Research conducted at Oregon Health & Science University suggests that contrary to popular belief, the body has more than one "body clock."
The previously known master body clock resides in a part of the brain called the suprachiasmatic nucleus (SCN). Researchers at OHSU's Oregon National Primate Research Center (ONPRC) have now revealed the existence of a secondary clock-like mechanism associated with the adrenal gland. The research also suggests a high likelihood that additional clocks exist in the body. The study results are printed in the current edition of the journal Molecular Endocrinology.
"We're all familiar with the idea that the body has a master clock that controls sleep-wake cycles. In fact, most of us have witnessed the impacts of this clock in the form of jet lag where it takes the body a number of days to adjust to a new time schedule following a long flight," explained Henryk Urbanski, Ph.D., senior author of the study and a senior scientist at ONPRC. "Our latest research suggests that a separate but likely related clock resides in the adrenal gland. The adrenal gland is involved in several important body functions, such as body temperature regulation, metabolism, mood, stress response and reproduction. The research also suggests that other peripheral clocks reside throughout the body and that these clocks are perhaps interconnected."
To conduct the research, scientists studied adrenal gland function in rhesus macaque monkeys which is very similar to human adrenal gland function. Specifically, researchers measured gene expression in the adrenal gland of monkeys during a 24-hour period (six times a day, four-hour intervals). In analyzing this information, researchers identified 322 genes in the adrenal gland with functions that varied rhythmically over a 24-hour period, meaning that each gene's function peaked and diminished at the same time each day. Interestingly, the scientists also noted that a subgroup of these 322 genes also exist in the SCN - the home of the body's master body clock. This suggests that the adrenal gland has its own timing mechanism that is related to, but separate from, the SCN body clock.