Effect of excess dietary omega-6 fatty acids on the rat colon mucosa with evaluation of the modulating effect of omega -3 a histological and immunohistochemical study

ABSTRACT

In the last few decades, dietary fat has received considerable attention due to its implication in the etiology of many diseases. Most people substitute polyunsaturated fatty acids [PUFAs] for saturated fatty acids due to their cholesterol lowering action. Recently, high dietary intake of omega-6 fatty acids was accounted for increased risk of,on cancer, whereas omega -3 fatty acids intake was suggested to have a protective effect. The present work aimed to study the effect of long-term high fat corn oil diet [rich in omega-6] on the structure of the distal colon of rat and to evaluate the role of omega-3 fatty acids in modulating such effects. Twenty adult male albino rats were used and were divided into 4 groups, 5 animals each. Group I was the control group where the rats were fed balanced diet Group II comprised the rats which were fed balanced diet with daily oral omega-3 supplementation. Group III consisted of rats which were fed high fat corn oil diet, and group IV included the animals which were fed the high fat corn oil diet together with the daily supplementation of omega-3. The duration of the experiment was 120 days. After the end of the experiment, the animals were killed and the distal colon was dissected. The specimens were processed for histological, immunohistochemical and morphometric study. In group III, the mucosa of the distal colon showed focal areas of crypts distortions. The lining cells of the affected crypts showed marked depletion or absence of goblet cells Localized areas of nuclear changes could also be observed in the nuclei of some cells lining the affected crypts immunohistochemical study revealed an apparent increase in PCNA positive nuclei in the cells of colonic crypts which appeared occupying about more than half length of the crypts. Moreover, the morphometric and statistical study showed a significant increase in PCNA index in group III when compared with the control group. In group IV omega-3 supplementation with high fat corn oil diet showed a potential protection of colonic mucosa from most of the adverse changes