The suppression of pineal melatonin content and N-acetyltransferase activity by different light irradiances in the Syrian hamster: a dose-response relationship

Endocrinology. 1983 Jul;113(1):293-6. doi: 10.1210/endo-113-1-293.


The purpose of this study was to test the influence of various irradiances of cool white fluorescent light on the suppression of pineal N-acetyltransferase activity (NAT) and melatonin content in hamsters. Groups of animals were exposed to light irradiances ranging from 0.00-1.86 microwatts (microW)/cm2 for 20 min during the night. Both pineal NAT and melatonin were similarly depressed by the light irradiances in a dose-related manner. The shape of the resultant dose-response curves and the calculated ED50 for NAT (0.066 microW/cm2) and melatonin (0.058 microW/cm2) were remarkably similar. These findings may be relevant to the physiological control of the pineal by natural illumination.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetyltransferases / metabolism*
  • Animals
  • Cricetinae
  • Dose-Response Relationship, Radiation
  • Male
  • Mathematics
  • Melatonin / analysis*
  • Mesocricetus
  • Photic Stimulation*
  • Pineal Gland / analysis*
  • Pineal Gland / radiation effects


  • Acetyltransferases
  • Melatonin