Chronic effect of aspartame versus stevioside on the cerebellar cortex of the adult albino rat: a histological and immunohistochemical study

Sweeteners have evolved rapidly over the last 20 years and are added to a wide variety of food items, drinks, drugs, and hygiene products. Aspartame is the most frequently used artificial sweetener. In contrast, stevioside is a sweet herb that seemed to be a promising natural candidate to replace artificial sweeteners but was found to have hazardous effects on the male reproductive system. The aim of this work was to compare between the histological changes in the cerebellar cortex of adult rats after administration of aspartame and stevioside for 6 months. The reversibility of these changes was also evaluated. A total of 25 albino rats aged 3 months were used in this study. They were divided into five groups comprising five rats each. The first group was the control group. Rats in the second group were given stevioside at a dose of 8.6 mg/day for 6 months. Rats in the third group were given stevioside for 6 months and were then allowed 1 month for recovery. Rats in the fourth group were given aspartame at a dose of 20 mg/day for 6 months. Rats in the fifth group were given aspartame for 6 months and were then allowed 1 month for recovery. Specimens of the cerebellar cortex were processed for H and E and subjected to immunohistochemical staining for glial fibrillary acidic protein [GFAP] and caspase-3 and electron microscopic study. Morphometric and statistical analyses were performed to count the number of Purkinje cells, the number of granular cells, and the number of GFAP and caspase-3 immunostained cells. The present study showed degenerative changes in the Purkinje and granular cell layers in both the aspartame-treated and stevioside-treated groups. This was confirmed by a significant increase in caspase-positive cells and a significant decrease in cell number. Moreover, there was marked increase in the number of astrocytes in areas of degeneration. This was confirmed by a significant increase in GFAP immunostaining. Recovery from stevioside was better than that from aspartame, as evidenced by the normal histological appearance of Purkinje cells and less vacuolated neuropils. This was supported by a significant increase in the number of neurons, significant decrease in caspase-positive cells, and significant decrease in GFAP immunostaining in the recovery group from stevioside compared with the recovery group from aspartame. Cessation of stevioside gives better results and leads to better improvement of the histological picture of the cerebellar cortex compared with cessation of aspartame