Nicotine has been shown to improve cognition in humans and in animal models.Hippocampal long term potentiation (LTP) is a useful synaptic model of learning and memory.Previous in vitro and in vivo studies have shown nicotine facilitates the induction of LTP in CA1 and dentate gyrus (DG) of hippocampus.In current study,we used selective nicotinic ligands for alpha4beta2 (TC-2559 and DHbE) and alpha7 (LY2070029,LY2129285 and MLA) subtypes to look more carefully of the role of nAChR subtypes in hippocampal neuronal plasticity.Experiments were performed on urethane anaesthetized (1.2 g/kg,i.p.) adult male Sprague rats.Recordings were made using 2% Pontamine Sky Blue in 2M NaC1 filled glass electrode with tip impedance of 2-3 MOme implanted in the DG (3.5-4.0 mm caudal and 1.8-2.2 nun lateral to bregma).