In this Issue
In this Issue
Unesterified docosahexaenoic acid is protective in neuroinflammation
Our study shows that chronically increased brain unesterified DHA levels, but not solely phospholipid DHA levels, attenuate neuroinflammation. Similar attenuations occur with acute increases in brain unesterified DHA or 17S-HpDHA levels, highlighting the importance of an available pool of precursor unesterified DHA for the production of enzymatically derived specialized pro-resolving mediators that are critical in the regulation of neuroinflammation.
Read the Editorial Highlight for this article on page 299 and the full article on page 378.
TRPC6 channel-mediated neurite outgrowth in PC12 cells and hippocampal neurons involves activation of RAS/MEK/ERK, PI3K, and CAMKIV signaling
Alterations in synaptic plasticity are considered to play an important role in the pathogenesis of depression. Beside several other proteins, TRPC6 channels regulate synaptic plasticity. This study demonstrates that different pathways including Ras/MEK/ERK, PI3K/Akt, and CAMKIV are involved in the improvement of synaptic plasticity by the TRPC6 activator hyperforin, the antidepressant active constituent of St. John's wort extract.
Read the full article on page 303.
Circadian phase-dependent effect of nitric oxide on L-type voltage-gated calcium channels in avian cone photoreceptors
In cone photoreceptors, the protein expression of neural nitric oxide synthase (nNOS) and NO production are under circadian control. NO-cGMP-protein kinase G (PKG) signaling serves in the circadian output pathway to regulate the circadian rhythms of L-type voltage-gated calcium channels (L-VGCCs) in part through regulating the phosphorylation states of extracellular-signal-regulated kinase (Erk) and protein kinase B (Akt).
Read the full article on page 314.
δ-opioid receptor activation leads to neurite outgrowth and neuronal differentiation via a STAT5B-Gαi/o pathway
We propose a novel signalling pathway for δ-opioid receptor (δ-ΟR)-mediated neurotropic events. STAT5B interacts with the δ-ΟR and upon prolonged receptor activation phosphorylates STAT5B in a Gi/Go dependent manner leading to increased neuronal survival, neurite outgrowth and differentiation. These findings contribute to a better understanding of the molecular and cellular events following δ-OR activation and suggest a possible neuroprotective role opioids could exert.
Read the full article on page 329.
In vivo induction of P-glycoprotein expression at the mouse blood–brain barrier: an intracerebral microdialysis study
Applying microdialysis, distribution of quinidine, a P-gp substrate, in mouse brain extracellular fluid (ECF) was investigated following ligand-mediated P-glycoprotein (P-gp) induction at the blood–brain barrier (BBB). We demonstrated that a PXR agonist (dexamethasone) significantly up-regulated P-gp in brain capillaries and reduced quinidine brain ECF concentrations. Our data suggest that drug–drug interactions as a result of P-gp induction at the BBB are possible.
Read the full article on page 342.
Metabolic products of [2-13C]ethanol in the rat brain after chronic ethanol exposure
The liver converts ethanol to acetate, which may contribute to long-term adaptation to drinking. Astroglia oxidize acetate and generate neurochemicals, while neurons and glia may also oxidize ethanol. When 13C-ethanol is administered intravenously, 13C-glutamine, glutamate, and GABA, normalized to 13C-acetate, were higher in chronic ethanol-exposed rats than in control rats, suggesting that ethanol exposure increases cerebral oxidation of circulating acetate.
Read the full article on page 353.
In vivo NMR studies of regional cerebral energetics in MPTP model of Parkinson's disease: recovery of cerebral metabolism with acute levodopa treatment
Cerebral atrophy, neurometabolite homeostasis, and neural energetics have been evaluated in an MPTP model of Parkinson's disease using MRI, in vivo 1H MRS and 1H-[13C]-NMR spectroscopy, respectively. MPTP treatment led to reduced paw grip strength and neuronal function. Acute Levodopa treatment was able to recover the diminished motor function and cerebral function. CMRGlc, Cerebral metabolic rate of glucose oxidation; MPTP, 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridin.
Read the full article on page 365.
Tuftsin signals through its receptor neuropilin-1 via the transforming growth factor beta pathway
Despite the 40-year history of the tetrapeptide tuftsin (TKPR), a macrophage and microglial activator, its mechanism of action has not been defined. Here, we report that the tuftsin-mediated anti-inflammatory M2 shift in microglia is caused specifically by tuftsin binding to the receptor neuropilin-1 (Nrp1) and signaling through TGFβ receptor-1, a coreceptor of Nrp1. We further show that tuftsin signals via the canonical TGFβ pathway and promotes TGFβ release from target cells.
Read the full article on page 394.
Human choroid plexus papilloma cells efficiently transport glucose and vitamin C
In choroid plexus papilloma cells, the vitamin C transporters SVCT2 and GLUT1 are polarized to the basolateral epithelial membrane, where SVCT2 is essential for AA flux from the blood vessels into the brain. However, neutrophils, attracted by inflammation or the tumor microenvironment, can oxidize extracellular AA to DHA, thereby enabling its uptake through GLUT1. For the first time, we show the in vivo and in vitro basolateral co-distribution of functional SVCT2 and GLUT1 in epithelial cells. We postulate that patients with choroid plexus papillomas may continue to transport vitamin C from the blood to CSF. However, increased transport of oxidized vitamin C could generate pro-oxidative conditions that may help control tumor growth.
Read the full article on page 403.
Increased prion protein processing and expression of metabotropic glutamate receptor 1 in a mouse model of Alzheimer's disease
Prion protein (PrPC) and metabotropic glutamate receptors (mGluR) are implicated in Alzheimer's disease (AD). We found age-dependent increase in PrPC processing, ADAM10 and mGluR1 levels in AD mouse model. These changes could be reproduced in cultured cortical neurons treated with Aβ peptide. Our findings suggest that increased levels of Aβ can trigger compensatory responses that may affect neuronal toxicity.
Read the full article on page 415.
BNIP3 mediates pre-myelinating oligodendrocyte cell death in hypoxia and ischemia
Pre-myelinating oligodendrocytes (preOLs) are known to be highly vulnerable to ischemic insults. It remains unclear, however, how preOLs die. This study shows that BNIP3, a proapoptotic member of the Bcl-2 family proteins, is a mediator of hypoxia/ischemia-induced preOLs death. The BNIP3 cell death pathway may therefore be a new target for protecting oligodendrocytes from death after stroke.
Read the full article on page 426.
Loss of Bace2 in zebrafish affects melanocyte migration and is distinct from Bace1 knock out phenotypes
Inhibition of BACE1 protease activity has therapeutic importance for Alzheimer's disease. Analysis of BACE1 and BACE2 knock-out zebrafish revealed that they exhibit distinct phenotypes. bace1 mutants display hypomyelination in the PNS and supernumerary neuromasts while in bace2 mutants the shape and migration of melanocytes is affected. These phenotypes are not further enhanced in the viable double mutants. Our data suggest that blocking BACE1 activity is a safe therapeutic approach.
Read the Editorial Highlight for this article on page 435 and the full article on page 471.
Vesicular GABA transporter (VGAT) transports β-alanine
Vesicular GABA transporter (VGAT) is expressed in GABAergic and glycinergic neurons, and is responsible for vesicular storage and subsequent exocytosis of these inhibitory amino acids. In the present study, we showed that proteoliposomes containing purified VGAT transport β-alanine using Δψ as a driving force. VGAT also facilitates Cl− uptake. Our findings indicated that VGAT functions as a vesicular β-alanine transporter.
Read the full article on page 482.
Estrogen receptor-β regulates human tryptophan hydroxylase-2 through an estrogen response element in the 5′ untranslated region
We illustrate a direct regulation of the TPH2 transcription by estradiol and ERβ via a newly identified ERE half-site within the TPH2 promoter: (i) Estradiol- or an ERβ agonist-induced TPH2 transcription was blocked by an ER antagonist, while (ii) membrane impermeable form of estradiol did not induce transcription. (iii) Deletion or mutation of the ERE half-site abolished ligand-induced TPH2 transcription.
Read the full article on page 487.
Neuron-specific specificity protein 4 bigenomically regulates the transcription of all mitochondria- and nucleus-encoded cytochrome c oxidase subunit genes in neurons
The present study discovered that among the specificity family of transcription factors, it is the less known neuron-specific Sp4 that regulates the expression of all 13 subunits of mitochondrial cytochrome c oxidase (COX) enzyme in primary neurons. Sp4 also regulates the three mitochondrial transcription factors (TFAM, TFB1M, and TFB2M) and a COX assembly protein SURF-1 in primary neurons.
Read the full article on page 496.
Urban air pollutants reduce synaptic function of CA1 neurons via an NMDA/NO˙ pathway in vitro
We present three new findings of rapid hippocampal slice responses to nPM (nano-sized particulate matter from urban traffic): increased NO˙ production within 15 min; nitrosylation of glutamatergic NMDA receptors; and, reduced excitatory postsynaptic currents in CA1 neurons. AP5 (NMDA receptor antagonist) blocked nPM-mediated NO˙ and receptor nitrosylation. Ca2+ influx is a likely mechanism.
Read the full article on page 509.
Effects of essential amino acid deficiency: down-regulation of KCC2 and the GABAA receptor; disinhibition in the anterior piriform cortex
The circuitry of the anterior piriform cortex (APC) is finely balanced between excitatory (glutamate, +) and inhibitory (GABA, −) transmission. GABAA receptors use Cl−, requiring the neural potassium chloride co-transporter (KCC2). Both are rapidly turning-over proteins, dependent on protein synthesis for repletion. In IAA (indispensable amino acid) deficiency, within 20 min, blockade of protein synthesis prevents restoration of these inhibitors; they are diminished; disinhibition ensues. GCN2 = general control non-derepressing kinase 2, eIF2α = α-subunit of the eukaryotic initiation factor 2.
Read the full article on page 520.
Growth hormone releasing hormone (GHRH) signaling modulates intermittent hypoxia-induced oxidative stress and cognitive deficits in mouse
Sleep apnea, characterized by chronic intermittent hypoxia (IH), is associated with substantial cognitive and behavioral deficits. Here, we show that administration of a GHRH agonist (JI-34) reduces oxidative stress, increases both HIF-1α nuclear binding and downstream expression of IGF1 and erythropoietin (EPO) in hippocampus and cortex, and markedly attenuates water maze performance deficits in mice exposed to intermittent hypoxia during sleep.
Read the full article on page 531.
Intravenous nicotine injection induces rapid, experience-dependent sensitization of glutamate release in the ventral tegmental area and nucleus accumbens
By using high-speed amperometry with glutamate (GLU) biosensors, we show that i.v. nicotine at a low, behaviorally relevant dose induces rapid GLU release in the NAcc and VTA that is enhanced following repeated drug injections. This is the first study reporting second-scale fluctuations in extracellular GLU levels induced by nicotine in two critical structures of the motivation-reinforcement circuit and rapid sensitization of GLU responses coupled with locomotor sensitization.
Read the full article on page 541.
Specific subcellular changes in oxidative stress in prefrontal cortex from patients with bipolar disorder
Oxidative stress has been shown to be higher in the brain of patients with bipolar disorder (BD). Here, we demonstrated increased levels of protein oxidation in synaptosomes from postmortem prefrontal cortex from patients from BD group, while 3-nitrotyrosine was increased in mitochondria from BD and schizophrenia (SCZ) groups. Moreover, lipid peroxidation was found increased in the BD when compared with controls; suggesting that in BD mitochondrial proteins are more susceptible to potentially reversible nitrosative damage while more longstanding oxidative damage occurs to synaptic proteins.
Read the full article on page 552.
Neuroprotective effects of donepezil against Aβ42-induced neuronal toxicity are mediated through not only enhancing PP2A activity but also regulating GSK-3β and nAChRs activity
We investigated neuroprotective mechanisms of donepezil against Aβ42 toxicity: Donepezil increased neuronal viability with reduced p-tau by enhancing PP2A activity. Despite of blocked PP2A activity, donepezil showed additional recovering effect on neuronal viability, which findings led us to assume that additional mechanisms of donepezil including its inhibitory effect on GSK-3β activity and activating role of nicotinic AChRs might be involved.
Read the full article on page 562.