Nicotine Enhances Object Recognition Memory Via Stimulating Alpha 4 Beta 2 And Alpha 7 Nicotinic Acetylcholine Receptors In The Medial Prefrontal Cortex Of Mice

Nicotine has been know n to enhance recognition memory in various species. However, the brain region where nicotine acts and exerts its effect remains unclear. Since the medial prefrontal cortex (mPFC) is associated with memory, we examined the role of the mPFC in nicotine-induced enhancement of recognition memory using the novel object recognition test in male C57BL/6J mice. Systemic nicotine administration 10min before training session significantly enhanced object recognition memory in test session that was performed 24h after the training. Intra-mPFC infusion of mecamylamine, a non-selective nicotinic acetylcholine receptor (nAChR) antagonist, 5min before nicotine administration blocked the effect of nicotine. Additionally, intra-mPFC infusion of dihydro-beta-erythroidine, a selective alpha 4/beta 2 nAChR antagonist, or methyllycaconitine, a selective alpha 7 nAChR antagonist, significantly suppressed the nicotine-induced object recognition memory enhancement. Finally, intra-mPFC infusion of nicotine 1 min before the training session augmented object recognition memory in a dose-dependent manner. These findings suggest that mPFC alpha 4/beta 2 and alpha 7 nAChRs mediate the nicotine-induced object recognition memory enhancement.