Effects of environmental enrichment on behavioral deficits and alterations in hippocampal BDNF induced by prenatal exposure to morphine in juvenile rats.
Prenatal morphine exposure throughout pregnancy can induce a series of neurobehavioral and neurochemical disturbances by affecting central nervous system development. This study was designed to investigate the effects of an enriched environment on behavioral deficits and changes in hippocampal brain-derived neurotrophic factor (BDNF) levels induced by prenatal morphine in rats. On pregnancy days 11-18, female Wistar rats were randomly injected twice daily with saline or morphine. Offspring were weaned on postnatal day (PND) 21. They were subjected to a standard rearing environment or an enriched environment on PNDs 22-50. On PNDs 51-57, the behavioral responses including anxiety and depression-like behaviors, and passive avoidance memory as well as hippocampal BDNF levels were investigated. The light/dark (L/D) box and elevated plus maze (EPM) were used for the study of anxiety, forced swimming test (FST) was used to assess depression-like behavior and passive avoidance task was used to evaluate learning and memory. Prenatal morphine exposure caused a reduction in time spent in the EPM open arms and a reduction in time spent in the lit side of the L/D box. It also decreased step-through latency and increased time spent in the dark side of passive avoidance task. Prenatal morphine exposure also reduced immobility time and increased swimming time in FST. Postnatal rearing in an enriched environment counteracted with behavioral deficits in the EPM and passive avoidance task, but not in the L/D box. This suggests that exposure to an enriched environment during adolescence period alters anxiety profile in a task-specific manner. Prenatal morphine exposure reduced hippocampal BDNF levels, but enriched environment significantly increased BDNF levels in both saline- and morphine-exposed groups. Our results demonstrate that exposure to an enriched environment alleviates behavioral deficits induced by prenatal morphine exposure and up-regulates the decreased levels of BDNF. BDNF may contribute to the beneficial effects of an enriched environment on prenatal morphine-exposed to rats.
Laboratory of Learning and Memory, Research Center and Department of Physiology, School of Medicine, Semnan University of Medical Sciences, 15131-38111 Semnan, Iran; Student's Research Committee, Semnan University of Medical Sciences, Semnan, Iran.
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Ahmadalipour
Laboratory of Learning and Memory, Research Center and Department of Physiology, School of Medicine, Semnan University of Medical Sciences, 15131-38111 Semnan, Iran; Student's Research Committee, Semnan University of Medical Sciences, Semnan, Iran.
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Sadeghzadeh
Laboratory of Learning and Memory, Research Center and Department of Physiology, School of Medicine, Semnan University of Medical Sciences, 15131-38111 Semnan, Iran.
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Vafaei
Laboratory of Endocrine Research, Research Center of Physiology and Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran.
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Bandegi
Laboratory of Learning and Memory, Research Center and Department of Physiology, School of Medicine, Semnan University of Medical Sciences, 15131-38111 Semnan, Iran.
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Mohammadkhani
Laboratory of Learning and Memory, Research Center and Department of Physiology, School of Medicine, Semnan University of Medical Sciences, 15131-38111 Semnan, Iran. Electronic address: Rashidy-Pour@semums.ac.ir.
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Rashidy-Pour
D000367:Age Factors; D000701:Analgesics, Opioid / Q000633:toxicity*; D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D004777:Environment; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D018782:Maze Learning; D001523:Mental Disorders / Q000378:metabolism / Q000451:nursing / Q000473:pathology; D009020:Morphine / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D013550:Swimming / Q000523:psychology; D013997:Time Factors
D000701:Analgesics, Opioid; D019208:Brain-Derived Neurotrophic Factor; D009020:Morphine
BDNF; anxiety; enriched environment; memory; prenatal morphine