Photoperiodic and light spectral conditions which inhibit circulating concentrations of thyroxine in the male hamster

M. K. Vaughan, G. C. Brainard, R. J. Reiter

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5 Scopus citations


Adult male Syrian hamsters were exposed daily for 12 weeks to 11 h/day of cool white fluorescent light (350 ± 50 μW/cm2) followed by an additional 3 h of near ultraviolet (339-317 nm), blue (435-500 nm), green (515-550 nm), yellow (558-636 nm) or red (653-668 nm) light at an irradiance of 0.2 μW/cm2 or to total darkness. Animals exposed to the wavelengths between 558-668 nm (yellow or red half peak bandwidths) or those receiving a total of 13 h of darkness/day had suppressed circulating levels of thyroxine (T4), a depressed free T4 index (FT4I) and a higher T3/T4 ratio compared to animals receiving a total of 14 h of white light (350 ± 50 μW/cm2). These results suggest that specific wavelengths of light can affect the neuroendocrine-thyroid axis.

Original languageEnglish (US)
Pages (from-to)2183-2188
Number of pages6
JournalLife Sciences
Issue number23
Publication statusPublished - Jun 10 1985


ASJC Scopus subject areas

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

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