Document Detail

Photoperiodic responses in Djungarian hamsters (Phodopus sungorus): importance of light history for pineal and serum melatonin profiles.
MedLine Citation:
PMID:  7819454     Owner:  NLM     Status:  MEDLINE    
Male Djungarian hamsters with previous light experience of long photoperiods of 16 h of light per day (16L:8D) or short photoperiods (8L:16D) were transferred either to the opposite photoperiods or to intermediate photoperiods (14L:10D). It was demonstrated that the same intermediate photoperiod could exert inhibitory or stimulatory effects on coat color, body weight, and the reproductive system, dependent on the previous light history. The response was graduated in accordance with the degree of change in day length. Despite opposite responses to the same photoperiod, diurnal patterns of melatonin in the pineal glands were identical. However, the circadian melatonin pattern in serum of photoinhibited hamsters had a more pronounced nighttime elevation than that found in the serum of photostimulated animals. In hamsters nonresponsive to short photoperiods, no proper short-day pattern was found. Melatonin production is a highly dynamic process, causing concentration shifts in the pineal gland and changes in the serum amplitude during prolonged exposure to short photoperiods. The different reactions to identical photoperiods are associated with different serum melatonin patterns, as shown here for the first time.
P Niklowitz; A Lerchl; E Nieschlag
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biology of reproduction     Volume:  51     ISSN:  0006-3363     ISO Abbreviation:  Biol. Reprod.     Publication Date:  1994 Oct 
Date Detail:
Created Date:  1995-02-13     Completed Date:  1995-02-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0207224     Medline TA:  Biol Reprod     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  714-24     Citation Subset:  IM    
Institute of Reproductive Medicine of the University, Münster, Germany.
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MeSH Terms
Circadian Rhythm
Hair Color
Melatonin / blood*,  metabolism*
Organ Size
Pineal Gland / metabolism*
Testis / anatomy & histology
Reg. No./Substance:

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