Effect of diabetes mellitus and chemical sympathectomy on tissue monoamine oxidase activity and norepinephrine concentration in the golden hamster

Abstract

The pancreatic islets of the golden hamster have an extremely high monoamine oxidase (MAO) activity and norepinephrine (NE) concentration. To determine the cellular component responsible for these high values, we assayed MAO activity and NE concentration in collagenase-isolated islets from normal, streptozotocin-induced diabetic, and 6-hydroxydopamine (6-OHDA) induced sympathectomized golden hamsters. There was a 53% reduction in islet MAO activity in the diabetic hamsters, with no alteration in islet MAO activity in the sympathectomized ones, suggesting that the pancreatic B cells contain a large proportion of the MAO activity. There was a 98% reduction in islet NE concentration in the sympathectomized hamsters, with no alteration in islet NE concentration in the diabetic hamsters, suggesting that the adrenergic nerve endings in the islets contain the majority of the NE. There was no alteration in the MAO activity or NE concentration in the cerebral cortex, pituitary gland, liver, kidney, acinar pancreas, or heart of diabetic hamsters. Although the MAO activity of the hypothalamus was not altered, the diabetic hamsters had a 166% increase in NE and a 199% increase in dopamine in their hypothalamus, with no change in these amines in their cerebral cortex.