Thursday, May 20, 2010

Study Suggests Source of Post-Menopausal Hot Flashes

Overview of biological circadian clock in huma...Image via Wikipedia

Beauty may be only skin deep, but hot goes to the bone.

Proteins involved in breaking down bones are also part of the body’s thermostat, a new study shows. The proteins — a receptor called RANK and the protein that binds to it, called RANKL — turn up the heat to cause fever during infections and also help regulate daily temperature rhythms in female rodents, a study published in the Nov. 26 Nature shows.

And the proteins, which are involved in osteoporosis, may also be a source of the hot flashes that post-menopausal women experience.

These proteins also participate in the daily rise and fall of body temperature dictated by circadian rhythms — at least in female mice. The female mice genetically engineered to lack RANK in their brains had increased body temperatures during the animals’ normal daytime sleeping period, a time when their body temperatures usually dip. For humans, a similar dip in body temperature happens at night. Researchers couldn’t find any differences in daily body temperature fluctuations between normal male mice and male mice lacking RANK in their brains.

Body temperature regulation by RANK and RANKL depends on female sex hormones made by the ovaries, the study found. The researchers speculate that in humans, rapid changes in the two proteins’ activity might lead to hot flashes in post-menopausal women who have lost the steadying influence of estrogen.

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