Neuroscience
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Itch induces a desire to scratch and leads to skin damage in some severe conditions. Much progress has been made in the peripheral and spinal level, and recent findings suggested that we need to focus on the central circuitry mechanism. However, the functional role of the thalamus in itch signal processing remains largely unknown. ⋯ We found that the calcium signal of Po neurons was increased during the histaminergic itch-induced scratching behavior in the cheek model, and pharmacogenetic suppression of Po neurons reduced the scratching behaviors. Retrograde mapping results suggested that the Po receives information from the somatosensory cortex, motor cortex, parabrachial nucleus (PBN), the principal sensory trigeminal nucleus (PrV) and the spinal trigeminal nucleus (SpV), which participate in itch signal transmission from head and body. Thus, our study indicates that the Po is critical in modulating facial histaminergic itch signal processing.
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Most memories of life experiences will be forgotten or modified over time. Although several studies have investigated the processes underlying memory formation, the mechanisms behind memory updating and forgetting remain unclear. The endocannabinoid system has been shown to be closely involved in various memory processes such as consolidation, destabilization, and extinction. ⋯ We found that the hippocampal infusion of CB1 antagonist prevented memory updating in the immediate footshock (context pre-exposure facilitation effect) and reversal learning. Also, CB1 antagonist accelerated forgetting in inhibitory avoidance. Thus, by indicating the important role played by the endocannabinoid system, our results extend current knowledge of the mechanisms underpinning memory updating and forgetting.
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The nucleotide oligomerization domain (NOD)-like receptor (NLR) pyrin domain-containing protein 1 (NLRP1) inflammasome has been shown to contribute to brain injury after ischemic stroke. Our previous study showed that microRNA-9a-5p (miR-9a-5p) ameliorates ischemic injury by regulating neuronal autophagy in rats subjected to middle cerebral artery occlusion (MCAO) surgery. The aims of this study were to investigate whether miR-9a-5p can influence the NLRP1 inflammasome following ischemic stroke and to clarify the mechanism involved. ⋯ Further investigation showed that NLRP1 was a target of miR-9a-5p and was downregulated by miR-9a-5p overexpression and upregulated by miR-9a-5p inhibition. Moreover, overexpression of miR-9a-5p not only decreased the levels of NLRP1, ASC and precursor caspase-1 but also reduced the levels of IL-1β and IL-18 in MCAO rats and OGD cells. Therefore, we conclude that miR-9a-5p is involved in NLRP1 inflammasome-mediated ischemic injury, which further suggests that the overexpression of miR-9 may be an effective way to ameliorate brain injury following ischemic stroke.
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Serotonin is an important neurotransmitter of the brain, but its role in song control remains to be fully demonstrated. Using male zebra finches (Taeniopygia guttata) that have song learning and production capabilities, we analysed the serotonin expression levels in the song nuclei and adjacent areas (peri-song nuclei) using immunohistochemistry. Key song nuclei were identified using combinations of Hoechst, choline acetyltransferase, and a neurofilament (NN18) marker in reference to the ZEBrA atlas. ⋯ However, the mean serotonin expression (in order of highest first) in the peri-song nuclei regions was: peri-DM > peri-nXIIts > supra-peri-HVC > peri-RA > peri-DLM > peri-Area X > infra-peri-HVC > peri-VRG > peri-LMAN > peri-Nif. Interestingly, serotoninergic fibers immunostained for serotonin or the serotonin transporter can be found as a basket-like peri-neuronal structure surrounding cholinergic cell bodies, and appear to form contacts onto dopaminergic neurones. In summary, serotonin fibers are present at discrete song nuclei, and peri-song nuclei regions, which suggest serotonin may have a direct and/or modulatory role in song control.
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Impulsivity includes hasty actions, social intrusiveness or premature decision-making. Neuropeptides like oxytocin alleviate haste and anxiety, and affect fear conditioning. However, no investigations have been done via gene-network based approach with cognitive and interventional genetic association studies to scrutinize the link between impulsive behavior and oxytocin. ⋯ Oxytocin group and participants with GG genotype showed a significantly decreased commission error and increased inhibition. This means that oxytocin alleviated impulsive behavior, and subjects with GG genotype had lower rate of impulsivity than those with GA and AA genotypes. rs2254298 may modulate the function or expression of the OXTR gene, implying that G allele may increase the expression of OXTR gene compared to A allele. We suggest that intranasal oxytocin may notably moderate impulsive behavior and tendency to make hasty or premature decisions.