Modulation of working, short- and long-term memory by nicotinic receptors in the basolateral amygdala in rats

Male Wistar rats were exposed to one-trial step-down inhibitory avoidance training using a 0.5 mA footshock. Through bilaterally implanted indwelling carmulae, they received bilateral 0.5 muL infusions of saline, mecamylamine (1.0 or 10.0 mug/side), or nicotine (0.6 or 3.0 mug/side) into the basolateral complex of the amygdaloid nucleus (BLA). Infusions were either 10min before training (Experiment 1) or 4 min after training (Experiment 2). In Experiment 1, the animals were tested three times: first for working memory (WM) 5 s after training, then for short-term memory (STM) 90 min later, and finally for long-term memory (LTM) 24 h later. Mecamylamine depressed and nicotine enhanced WM, STM, and LTM. In Experiment 2, the treatments were given after WM was presumably over. Again, mecamylamine inhibited and nicotine enhanced STM and LTM. The results indicate that nAChRs in BLA participate in the regulation of WM formation and STM and LTM acquisition and consolidation. (C) 2004 Elsevier Inc. All rights reserved.