Alteration in dendritic morphology of cortical neurons in rats with diabetes mellitus induced by streptozotocin.

The animal model of streptozotocin-induced diabetes mellitus is used to study the changes produced by an increase in glucemia. The morphology of the pyramidal neurons of the prefrontal cortex, occipital cortex, and hippocampus was investigated in rats. The level of glucose in the blood was evaluated at 2 months, and the animals that exhibited more than 200 mg/dL were used. After 2 months of increasing blood-glucose level, the animals were sacrificed by an overdose of sodium pentobarbital and perfused intracardially with a 0.9% saline solution. The brains were removed, processed by the Golgi-Cox stain method, and analyzed by the Sholl method. Clearly, the rats with diabetes mellitus induced by streptozotocin showed a decrease in the dendritic length of pyramidal cells from all the analyzed regions (20% to 45%). Furthermore, the density of dendritic spines was decreased in all the pyramidal cells from the diabetic animals (36% to 58%). However, the pyramidal neurons of the CA1 hippocampus region were the most affected (58%). In addition, the Sholl analyses showed that the diabetic rats exhibited a decrease in the number of Sholl intersections when compared with the control group. The present results suggest that diabetes mellitus may in part affect the dendritic morphology in the limbic structures, such as prefrontal cortex, occipital cortex, and hippocampus, which are implicated in cognitive disorders.