A malfunction in the pancreas’s “circadian clock*,” the built-in timer found in all living things that regulates major biological processes, may be one of the reasons that people develop diabetes.
Scientists at Northwestern University near Chicago have found that the insulin-producing beta cells in the pancreas have their own biological clock that controls the production of insulin over a 24-hour period. If that clock is tampered with, beta cells lose their ability to produce insulin-a lack that is a known precursor to diabetes.
The researchers experimented on mice by inhibiting genes in their pancreases that they had determined control the organs’ circadian clocks. Once they did so, the animals began losing the ability to produce insulin, became glucose-intolerant, and developed full-blown diabetes.
Before blocking the genes, the scientists used bioluminescent imaging to show that the pancreas has an autonomous circadian clock. When the islet cells produced insulin, they stimulated a bioluminescent substance and gave off light. Because insulin production came at regular 24-hour intervals, this was proof of an internal timing mechanism.
While establishing that there is a circadian clock in the pancreas (along with tissue in other parts of the body, such as the liver, lungs, heart, and skeletal muscles), the Northwestern researchers could not say what causes it to fail or malfunction.
One next step may be to seek ways to manipulate the clock, perhaps genetically, to operate normally. That could become the basis for a therapy that attempts to restore beta cell functioning.
*Circadian is based on the Latin words circa-“about” and diem-“day” to denote a 24-hour biological rhythm.
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Circadian clock in pancreas linked to diabetes