1Contextual cues associated with drugs of abuse, such as ethanol, can trigger craving and drug 2 seeking behavior. Pavlovian procedures, such as place conditioning, have been widely used to 3 study the rewarding/aversive properties of drugs and the association between environmental 4 cues and drug seeking. Previous research has shown that ethanol as an unconditioned stimulus 5 can induce a strong conditioned place preference (CPP) or aversion (CPA) in rodents. However, 6 the neural mechanisms underlying ethanol induced reward and aversion have not been 7 thoroughly investigated. The bed nucleus of the stria terminalis (BNST), an integral part of the 8 extended amygdala, is engaged by both rewarding and aversive stimuli and plays a role in 9 ethanol seeking behavior. Here, we used ex-vivo slice physiology to probe learning-induced 10 synaptic plasticity in the BNST following ethanol-induced CPP and CPA. Male DBA/2J mice (2-3 11 months old) were conditioned using previously reported ethanol-induced CPP/CPA procedures.
12Ethanol-induced CPP was associated with increased neuronal excitability in the ventral BNST 13 (vBNST). Conversely, ethanol-induced CPA resulted in a significant decrease in spontaneous 14 glutamatergic transmission without alterations in GABAergic signaling. Ethanol-CPA also led to 15 significant increase in paired pulse ratio at excitatory synapses, suggestive of a decrease in 16 presynaptic glutamate release. Collectively, these data demonstrate that the vBNST is involved 17 in the modulation of contextual learning associated with both the rewarding and the aversive 18 properties of ethanol in mice.
1920 33 Schuckit et al, 2004). Therefore, alcohol use can be seen as a function of the balance between 34 reward and aversion wherein alcohol's rewarding properties promote its use while its aversive 35 properties limit its use (Verendeev and Riley, 2012). Thus, understanding the neuroadaptations 36 that underlie these associative memories is integral to the development of better treatment 37 strategies.
38A critical neural structure that is widely implicated in associative learning and stress-induced 39 drug seeking is the bed nucleus of the stria terminalis (BNST). BNST is a sexually dimorphic, 40 limbic forebrain region that regulates stress and anxiety states, as well as aversive and reward-41 related behaviors (for review, see Lebow and Chen, 2016; Vranjkovic et al, 2017). It is a 42 complex structure comprising several sub nuclei and heterogenous cell populations (Dong et al, 43 2001a, 2001b, Dong and Swanson, 2006a, 2006b). The anterior commissure divides the BNST 44 into dorsal and ventral (vBNST) divisions. The vast majority of neurons in the BNST are 45 GABAergic in phenotype scattered with a sparse population of glutamatergic cells (Poulin et al,48 Cassell, 1993). Dense glutamatergic inputs arise from the prefrontal cortex, the basal amygdala, 49 the hippocampus and the insular cortex (Canteras and Swanson, 1992; Cullinan et al, 1993; 50 Vertes, 2004). Also, both dorsal and vBNST send pr...