The aim of the present doctoral thesis has to study the differential effects of control liquid diets containing either monounsaturated fatty acids (olive oil) or polyunsaturated fatty acids (corn oil) on the oxidative metabolism of rats. The double bonds of fatty-acid molecules represent vulnerable points for oxidation reactions which can cause lipid peroxidation. These peroxidation products are potentially toxic and can produce serious cell injury (e.g. alterations in cell permeability and production of prostaglandins). To prevent cellular damage induced by oxidative stress, aerobic organisms utilize intracellular defense mechanisms, antioxidant systems that may be classified as enzymatic and nonenzymatic. Vitamin E???????tocopherol), a potent lipophilic antioxidant, belongs to the second group and acts as scavenger of free radicals. 

	Indeed, a possible interaction of lipid peroxidation products with DNA has been suggested in liver rat cells. The induction of 8-oxo-2’-deoxiguanosine (8-oxo-dG), a maker of oxidative DNA damage has been analysed.

In the present study, the status of antioxidant systems was differentially affected by the composition and intake levels of dietary lipids. Rats receiving olive oil with its high content of monounsaturated fatty acids were significantly more resistant to oxidative modifications than the group maintained on corn oil which contains a high proportion of polyunsaturated fatty acids. Olive-oil fed rats displayed higher levels of the endogenous antioxidants superoxide dismutase, catalase and glutathione peroxidase in liver and white adipose tissue. However, in brown fat and blood cells, the activity of these antioxidants was slightly decreased. 

Rats which received corn-oil fed controls had lower levels of glutathione (GSH) in liver and blood as compared to olive-oil fed controls, thereby confirming that polyunsaturated fatty acids clearly induce lipid oxidation products. However, increased levels of GSH were observed in hepatocytes