Luminance-dependent decrease in vasoactive intestinal polypeptide in the rat suprachiasmatic nucleus

Neurosci Lett. 1998 Jul 17;251(1):21-4. doi: 10.1016/s0304-3940(98)00491-1.


Light responsiveness of the vasoactive intestinal polypeptide (VIP) content in the suprachiasmatic nucleus (SCN) of the rat with pupils dilated by atropine was examined by enzyme immunoassay. After exposure to 6 h light at 3-1000 lux VIP levels in the SCN decreased as a monotonic function with a working range from 3 to 300 lux. At 12 h, 30 lux light decreased the VIP content to the minimum level that was attained by 300 lux light exposure in 6 h, suggesting that brighter illumination decreases VIP levels more rapidly, but light at a luminance of 0.05 lux for 3 days did not suppress VIP levels. These results suggest that VIP in the SCN codes visual information on luminance with a small working range and a relative high threshold.

MeSH terms

  • Animals
  • Atropine
  • Dose-Response Relationship, Radiation
  • Light*
  • Lighting
  • Male
  • Pupil
  • Rats
  • Rats, Wistar
  • Suprachiasmatic Nucleus / metabolism
  • Suprachiasmatic Nucleus / radiation effects*
  • Time Factors
  • Vasoactive Intestinal Peptide / metabolism*


  • Vasoactive Intestinal Peptide
  • Atropine