Table 3.

Serum levels of corticosterone and estradiol in rats exposed to increasing light intensities during darkness

Light intensity (μW/cm2)Nude rat serum corticosterone (ng/mL)Nude rat serum estradiol (pg/mL)Buffalo rat serum corticosterone (ng/mL)
Constant light, 345196.2 ± 53.525.1 ± 11.353.25 ± 23.7
0.08265.0 ± 28.1719.9 ± 10.1120.83 ± 19.6
0.06322.7 ± 43.827.1 ± 16.8105.08 ± 25.8
0.05289.3 ± 41.820.3 ± 10.78155.5 ± 19.1
0.02266.8 ± 34.725.1 ± 5.9138.75 ± 26.8
Dark266.1 ± 34.419.3 ± 10.7111.08 ± 29.5
  • NOTE: See Figs. 3 and 4 legends for further details. Blood samples were taken during the middle of the true dark or subjective dark phase. Mean serum hormone (±SE); n = 6 rats per group. There were no significant differences in hormone levels among any of the groups exposed to different light intensities.