PLATELET SEROTONIN TRANSPORT IS ALTERED IN STREPTOZOTOCIN-INDUCED DIABETIC RATS

The present work was conducted to examine whether experimental diabete s (streptozotocin-induced) promotes changes in mean platelet volume, a nd platelet serotonin (5HT) uptake and content. These variables were m easured in from four experimental groups: control, diabetic, diabeticinsulin, and non-diabetic+insulin. Animals treated fifteen days before with streptozotocin had platelets with higher 5HT uptake affinity, 5H T content, and volume. The insulin therapy reestablished the control v alues of all of these three variables. Non-diabetic animals treated on e week with insulin did not show any variations. The effects of in vit ro application of insulin, hyperglycaemic incubation medium, and strep tozotocin on platelet amine uptake and release were also examined. Onl y those platelets incubated with streptozotocin showed an altered plat elet 5HT uptake. No changes were observed for spontaneous 5HT release. The results are consistent with: a) an increase of platelet uptake ca pacity, as a consequence of an increase in platelet turnover, for expl aining alterations of intraplatelet 5HT contents in experimental diabe tes; b) a non-direct effect of insulin and glucose levels on platelet 5HT uptake -for explaining its dysfunctions in experimental diabetes-; c) the contribution of alterations in platelet 5HT transport for expl aining the higher incidence of vascular complications in diabetic pati ents; d) the suitability of platelet as a model for investigating neur onal 5HT reuptake.