The role of altered tissue norepinephrine concentration in the hereditary obese-hyperglycemic syndrome of mice.

The purpose of this study was to determine if the elevated concentration of norepinephrine in the hypothalamus of the obese-hyperglycemic mouse plays a role in the development of this syndrome. We treated normal and obese mice with the monoamine oxidase inhibitors pargyline or clorgyline for 25 weeks. This resulted in significant inhibition of monoamine oxidase in their hypothalamus, cerebral cortex, kidney, heart and epididymal fat. There was a significant increase in the norepinephrine concentration of the hypothalamus of the normal mice and the cerebral cortex of the obese mice. The obese mice receiving clorgyline had an increase in plasma glucose (313 +/- 9 mg/dl). However, the increase in tissue norepinephrine concentration did not result in increased weight gain or alterations in organ weights in the mice. Thus, the elevated hypothalamic norepinephrine concentration in obese mice is probably not the cause of their obesity.