NICOTINE IMPROVES LEARNING AND MEMORY IN RATS: MORPHOLOGICAL EVIDENCE FOR ACETYLCHOLINE INVOLVEMENT

• Published in: International journal of neuroscience Vol. 114; no. 9; pp. 1163 - 1179
• Main Authors: ÜZÜM, Gülay, DILER, A. Sarper, BAHCEKAPILI, Nesrin, TASYÜREKLI, Mustafa, ZIYLAN, Y. Ziya
• Format: Journal Article
• Language: English
• Published: London Informa UK Ltd 01.09.2004; Taylor & Francis
• Subjects: Acetylcholine - analysis; Acetylcholine - physiology; Activity levels. Psychomotricity; Animals; Avoidance Learning - drug effects; Avoidance Learning - physiology; Biological and medical sciences; Frontal Lobe - drug effects; Frontal Lobe - physiology; Fundamental and applied biological sciences. Psychology; Hippocampus - drug effects; Hippocampus - physiology; Human; Learning; Learning. Memory; Male; Memory; Memory - drug effects; Memory - physiology; Microscopy, Electron; Nicotine - pharmacology; Nicotinic Agonists - pharmacology; Presynaptic Terminals - chemistry; Presynaptic Terminals - ultrastructure; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Wistar; Synaptic Vesicles - chemistry; Synaptic Vesicles - ultrastructure; Vigilance. Attention. Sleep; Human; Memory; Central nervous system; Cognition; Experimental study; Retention; Encephalon; Learning; Cholinergic receptor; Acquisition process; Information processing; Avoidance; Nicotine
• ISSN: 0020-7454; 1563-5279; 1543-5245
• DOI: 10.1080/00207450490475652

It has been suggested that nicotine improves rapid information processing (learning and memory) tasks. However, it is not clear which aspects of cognition actually underlie these improvements because relatively less attention has been given to nicotinic cholinergic systems compared to muscarinic systems. The authors therefore studied the effects of nicotine on the learning and memory performance by a step-through passive avoidance task. Nicotine (0.4 mg/kg) was administered s.c. single dose (acute group), once a day for 3 days (subchronic group) or 21 days (chronic group). Nicotine treated and control rats were trained in one trial learning step-through passive avoidance task, where retention latencies were carried out 1 h, 24 h, and 3 days after learning trial. Treatment with nicotine before training session prolonged the latencies significantly (p < .01). Control group, acute, subacute and chronic nicotine treatment groups showed latencies 4.75 ± 0.6, 69.4 ± 14, 116.2 ± 30, and 118.5 ± 23 s, respectively. In addition, to prove the actual contribution of nicotinic cholinergic system in improvement of learning and memory processing, histological methods that permit the visualization and quantification of ACh levels were used. Electron microscopic evaluation revealed increased numbers of Ach-containing vesicles especially in hippocampus in chronic nicotine-treated rats; although frontal and temporal cortex in addition to hippocampus showed increment in Ach vesicles in a lesser extent in all nicotine treatment groups. These results indicate that long-term nicotine treatment can be important for improving cognitive function in regard to increased cholinergic activity.