scholarly journals Acute and chronic ethanol exposure differentially regulate CB1 receptor function at glutamatergic synapses in the rat basolateral amygdala

2016 ◽  
Vol 108 ◽  
pp. 474-484 ◽  
Author(s):  
Stacey L. Robinson ◽  
Nancy J. Alexander ◽  
Rebecca J. Bluett ◽  
Sachin Patel ◽  
Brian A. McCool
1980 ◽  
Vol 6 (1-2) ◽  
pp. 104-105 ◽  
Author(s):  
Paula L. Hoffman ◽  
Stephan Urwyler ◽  
Boris Tabakoff

2019 ◽  
Author(s):  
Molly M. McGinnis ◽  
Brian C. Parrish ◽  
Brian A. McCool

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.


2019 ◽  
Author(s):  
Molly M. McGinnis ◽  
Brian C. Parrish ◽  
Ann M. Chappell ◽  
Brian A. McCool

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.


2007 ◽  
Vol 98 (6) ◽  
pp. 3185-3196 ◽  
Author(s):  
Anna K. Läck ◽  
Marvin R. Diaz ◽  
Ann Chappell ◽  
Dustin W. DuBois ◽  
Brian A. McCool

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.


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