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Exercise increases insulin signaling in the hippocampus: Physiological effects and pharmacological impact of intracerebroventricular insulin administration in mice.
MedLine Citation:
PMID:  20824731     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Increasing evidence indicates that physical exercise induces adaptations at the cellular, molecular, and systemic levels that positively affect the brain. Insulin plays important functional roles within the brain that are mediated by insulin-receptor (IR) signaling. In the hippocampus, insulin improves synaptic plasticity, memory formation, and learning via direct modulation of GABAergic and glutamatergic receptors. Separately, physical exercise and central insulin administration exert relevant roles in cognitive function. We here use CF1 mice to investigate (i) the effects of voluntary exercise on hippocampal insulin signaling and memory performance and (ii) whether central insulin administration alters the effects of exercise on hippocampal insulin signaling and memory performance. Adult mice performed 30 days of voluntary exercise on running wheel and afterward both, sedentary and exercised groups, received intracerebroventricular (icv) injection of saline or insulin (0.5-5 mU). Memory performance was assessed using the inhibitory avoidance and water maze tasks. Hippocampal tissue was measured for [U-(14) C] glucose oxidation and the immunocontent of insulin receptor/signaling (IR, pTyr, pAktser473). Additionally, the phosphorylation of the glutamate NMDA receptor NR2B subunit and the capacity of glutamate uptake were measured, and immunohistochemistry was used to determine glial reactivity. Exercise significantly increased insulin peripheral sensitivity, spatial learning, and hippocampal IR/pTyrIR/pAktser473 immunocontent. Glucose oxidation, glutamate uptake, and astrocyte number also increased relative to the sedentary group. In both memory tasks, 5 mU icv insulin produced amnesia but only in exercised animals. This amnesia was associated a rapid (15 min) and persistent (24 h) increase in hippocampal pNR2B immunocontent that paralleled the increase in glial reactivity. In conclusion, physical exercise thus increased hippocampal insulin signaling and improved water maze performance. Overstimulation of insulin signaling in exercised animals, however, via icv administration impaired behavioral performance. This effect was likely the result of aberrant phosphorylation of the NR2B subunit. © 2010 Wiley-Liss, Inc.
Authors:
Alexandre P Muller; Jussânia Gnoatto; Julia D Moreira; Eduardo R Zimmer; Clarissa B Haas; Francisco Lulhier; Marcos L S Perry; Diogo O Souza; Ignácio Torres-Aleman; Luis V Portela
Publication Detail:
Type:  Journal Article     Date:  2010-09-07
Journal Detail:
Title:  Hippocampus     Volume:  21     ISSN:  1098-1063     ISO Abbreviation:  Hippocampus     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-09-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9108167     Medline TA:  Hippocampus     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1082-92     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Wiley-Liss, Inc.
Affiliation:
Departamento de Bioquímica, ICBS, UFRGS, Programa de Pós Graduação em Ciências Biológicas-Bioquímica, Rua Ramiro Barcelos, 2600 anexo, CEP 90035-003, Porto Alegre, RS, Brazil.
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