Effect of Aspartame on the Frontal Cortex of Adult Male Albino Rats. A Light and Electron Microscopic Study

Introduction: Aspartame is an artificial sweetener added to 9,000 food drink products. Studies and investigations are thus important to prove or disapprove the existing fears concerning aspartame. Aim of the Work: Was to evaluate, the toxic effects of long term aspartame administration on the frontal cortex. And to investigate whether immunostaining for neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP), could help as valuable markers for evaluating neuronal and glial response to aspartame-induced injury. Materials and Methods: Fifteen adult male albino rats were used; the rats were divided into three equal groups. Group I served as a control group. Group II received aspartame orally in a dose of (250mg kgday) for 8 weeks. Group III received aspartame as in group II, but rats were then left for 4 weeks to recover. Results: Pyramidal cells of animals receiving aspartame showed significant morphological necrotic changes and appeared darkly stained or vacuolated, irregular in shape with pyknotic or faint nuclei. Ultra structurally, the cytoplasm of pyramidal cells showed prominent vacuolization, mitochondria with indistinct cristae. Neurons in aspartame group were statistically significantly less stained by anti-NSE antibody than control group. A significant increase in the number of GFAP immunoreactive astrocytes was also detected. Whereas, sections obtained from rats of group III showed significant improvement of the aspartame produced changes but never returned to control ones. The results of the study demonstrated that the content of NSE of neurons and the number of GFAP (+) astrocytes could serve as molecular markers for neuronal injury, regeneration and astrocytic proliferation, respectively. Conclusion: Chronic aspartame ingestion could result in marked affection of the frontal cortex. Four weeks of cessation was not sufficient to obtain a normal histological appearance.