Ethanol state-dependent memory: Involvement of dorsal hippocampal muscarinic and nicotinic receptors

Activation of the Nitric-Oxide System in Nucleus Accumbens Inhibits the Nicotine Reversal Effects upon Ethanol-Induced Amnesia

“…According to the present data, the pre-training or pre-test injection of ethanol could decrease the step-through latency in a dose-dependent manner when animals were tested following 24 h. Other investigations have similarly shown that the pre-training ethanol inhibits the acquisition of memory in different paradigms such as inhibitory avoidance (7,8), working (9) and spatial memory (10)(11)(12).Our findings also showed that administration of the same dose of ethanol before retention, reverses the ethanol-induced amnesia. This phenomenon, called ethanol statedependent learning, has previously been studied in our laboratory (6)(7)(8) and by others as well. Studies have proposed that the acquired information in one drug state is better remembered when the retrieval is tested in the same drug state (7,8,41,64,65).…”

“…While many reports have suggested the dorsal hippocampus as the main site for modulation of memory (59,63), accumulating evidence have proposed that NAc or other sites of the brain may be involved in memory processes (7). According to the present data, the pre-training or pre-test injection of ethanol could decrease the step-through latency in a dose-dependent manner when animals were tested following 24 h. Other investigations have similarly shown that the pre-training ethanol inhibits the acquisition of memory in different paradigms such as inhibitory avoidance (7,8), working (9) and spatial memory (10)(11)(12).Our findings also showed that administration of the same dose of ethanol before retention, reverses the ethanol-induced amnesia. This phenomenon, called ethanol statedependent learning, has previously been studied in our laboratory (6)(7)(8) and by others as well.…”

“…A considerable body of evidence suggests a solid interaction between ethanol and nicotine in the central nervous system (Collins et al 1993(Collins et al , 1996Smith et al 1999;Lê et al 2003) in which the nicotinic acetylcholine receptors seem to have an important role for such interrelation (3,15,16).Former reports have indicated that the combination of alcohol and nicotine may produce state-dependent learning in humans (17). In addition, according to some later studies, the administration of nicotinic receptor agonists reversed the ethanol-induced amnesia in laboratory animals (7,(18)(19)(20).While nicotine may reverse the ethanol-induced amnesia (similar to pre-test ethanol), the drugs have some opposite effects on other cognitive functions (6,8,21). Where nicotine enhances learning either through a direct effect on attention or affecting the pre-synaptic nicotinic acetylcholine receptors, ethanol may potentially impair learning (4)(5)(6).…”

“…Both ethanol and nicotine can potentially activate the mesolimbic dopaminergic system projecting from the ventral tegmental area to the nucleus accumbens, hippocampus, amygdala and the prefrontal cortex. These drugs have therefore an important role in reward and rewardrelated learning (3).The impairing effects of ethanol on learning and memory have been well-established in different experimental models (4)(5)(6)including the inhibitory avoidance (7,8), working (9) and spatial memory (10)(11)(12). In agreement with some earlier reports (4,13,14), we noticed that ethanol, when administered both pre-and post-training, can impair inhibitory avoidance memory in a state-dependent manner, and the effect is reversible by pre-test ethanol treatment.…”

“…Where nicotine enhances learning either through a direct effect on attention or affecting the pre-synaptic nicotinic acetylcholine receptors, ethanol may potentially impair learning (4)(5)(6). Taken together, the opposite effects of ethanol and nicotine on cognitive functions (5,8,21) have made the interaction between them complex and hence not fully understood yet.…”