Circadian rhythms of self-selected lighting in golden hamsters: relation to gonadal condition
Warden, A.W.
Chronobiologia 5(1): 28-38
1978
ISSN/ISBN: 0390-0037 PMID: 688847 Document Number: 134144
Golden hamsters (20 males, 8 females) were maintained in isolation boxes for 47 wk. The animals had access to running wheels and selected their own lighting by pressing 1 bar to turn the light-on and another bar to turn the light-off. All hamsters maintained circadian rhythms of wheel-running activity. Seventeen of 28 hamsters selected lighting with a circadian periodicity. For 9 hamsters, there was a significant positive correlation between wheel-running activity and self-selected darkness, while this correlation was significantly negative for 10 hamsters. Four hamsters had regressed testes at the end of the experiment. These 4 had significant positive correlations between activity and self-selected darkness, while none of the hamsters with significant negative correlations between activity and self-selected darkness had regressed testes. Light in phase with activity seems to be more important to the prevention of testicular regression than is the total daily amount of light.