Actin dynamics in development of behavioral sensitization after withdrawal from long-term ethanol administration to mice

Abstract

Background and methods: The present study investigated the role of actin depolymerizing factor (ADF) in the brain of mice after withdrawal from continuous ethanol (EtOH) vapor inhalation for 9 days using C57BL/6J and ADF mutant mice.

Results: C57BL/6J mice with withdrawal signs 10 hours after withdrawal from EtOH vapor inhalation showed transient and significant enhancement of locomotor activity by a single injection of EtOH (2 g/kg, i.p.) and of EtOH-induced place preference 3 days after withdrawal from EtOH vapor inhalation, suggesting the development of sensitization of locomotion activity to EtOH and of place preference 3 days after withdrawal from EtOH in C57BL/6J mice with EtOH physical dependence. The levels of ADF and G-actin in the ventral tegmental area, including a little bit of surrounding tissues, increased immediately (0 hours), 10 hours, and 3 days after withdrawal from EtOH vapor. F-actin, synaptic vesicle-associated protein 38, and postsynaptic density 95 increased 0 hours and 3 days after withdrawal with their decreases 10 hours after withdrawal from EtOH vapor. An F-actin stabilizing agent phalloidin (3 nmol/mouse/d, i.c.v., once a day) administered daily for 3 days after withdrawal from continuous EtOH vapor inhalation for 9 days significantly suppressed the increase in both EtOH-induced place preference and locomotor activity by a single injection of EtOH 3 days after withdrawal from long-term EtOH vapor inhalation for 9 days. In addition, the changes in behavioral sensitization in ADF mutant mice were significantly weaker than those observed in C57BL/6J mice (wild-type mice for ADF mutant mice).

Conclusions: The findings presented here suggest that withdrawal from EtOH physical dependence causes behavioral sensitization to EtOH, which may be, at least in part, mediated by alternation of actin dynamics.