Endogenous epinephrine protects against obesity induced insulin resistance

Epinephrine (E) is a hormone released from the adrenal medulla in response to low blood sugar and other stresses. E and related beta 2-adrenergic agonists are used to treat asthma, but a side effect is high blood sugar. C57BL/6 mice prone to overfeeding induced type II diabetes had the PNMT gene knocked out to prevent E synthesis. These E deficient mice were very similar to control animals on a 14% fat diet. On a 40.6% fat diet they gained 20 to 33% more weight than control animals and increased their blood glucose response to a glucose tolerance test because they became resistant to insulin. Although the short term effect of beta 2-agonists such as E is to raise blood glucose, some long acting beta 2-agonists improve muscle glucose uptake. Endogenous E protects against overfeeding induced diabetes. Since adrenal E release can be impaired with aging and diabetes, endogenous E may help prevent adult onset diabetes. (C) 2011 Elsevier B.V. All rights reserved.