Serotonin is a vasoactive amine which has been suggested to be a mediator in a wide number of vascular pathologies. Alterations in peripheral serotonin have been related to a major risk in suffering vascular diseases in the diabetic population. Intraperitoneal administration of streptozotocin (STZ) to rats lead to a symptomatology similar to the diabetic syndrome type I in humans, making this model suitable for studying changes in peripheral 5-HT in diabetes mellitus type I. Changes in the levels and metabolism of serotonin in several peripheral tissues, gastrointestinal tract, liver, lung, kidney, plasma and platelets, is discussed in STZ-diabetic rats. An emphasis is made on serotonin transport mechanism in platelets. As a whole, in the diabetes mellitus type I, the data point to an alteration in the uptake/release of 5-HT in platelets as well as to changes in 5-HT release from intestine, while no major changes are apparent in hepatic, renal and lung metabolism.
