Dementia is one of the most important problems nowadays. Aging is associated with learning and memory impairments. Diet rich in cholesterol has been shown to be detrimental to cognitive performance. This work was carried out to compare the effect of high cholesterol diet on the hippocampus of adult and aged male albino rats. Twenty adult and twenty aged male rats were used in this study. According to age, the rats were randomly subdivided into balanced and high cholesterol diet fed groups. The diet was 15 g/rat/day for adult rats and 20 g/rat/day for aged rats for eight weeks. Serial coronal sections of hippocampus and blood samples were taken from each rat. For diet effect evaluation, Clinical, biochemical, histological, immunohistochemical, and morphometric assessments were done. In compare to a balanced diet fed rat, examination of Cornu Ammonis 1 (CA 1) area in the hippocampus of the high cholesterol diet adult rats showed degeneration, a significant decrease of the pyramidal cells, attenuation and/or thickening of small blood vessels, apparent increase of astrocytes and apparent decrease of Nissl's granules content. Moreover, the high cholesterol diet aged rats showed aggravation of senility changes of the hippocampus together with Alzheimer like pathological changes. In conclusion, the high cholesterol diet has a significant detrimental effect on the hippocampus and aging might pronounce this effect. So, we should direct our attention to limit cholesterol intake in our food to maintain a healthy life style for a successful aging.

Objectives: Fluoride is a toxic and reactive element. Human beings are exposed to fluoride from various sources such as toothpastes, mouth rinses, dietary supplements and ordinary drinking water. This work investigated the effect of sodium fluoride (NaF), alone or with green tea, on the grey matter of spinal cord of adult male albino rats. Methods:Spinal cord sections were examined using light and electron microscopy. Immunohistochemical assessments for the expression of caspase-3 and glial fibrillary acidic protein were performed. Agarose gel electrophoresis was used for DNA fragmentation. Results:Our results showed that NaF produced neurodegeneration, vacuolation and haemorrhage with some abnormal blood vessels and a significant increase in the number and size of astrocytes. In addition, the neurons showed a significant decrease of their Nissl's granules content and significant increased expression of caspase-3. Conclusion:Green tea exerted a protective effect against NaF-induced neurotoxicity. The results of this work add to the known toxic effects of NaF and provide a new insight into the possible use of green tea to ameliorate these effects.