en Learning and Memory Neurophysiology/Pharmacology Experimental research article Experimental research article <div style="text-align: justify;">Introduction: Cholinergic neuronal deficiency is one of the main causes of Alzheimer&#39;s pathology, which leads to learning and memory impairment. Scopolamine is a muscarinic cholinergic antagonist commonly used to induce Alzheimer&#39;s disease (AD). Insulin also regulates learning and memory function. Thus, the aim of this study was to determine the effect of central administration of insulin on passive avoidance learning. Methods: In this experiment, fifty-nine rats were divided into 6 groups: (1) intact, (2) sham, (3) scopolamine-saline, (4) scopolamine-insulin4, (5) scopolamine-insulin8 and (6) scopolamine-insulin16. In addition, scopolamine (70nmol/2&mu;l) was injected into the right lateral ventricle, before the retrieval test of the inhibitory avoidance task. Then the effects of three doses of insulin (4, 8 or 16 mU/2&mu;l) were investigated on the passive avoidance learning in an amnestic model induced by scopolamine. Results: Our results indicate that the retrieval of passive avoidance memory was significantly improved by intracerebroventricular administration of insulin in 4 and 8 mU/2&mu;l doses but not in 16 mU/2&mu;l. Conclusion: These results confirmed that insulin could improve the retrieval phase of passive avoidance memory that was impaired by scopolamine.</div> Insulin, Scopolamine, Learning, Memory, Passive avoidance learning 240 246 http://ppj.phypha.ir/browse.php?a_code=A-10-1140-1&slc_lang=en&sid=1 Simin Ehsani sehsani@mazums.ac.ir 3200319475328460020585 3200319475328460020585 No Department of Physiology and Pharmacology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Esmaeil Akbari akbari_esmaeil@mazums.ac.ir 3200319475328460020586 3200319475328460020586 No Department of Physiology and Pharmacology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Motahareh Rouhi Ardeshiri s.rouhi89@sbmu.ac.ir 3200319475328460020587 3200319475328460020587 Yes Department of Physiology and Pharmacology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran