Significance of serotonin in the pathogenesis of diabetic retinopathy and central chorioretinal dystrophy

A total of 147 patients with preproliferative and proliferative diabetic retinopathy (DR), with the exudative hemorrhagic and nonexudative stages (93 females and 54 males), were consulted at Helmholtz Institute of Ophthalmic Diseases in 1997-2001. Control group consisted of 39 healthy subjects aged 25-76 years. The group of patients with preproliferative DR consisted of 27 patients with compensated diabetes mellitus. The course of diabetes in 39 patients with proliferative DR was evaluated as medium severe during the subcompensation stage. The clinical picture of the fundus oculi was characterized by pronounced hemorrhagic activity. Slight retinal hemorrhages were seen in the patients with preproliferative DR. Nodules, defects of pigmented epithelium, atrophic foci were seen in the central zone of the fundus oculi in patients with nonexudative stage of central chorioretinal dystrophy; edema in the central zone, polymorphic hemorrhages, solid exudate were observed in the patients with the exudative hemorrhagic stage; subretinal neovascular membrane was detected in some patients. Erythrocyte deformability coefficient, platelet aggregation coefficient to ADP, and platelet factor were evaluated by common methods. Serotonin was measured by the fluorometric method (B. M. Kogan's method) at clinical biochemical laboratory of urgent methods of examination of N. V. Sklifosovsky Institute of Emergency. The erythrocyte deformability coefficient was notably increased in the patients with proliferative DR and central chorioretinal dystrophy in comparison with the normal value. Plasma serotonin concentration was increased significantly only in the patients with proliferative DR, while in the rest groups this concentration was notably decreased. Study of platelet aggregation gave contradictory results. The values of platelet factor 4 differed from the control negligibly. Serotonin insufficiency in patients with proliferative DR was paralleled by increased plasma serotonin concentration and thrombocytopathy. In patients with preproliferative DR and central chorioretinal dystrophy serotonin insufficiency was associated with decreased concentration of serotonin and thrombocytopathy. Erythrocyte rigidity was similarly increased in patients with proliferative DR and central chorioretinal dystrophy.