Simin Ehsani - Department of Physiology and Pharmacology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
Esmaeil Akbari - Immunogenetics Research Center, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
Motahareh Rouhi Ardeshiri - Immunogenetics Research Center, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran

Cholinergic neuronal cells deficit is known to be one of the main causes of Alzheimer’s pathology, which results in learning and memory impairments. Scopolamine a muscarinic cholinergic antagonist is commonly used to mimic Alzheimer s disease (AD) pathological appearance. Insulin also regulate learning and memory function through an action on particular central sites of the brain. It is considerable that cholinergic activity is associated with the effects of glucose memory enhancement. The objective of this study was to determine the effects of insulin on memory impairment that was induced by scopolamine (a muscarinic cholinergic antagonist). Thus in this study, the rats (n=59) were divided into 6 experimental groups. These six groups were described as: (1) intact, (2) sham, (3) scopolamine-saline, (4) scopolamine- insulin 4, (5) scopolamine- insulin 8 and (6) scopolamine- insulin 16. Then the animals were injected into the right lateral ventricle a muscarinic cholinergic antagonist, scopolamine (70 nmol/2m) 35 min before retrieval test of the inhibitory avoidance task. Then the effects of three doses of insulin (4, 8, or 16 mU/2ml) were investigated on the passive avoidance learning. Our results indicated that retrieval of passive avoidance memory were significantly improved by insulin Intracerebroventricular (icv) administration in 4 and 8 mU/2ml doses but not in 16 mU/2ml. This information confirmed that insulin could improve retrieval phase of avoidance memory that was impaired by scopolamine.

Insulin, Scopolamine, Learning, Memory, Passive avoidance learning