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This Article Accepted manuscript (PDF) All Versions of this Article: JOE-08-0437v1 201/2/275    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lemos, D. Articles by Urbanski, H. Search for Related Content PubMed PubMed Citation Articles by Lemos, D. Articles by Urbanski, H.

D Lemos, Beaverton, United States
J Downs, Beaverton, United States
M Raitiere, Portland, United States
H Urbanski, Neuroscience (ONPRC), Oregon Health and Science University, Beaverton, United States

Correspondence: Henryk Urbanski, Email: urbanski{at}ohsu.edu

Abstract

In Temperate zones day length changes markedly across the year, and in many mammals these photoperiodic variations are associated with physiological adaptations. However, the influence of this environmental variable on human behavior and physiology is less clear, and the potential underlying mechanisms are unknown. To address this issue we examined the effect of changing photoperiods on adrenal gland function in ovariectomized female rhesus macaques (<i>Macaca mulatta</i>), both in terms of steroid hormone output and in terms of gene expression. The animals were sequentially exposed to the following lighting regimens, which were designed to simulate photoperiods associated with winter, spring/autumn and summer, respectively: 8L:16D (short days), 12L:12D and 16L:8D (long days). Remote 24-hour serial blood sampling failed to disclose any effect of photoperiod on mean or peak plasma levels of cortisol or dehydroepiandrosterone sulfate (DHEAS). However, there was a marked phase-advancement of both hormonal rhythms in short days, which was reflected as a similar phase-advancement of the daily motor activity rhythm. Gene microarray analysis of the adrenal gland transcriptome revealed photoperiod-induced differences in the expression of genes associated with homeostatic functions, including: development, lipid synthesis and metabolism, and immune function. Taken together the results indicate that in primates, both circadian adrenal physiology and circadian gene expression are influenced by seasonal changes in day length, which may have implications for adrenal-regulated physiology and behavior.