Neuroscience
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The ability to distinguish between threatening (repulsors), neutral and appetitive stimuli (attractors) stimuli is essential for survival. The orexinergic neurons of hypothalamus send projections to the limbic structures, such as different subregions of the medial prefrontal cortex (mPFC), suggesting that the orexinergic mechanism in the prelimbic cortex (PL) is involved in the processing of fear and anxiety. ⋯ We interpret these findings as evidence for an altered cognitive appraisal of the potential threatening stimulus. Consequently, the orexin system seems to bias the perception of stimuli towards danger or threat via OX1R and OX2R in the PL.
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Although conditioned pain modulation (CPM) is considered to represent descending pain inhibitory mechanisms triggered by noxious stimuli applied to a remote area, there have been no previous studies comparing CPM between pain and tactile systems. In this study, we compared CPM between the two systems objectively using blink reflexes. Intra-epidermal electrical stimulation (IES) and transcutaneous electrical stimulation (TS) were applied to the right skin area over the supraorbital foramen to evoke a nociceptive or a non-nociceptive blink reflex, respectively, in 15 healthy males. ⋯ Both the NRS score and nociceptive R2 were significantly decreased in the third session for IES, with a significant correlation between the two variables; whereas, TS-induced non-nociceptive R2 did not change among the sessions. Although the conditioning stimulus decreased the NRS score for TS, the CPM effect was significantly smaller than that for IES (p = 0.002). The present findings suggest the presence of a pain-specific CPM effect to a heterotopic noxious stimulus.
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The nonapeptides vasopressin (VP) and oxytocin (OT) are present in some form in most vertebrates. VP and OT play critical roles in modulating physiology and are well-studied for their influences on a variety of social behaviors, ranging from affiliation to aggression. Their anatomical distributions have been mapped for numerous species across taxa, demonstrating relatively strong evolutionary conservation in distributions throughout the basal forebrain and midbrain. ⋯ However, we observed a sex difference in only one VP cell group - that of the bed nucleus of the stria terminalis (BST), a VP neuronal population that exhibits a phylogenetically widespread sexual dimorphism. These findings provide mapping distributions of VP and OT neurons in Acomys cahirinus. Spiny mice lend themselves to the study of mammalian cooperation and sociality, and the nonapeptide neuronal mapping presented here can serve as a basic foundation for the study of nonapeptide-mediated behavior in a group of highly social rodents.
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Mitochondrial permeability transition pore (mPTP) opening is critical to mitochondrial apoptosis during ischemic injury. Sirtuin 3 (Sirt3) is a mitochondrial deacetylase known to play a major role in stress resistance and cell death. Our previous studies have shown that Sirt3 activates superoxide dismutase 2 and forkhead box O3a to reduce cellular reactive oxygen species. ⋯ Sirt3 overexpression suppressed the increase in VDAC1, ANT1 and cleaved caspase 3 that were induced by the serum and glucose deprivation (SGD) condition. Our studies suggest that ischemic injury induced mPTP opening and apoptosis by reducing Sirt3. It helps to identify new therapeutic targets for ischemic stroke.
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Acute seizures can severely affect brain function and development. However, the underlying pathophysiological mechanisms are still poorly understood. Disturbances of the glutamatergic system are considered one of the critical mechanisms of neurological abnormalities. ⋯ Significant alterations in the expression of different receptor subunits in the mRNA but not protein levels were observed in the entorhinal cortex and amygdala. In contrast, in the medial prefrontal and temporal cortex, we found almost no changes in the expression of the studied genes. The identified changes deepen our understanding of post-seizure disturbances in the developing brain and confirm that although various brain structures are involved in seizures, the hippocampus is the most vulnerable.