Canadian scientists have reported that a hormone found in the gut has the power to lower glucose production by signaling the brain and liver to do so. When the researchers activated its receptors in lab rats, they found that the hormone, called cholecystokinin (CCK) peptide, rapidly lowered the animals’ blood glucose levels.
However, they also found a drawback: CCK’s power is blunted when there are high levels of fat in the bloodstream. In rodents that were fed a high-fat diet for three days, the hormone failed to have any effect on glucose levels.
CCK lowers glucose production by binding the receptors of nerves in the small intestine and making them send a signal to the brain to stop production. The brain, in turn, sends the command to the liver.
The scientists found that CCK and its variants work independently of the levels of insulin in the bloodstream. But the fly in the ointment is the introduction of fat into the diet. Only a few days of high fat intake create a resistance to CCK that is similar to insulin resistance.
If the researchers can duplicate CCK’s effects in humans, the next goal will be to find a way to get the hormone to work despite high bloodstream fat levels. If so, it could become the basis of a more benign therapy that works by lowering glucose production, but not by addressing the liver directly.
The Canadians published their findings in the August 2009 issue of Cell Metabolism in an article called, “Intestinal Cholecystokinin Controls Glucose Production Through a Neuronal Network.”