Corticosterone synthesis inhibitor metyrapone ameliorates chronic hypobaric hypoxia induced memory impairment in rat. 2012

Iswar Baitharu, and Satya Narayan Deep, and Vishal Jain, and Kalpana Barhwal, and Anand Swaroop Malhotra, and Sunil Kumar Hota, and Dipti Prasad, and Govindasamy Ilavazhagan
Defence Institute of Physiology and Allied Sciences, Defence Research Development Organisation, Lucknow Road, Delhi-54, India.

Chronic exposure to hypobaric hypoxia causes oxidative stress and neurodegeneration leading to memory impairment. The present study aimed at investigating the role of corticosterone in hypoxia induced neurodegeneration and effect of metyrapone, a corticosterone synthesis inhibitor that reduces the stress induced elevation of corticosterone without affecting the basal level, in ameliorating chronic hypobaric hypoxia induced cognitive decline. Rats were exposed to simulated altitude of 25,000 ft for 0, 3, 7, 14 and 21 days to determine the temporal alterations in corticosterone and its receptors following exposure to hypobaric hypoxia. Our results showed an elevation of corticosterone in plasma and hippocampal tissue following 7 days of exposure, which declined on prolonged hypoxic exposure for 21 days. A concomitant increase in ROS and lipid peroxidation was observed along with depletion of intracellular antioxidants. Glucocorticoid and mineralocorticoid receptors were upregulated on 3 and 7 days of hypoxic exposure. Though expression of Glut1 and Glut3 were upregulated on 3 days of hypoxic exposure, sharp decline in Glut1 expression following 7 days of hypoxic exposure leads to reduced neuronal glucose uptake. Administration of metyrapone from 3rd to 7th day of hypoxic exposure to suppress hypoxia induced increase in corticosterone levels resulted in reduced oxidative damage, neurodegeneration and improvement of intracellular energy status. The metyrapone treated hypoxic animals performed better in the Morris Water Maze. Further, administration of exogenous corticosterone along with metyrapone during hypoxic exposure blunted the neuroprotective effect of metyrapone indicating a role for corticosterone in mediating hypobaric hypoxia induced neurodegeneration and memory impairment.

UI MeSH Term Description Entries
D008297 Male Males
D008569 Memory Disorders Disturbances in registering an impression, in the retention of an acquired impression, or in the recall of an impression. Memory impairments are associated with DEMENTIA; CRANIOCEREBRAL TRAUMA; ENCEPHALITIS; ALCOHOLISM (see also ALCOHOL AMNESTIC DISORDER); SCHIZOPHRENIA; and other conditions. Memory Loss,Age-Related Memory Disorders,Memory Deficits,Memory Disorder, Semantic,Memory Disorder, Spatial,Memory Disorders, Age-Related,Retention Disorders, Cognitive,Semantic Memory Disorder,Spatial Memory Disorder,Age Related Memory Disorders,Age-Related Memory Disorder,Cognitive Retention Disorder,Cognitive Retention Disorders,Deficit, Memory,Deficits, Memory,Memory Deficit,Memory Disorder,Memory Disorder, Age-Related,Memory Disorders, Age Related,Memory Disorders, Semantic,Memory Disorders, Spatial,Memory Losses,Retention Disorder, Cognitive,Semantic Memory Disorders,Spatial Memory Disorders
D008797 Metyrapone An inhibitor of the enzyme STEROID 11-BETA-MONOOXYGENASE. It is used as a test of the feedback hypothalamic-pituitary mechanism in the diagnosis of CUSHING SYNDROME. Methbipyranone,Methopyrapone,Metopiron,Metopirone,Métopirone,SU 4885
D011965 Receptors, Glucocorticoid Cytoplasmic proteins that specifically bind glucocorticoids and mediate their cellular effects. The glucocorticoid receptor-glucocorticoid complex acts in the nucleus to induce transcription of DNA. Glucocorticoids were named for their actions on blood glucose concentration, but they have equally important effects on protein and fat metabolism. Cortisol is the most important example. Corticoid Type II Receptor,Glucocorticoid Receptors,Glucocorticoids Receptor,Corticoid II Receptor,Corticoid Type II Receptors,Glucocorticoid Receptor,Receptors, Corticoid II,Receptors, Corticoid Type II,Receptors, Glucocorticoids,Corticoid II Receptors,Glucocorticoids Receptors,Receptor, Corticoid II,Receptor, Glucocorticoid,Receptor, Glucocorticoids
D003345 Corticosterone An adrenocortical steroid that has modest but significant activities as a mineralocorticoid and a glucocorticoid. (From Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1437)
D004347 Drug Interactions The action of a drug that may affect the activity, metabolism, or toxicity of another drug. Drug Interaction,Interaction, Drug,Interactions, Drug
D005947 Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Dextrose,Anhydrous Dextrose,D-Glucose,Glucose Monohydrate,Glucose, (DL)-Isomer,Glucose, (alpha-D)-Isomer,Glucose, (beta-D)-Isomer,D Glucose,Dextrose, Anhydrous,Monohydrate, Glucose
D006624 Hippocampus A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation. Ammon Horn,Cornu Ammonis,Hippocampal Formation,Subiculum,Ammon's Horn,Hippocampus Proper,Ammons Horn,Formation, Hippocampal,Formations, Hippocampal,Hippocampal Formations,Hippocampus Propers,Horn, Ammon,Horn, Ammon's,Proper, Hippocampus,Propers, Hippocampus,Subiculums
D000532 Altitude Sickness Multiple symptoms associated with reduced oxygen at high ALTITUDE. Mountain Sickness,Altitude Hypoxia,Altitude Hypoxias,Hypoxia, Altitude,Sickness, Altitude,Sickness, Mountain
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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