Nitric oxide in the nucleus accumbens is involved in retrieval of inhibitory avoidance memory by nicotine

► Pre-test injection of nicotine and/or morphine reverse morphine induced amnesia. ► Morphine amnesia was also prevented by pre-test intra-NAc injection of l-NAME. ► Ineffective dose of nicotine potentiate l-NAME effect on morphine amnesia. ► Injection of l-arginine prevented improving effect of nicotine on morphine amnesia.