SELECTIVE DECREASE OF DENDRITIC SPINES IN THE NUCLEUS ACCUMBENS OF ETHANOL DEPENDENT RATS.

Neuronal refinement and stabilization are hypothesized to confer resilience to poor decision-making and addictive-like behaviors, such as excessive ethanol drinking and dependence. Accordingly, structural abnormalities are likely to contribute to the appearance of alcohol withdrawal signs and symptoms, that occur from suddenly ceasing the use of alcohol after chronic ingestion, thus perpetuating the addictive cycle. Here we show that ethanol dependent rats display a loss of dendritic spines in medium spiny neurons of the Nacc, accompanied by a reduction of TH-positive terminals and PSD-95 positive elements. Further analysis indicates that ‘long thin’, but not ‘mushroom’, spines are selectively affected. These changes are restricted to the withdrawal phase of ethanol dependence suggesting their relevance in the genesis of signs and/or symptoms affecting ethanol withdrawal, and thus the whole addicting cycle. Overall these results highlight the importance of spine function on the evolution of alcohol dependence and suggest that the selective loss of ‘long thin’ spines may affect learning dysfunctions and significantly contribute to further ‘impoverish’ the already deficient dopaminergic transmission whose hypofunctionality is a major factor for the emergence of the harmful consequences of alcohol abuse/dependence.