Document Detail

Removal of the olfactory bulbs delays photic reentrainment of circadian activity rhythms and modifies the reproductive axis in male Octodon degus.
MedLine Citation:
PMID:  9593909     Owner:  NLM     Status:  MEDLINE    
The diurnal rodent, Octodon degus, exhibits robust sex differences in several circadian measures, including circadian period (tau) and reentrainment rates to photic and nonphotic (social) zeitgebers. The neural substrates underlying such physiological differences remain unknown. In female degus, olfactory bulbectomies (BX) inhibit socially-facilitated reentrainment, but do not alter photic reentrainment, entrained measures, or tau in constant darkness (DD). This experiment investigated the effects of BX in male degus on (i) photic reentrainment rates of circadian rhythms following a 6-h phase advance of the light-dark (LD) cycle; (ii) photic entrainment; (iii) tau of free-running activity rhythms in DD; and (iv) body weight, paired testis weight, and the reproductive hormones, testosterone, androstenedione and follicle stimulating hormone (FSH). BX significantly delayed photic reentrainment rates. They did not, however, modify tau, the phase of activity onset or offset, amplitude or duration (alpha) of the activity rhythm, mean daily locomotor activity levels, or body weight. FSH, testosterone and androstenedione were unaffected by BX, whereas paired testis weights were significantly greater in BX degus compared with shams. Thus, the olfactory bulbs influence photic reentrainment of circadian rhythms and modestly affect the reproductive axis in male degus. Our results suggest that the olfactory bulbs may be a neural source of observed sex differences in photic reentrainment in degus, and highlight interspecies variation in the olfactory bulbs' effects on entrained and free-running circadian rhythms and on reproduction.
N Goel; T M Lee; D R Pieper
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Brain research     Volume:  792     ISSN:  0006-8993     ISO Abbreviation:  Brain Res.     Publication Date:  1998 May 
Date Detail:
Created Date:  1998-07-20     Completed Date:  1998-07-20     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0045503     Medline TA:  Brain Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  229-36     Citation Subset:  IM    
Copyright Information:
Copyright 1998 Elsevier Science B.V.
Department of Psychology, 525 East University, University of Michigan, Ann Arbor, MI 48109, USA.
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MeSH Terms
Circadian Rhythm / physiology*
Follicle Stimulating Hormone / blood
Olfactory Bulb / physiology*,  surgery
Organ Size
Photic Stimulation
Reproduction / physiology*
Sex Factors
Testis / physiology
Testosterone / blood
Grant Support
Reg. No./Substance:
58-22-0/Testosterone; 9002-68-0/Follicle Stimulating Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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