Neuroscience
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Small-for-gestational age (SGA) human newborns have an increased risk of hyperphagia and obesity, as well as a spectrum of neurologic and neurobehavioral abnormalities. We have shown that the SGA hypothalamic (appetite regulatory site) neuroprogenitor cells (NPCs) exhibit reduced proliferation and neuronal differentiation. DNA methylation (DNA methyltransferase; DNMT1) regulates neurogenesis by maintaining NPC proliferation and suppressing premature differentiation. ⋯ In vivo data replicated these findings. In SGA offspring, impaired neurogenesis is epigenetically mediated, in part, via reduction in DNMT1 expression and suppression of Hes1 resulting in NPC differentiation. It is likely that the maturation of regions beyond the hypothalamus (e.g., cerebral cortex, hippocampus) may be impacted, contributing to poor cognitive and neurobehavioral competency in SGA offspring.
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Neuroglobin (Ngb) is a REST/NRSF-regulated protein, active in reactive oxygen species detoxification and cytochrome c inhibition, which provides a beneficial outcome in pathologies as Alzheimer's disease and strokes. Considering that oxidative stress and cell death are typical hallmarks of amyotrophic lateral sclerosis (ALS), we sought to explore Ngb's involvement along this disease progression. Ngb transcription was detected to be two-fold down-regulated in late-stage SODG93A mice, similarly as previously described for Alzheimer disease. ⋯ To look further into the link between Ngb and ALS, we generated a double mutant Ngb-/-SODG93A mouse model, which shows an earlier onset and severity of hind limb deficits. Mitochondria derived thereof showed an altered mean volume, granularity and Ca2+-induced swelling as compared to NgbWt/WtSODG93A mice. These results indicate Ngb to be involved in and affected by the SOD1G93A pathology, which could in part be attributed to its role in halting destabilizing events of mitochondrial swelling and phenotypes.
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Stroke is a devastating brain disorder. The pathophysiology of stroke is associated with an impaired excitation-inhibition balance in the area that surrounds the infarct core after the insult, the peri-infarct zone. Here we exposed slices from adult mouse prefrontal cortex to oxygen-glucose deprivation and reoxygenation (OGD-RO) to study ischemia-induced changes in the activity of excitatory pyramidal neurons and inhibitory parvalbumin (PV)-positive interneurons. ⋯ Disynaptic inhibitory postsynaptic currents (dIPSCs) in pyramidal neurons produced predominantly by PV-positive interneurons were reduced by OGD-RO. Following OGD-RO, dendrites of PV-positive interneurons exhibited more pathological beading than those of pyramidal neurons. Our data support the hypothesis that the differential vulnerability to ischemia-like conditions of excitatory and inhibitory neurons leads to the altered excitation-inhibition balance associated with stroke pathophysiology.
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Neuroinflammation is considered to be a critical component in the pathological process after intracerebral hemorrhage (ICH). Microglia are the foremost and earliest inflammatory cells participating in the pathological process of ICH. AdipoRon is the agonist of AdipoR1 (Adiponectin receptor 1), which enhances P-AMPK (phosphorylated AMP-activated protein kinase) activation. ⋯ The in vitro experiment showed that AdipoRon not only directly inhibited neuronal ROS overproduction, but also indirectly decreased the neuronal death in a transwell co-culture system. In summary, AdipoRon protects against ICH induced injury through promoting M2a microglia polarization and reducing neuronal death. These effects of AdipoRon rely on the activation of AdipoR1-AMPK signaling pathway.
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High voltage-activated (HVA) Ca2+ (CaV) channels are oligomeric complexes formed by an ion-conducting main subunit (Cavα1) and at least two auxiliary subunits (Cavβ and CaVα2δ). It has been reported that the expression of CaVα2δ1 increases in the dorsal root ganglia (DRGs) of animals with mechanical allodynia, and that the transcription factor Sp1 regulates the expression of the auxiliary subunit. Hence, the main aim of this work was to investigate the role of Sp1 as a molecular determinant of the exacerbated expression of CaVα2δ-1 in the nerve ligation-induced model of mechanical allodynia. ⋯ Interestingly, intrathecal administration of the Sp1 inhibitor mithramycin A (Mth) prevented allodynia and decreased the expression of Sp1 and CaVα2δ-1. Likewise, electrophysiological recordings showed that incubation with Mth decreased Ca2+ current density in the DRG neurons, acting mostly on HVA channels. These results suggest that L5/L6 SNL produces mechanical allodynia and increases the expression of the transcription factor Sp1 and the subunit CaVα2δ-1 in the DRGs, while Mth decreases mechanical allodynia and Ca2+ currents through HVA channels in sensory neurons by reducing the functional expression of the CaVα2δ-1 subunit.