185 JKMU Journal of Kerman University of Medical Sciences, 2019; 26 (3): 185-191 The Effect of Intrahippocampal Injection of Insulin-like Growth Factor-1 on Morphine-Induced Amnesia in Wistar Rats Parvin Babaei, Ph.D. 1 , Kurosh Mojtabavi, M.D. 2 , Somayeh Kouhestani, M.Sc. 3 1. Professor, Cellular and Molecular Research Center & Department of Physiology , School of Medicine, Guilan University of Medical Sciences ; Neuroscience Research Center, Guilan University of Medical Sciences, Rasht, Iran 2. M.D., Cellular and Molecular Research Center & Department of Physiology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran 3. M.Sc., Cellular and Molecular Research Center & Department of Physiology, School of Medicine, Guilan University of Medical Sciences Rasht, Iran (Corresponding author; E-mail: Kouhestani.somaye@gmail.com) Received: 6 April, 2019 Accepted: 8 May, 2019 ARTICLE INFO Article type: Original Article Keywords: Morphine Hippocampus Amnesia IGF-1 Memory Abstract Background: Morphine is wildly used as a painkiller in clinics, but causes several side effects such as hyperalgesia, depression and more notably amnesia. Here, we assumed that insulin- like Growth Factor-1 (IGF-1) as a peptide with widespread distribution of receptors in brain regions, especially hippocampus, might be capable to alleviate morphine-induced amnesia. Methods: Thirty one male Wistar rats were divided into four groups including: morphine+saline, saline+saline, Morphine+IGF-1 and Saline+IGF-1 groups. The animals were cannulated in hippocampus using stereotaxic apparatus. IGF- 1 (5 μg/ 1μL /rat) was intrahippocampally injected 30 minutes prior to morphine (10 mg/kg/i.p) injection, and then rats were trained in step-through passive avoidance task. First Latency time (FLT) to enter and total time spent (TTS) in dark were measured 1.5 and 24 hours later. Control group received the same volume of saline. Results: The results showed that injection of 10 mg/kg morphine, compared with saline, significantly decreased FLT ( p=0.001), but increased TTS (p=0.001) 24 hours after the training. Whereas, administration of IGF-1 compared with morphine, significantly increased FLT ( p=0.001), but decreased TTS ( p=0.001) assessed 24 hours after the training, Conclusions: These findings indicate that administration of morphine disturbs passive avoidance learning and memory and injection of IGF-1, 30 minutes before morphine injection, prevents amnesia. Copyright: 2019 The Author(s); Published by Kerman University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Citation: Babaei P, Mojtabavi K, Kouhestani S. The Effect of Intrahippocampal Injection of Insulin-like Growth Factor-1 on Morphine-Induced Amnesia in Wistar Rats. Journal of Kerman University of Medical Sciences , 2019; 26 (3): 185-191. Introduction Morphine is an important opioid ligand used as a pain reliever because of its ability to activate opioid receptor in the central nervous system (1). However, it causes various side effects such as hyperalgesia, nausea, constipation, physical dependence, depression and amnesia (2). It has been well recognized that the opioid system is involved in learning and memory functions (3). Both pre- and post-training administrations of morphine in hippocampus cause retention memory impairment in passive avoidance task (4, 5), in a dose- and time-dependent manner (6, 7). Convergent findings from humans and animals studies have shown that