Neuroprotective effects of basil extract (Ocimum gratissimum) on hippocampal neuronal loss and spatial memory in a streptozotocininduced experimental Alzheimer’s disease model in rats using the Eight-arm Radial Maze Test

Objective: Alzheimer’s disease is the most common cause of age-related dementia. This disease is a progressive, degenerative centralnervous system disease. Neuron loss is more pronounced in hippocampal pyramidal cells. Although various agents are known for itstreatment, a stronger or definitive treatment has not yet been found. Alzheimer’s disease is seen in more than half of diabetes mellituspatients. The main similarities between these two diseases are insulin resistance and inflammatory pathways. Therefore, Alzheimer’sdisease is also called type 3 diabetes. The antidiabetic effect of Ocimum gratissimum (O. gratissimum) extract, commonly known asbasil extract are well documented worldwide. However, its behavioral and neuroprotective effects in Alzheimer’s disease have not beensufficiently studied yet. Our aim is to demonstrate the anti-apoptotic effect of O. gratissimum on hippocampal pyramidal cells in anexperimental rat model of Alzheimer’s disease induced by streptozotocin (STZ) and in paralel, to test learning-related behaviors in rats.Materials and Methods: Thirty-three 4-month-old male Wistar rats were used and randomly divided into five groups: control, sham,STZ, O. gratissimum, and O. gratissimum+STZ. The eight-arm radial maze test was taught to all animals that were kept under suitableconditions. Finally, STZ and O. Gratissimum extract were given to rats together intraperitoneally. Blood glucose and the weight of allrats were measured regularly. After the eight-arm radial maze test was performed on the rats in all groups, the rats were decapitated,their brains were sectioned by histological methods, and all apoptotic cells in the hippocampus were counted with TUNEL method.All groups were compared by statistical analysis (ANOVA).Results: In rats whose learning was impaired with STZ, learning behavior improved in a statistically significant way with O. gratissimumextract (p