SNARE Complex-Associated Proteins in the Lateral Amygdala of Macaca mulatta Following Long-Term Ethanol Drinking

BACKGROUND: Recent work with long-term ethanol self-administration in non-human primate models has revealed a complex array of behavioral and physiological effects that closely mimic human alcohol abuse. Detailed neurophysiological analysis in these models suggests a myriad of pre- and postsynaptic neurobiological effects that may contribute to the behavioral manifestations of long-term ethanol drinking. The molecular mechanisms regulating presynaptic effects of this chronic ethanol exposure are largely unknown. To this end, we analyzed the effects of long-term ethanol self-administration on the levels of presynaptic SNARE complex proteins in Mucacca mullatta basolateral amygdala, a brain region known to regulate both aversive and reward-seeking behaviors. METHODS: Basolateral amygdala samples from control and ethanol-drinking male and female monkeys were processed. Total basolateral amygdala protein was analyzed by Western blotting using antibodies directed against both core-SNARE and SNARE-associated proteins. We also performed correlational analyses between protein expression levels and a number of ethanol drinking parameters, including life-time grams of ethanol consumed, preference, and blood ethanol concentration. RESULTS: Significant interactions or main effects of sex/drinking were seen for a number of SNARE core and SNARE-associated proteins. Across the range of ethanol drinking phenotypes, SNAP25 and Munc13-1 proteins levels were significantly different between males and females; and Munc13-2 levels were significantly lower in animals with a history of ethanol drinking. A separate analysis of very-heavy drinking individuals revealed significant decreases in Rab3c (females) and Complexin 2 (males). CONCLUSIONS: Protein expression analysis of basolateral amygdala total protein from controls and animals following long-term ethanol self-administration suggest a number of alterations in core SNARE or SNARE-associated components that could dramatically alter presynaptic function. A number of proteins or multi-protein components were also correlated with ethanol drinking behavior, which suggest a potentially heritable role for presynaptic SNARE proteins.