Functional and Molecular Changes in the Prefrontal Cortex of the Chronic Mild Stress Rat Model of Depression and Modulation by Acute Ketamine

Stress is a primary risk factor in the onset of neuropsychiatric disorders, including major depressive disorder (MDD). We have previously used the chronic mild stress (CMS) model of depression in male rats to show that CMS induces morphological, functional, and molecular changes in the hippocampus of vulnerable animals, the majority of which were recovered using acute subanesthetic ketamine in just 24 h. Here, we focused our attention on the medial prefrontal cortex (mPFC), a brain area regulating emotional and cognitive functions, and asked whether vulnerability/resilience to CMS and ketamine antidepressant effects were associated with molecular and functional changes in the mPFC of rats. We found that most alterations induced by CMS in the mPFC were selectively observed in stress-vulnerable animals and were rescued by acute subanesthetic ketamine, while others were found only in resilient animals or were induced by ketamine treatment. Importantly, only a few of these modifications were also previously demonstrated in the hippocampus, while most are specific to mPFC. Overall, our results suggest that acute antidepressant ketamine rescues brain-area-specific glutamatergic changes induced by chronic stress

The TOTEM Experiment at the CERN Large Hadron Collider

The TOTEM Experiment will measure the total pp cross-section with the luminosity independent method and study elastic and diffractive scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, will be installed on each side in the pseudorapidity region 3,1 <h< 6,5, and Roman Pot stations will be placed at distances of 147m and 220m from IP5. Being an independent experiment but technically integrated into CMS, TOTEM will first operate in standalone mode to pursue its own physics programme and at a later stage together with CMS for a common physics programme. This article gives a description of the TOTEM apparatus and its performance

In-vitro and in-vivo studies depict metabotropic glutamate receptor 5 as a potential pharmacological target to modulate disease progression in ALS

BACKGROUND Amyotrophic lateral sclerosis (ALS) is fatal neurodegenerative disease due to a progressive degeneration of motor neurons (MNs). The aetiology is still largely obscure, and several mechanisms have been proposed, including glutamate (Glu)-mediated excitotoxicity. In this context, group I metabotropic Glu receptors (mGluR1/5) play an active role, since their expression and functions are altered, especially in glial cells. Moreover, we previously showed that group I mGluRs sustains the excessive Glu release in the spinal cord of the SOD1G93A mouse model of ALS, and this alteration is already present at the onset of the pathology. METHODS We first investigated in-vivo the effect of mGlu5 receptor genetic ablation in SOD1G93A mice (SOD1G93A-mGluR5-/-). We then tested in-vivo the pharmacological blockade of mGluR5 by oral administration of the mGluR5 negative allosteric modulator CTEP (4 mg/kg every 24h, from 90 days of life). Finally, we studied in-vitro the effects of the mGluR5 genetic downregulation, on the reactive phenotype of spinal cord astrocytes cultured from symptomatic SOD1G93A mice. Histological, functional and biochemical experiments have been performed to characterise astrocytes and their cytotoxicity towards MNs. RESULTS The in-vivo genetic ablation of mGluR5 demonstrates that SOD1G93A-mGluR5-/- mice showed a delayed disease onset and a significant prolonged survival probability. These effects were paralleled by a significant MNs preservation, a decreased astrocyte and microglia activation and by a normalization of the excessive Glu release, compared to age matched SOD1G93A mice. Subsequently, we tested the pharmacological modulation of mGluR5 by CTEP. Behavioural studies showed that, as for the genetic ablation, also CTEP in-vivo treatment significantly slowdown the clinical progression of the pathology and increased the survival probability in SOD1G93A mice. Moreover, we also observed a reduced glial activation and a significant MNs preservation. In-vitro experiments with primary spinal cord astrocytes showed that the elevated cytosolic calcium concentration as well as the over expression of astrogliosis markers (GFAP, S100, Vimentin, NLRP3) were significantly reduced in cells genetically lacking the mGluR5 (SOD1G93A_mGluR5+/-) compared to SOD1G93A astrocytes. Most importantly, the modulation of the reactive phenotype in SOD1G93A_mGluR5+/-astrocytes translates into a reduced release of neuroinflammatory cytokines (IL1b, IL-6, TNFa), improved bioenergetics and a less toxic effect toward co-cultured MNs. CONCLUSIONS Our results demonstrate that a lower constitutive level of mGluR5, or the pharmacological blockade of the receptor by CTEP, has a positive clinical outcome in SOD1G93A ALS mice. The in-vivo effects can be mainly ascribed to a reduced reactive astrogliosis, supporting the role of mGluR5 as a therapeutic target to obtain a shift from a pathological toward a less noxious phenotype of astrocytes in SOD1G93A mice

Mechanisms underlying the predictive power of high skeletal muscle uptake of FDG in amyotrophic lateral sclerosis

Background: We recently reported that enhanced [18F]-fluorodeoxyglucose (FDG) uptake in skeletal muscles predicts disease aggressiveness in patients with amyotrophic lateral sclerosis (ALS). The present experimental study aimed to assess whether this predictive potential reflects the link between FDG uptake and redox stress that has been previously reported in different tissues and disease models. Methods: The study included 15 SOD1G93A mice (as experimental ALS model) and 15 wildtype mice (around 120 days old). Mice were submitted to micro-PET imaging. Enzymatic pathways and response to oxidative stress were evaluated in harvested quadriceps and hearts by biochemical, immunohistochemical, and immunofluorescence analysis. Colocalization between the endoplasmic reticulum (ER) and the fluorescent FDG analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG) was performed in fresh skeletal muscle sections. Finally, mitochondrial ultrastructure and bioenergetics were evaluated in harvested quadriceps and hearts. Results: FDG retention was significantly higher in hindlimb skeletal muscles of symptomatic SOD1G93A mice with respect to control ones. This difference was not explained by any acceleration in glucose degradation through glycolysis or cytosolic pentose phosphate pathway (PPP). Similarly, it was independent of inflammatory infiltration. Rather, the high FDG retention in SOD1G93A skeletal muscle was associated with an accelerated generation of reactive oxygen species. This redox stress selectively involved the ER and the local PPP triggered by hexose-6P-dehydrogenase. ER involvement was confirmed by the colocalization of the 2-NBDG with a vital ER tracker. The oxidative damage in transgenic skeletal muscle was associated with a severe impairment in the crosstalk between ER and mitochondria combined with alterations in mitochondrial ultrastructure and fusion/fission balance. The expected respiratory damage was confirmed by a deceleration in ATP synthesis and oxygen consumption rate. These same abnormalities were represented to a markedly lower degree in the myocardium, as a sample of non-voluntary striated muscle. Conclusion: Skeletal muscle of SOD1G93A mice reproduces the increased FDG uptake observed in ALS patients. This finding reflects the selective activation of the ER-PPP in response to significant redox stress associated with alterations of mitochondrial ultrastructure, networking, and connection with the ER itself. This scenario is less severe in cardiomyocytes suggesting a relevant role for either communication with synaptic plaque or contraction dynamics