Glucagon
If blood sugar levels fall below the specified value, the pancreas produces more of the hormone glucagon and releases it into the blood. Target cells that detect glucagon via their receptors respond, for example, by “breaking down” glycogen, so that glucose can be released into the blood. Blood sugar levels therefore rise. In addition, glucagon also stimulates the new synthesis of glucose from amino acids. Furthermore, fat breakdown is activated, which leads to an increase in free fatty acids in the blood.
To find out why horses must not be given a radical diet for this reason, see “Reduction diet”.