The Small G-Protein Rac1 in the Dorsomedial Striatum Promotes Alcohol-Dependent Structural Plasticity and...

Area of Science:

• Neuroscience
• Molecular Biology
• Addiction Research

Background:

• Alcohol consumption alters brain structure, particularly dendritic spines in the nucleus accumbens (NAc) and dorsomedial striatum (DMS).
• The small G-protein Rac1 regulates filamentous actin (F-actin) polymerization, a key component of dendritic spines.

Purpose of the Study:

• To investigate the role of Rac1 in alcohol-induced structural adaptations in the mouse striatum.
• To determine if Rac1 activation mediates alcohol's effects on F-actin and dendritic morphology.
• To explore Rac1's involvement in alcohol-associated learning.

Main Methods:

• Mice underwent chronic intermittent access to alcohol.
• Rac1 activity was measured in striatal tissue.
• Adeno-associated virus (AAV) expressing dominant-negative Rac1 (Rac1-DN) was used to inhibit Rac1 in the DMS.
• Changes in F-actin polymerization, dendritic arborization, and spine maturation were assessed.
• Alcohol-associated goal-directed learning was evaluated.

Main Results:

• Chronic alcohol intake specifically activated Rac1 in the DMS of male mice.
• Rac1 activation by alcohol was not observed in the NAc, DLS, female mice, or with moderate alcohol/natural rewards.
• Inhibition of Rac1 in the DMS attenuated alcohol-induced F-actin polymerization, dendritic changes, and spine maturation.
• Rac1 in the DMS was implicated in alcohol-associated goal-directed learning.

Conclusions:

• Rac1 in the DMS is a key mediator of alcohol-dependent structural plasticity.
• Rac1 signaling in the DMS contributes to aberrant learning associated with alcohol use.
• Targeting Rac1 in the DMS may offer therapeutic potential for alcohol use disorders.