scholarly journals Expression of Microbial Enzymes in Mammalian Astrocytes to Modulate Lactate Release

2021 ◽  
Vol 11 (8) ◽  
pp. 1056
Author(s):  
Barbara Vaccari Cardoso ◽  
Iliana Barrera ◽  
Valentina Mosienko ◽  
Alexander V. Gourine ◽  
Sergey Kasparov ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Lactate Production ◽  
Lactate Oxidase ◽  
Microbial Enzymes ◽  
Lactate Release ◽  
Vital Functions ◽  
Cardiovascular Performance ◽  
Transgenic Tools ◽  
The Brain

Astrocytes support and modulate neuronal activity through the release of L-lactate. The suggested roles of astrocytic lactate in the brain encompass an expanding range of vital functions, including central control of respiration and cardiovascular performance, learning, memory, executive behaviour and regulation of mood. Studying the effects of astrocytic lactate requires tools that limit the release of lactate selectively from astrocytes. Here, we report the validation in vitro of novel molecular constructs derived from enzymes originally found in bacteria, that when expressed in astrocytes, interfere with lactate handling. When lactate 2-monooxygenase derived from M. smegmatis was specifically expressed in astrocytes, it reduced intracellular lactate pools as well as lactate release upon stimulation. D-lactate dehydrogenase derived from L. bulgaricus diverts pyruvate towards D-lactate production and release by astrocytes, which may affect signalling properties of lactate in the brain. Together with lactate oxidase, which we have previously described, this set of transgenic tools can be employed to better understand astrocytic lactate release and its role in the regulation of neuronal activity in different behavioural contexts.

Pyruvate Kinase Isoenzyme M2 Impairs Cognition in Systemic Lupus Erythematosus by Promoting Microglial Synaptic Pruning via β-Catenin Signaling Pathway

2020 ◽  
Author(s):  
Li Lu ◽  
Hailin Wang ◽  
Xuan Liu ◽  
Liping Tan ◽  
Xiaoyue Qiao ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Signaling Pathway ◽  
Pyruvate Kinase ◽  
Brain Damage ◽  
Lupus Erythematosus ◽  
Lactate Production ◽  
Systemic Lupus ◽  
Neuronal Synapses ◽  
The Brain

Abstract Background Neuropsychiatric systemic lupus erythematosus (NPSLE) is the severest complication of SLE, which often involves pathological damage to the brain and cognitive function. Glucose metabolic changes are observed in SLE patients with cognitive impairments by medical imaging. Pyruvate kinase isoform M2 (PKM2) is a vital catalyzer of glucose catabolic pathways and in neurological diseases. However, PKM2 regarding the progress of NPSLE remains poorly studied. Thus, this study aimed to analyze and compare the central carbon metabolites in the validated neuropsychiatric lupus model and control mice. Methods MRL/Mp-Faslpr (MRL/lpr) female mice were used as NPSLE mouse model, C57BL6 as control. Metabolomics to assess hippocampa glycolysis level. Glucose, lactic acid, IL-6 and IL-1β of hippocampal were detected by ELISA. The expression of PKM2 was detected by qRT-PCR and western blotting, and the localization of PKM2 in microglia and neurons was assessed with IBA-1, NeuN and PKM2 immunohistochemistry. Flow cytometry was used to detect the number and phenotype of microglia. In vitro, after transfected PKM2 overexpression plasmid on BV2, the effect on microglia and β-catenin signaling pathway were detected. Finally, PKM2 inhibitor Shikonin was injected into MRL/lpr mice, behavioral testing were performed to assess cognition, HE and FJB staining were used to evaluate brain damage.Results Glycolysis was elevated in the hippocampal tissues from MRL/lpr lupus mice, accompanied by an increase in glucose consumption and lactate production. Based on these metabolic variations, PKM2 activation was revealed in hippocampal microglia from lupus mice. Furthermore, PKM2 facilitated microglial phagocytic activity and engulfment of neurons via β-catenin signaling. In vivo, an inhibitor of PKM2, Shikonin, was shown to reduce microglial activation, loss of neuronal synapses, and block β-catenin signaling. Accordingly, the cognitive impairment and brain damage of MRL/lpr mice were relieved. Conclusion These results indicated that abnormal glycolytic metabolism in the brain tissue of NPSLE mice was induced by PKM2 overexpression, which increased the activation of microglia and the ability of phagocytizing neuronal synapses, leading to neuronal loss and cognitive dysfunction in lupus. These phenomena indicated that inhibition on PKM2 would be a novel therapeutic target for the treatment of lupus encephalopathy.

Do the suprachiasmatic nuclei oscillate in old rats as they do in young ones?

1993 ◽  
Vol 265 (5) ◽  
pp. R1216-R1222 ◽  
Author(s):  
E. Satinoff ◽  
H. Li ◽  
T. K. Tcheng ◽  
C. Liu ◽  
A. J. McArthur ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Brain Slices ◽  
Neuronal Firing ◽  
Suprachiasmatic Nuclei ◽  
Firing Rates ◽  
Behavioral Rhythms ◽  
Behavioral Rhythm ◽  
Old Rats ◽  
The Brain

The basis of the decline in circadian rhythms with aging was addressed by comparing the patterns of three behavioral rhythms in young and old rats with the in vitro rhythm of neuronal activity in the suprachiasmatic nuclei (SCN), the primary circadian pacemaker. In some old rats, rhythms of body temperature, drinking, and activity retained significant 24-h periodicities in entraining light-dark cycles; in others, one or two of the rhythms became aperiodic. When these rats were 23-27.5 mo old they were killed, and single-unit firing rates in SCN brain slices were recorded continuously for 30 h. There was significant damping of mean peak neuronal firing rates in old rats compared with young. SCN neuronal activities were analyzed with reference to previous entrained behavioral rhythm patterns of individual rats as well. Neuronal activity from rats with prior aperiodic behavioral rhythms was erratic, as expected. Neuronal activity from rats that were still maintaining significant 24-h behavioral rhythmicity at the time they were killed was erratic in most cases but normally rhythmic in others. Thus there was no more congruence between the behavioral rhythms and the brain slice rhythms than there was among the behavioral rhythms alone. These results, the first to demonstrate aberrant SCN firing patterns and a decrease in amplitude in old rats, imply that aging could either disrupt coupling between SCN pacemaker cells or their output, or cause deterioration of the pacemaking properties of SCN cells.

scholarly journals An Open-Source Wireless Electrophysiological Complex for In Vivo Recording Neuronal Activity in the Rodent’s Brain

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7189
Author(s):  
Alexander Erofeev ◽  
Dmitriy Kazakov ◽  
Nikita Makarevich ◽  
Anastasia Bolshakova ◽  
Evgenii Gerasimov ◽  
...  
Keyword(s):  
Open Source ◽  
Neuronal Activity ◽  
Ex Vivo ◽  
Electrode Arrays ◽  
Charging Station ◽  
In Vivo Experiments ◽  
The Brain ◽  
Schematic Diagrams

Multi-electrode arrays (MEAs) are a widely used tool for recording neuronal activity both in vitro/ex vivo and in vivo experiments. In the last decade, researchers have increasingly used MEAs on rodents in vivo. To increase the availability and usability of MEAs, we have created an open-source wireless electrophysiological complex. The complex is scalable, recording the activity of neurons in the brain of rodents during their behavior. Schematic diagrams and a list of necessary components for the fabrication of a wireless electrophysiological complex, consisting of a base charging station and wireless wearable modules, are presented.

scholarly journals Profiling DNA break sites and transcriptional changes in response to contextual fear learning

2021 ◽  
Author(s):  
Ryan Stott ◽  
Oleg Kritsky ◽  
Li-Huei Tsai
Keyword(s):  
Neuronal Activity ◽  
Early Response ◽  
Contextual Fear Conditioning ◽  
Fear Learning ◽  
Dna Breaks ◽  
Learning Behaviors ◽  
Contextual Fear ◽  
Transcriptional Changes ◽  
The Brain

Neuronal activity generates DNA double-strand breaks (DSBs) at specific loci in vitro and this facilitates the rapid transcriptional induction of early response genes (ERGs). Physiological neuronal activity, including exposure of mice to learning behaviors, also cause the formation of DSBs, yet the distribution of these breaks and their relation to brain function remains unclear. Here, following contextual fear conditioning (CFC) in mice, we profiled the locations of DSBs genome-wide in the medial prefrontal cortex and hippocampus using γH2AX ChIP-Seq. Remarkably, we found that DSB formation is widespread in the brain compared to cultured primary neurons and they are predominately involved in synaptic processes. We observed increased DNA breaks at genes induced by CFC in neuronal and non-neuronal nuclei. Activity-regulated and proteostasis-related transcription factors appear to govern some of these gene expression changes across cell types. Finally, we find that glia but not neurons have a robust transcriptional response to glucocorticoids, and many of these genes are sites of DSBs. Our results indicate that learning behaviors cause widespread DSB formation in the brain that are associated with experience-driven transcriptional changes across both neuronal and glial cells.

scholarly journals Profiling DNA break sites and transcriptional changes in response to contextual fear learning

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0249691
Author(s):  
Ryan T. Stott ◽  
Oleg Kritsky ◽  
Li-Huei Tsai
Keyword(s):  
Neuronal Activity ◽  
Early Response ◽  
Contextual Fear Conditioning ◽  
Fear Learning ◽  
Dna Breaks ◽  
Learning Behaviors ◽  
Contextual Fear ◽  
Transcriptional Changes ◽  
The Brain

Neuronal activity generates DNA double-strand breaks (DSBs) at specific loci in vitro and this facilitates the rapid transcriptional induction of early response genes (ERGs). Physiological neuronal activity, including exposure of mice to learning behaviors, also cause the formation of DSBs, yet the distribution of these breaks and their relation to brain function remains unclear. Here, following contextual fear conditioning (CFC) in mice, we profiled the locations of DSBs genome-wide in the medial prefrontal cortex and hippocampus using γH2AX ChIP-Seq. Remarkably, we found that DSB formation is widespread in the brain compared to cultured primary neurons and they are predominately involved in synaptic processes. We observed increased DNA breaks at genes induced by CFC in neuronal and non-neuronal nuclei. Activity-regulated and proteostasis-related transcription factors appear to govern some of these gene expression changes across cell types. Finally, we find that glia but not neurons have a robust transcriptional response to glucocorticoids, and many of these genes are sites of DSBs. Our results indicate that learning behaviors cause widespread DSB formation in the brain that are associated with experience-driven transcriptional changes across both neuronal and glial cells.

scholarly journals Astrocytes regulate brain extracellular pH via a neuronal activity-dependent bicarbonate shuttle

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Shefeeq M. Theparambil ◽  
Patrick S. Hosford ◽  
Iván Ruminot ◽  
Olga Kopach ◽  
James R. Reynolds ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Extracellular Ph ◽  
Ph Homeostasis ◽  
Sodium Bicarbonate Cotransporter ◽  
Highly Sensitive ◽  
Activity Dependent ◽  
The Brain ◽  
Local Brain

Abstract Brain cells continuously produce and release protons into the extracellular space, with the rate of acid production corresponding to the levels of neuronal activity and metabolism. Efficient buffering and removal of excess H+ is essential for brain function, not least because all the electrogenic and biochemical machinery of synaptic transmission is highly sensitive to changes in pH. Here, we describe an astroglial mechanism that contributes to the protection of the brain milieu from acidification. In vivo and in vitro experiments conducted in rodent models show that at least one third of all astrocytes release bicarbonate to buffer extracellular H+ loads associated with increases in neuronal activity. The underlying signalling mechanism involves activity-dependent release of ATP triggering bicarbonate secretion by astrocytes via activation of metabotropic P2Y1 receptors, recruitment of phospholipase C, release of Ca2+ from the internal stores, and facilitated outward HCO3− transport by the electrogenic sodium bicarbonate cotransporter 1, NBCe1. These results show that astrocytes maintain local brain extracellular pH homeostasis via a neuronal activity-dependent release of bicarbonate. The data provide evidence of another important metabolic housekeeping function of these glial cells.

scholarly journals Hibernation induces pentobarbital insensitivity in medulla but not cortex

2009 ◽  
Vol 297 (4) ◽  
pp. R1028-R1036 ◽  
Author(s):  
Keith B. Hengen ◽  
Mary Behan ◽  
Hannah V. Carey ◽  
Mathew V. Jones ◽  
Stephen M. Johnson
Keyword(s):  
Neuronal Activity ◽  
Nucleus Tractus Solitarius ◽  
Selective Inhibition ◽  
Extreme Environment ◽  
Pentobarbital Sodium ◽  
Cardiorespiratory Function ◽  
Dependent Inhibition ◽  
Spontaneous Neuronal Activity ◽  
The Brain

The 13-lined ground squirrel ( Ictidomys tridecemlineatus), a hibernating species, is a natural model of physiological adaption to an extreme environment. During torpor, body temperature drops to 0–4°C, and the cortex is electrically silent, yet the brain stem continues to regulate cardiorespiratory function. The mechanisms underlying selective inhibition in the brain during torpor are not known. To test whether altered GABAergic function is involved in regional and seasonal differences in neuronal activity, cortical and medullary slices from summer-active (SA) and interbout aroused (IBA) squirrels were placed in a standard in vitro recording chamber. Silicon multichannel electrodes were placed in cortex, ventral respiratory column (VRC), and nucleus tractus solitarius (NTS) to record spontaneous neuronal activity. In slices from IBA squirrels, bath-applied pentobarbital sodium (300 μM) nearly abolished cortical neuronal activity, but VRC and NTS neuronal activity was unaltered. In contrast, pentobarbital sodium (300 μM) nearly abolished all spontaneous cortical, VRC, and NTS neuronal activity in slices from SA squirrels. Muscimol (20 μM; GABAA receptor agonist) abolished all neuronal activity in cortical and medullary slices from both IBA and SA squirrels, thereby demonstrating the presence of functional GABAA receptors. Pretreatment of cortical slices from IBA squirrels with bicuculline (100 μM; GABAA receptor antagonist) blocked pentobarbital-dependent inhibition of spontaneous neuronal activity. We hypothesize that GABAA receptors undergo a seasonal modification in subunit composition, such that cardiorespiratory neurons are uniquely unaffected by surges of an endogenous positive allosteric modulator.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

ÉTUDE IN VITRO DU MÉTABOLISME DES HYDRATES DE CARBONE DANS LE LEUCOCYTE CIRCULANT DU COBAYE TRAITÉ À LA CORTISONE

1966 ◽  
Vol 51 (2) ◽  
pp. 193-202
Author(s):  
J. A. Antonioli ◽  
A. Vannotti
Keyword(s):  
Glucose Concentration ◽  
Intramuscular Injection ◽  
Acute Inflammation ◽  
Glycogen Content ◽  
Glycogen Synthesis ◽  
Lactate Production ◽  
Glucose Consumption ◽  
List Type ◽  
Hydrates De Carbone

ABSTRACT 1. The metabolism of suspensions of circulating leucocytes has been studied after intramuscular injection of a dose of 50 mg/kg of a corticosteroid (cortisone acetate). The suspensions were incubated under aerobic conditions in the presence of a glucose concentration of 5.6 mm. Glucose consumption, lactate production, and variations in intracellular glycogen concentration were measured. After the administration of the corticosteroid, the anabolic processes of granulocyte metabolism were reversibly stimulated. Glucose consumption and lactate production increased 12 hours after the injection, but tended to normalize after 24 hours. The glycogen content of the granulocytes was enhanced, and glycogen synthesis during the course of the incubation was greatly stimulated. The action of the administered corticosteroid is more prolonged in females than in males. The injection of the corticosteroid caused metabolic modifications which resemble in their modulations and in their chronological development those found in circulating granulocytes of guinea-pigs suffering from sterile peritonitis. These results suggest, therefore, that, in the case of acute inflammation, the glucocorticosteroids may play an important role in the regulation of the metabolism of the blood leucocytes.

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