Differential response of pineal melatonin levels to light at night in laboratory-raised and wild-captured 13-lined ground squirrels (Spermophilus Tridecemlineatus)

Russel J. Reiter, Stephan Steinlechner, Bruce A. Richardson, Thomas S. King

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Pineal melatonin levels were compared in laboratory-raised or wild-captured 13-lined ground squirrels (Spermophilus tridecemlineatus) that were either exposed to 10 h of darkness at night or to light which had an irradiance of 400 μW/cm2. In laboratory-born squirrels the period of darkness was associated with a gradual rise in pineal melatonin levels with peak values being reached at 0200 h, 6 h after darkness onset. Thereafter, melatonin levels decreased and were back to low daytime levels by 0800 h, 2 h after light onset. The exposure of laboratory-raised animals to an irradiance of 400 μW/cm2 during the night totally prevented the nocturnal rise in pineal melatonin levels in these animals. In wild-captured ground squirrels the period of darkness at night was associated with a rapid rise in pineal melatonin such that by 2200 h, 2 h after lights out, peak melatonin values were already attained; additionally, melatonin levels remained high throughout the period of darkness but returned to daytime values by 0800 h. Exposure of wild-captured squirrels to a light irradiance of 400 μW/cm2 during the normal dark period was completely incapable of suppressing pineal melatonin levels. The difference in the sensitivity of the pineal gland of laboratory-raised and wild-captured ground squirrels may relate to their previous lighting history.

Original languageEnglish (US)
Pages (from-to)2625-2629
Number of pages5
JournalLife Sciences
Volume32
Issue number23
DOIs
StatePublished - Jun 6 1983

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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