Anterior and Posterior Basolateral Amygdala Projections of Cell Type-Specific D1-Expressing Neurons From the Medial Prefrontal Cortex Differentially Control Alcohol-Seeking Behavior.

BACKGROUND: Alcohol use disorder is characterized by compulsive alcohol-seeking behavior, which is associated with dysregulation of afferent projections from the medial prefrontal cortex to the basolateral amygdala (BLA). However, the contribution of the cell type-specific mechanism in this neuronal circuit to alcohol-seeking behavior remains unclear. METHODS: Mice were trained with 2-bottle choice and operant alcohol self-administration procedures. Anterograde and retrograde viral methods traced the connection between dopamine type 1 receptor (D1R) neurons and BLA neurons. Electrophysiology and in vivo optogenetic techniques were used to test the function of neural circuits in alcohol-seeking behavior. RESULTS: Chronic alcohol consumption preferentially changed the activity of posterior BLA (pBLA) neurons but not anterior BLA (aBLA) neurons and overexcited D1R neurons in the medial prefrontal cortex. Interestingly, we found that 2 populations of D1R neurons, anterior and posterior (pD1R) neurons, separately targeted the aBLA and pBLA, respectively, and only a few D1R neurons innervated both aBLA and pBLA neurons. Furthermore, pD1R neurons exhibited more excitability than anterior D1R neurons in alcohol-drinking mice. Moreover, we observed enhanced glutamatergic transmission and an increased NMDA/AMPA receptor ratio in the medial prefrontal cortex inputs from pD1R neurons to the pBLA. Optogenetic long-term depression induction of the pD1R-pBLA circuit reduced alcohol-seeking behavior, while optogenetic long-term depression or long-term potentiation induction of the anterior D1R-aBLA circuit produced no change in alcohol intake. CONCLUSIONS: The pD1R-pBLA circuit mediates chronic alcohol consumption, which may suggest a cell type-specific neuronal mechanism underlying reward-seeking behavior in alcohol use disorder.

Construction and evaluation of an alcohol vapor chamber system.

An increasing number of studies demonstrated that alcohol vapor chamber is an effective way to model physical signs of alcohol use disorders. Although researchers are developing different vapor chambers to study chronic alcohol exposure model worldwide, few studies build and modify their own vapor chambers in China. Here, we designed and established an alcohol vapor chamber system for small animals. We described a paradigm showing how to control and monitor alcohol concentration in whole system. The vapor chamber system with several advantages including accommodating up to ten standard mouse cages. Furthermore, the system was tested by evaluating the blood alcohol concentration and neuron injury in mice. Importantly, the alcohol withdrawal after vapor exposure caused motor coordination impairment, anxiolytic- and depression-like behavior. Finally, the N-methyl-D-aspartate receptor (NMDAR)-mediated glutamatergic transmissions in the medial prefrontal cortex was changed after alcohol vapor exposure-induced behaviors. The frequency and amplitude of spontaneous excitatory postsynaptic currents between control and alcohol groups were not different, suggesting that alcohol exposure-induced behaviors are associated with the change in NMDAR response. Taken together, the new alcohol vapor chamber system was constructed, which would help to research the relationship between the stable alcohol exposure and withdrawal behaviors and to study chronic alcohol exposure-induced disorders in China.

NLRP3 deficiency decreases alcohol intake controlling anxiety-like behavior via modification of glutamatergic transmission in corticostriatal circuits.

BACKGROUND: Alcohol use disorders result from repeated binge and chronic alcohol consumption followed by negative effects, such as anxiety, upon cessation. This process is associated with the activation of NLRP3 inflammasome-mediated responses. However, whether and how inhibition of the NLRP3 inflammasome alters alcohol intake and anxiety behavior remains unclear. METHODS: A combination of drinking-in-the-dark and gavage was established in NLRP3-knockout and control mice. Behavior was assessed by open-field and elevated plus maze tests. Binge alcohol drinking was measured at 2 h and 4 h. A 2 h/4 h/24 h voluntary drinking was determined by a two-bottle choice paradigm. Western blotting and ELISA were applied to examine the levels of the NLRP3 inflammasome and- inflammatory factors, such as IL-1ß and TNF-α. Nissl staining was used to measure neuronal injury. The electrophysiological method was used to determine glutamatergic transmission in corticostriatal circuits. In vivo optogenetic LTP and LTD were applied to control the function of corticostriatal circuits on the behavior of mice. MCC950 was used to antagonize the NLRP3 inflammasome. RESULTS: The binge alcohol intake was decreased in NLRP3 KO mice compared to the control mice. During alcohol withdrawal, NLRP3 deficiency attenuated anxiety-like behavior and neuronal injury in the mPFC and striatum. Moreover, we discovered that glutamatergic transmission to striatal neurons was reduced in NLRP3 KO mice. Importantly, in vivo optogenetic induction of long-term potentiation (LTP) of corticostriatal circuits reversed the effects of NLRP3 deficiency on glutamatergic transmission and anxiety behavior. We also demonstrated that optogenetic induction of LTD decreased anxiety-like behavior and caused a reduction in glutamatergic transmission. Interestingly, NLRP3 deficiency or inhibition (MCC950 injection) attenuated the anxiety-like behavior, but it did not prevent DID + gavage paradigm-induced a persistent enhancement of drinking in a two-bottle choice at 2 and 4 days into withdrawal. CONCLUSION: Our results demonstrate that NLRP3 deficiency decreases binge alcohol intake and anxiety-like behavior through downregulation of glutamatergic transmission in corticostriatal circuits, which may provide an anti-inflammatory target for treating alcohol use disorders.