A stereological and histological analysis of spleen on obese female rats, fed with high fat diet.

OBJECTIVE To determine if there is an association between fatty diet induced obesity and spleen enlargement by means of Cavalieri principle, unbiased stereological method and light microscopic examination. METHODS In this study, we used 16 adult female Sprague Dawley rats, weighing between 150-200 g. All animals were obtained from the Ataturk University Experimental Research and Applying Center, Turkey in 2005. We performed rat models, fed with normal or high-fat diet for duration of 3 months. After this controlled nutritional process, spleens are removed from all anesthetized rats and performed by routine histological process. Stereologically, we estimated the spleen volumes in consecutive serial sections using Cavalieri method in control and treatment groups. Then, we examined histologically all those sections by a light microscope with camera attachment. RESULTS Mean spleen volumes were 1.40 ml in the control and 2.03 ml in the treatment group, suggesting splenomegaly. Volumes of spleens in 2 groups revealed statistical significant difference (p<0.05, independent samples t-test). In studying spleen slices, many macrophages and necrotic figures were defined. Also, sinusoidal dilatation and hemosiderin deposits were observed and we found macrophages, filled with hemosiderin droplets. In some sections, especially around small vessels, eosinophilic aggregations and lipid accumulations in dilated sinusoids were detected. CONCLUSION Spleen enlargement at significant levels (38%) in obese patients was determined by Cavalieri stereologic volume calculation method; an unbiased stereological method. Finally, our results clearly indicated that high fat diet caused to splenomegaly via sinusoidal dilatation and intra-cellular or intercellular deposits.