hcy in the SN without causing aggravated neurodegeneration in parkinsonian mice model.
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Neuroscience letters · Aug 2016
Propofol anesthesia reduces Lempel-Ziv complexity of spontaneous brain activity in rats.
Consciousness is thought to scale with brain complexity, and it may be diminished in anesthesia. Lempel-Ziv complexity (LZC) of field potentials has been shown to be a promising measure of the level of consciousness in anesthetized human subjects, neurological patients, and across the sleep-wake states in rats. Whether this relationship holds for intrinsic networks obtained by functional brain imaging has not been tested. ⋯ Dynamic brain networks were defined at voxel level by sliding window analysis of regional homogeneity (ReHo) of the BOLD signal. From scans performed at low to high propofol dose, the LZC was significantly reduced by 110%. The results suggest that the difference in LZC between conscious sedated and anesthetized unconscious subjects is conserved in rats and this effect is detectable in large-scale brain network obtained from fMRI.