In intact animals, time of drug administration may be an important factor influencing drug response. Our general goal seeks to incorporate circadian time into the study of corticosteroid regulated gene expression. Since levels of endogenous steroid exhibit circadian fluctuations, it is our hypothesis that the expression of genes controlled by corticosteroids either directly or indirectly, will also exhibit a circadian pattern in normal animals. Keywords: time series design
Overall design
This study is designed to examine fluctuations in gene expression in liver within the 24 hour circadian cycle in normal animals. Fifty-four male normal Wistar rats (250-350 g body weight) were housed in a strictly controlled stress free environment with light:dark cycles of 12 hr:12hr. Three animals were sacrificed at each of 18 selected time points within the 24 hour cycle. RNA was prepared from livers for gene arrays. Time point designations reflect time after lights on in hours.
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