scholarly journals Chronic Ethanol and Withdrawal Differentially Modulate Pre- and Postsynaptic Function at Glutamatergic Synapses in Rat Basolateral Amygdala

2007 ◽  
Vol 98 (6) ◽  
pp. 3185-3196 ◽  
Author(s):  
Anna K. Läck ◽  
Marvin R. Diaz ◽  
Ann Chappell ◽  
Dustin W. DuBois ◽  
Brian A. McCool
Keyword(s):  
Ampa Receptor ◽  
Basolateral Amygdala ◽  
Physical Symptoms ◽  
Ethanol Exposure ◽  
Chronic Ethanol ◽  
Glutamatergic Synapses ◽  
Chronic Intermittent Ethanol ◽  
Acute Ethanol ◽  
Learned Fear ◽  
Fear And Anxiety

Withdrawal anxiety is a significant factor contributing to continued alcohol abuse in alcoholics. This anxiety is long-lasting, can manifest well after the overt physical symptoms of withdrawal, and is frequently associated with relapse in recovering alcoholics. The neurobiological mechanisms governing these withdrawal-associated increases in anxiety are currently unknown. The basolateral amygdala (BLA) is a major emotional center in the brain and regulates the expression of both learned fear and anxiety. Neurotransmitter system alterations within this brain region may therefore contribute to withdrawal-associated anxiety. Because evidence suggests that glutamate-gated neurotransmitter receptors are sensitive to acute ethanol exposure, we examined the effect of chronic intermittent ethanol (CIE) and withdrawal (WD) on glutamatergic synaptic transmission in the BLA. We found that slices prepared from CIE and WD animals had significantly increased contributions by synaptic NMDA receptors. In addition, CIE increased the amplitude of AMPA-receptor–mediated spontaneous excitatory postsynaptic currents (sEPSCs), whereas only WD altered the amplitude and kinetics of tetrodotoxin-resistant spontaneous events (mEPSCs). Similarly, the frequency of sEPSCs was increased in both CIE and WD neurons, although only WD increased the frequency of mEPSCs. These data suggest that CIE and WD differentially alter both pre- and postsynaptic properties of BLA glutamatergic synapses. Finally, we show that microinjection of the AMPA-receptor antagonist, DNQX, can attenuate withdrawal-related anxiety-like behavior. Together, our results suggest that increased glutamatergic function may contribute to anxiety expressed during withdrawal from chronic ethanol.

scholarly journals Withdrawal from Chronic Ethanol Exposure Increases Postsynaptic Glutamate Function of Insular Cortex Projections to the Rat Basolateral Amygdala

2019 ◽  
Author(s):  
Molly M. McGinnis ◽  
Brian C. Parrish ◽  
Brian A. McCool
Keyword(s):  
Synaptic Plasticity ◽  
Negative Affect ◽  
Basolateral Amygdala ◽  
Glutamate Release ◽  
Insular Cortex ◽  
Ethanol Exposure ◽  
Ethanol Withdrawal ◽  
Chronic Ethanol ◽  
Chronic Ethanol Exposure ◽  
Chronic Intermittent Ethanol

AbstractA key feature of alcohol use disorder (AUD) is negative affect during withdrawal, which often contributes to relapse and is thought to be caused by altered brain function, especially in circuits that are important mediators of emotional behaviors. Both the agranular insular cortex (AIC) and the basolateral amygdala (BLA) regulate emotions and are sensitive to ethanol-induced changes in synaptic plasticity. The AIC and BLA are reciprocally connected, however, and the effects of chronic ethanol exposure on this circuit have yet to be explored. Here, we use a combination of optogenetics and electrophysiology to examine the pre- and postsynaptic changes that occur to AIC – BLA synapses following withdrawal from 7- or 10-days of chronic intermittent ethanol (CIE) exposure. While CIE/withdrawal did not alter presynaptic glutamate release probably from AIC inputs, withdrawal from 10, but not 7, days of CIE increased AMPA receptor-mediated postsynaptic function at these synapses. Additionally, NMDA receptor-mediated currents evoked by electrical stimulation of the external capsule, which contains AIC afferents, were also increased during withdrawal. Notably, a single subanesthetic dose of ketamine administered at the onset of withdrawal prevented the withdrawal-induced increases in both AMPAR and NMDAR postsynaptic function. Ketamine also prevented the withdrawal-induced increases in anxiety-like behavior measured using the elevated zero maze. Together, these findings suggest that chronic ethanol exposure increases postsynaptic function within the AIC – BLA circuit and that ketamine can prevent ethanol withdrawal-induced alterations in synaptic plasticity and negative affect.

scholarly journals Chronic intermittent ethanol exposure selectively increases synaptic excitability in the ventral domain of the rat hippocampus

2018 ◽  
Author(s):  
Sarah E. Ewin ◽  
James W. Morgan ◽  
Farr Niere ◽  
Nate P. McMullen ◽  
Samuel H. Barth ◽  
...  
Keyword(s):  
Affective State ◽  
Ethanol Exposure ◽  
Chronic Ethanol ◽  
Spatial Learning And Memory ◽  
List Type ◽  
Chronic Ethanol Exposure ◽  
Ca1 Region ◽  
Chronic Intermittent Ethanol ◽  
Long Evans ◽  
Chronic Intermittent Ethanol Exposure

AbstractMany studies have implicated hippocampal dysregulation in the pathophysiology of alcohol use disorder (AUD). However, over the past twenty years, a growing body of evidence has revealed distinct functional roles of the dorsal (dHC) and ventral (vHC) hippocampal subregions, with the dHC being primarily involved in spatial learning and memory and the vHC regulating anxiety-and depressive-like behaviors. Notably, to our knowledge, no rodent studies have examined the effects of chronic ethanol exposure on synaptic transmission along the dorsal/ventral axis. To that end, we examined the effects of the chronic intermittent ethanol vapor exposure (CIE) model of AUD on dHC and vHC synaptic excitability. Adult male Long-Evans rats were exposed to CIE or air for 10 days (12 hrs/day; targeting blood ethanol levels of 175-225 mg%) and recordings were made 24 hours into withdrawal. As expected, this protocol increased anxiety-like behaviors on the elevated plus-maze. Extracellular recordings revealed marked CIE-associated increases in synaptic excitation in the CA1 region that were exclusively restricted to the ventral domain of the hippocampus. Western blot analysis of synaptoneurosomal fractions revealed that the expression of two proteins that regulate synaptic strength, GluA2 and SK2, was dysregulated in the vHC, but not the dHC, following CIE. Together, these findings suggest that the ventral CA1 region may be particularly sensitive to the maladaptive effects of chronic ethanol exposure and provide new insight into some of the neural substrates that may contribute to the negative affective state that develops during withdrawal.HighlightsChronic intermittent ethanol exposure produces robust increases in anxiety-like behavior in male Long Evans rats.Chronic intermittent ethanol exposure increases synaptic excitability in the ventral, but not the dorsal, domain of the hippocampus.These changes in excitability are associated with alterations in synaptoneurosomal expression of small conductance calcium-activated potassium channels and the GluA2 AMPA receptor subunit that are also restricted to the ventral hippocampus.

scholarly journals Chronic Ethanol Differentially Modulates Glutamate Release from Dorsal and Ventral Prefrontal Cortical Inputs onto Rat Basolateral Amygdala Principal Neurons

2019 ◽  
Author(s):  
Molly M. McGinnis ◽  
Brian C. Parrish ◽  
Ann M. Chappell ◽  
Brian A. McCool
Keyword(s):  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Basolateral Amygdala ◽  
Glutamate Release ◽  
Ethanol Exposure ◽  
Chronic Ethanol ◽  
Sprague Dawley ◽  
Behavioral Alterations ◽  
Release Probability ◽  
Chronic Ethanol Exposure

AbstractThe medial prefrontal cortex (mPFC) and the basolateral amygdala (BLA) have strong reciprocal connectivity. Projections from the BLA to the mPFC can bidirectionally modulate anxiety-related behaviors but it is unclear if the same is true for mPFC to BLA projections. Our laboratory is specifically interested in withdrawal-related anxiety-like behavior and the underlying synaptic plasticity. Here, we use optogenetics and chemogenetics to characterize the neurophysiological and behavioral alterations produced by chronic ethanol exposure and withdrawal on dorsal mPFC/prelimbic (dmPFC/PL) and ventral mPFC (vmPFC/IL) terminals in the BLA. We exposed adult male Sprague-Dawley rats to chronic intermittent ethanol (CIE) using vapor chambers, measured anxiety-like behavior on the elevated zero maze (EZM), and used electrophysiology to record glutamatergic and GABAergic responses in BLA principal neurons. We found that 24-hour withdrawal following a 7-day CIE exposure significantly increased the glutamate release probability from PL/dmPFC terminals, but significantly decreases the glutamate release probability from IL/vmPFC terminals. Chemogenetic inhibition of PL/dmPFC terminals in the BLA attenuated the increased withdrawal-dependent, anxiety-like behavior. These data demonstrate that chronic ethanol exposure and withdrawal strengthens the PL/dmPFC – BLA pathway but weakens the IL/vmPFC – BLA pathway. Moreover, we provide novel evidence that the PL/dmPFC – BLA pathway can modulate anxiety-like behavior. These findings suggest that mPFC-BLA circuits known to regulate the acquisition of aversive behaviors are up-regulated by chronic ethanol while those involved with the extinction of these behaviors are down-regulated.Significance StatementAccumulating evidence suggests that the medial prefrontal cortex and its projections to the basolateral amygdala bidirectionally modulate fear-related behaviors. Since the neuronal circuits for fear and anxiety are thought to overlap, we sought to examine the role of prelimbic and infralimbic subdivisions of the medial prefrontal cortex and their inputs to the basolateral amygdala in regulating anxiety. Specifically, we focused on alcohol withdrawal-induced anxiety-like behavior, which is a commonly reported cause of relapse in human alcoholics. In our study, we used optogenetics and chemogenetics to demonstrate, for the first time, that withdrawal from chronic ethanol exposure strengthens prelimbic synapses, but weakens infralimbic synapses in the basolateral amygdala and that inhibiting glutamate release from prelimbic terminal in the basolateral amygdala reduces anxiety-like behavior.

scholarly journals Moderate adolescent chronic intermittent ethanol exposure sex-dependently disrupts synaptic transmission and kappa opioid receptor function in the basolateral amygdala of adult rats

2020 ◽  
Author(s):  
Kathryn R. Przybysz ◽  
Meredith E. Gamble ◽  
Marvin R. Diaz
Keyword(s):  
Opioid Receptor ◽  
Basolateral Amygdala ◽  
Alcohol Exposure ◽  
Ethanol Exposure ◽  
Kappa Opioid Receptor ◽  
Kappa Opioid ◽  
Adolescent Alcohol ◽  
Chronic Intermittent Ethanol ◽  
Glutamate Transmission

AbstractAdolescent alcohol exposure is associated with many negative outcomes that persist into adulthood, including altered affective and reward-related behaviors. However, the long-term neurological disruptions underlying these behavioral states are not fully understood. The basolateral amygdala (BLA) plays a critical role in many of these behaviors, and shifts in the excitatory/inhibitory balance in this area are capable of directly modulating their expression. While changes to BLA physiology have been demonstrated during the acute withdrawal phase following adolescent ethanol exposure, no studies to date have examined whether these persist long-term. The kappa opioid receptor (KOR) system is a neuromodulatory system that acts as a prominent mediator of negative affective behaviors, and alterations of this system have been implicated in the behavioral profile caused by chronic alcohol exposure in adulthood. Notably, in the BLA, the KOR system undergoes functional changes between adolescence and adulthood, but whether BLA KORs are functionally disrupted by adolescent ethanol exposure has not been examined. In this study, we exposed male and female Sprague-Dawley rats to a vapor inhalation model of moderate adolescent chronic intermittent ethanol (aCIE) and examined the long-term effects on GABAergic and glutamatergic neurotransmission within the adult BLA using whole-cell patch-clamp electrophysiology. We also assessed how KOR activation modulated these neurotransmitter systems in aCIE versus control rats using the selective KOR agonist, U69593. This investigation revealed that aCIE exposure disrupted basal glutamate transmission in females by increasing spontaneous excitatory postsynaptic current (sEPSC) frequency, while having no effects on glutamate transmission in males or GABA transmission in either sex. Interestingly, we also found that aCIE exposure unmasked a KOR-mediated suppression of spontaneous inhibitory postsynaptic current (sIPSC) frequency and sEPSC amplitude only in males, with no effects of aCIE exposure on KOR function in females. Together, these data suggest that moderate-level adolescent ethanol exposure produces long-term changes to BLA physiology and BLA KOR function, and that these changes are sex-dependent. This is the first study to examine persistent adaptations to both BLA physiology and KOR function following adolescent alcohol exposure, and opens a broad avenue for future investigation into other neurobiological and behavioral consequences of adolescent ethanol exposure-induced disruptions of these systems.

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