Upregulation of γ-aminobutyric acid transporter expression: role of alkylated γ-aminobutyric acid derivatives

2001 ◽  
Vol 29 (6) ◽  
pp. 736-741 ◽  
Author(s):  
T. L. Whitworth ◽  
M. W. Quick
Keyword(s):  
Plasma Membrane ◽  
Tyrosine Kinases ◽  
Fold Increase ◽  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Prolonged Incubation ◽  
Gaba Derivatives ◽  
Brain Gaba ◽  
The Brain

Pregabalin [(S)-(+)-3-isobutylgaba] and gabapentin [1-(aminomethyl)cyclohexane acetic acid] are γ-aminobutyric acid (GABA) derivatives that are effective in the treatment of behavioural disorders, convulsions, epilepsy and hyperalgesia. The mechanisms underlying the diverse actions of these compounds in the brain have not been well elucidated. To test the hypothesis that these compounds exert some of their effects on GABA-ergic systems in the brain, we examined their role in regulating the rat brain GABA transporter GAT1, a plasma membrane protein involved in regulating synaptic transmitter levels. Prolonged incubation of hippocampal cultures, which endogenously express GAT1, with gabapentin and pregabalin caused a 2-fold increase in subsequent GABA uptake, which was concentration- and time-dependent. This increase in uptake was correlated with a redistribution of GAT1 protein from intracellular locations to the plasma membrane. Further experiments also suggested that the signal transduction cascade that modulates pregabalin-mediated GAT1 redistribution may involve pathways activated by specific GAT1 substrates and antagonists but does not involve protein kinase C and tyrosine kinases, two other pathways known to regulate GAT1 redistribution. These data suggest that pregabalin and gabapentin may exert some of their actions in the brain by altering GABAergic signalling.

Effect of adrenalectomy on convulsions induced by high-pressure oxygen

1979 ◽  
Vol 57 (7) ◽  
pp. 688-694 ◽  
Author(s):  
A. K. Singh ◽  
E. W. Banister
Keyword(s):  
High Pressure ◽  
Acid Level ◽  
Amino Acid Level ◽  
Aminobutyric Acid ◽  
Pressure Oxygen ◽  
Significant Difference ◽  
High Pressure Oxygen ◽  
Brain Gaba ◽  
The Brain ◽  
Adrenalectomized Rats

Adrenalectomized rats exposed to high pressure oxygen (OHP) until convulsion convulse much later than sham-operated or normal rats. No significant changes in the concentration of noradrenaline (NA) and total catecholamines (TC) in the brain were noted in sham-operated or adrenalectomized rats resulting from sham or real surgery and no change occurred in these variables in normal sham-operated or adrenalectomized animals after OHP leading to convulsion. Brain adrenaline (A) concentration, however, decreased significantly in all three groups following OHP-induced convulsions. Activity of catecholamine O-methyltransferase (COMT) decreased significantly only in adrenalectomized rats. Brain γ-aminobutyric acid (GABA), glutamate, and other amino acid level remained unchanged after adrenalectomy whereas the concentration of ammonia decreased significantly when normal rats were adrenalectomized. After OHP-induced convulsions, the concentrations of brain GABA and glutamate decreased and ammonia and glutamine plus asparagine increased significantly in normal, sham-operated, and adrenalectomized rats. In the blood no significant difference was noted in the concentration of the catecholamines, ammonia, and amino acids either in normal or sham-operated rats. In adrenalectomized rats, the blood A and NA concentrations decreased significantly and tyrosine increased significantly. The concentration of NA, ammonia, and glutamine plus asparagine in rats from all three groups increased after OHP-induced convulsions, whereas the concentration of glutamate decreased significantly. Since the concentration of A increased significantly after convulsions in normal and sham-operated rats but did not change in adrenalectomized rats, it might be proposed that adrenalectomy protects against OHP-induced convulsions by reducing the circulating concentration of A and ammonia.However, these are not the only factors involved in the protection since the sham-operated rats also convulsed much later than normal rats but had similar ammonia and A concentrations to normal animals.

scholarly journals Neuronal spreading and plaque induction of intracellular Aβ and its disruption of Aβ homeostasis

2021 ◽  
Author(s):  
Tomas T. Roos ◽  
Megg G. Garcia ◽  
Isak Martinsson ◽  
Rana Mabrouk ◽  
Bodil Israelsson ◽  
...  
Keyword(s):  
Brain Homogenate ◽  
Fold Increase ◽  
Amyloid Beta Peptide ◽  
Intracellular Accumulation ◽  
Brain Areas ◽  
Cellular Models ◽  
Beta Peptide ◽  
The Brain

AbstractThe amyloid-beta peptide (Aβ) is thought to have prion-like properties promoting its spread throughout the brain in Alzheimer’s disease (AD). However, the cellular mechanism(s) of this spread remains unclear. Here, we show an important role of intracellular Aβ in its prion-like spread. We demonstrate that an intracellular source of Aβ can induce amyloid plaques in vivo via hippocampal injection. We show that hippocampal injection of mouse AD brain homogenate not only induces plaques, but also damages interneurons and affects intracellular Aβ levels in synaptically connected brain areas, paralleling cellular changes seen in AD. Furthermore, in a primary neuron AD model, exposure of picomolar amounts of brain-derived Aβ leads to an apparent redistribution of Aβ from soma to processes and dystrophic neurites. We also observe that such neuritic dystrophies associate with plaque formation in AD-transgenic mice. Finally, using cellular models, we propose a mechanism for how intracellular accumulation of Aβ disturbs homeostatic control of Aβ levels and can contribute to the up to 10,000-fold increase of Aβ in the AD brain. Our data indicate an essential role for intracellular prion-like Aβ and its synaptic spread in the pathogenesis of AD.

scholarly journals Putrescine, a source of γ-aminobutyric acid in the adrenal gland of the rat

1988 ◽  
Vol 251 (2) ◽  
pp. 559-562 ◽  
Author(s):  
P C Caron ◽  
L J Cote ◽  
L T Kremzner
Keyword(s):  
Adrenal Gland ◽  
Diamine Oxidase ◽  
Cell Metabolism ◽  
Turnover Time ◽  
Oxidase Inhibitor ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Gaba Concentration ◽  
The Brain

Putrescine is the major source of gamma-aminobutyric acid (GABA) in the rat adrenal gland. Diamine oxidase, and not monoamine oxidase, is essential for GABA formation from putrescine in the adrenal gland. Aminoguanidine, a diamine oxidase inhibitor, decreases the GABA concentration in the adrenal gland by more than 70% after 4 h, and almost to zero in 24 h. Studies using [14C]putrescine confirm that [14C]GABA is the major metabolite of putrescine in the adrenal gland. Inhibition of GABA transaminase by amino-oxyacetic acid does not change the GABA concentration in the adrenal gland, as compared with the brain, where the GABA concentration rises. With aminoguanidine, the turnover time of GABA originating from putrescine in the adrenal gland is 5.6 h, reflecting a slower rate of GABA metabolism compared with the brain. Since GABA in the adrenal gland is almost exclusively derived from putrescine, the role of GABA may relate to the role of putrescine as a growth factor and regulator of cell metabolism.

scholarly journals LOCALIZATION OF THE SITES OF γ-AMINOBUTYRIC ACID (GABA) UPTAKE IN LOBSTER NERVE-MUSCLE PREPARATIONS

1971 ◽  
Vol 49 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Paula M. Orkand ◽  
Edward A. Kravitz
Keyword(s):  
Amino Acid ◽  
Connective Tissue ◽  
Electron Micrographs ◽  
Aminobutyric Acid ◽  
Gaba Uptake ◽  
Tissue Cell ◽  
Connective Tissue Cell ◽  
Cell Cytoplasm ◽  
Nerve Muscle

The principal sites of γ-aminobutyric acid (GABA) uptake in lobster nerve-muscle preparations have been determined with radioautographic techniques after binding of the amino acid to proteins by aldehyde fixation. Semiquantitative studies showed that about 30% of the radioactive GABA taken into the tissue was bound to protein by fixation. Both light and electron micrographs showed dense accumulations of label over Schwann and connective tissue cell cytoplasm; muscle was lightly labeled, but axons and terminals were almost devoid of label. The possible role of Schwann and connective tissue cells in the inactivation of GABA released from inhibitory axons is discussed.

scholarly journals Role of astroglial Connexin 43 in pneumolysin cytotoxicity and during pneumococcal meningitis

2020 ◽  
Vol 16 (12) ◽  
pp. e1009152
Author(s):  
Chakir Bello ◽  
Yasmine Smail ◽  
Vincent Sainte-Rose ◽  
Isabelle Podglajen ◽  
Alice Gilbert ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Connexin 43 ◽  
Critical Role ◽  
Neurovascular Unit ◽  
Brain Slices ◽  
Host Cells ◽  
Intermediate Filament Protein ◽  
Young Infants ◽  
The Brain

Streptococcus pneumoniae or pneumococcus (PN) is a major causative agent of bacterial meningitis with high mortality in young infants and elderly people worldwide. The mechanism underlying PN crossing of the blood brain barrier (BBB) and specifically, the role of non-endothelial cells of the neurovascular unit that control the BBB function, remains poorly understood. Here, we show that the astroglial connexin 43 (aCx43), a major gap junctional component expressed in astrocytes, plays a predominant role during PN meningitis. Following intravenous PN challenge, mice deficient for aCx43 developed milder symptoms and showed severely reduced bacterial counts in the brain. Immunofluorescence analysis of brain slices indicated that PN induces the aCx43–dependent destruction of the network of glial fibrillary acid protein (GFAP), an intermediate filament protein specifically expressed in astrocytes and up-regulated in response to brain injury. PN also induced nuclear shrinkage in astrocytes associated with the loss of BBB integrity, bacterial translocation across endothelial vessels and replication in the brain cortex. We found that aCx4-dependent astrocyte damages could be recapitulated using in vitro cultured cells upon challenge with wild-type PN but not with a ply mutant deficient for the pore-forming toxin pneumolysin (Ply). Consistently, we showed that purified Ply requires Cx43 to promote host cell plasma membrane permeabilization in a process involving the Cx43-dependent release of extracellular ATP and prolonged increase of cytosolic Ca2+ in host cells. These results point to a critical role for astrocytes during PN meningitis and suggest that the cytolytic activity of the major virulence factor Ply at concentrations relevant to bacterial infection requires co-opting of connexin plasma membrane channels.

scholarly journals Time Course of Anoxia-Induced Increase in Cerebral Blood Flow Rate in Turtles: Evidence for a Role of Adenosine

1994 ◽  
Vol 14 (5) ◽  
pp. 877-881 ◽  
Author(s):  
Patrick Hylland ◽  
Göran E. Nilsson ◽  
Peter L. Lutz
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Rate ◽  
Time Course ◽  
Blood Flow Rate ◽  
Fold Increase ◽  
Systemic Blood Pressure ◽  
The Brain ◽  
Survival Mechanisms

The exceptional ability of the turtle brain to survive prolonged anoxia makes it a unique model for studying anoxic survival mechanisms. We have used epiillumination microscopy to record blood flow rate in venules on the cortical surface of turtles ( Trachemys scripta). During anoxia, blood flow rate increased 1.7 times after 45–75 min, whereupon it fell back, reaching preanoxic values after 115 min of anoxia. Topical super-fusion with adenosine (50 μ M) during normoxia caused a 3.8-fold increase in flow rate. Superfusing the brain with the adenosine receptor blocker aminophylline (250 μ M) totally inhibited the effects of both adenosine and anoxia, while aminophylline had no effect on normoxic flow rate. None of the treatments affected systemic blood pressure. These results indicate an initial adenosine-mediated increase in cerebral blood flow rate during anoxia, probably representing an emergency response before deep metabolic depression sets in.

scholarly journals Critical Role of Ser-520 Phosphorylation for Membrane Recruitment and Activation of the ZAP-70 Tyrosine Kinase in T Cells

2003 ◽  
Vol 23 (21) ◽  
pp. 7667-7677 ◽  
Author(s):  
Yaoming Yang ◽  
Patricia Villain ◽  
Tomas Mustelin ◽  
Clément Couture
Keyword(s):  
T Cells ◽  
Plasma Membrane ◽  
Tyrosine Kinases ◽  
Critical Role ◽  
Gene Activation ◽  
Interleukin 2 ◽  
Antigen Receptor ◽  
Membrane Recruitment ◽  
Receptor Ligation

ABSTRACT Regulation of protein tyrosine kinases (PTKs) by tyrosine phosphorylation is well recognized; in fact, nearly all PTKs require phosphorylation of tyrosine residues in their “activation loop” for catalytic activity. In contrast, the phosphorylation of PTKs on serine and threonine residues has not been studied nearly as much. We report that the ZAP-70 PTK contains predominately phosphoserine in normal T lymphocytes as well as in Jurkat T leukemia cells. We have identified one site of phosphorylation as Ser-520 and find this site to be important for the recruitment and activation of ZAP-70 in T cells. Mutant ZAP-70-S520A had reduced ability to autophosphorylate and to mediate antigen receptor-induced interleukin 2 gene activation and was not enriched at the plasma membrane. These defects were rescued by addition of a myristylation signal to the N terminus of ZAP-70-S520A to force its plasma membrane and lipid raft localization. We conclude that phosphorylation of ZAP-70 at Ser-520 plays an important role in the correct localization of ZAP-70 and in priming ZAP-70 for its acute recruitment and activation upon antigen receptor ligation.

scholarly journals Role of β-arrestin1/ERK MAP kinase pathway in regulating adenosine A1 receptor desensitization and recovery

2010 ◽  
Vol 298 (1) ◽  
pp. C56-C65 ◽  
Author(s):  
Sarvesh Jajoo ◽  
Debashree Mukherjea ◽  
Sunny Kumar ◽  
Sandeep Sheth ◽  
Tejbeer Kaur ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
De Novo ◽  
Fold Increase ◽  
Nuclear Factor Κb ◽  
Activator Protein 1 ◽  
De Novo Synthesis ◽  
Ductus Deferens ◽  
A1 Receptor ◽  
Interfering Rna

Exposure of cells to adenosine receptor (AR) agonists leads to receptor uncoupling from G proteins and downregulation of the A1AR. The receptor levels on the cell surface generally recover on withdrawal of the agonist, because of either translocation of the sequestered A1AR back to plasma membrane or de novo synthesis of A1AR. To examine the mechanism(s) underlying A1AR downregulation and recovery, we treated ductus deferens tumor (DDT1 MF-2) cells with the agonist R-phenylisopropyladenosine ( R-PIA) and showed a decrease in membrane A1AR levels by 24 h, which was associated with an unexpected 11-fold increase in A1AR mRNA. Acute exposure of these cells to R-PIA resulted in a rapid translocation of β-arrestin1 to the plasma membrane. Knockdown of β-arrestin1 by short interfering RNA (siRNA) blocked R-PIA-mediated downregulation of the A1AR, suppressed R-PIA-dependent ERK1/2 and activator protein-1 (AP-1) activity, and reduced the induction of A1AR mRNA. Withdrawal of the agonist after a 24-h exposure resulted in rapid recovery of plasma membrane A1AR. This was dependent on the de novo protein synthesis and on the activity of ERK1/2 but independent of β-arrestin1 and nuclear factor-κB. Together, these data suggest that exposure to A1AR agonist stimulates ERK1/2 activity via β-arrestin1, which subserves receptor uncoupling and downregulation, in addition to the induction of A1AR expression. We propose that such a pathway ensures both the termination of the agonist signal and recovery by priming the cell for rapid de novo synthesis of A1AR once the drug is terminated.

The GABA system and addiction

2018 ◽  
Author(s):  
David J. Nutt ◽  
Liam J. Nestor
Keyword(s):  
Potential Role ◽  
Abuse Liability ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Substance Addiction ◽  
Inhibitory Neurotransmitter ◽  
Gaba System ◽  
Clinical Potential ◽  
The Brain

Research points to the potential role of gamma-aminobutyric acid (GABA) in substance addiction. GABA is the major inhibitory neurotransmitter in the brain. Disturbances in the GABA system may predate substance abuse and addiction, whereby its efficacy to modulate other neurotransmitter systems (e.g. dopamine) strongly implicated in substance addiction behaviours is impaired. There are a number of addictive substances that boost GABA functioning, however, such as alcohol and benzodiazepines. Medications that boost the availability of GABA or mimic its effects at receptors may possess some clinical potential in treating addiction, but also have abuse liability.

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