Document Detail


Sex-dependent effects of long-term oral methylphenidate treatment on spontaneous and learned fear behaviors.
MedLine Citation:
PMID:  21463660     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
In previous studies, chronic low-dose methylphenidate (MPH) administration during early development has been shown to increase emotional responding in adulthood. However, most studies employed male subjects, which generally show enhanced fear relative to females in laboratory tests of anxious behaviors. The present study examined the sex-dependent effects of MPH treatment on innate and learned fear behaviors. Rats were treated for 4 weeks from periadolescence through early adulthood with oral MPH. In open field testing, females showed greater levels of activity than males, and MPH (5mg/kg) decreased locomotion relative to control and 2mg/kg treatment in both sexes. In contextual fear conditioning, females exhibited less freezing than males at all retention intervals. Both sexes treated with 5mg/kg MPH showed increased fear to the shock context, although MPH treatment did not interfere with contextual discrimination in either sex. Upon reexposure to the shock context at 24h, only females treated with 5mg/kg MPH exhibited increases in freezing. MPH treatment did not disrupt extinction of contextual fear (48 hr post-conditioning) in either sex. These findings illustrate subtle sex differences in the effects of prolonged MPH exposure on fear behaviors, and highlight the need to examine further the underlying mechanisms in both sexes.
Authors:
José A Bethancourt; Carol E Vásquez; Gabrielle B Britton
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-4-1
Journal Detail:
Title:  Neuroscience letters     Volume:  -     ISSN:  1872-7972     ISO Abbreviation:  -     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-4-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7600130     Medline TA:  Neurosci Lett     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier Ireland Ltd.
Affiliation:
Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Panamá
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