scholarly journals Effects of Cocaine Exposure on Astrocytic Glutamate Transporters and Relapse-Like Ethanol-Drinking Behavior in Male Alcohol-Preferring Rats

2020 ◽  
Vol 55 (3) ◽  
pp. 254-263 ◽  
Author(s):  
Alaa M Hammad ◽  
Youssef Sari
Keyword(s):  
Drugs Of Abuse ◽  
Drinking Behavior ◽  
Glutamate Transporter ◽  
Glutamate Transporters ◽  
Brain Regions ◽  
Ethanol Intake ◽  
Free Access ◽  
Cocaine Exposure ◽  
Extracellular Glutamate ◽  
Lactam Antibiotic

Abstract Aim Glutamate has been considered as neurotransmitter that is critical in triggering relapse to drugs of abuse, including ethanol and cocaine. Extracellular glutamate concentrations are tightly regulated by several mechanisms, including reuptake through glutamate transporters. Glutamate transporter type 1 (GLT-1) is responsible for clearing the majority of extracellular glutamate. The astrocytic cystine/glutamate antiporter (xCT) regulates also glutamate homeostasis. In this study, we investigated the effects of cocaine exposure and ampicillin/sulbactam (AMP/SUL), a β-lactam antibiotic known to upregulate GLT-1 and xCT, on relapse-like ethanol intake and the expression of astrocytic glutamate transporters in mesocorticolimbic brain regions. Methods Male alcohol-preferring (P) rats had free access to ethanol for 5 weeks. On Week 6, rats were exposed to either cocaine (20 mg/kg, i.p.) or saline for 12 consecutive days. Ethanol bottles were then removed for 7 days; during the last 5 days, either AMP/SUL (100 or 200 mg/kg, i.p.) or saline was administered to the P rats. Ethanol bottles were reintroduced, and ethanol intake was measured for 4 days. Results Cocaine exposure induced an alcohol deprivation effect (ADE), which was associated in part by a decrease in the expression of GLT-1 and xCT in the nucleus accumbens (NAc) core. AMP/SUL (100 mg/kg, i.p.) attenuated the ADE, while AMP/SUL (200 mg/kg, i.p.) reduced ethanol intake during 4 days of ethanol re-exposure and upregulated GLT-1 and xCT expression in the NAc core, NAc shell and dorsomedial prefrontal cortex (dmPFC). Conclusion This study suggests that these astrocytic glutamate transporters might be considered as potential targets for the treatment of polysubstance abuse.

Effect of Modulation of the Astrocytic Glutamate Transporters’ Expression on Cocaine-Induced Reinstatement in Male P Rats Exposed to Ethanol

2020 ◽  
Author(s):  
Alaa M Hammad ◽  
Fawaz Alasmari ◽  
Youssef Sari
Keyword(s):  
Locomotor Activity ◽  
Glutamate Transporter ◽  
Glutamate Transporters ◽  
Ethanol Exposure ◽  
Ethanol Intake ◽  
Cocaine Exposure ◽  
Cocaine Seeking ◽  
Seeking Behavior ◽  
Lactam Antibiotic ◽  
Glutamate Transporter 1

Abstract Aim Reinforcing properties of ethanol and cocaine are mediated in part through the glutamatergic system. Extracellular glutamate concentration is strictly maintained through several glutamate transporters, such as glutamate transporter 1 (GLT-1), cystine/glutamate transporter (xCT) and glutamate aspartate transporter (GLAST). Previous findings revealed that cocaine and ethanol exposure downregulated GLT-1 and xCT, and that β-lactam antibiotics restored their expression. Methods In this study, we investigated the effect of ampicillin/sulbactam (AMP/SUL) (200 mg/kg, i.p.), a β-lactam antibiotic, on cocaine-induced reinstatement and locomotor activity in male alcohol preferring (P) rats using free choice ethanol (15 and 30%, v/v) and water. We also investigated the effect of co-exposure to ethanol and cocaine (20 mg/kg, i.p.) on GLT-1, xCT and GLAST expression in the nucleus accumbens (NAc) core, NAc shell and dorsomedial prefrontal cortex (dmPFC). Results Cocaine exposure decreased ethanol intake and preference. Cocaine and ethanol co-exposure acquired place preference and increased locomotor activity compared to ethanol-exposed rats. GLT-1 and xCT expression were downregulated after cocaine and ethanol co-exposure in the NAc core and shell, but not in dmPFC. AMP/SUL attenuated reinstatement to cocaine as well attenuated the decrease in locomotor activity and ethanol intake and preference. These effects were associated with upregulation of GLT-1 and xCT expression in the NAc core/shell and dmPFC. GLAST expression was not affected after ethanol and cocaine co-exposure or AMP/SUL treatment. Conclusion Our findings demonstrate that astrocytic glutamate transporters within the mesocorticolimbic area are critical targets in modulating cocaine-seeking behavior while being consuming ethanol.

scholarly journals The Effect of GLT-1 Upregulation on Extracellular Glutamate Dynamics

2021 ◽  
Vol 15 ◽  
Author(s):  
Crystal M. Wilkie ◽  
Jessica C. Barron ◽  
Kyle J. Brymer ◽  
Jocelyn R. Barnes ◽  
Firoozeh Nafar ◽  
...  
Keyword(s):  
Glutamate Uptake ◽  
Glutamate Release ◽  
Glutamate Transporter ◽  
Brain Regions ◽  
Brain Diseases ◽  
Dependent Manner ◽  
Beta Lactam ◽  
Lactam Antibiotic ◽  
Glutamate Transporter 1 ◽  
Activity Dependent

Pharmacological upregulation of glutamate transporter-1 (GLT-1), commonly achieved using the beta-lactam antibiotic ceftriaxone, represents a promising therapeutic strategy to accelerate glutamate uptake and prevent excitotoxic damage in neurological conditions. While excitotoxicity is indeed implicated in numerous brain diseases, it is typically restricted to select vulnerable brain regions, particularly in early disease stages. In healthy brain tissue, the speed of glutamate uptake is not constant and rather varies in both an activity- and region-dependent manner. Despite the widespread use of ceftriaxone in disease models, very little is known about how such treatments impact functional measures of glutamate uptake in healthy tissue, and whether GLT-1 upregulation can mask the naturally occurring activity-dependent and regional heterogeneities in uptake. Here, we used two different compounds, ceftriaxone and LDN/OSU-0212320 (LDN), to upregulate GLT-1 in healthy wild-type mice. We then used real-time imaging of the glutamate biosensor iGluSnFR to investigate functional consequences of GLT-1 upregulation on activity- and regional-dependent variations in glutamate uptake capacity. We found that while both ceftriaxone and LDN increased GLT-1 expression in multiple brain regions, they did not prevent activity-dependent slowing of glutamate clearance nor did they speed basal clearance rates, even in areas characterized by slow uptake (e.g., striatum). Unexpectedly, ceftriaxone but not LDN decreased glutamate release in the cortex, suggesting that ceftriaxone may alter release properties independent of its effects on GLT-1 expression. In sum, our data demonstrate the complexities of glutamate uptake by showing that GLT-1 expression does not necessarily translate to accelerated uptake. Furthermore, these data suggest that the mechanisms underlying activity- and regional-dependent differences in glutamate dynamics are independent of GLT-1 expression levels.

scholarly journals Differential Promotion of Glutamate Transporter Expression and Function by Glucocorticoids in Astrocytes from Various Brain Regions

2005 ◽  
Vol 280 (41) ◽  
pp. 34924-34932 ◽  
Author(s):  
Jürgen Zschocke ◽  
Nadhim Bayatti ◽  
Albrecht M. Clement ◽  
Heidrun Witan ◽  
Maciej Figiel ◽  
...  
Keyword(s):  
Glutamate Transporter ◽  
Brain Regions ◽  
And Function ◽  
Transporter Expression

scholarly journals Ischemic Preconditioning Reveals that GLT1/EAAT2 Glutamate Transporter is a Novel PPARγ Target Gene Involved in Neuroprotection

2007 ◽  
Vol 27 (7) ◽  
pp. 1327-1338 ◽  
Author(s):  
Cristina Romera ◽  
Olivia Hurtado ◽  
Judith Mallolas ◽  
Marta P Pereira ◽  
Jesús R Morales ◽  
...  
Keyword(s):  
Nervous System ◽  
Ischemic Preconditioning ◽  
Transcriptional Activity ◽  
Target Gene ◽  
Glutamate Uptake ◽  
Glutamate Release ◽  
Glutamate Transporter ◽  
Glutamate Transport ◽  
Extracellular Glutamate ◽  
Pparγ Agonist

Excessive levels of extracellular glutamate in the nervous system are excitotoxic and lead to neuronal death. Glutamate transport, mainly by glutamate transporter GLT1/EAAT2, is the only mechanism for maintaining extracellular glutamate concentrations below excitotoxic levels in the central nervous system. We recently showed that neuroprotection after experimental ischemic preconditioning (IPC) involves, at least partly, the upregulation of the GLT1/EAAT2 glutamate transporter in astrocytes, but the mechanisms were unknown. Thus, we decided to explore whether activation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)γ, known for its antidiabetic and antiinflammatory properties, is involved in glutamate transport. First, we found that the PPARγ antagonist T0070907 inhibits both IPC-induced tolerance and reduction of glutamate release after lethal oxygen-glucose deprivation (OGD) (70.1% ± 3.4% versus 97.7% ± 5.2% of OGD-induced lactate dehydrogenase (LDH) release and 61.8% ± 5.9% versus 85.9% ± 7.9% of OGD-induced glutamate release in IPC and IPC + T0070907 1 μmol/L, respectively, n = 6 to 12, P < 0.05), as well as IPC-induced astrocytic GLT-1 overexpression. IPC also caused an increase in nuclear PPARγ transcriptional activity in neurons and astrocytes (122.1% ± 8.1% and 158.6% ± 22.6% of control PPARγ transcriptional activity, n = 6, P < 0.05). Second, the PPARγ agonist rosiglitazone increased both GLT-1/EAAT2 mRNA and protein expression and [3H]glutamate uptake, and reduced OGD-induced cell death and glutamate release (76.3% ± 7.9% and 65.5% ± 15.1% of OGD-induced LDH and glutamate release in rosiglitazone 1 μmol/l, respectively, n = 6 to 12, P < 0.05). Finally, we have identified six putative PPAR response elements (PPREs) in the GLT1/EAAT2 promoter and, consistently, rosiglitazone increased fourfold GLT1/EAAT2 promoter activity. All these data show that the GLT1/EAAT2 glutamate transporter is a target gene of PPARγ leading to neuroprotection by increasing glutamate uptake.

scholarly journals Behavioral and Neurobiological Consequences of Hedonic Feeding on Alcohol Drinking

2020 ◽  
Vol 26 (20) ◽  
pp. 2309-2315 ◽  
Author(s):  
Julianna Brutman ◽  
Jon F. Davis ◽  
Sunil Sirohi
Keyword(s):  
Alcohol Drinking ◽  
Alcohol Intake ◽  
Energy Homeostasis ◽  
Drugs Of Abuse ◽  
Drinking Behavior ◽  
The Body ◽  
Alcohol And Drugs ◽  
Signaling Mechanisms ◽  
Functional Consequences ◽  
Neuropsychiatric Conditions

A complex interplay of peripheral and central signaling mechanisms within the body of an organism maintains energy homeostasis. In addition, energy/food intake is modified by various external factors (e.g., palatability, food availability, social and environmental triggers). Highly palatable foods can provoke maladaptive feeding behavior, which in turn disrupts normal homeostatic regulation resulting in numerous health consequences. Furthermore, neuroendocrine peptides, traditionally considered to regulate appetite and energy homeostasis, also control the intake and reinforcing properties of alcohol and drugs of abuse. Therefore, dysregulated eating as a result of a hedonic/binge-like intake of hyper-palatable food may impact alcohol drinking behavior. Relevant in this case is the fact that eating disorders are highly comorbid with several neuropsychiatric conditions, including alcohol use disorder. The present review is intended to summarize the neurobiological and functional consequences of hedonic feeding on alcohol intake.

scholarly journals Optogenetic approaches for the analysis of the role of dopaminergic neurotransmission in the development of alcohol dependence: from correlations to mechanisms

2019 ◽  
pp. 39-40
Author(s):  
E. A. Budygin
Keyword(s):  
Alcohol Drinking ◽  
Dopamine Release ◽  
Drinking Behavior ◽  
Brain Regions ◽  
Alcohol Addiction ◽  
Addictive Behaviors ◽  
Technological Advances ◽  
Dopaminergic Mechanisms ◽  
Neurochemical Changes

Despite many years of work on dopaminergic mechanisms of alcohol addiction, much of this evidence remains mostly correlative in nature. Fortunately, the latest technological advances have provided the opportunity to explore the causal role of neurochemical changes within brain regions involved in addictive behaviors. In this work using optogenetics, we have attempted to answer the question of how dopamine release dynamics control the motivational component of alcohol drinking behavior.

scholarly journals Acamprosate-responsive brain sites for suppression of ethanol intake and preference

2011 ◽  
Vol 301 (4) ◽  
pp. R1032-R1043 ◽  
Author(s):  
Allison Brager ◽  
Rebecca A. Prosser ◽  
J. David Glass
Keyword(s):  
Alcohol Intake ◽  
Free Choice ◽  
Clock Gene ◽  
Brain Regions ◽  
Ethanol Intake ◽  
Mutant Mice ◽  
Wild Type ◽  
Circadian Clock Gene ◽  
Recovering Alcoholics ◽  
Brain Reward

Acamprosate suppresses alcohol intake and craving in recovering alcoholics; however, the central sites of its action are unclear. To approach this question, brain regions responsive to acamprosate were mapped using acamprosate microimplants targeted to brain reward and circadian areas implicated in alcohol dependence. mPer2 mutant mice with nonfunctional mPer2, a circadian clock gene that gates endogenous timekeeping, were included, owing to their high levels of ethanol intake and preference. Male wild-type (WT) and mPer2 mutant mice received free-choice (15%) ethanol/water for 3 wk. The ethanol was withdrawn for 3 wk and then reintroduced to facilitate relapse. Four days before ethanol reintroduction, mice received bilateral blank or acamprosate-containing microimplants releasing ∼50 ng/day into reward [ventral tegmental (VTA), peduculopontine tegmentum (PPT), and nucleus accumbens (NA)] and circadian [intergeniculate leaflet (IGL) and suprachiasmatic nucleus (SCN)] areas. The hippocampus was also targeted. Circadian locomotor activity was measured throughout. Ethanol intake and preference were greater in mPer2 mutants than in wild-type (WT) mice (27 g·kg−1·day−1 vs. 13 g·kg−1·day−1 and 70% vs. 50%, respectively; both, P < 0.05). In WTs, acamprosate in all areas, except hippocampus, suppressed ethanol intake and preference (by 40–60%) during ethanol reintroduction. In mPer2 mutants, acamprosate in the VTA, PPT, and SCN suppressed ethanol intake and preference by 20–30%. These data are evidence that acamprosate's suppression of ethanol intake and preference are manifest through actions within major reward and circadian sites.

Continuous versus intermittent theta burst stimulation in the treatment of experimental autoimmune encephalomyelitis: a glutamate transporters study

2020 ◽  
Author(s):  
Milica Ninkovic ◽  
Mirjana Djukic ◽  
Bojana Mancic ◽  
Petar Milosavljevic ◽  
Ivana Stojanovic ◽  
...  
Keyword(s):  
Glutamate Transporter ◽  
Glutamate Transporters ◽  
Dark Agouti ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
Autoimmune Encephalomyelitis ◽  
Glial Glutamate Transporter ◽  
Elevated Expression ◽  
Underlying Mechanisms ◽  
Theta Burst

Abstract Background: Synaptic overload with glutamate aggravates neurotransmission and worsen the progression of the neurodegenerative disease, such as multiple sclerosis (MS). The experimentally induced autoimmune encephalomyelitis (EAE) in rats is a well-established animal model to study MS. Glutamate reuptake occurs by glial glutamate transporter (GLT-1), and glutamate-aspartate transporter (GLAST) localized predominantly in astrocytes terminals. The focus of the study addressing the expression of these transporters in EAE rats and those subjected to theta burst stimulation (TBS), that promotes long-lasting modulation of neuronal activity in rats/humans. Leading by the reported outcomes of TBS, we examined if TBS underlying mechanisms refer to astroglial glutamate transporters status.Methods : We studied changes in the expression of glial glutamate transporter GLT-1 and glutamate-aspartate transporter (GLAST), and glial fibrillary acidic protein (GFAP), in the spinal cord of EAE rats, subjected to intermittent (iTBS) and continuous (cTBS) theta burst stimulation. We quantified the expression of GLAST, GLT-1, and GFAP by immunofluorescence in control and experimental groups of Dark Agouti rats.Results: EAE elevated expression of GFAP, GLAST, and GLT-1. Both TBSs reduced the expression of GFAP. Continual TBS did not interfere with glutamate transporters in EAE rats, while iTBS decreased GLT-1, and increased GLAST.Conclusion: Continual TBS reduced astrogliosis more efficiently than iTBS, in EAE rats. Besides, it did not mitigate the glutamate transporters' expression; thus, glutamate reuptake remained upraised in cTBS exposed EAE rats. Accordingly, we concluded that cTBS might advance the remyelination of damaged neuronal cells in EAE rats. The future clinical trials on the treatment of MS may consider the data of this pre-clinical animal study.

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