Low temperature stimulates pineal activity in Syrian hamsters

Karl‐Ame ‐A Stokkan, Keico O. Nonaka, Alexander Lerchl, Mary K. Vaughan, Russel J. Reiter

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Stokkan K‐A, Nonaka KO, Lerchl A, Vaughan MK, Reiter RJ. Low temperature stimulates pineal activity in Syrian hamsters. J Pineal Res 1991 : 10:4348. The effect of 24‐hr exposure to cold (5°C) was studied in male Syrian hamsters adapted to short days (LD 8:16). Both pineal N‐acetyltransferase (NAT) activity and pineal and serum concentrations of melatonin showed a clear, diel rhythm with a moderate but significant increase late in the dark period. The nighttime peak levels of NAT activity and pineal and serum melatonin were significantly higher in the animals that had been exposed to cold than in those remaining in warm (22°C) conditions. The activity of type‐II 5'‐deiodinase (5'D) in the brown adipose tissue (BAT) was not different after 24 hr of cold exposure between cold‐ and warm‐exposed hamsters, and the enzyme did not show any diel rhythmicity. It has been speculated that some effects of cold exposure may be simulated by melatonin treatment; the present data further support this notion. The apparent lack of response in BAT 5'D activity remains enigmatic and needs further investigation.

Original languageEnglish (US)
Pages (from-to)43-48
Number of pages6
JournalJournal of pineal research
Issue number1
StatePublished - Jan 1991
Externally publishedYes


  • Key words: N‐acetyltransferase—melatonin—cold—5'‐deiodinase—photoperiod

ASJC Scopus subject areas

  • Endocrinology


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