Changes of Spleen in Wistar Rats Exposed to Therapeutic Doses of Dexamethasone and Medroxyprogesterone Acetate Evaluated by Stereological Parameters.

The aim of our investigation was to evaluate the immunosuppressive effect of medroxyprogesterone acetate (MPA) determining the volume densities of the structural components of the spleen. The volume densities of the same structural components of spleen were determined after administration of dexamethasone too, in order to see whether the morphological changes induced by MPA are in the same line with the changes caused by dexamethasone. 60 female Wistar rats were divided into 5 groups. The control group of rats was administered physiological solution. The remaining, 4 experimental groups were administered: dexamethasone at a therapeutic daily dose of 0.6 mg/kg bw and maximal therapeutic dose of 3 mg/kg bw, and MPA at a therapeutic dose of 30 mg/kg bw and maximal therapeutic dose of 150 mg/kg bw. The drugs were applied intramuscularly for 7 days. Spleen paraffin sections were stained according to the methods: hematoxylin-eosin, Masson and Elastica van-Gieson. Stereological measurements were performed by using the Weibl's multipurpose test system (M-42). The histological analyses of the structural components of the spleen in rats treated with dexamethasone and MPA have shown reduction of the white pulp and the marginal zone and an apparent decrease of the cellular density of the lymphocyte component of the pulp. The stereological analysis of the spleen showed significant decrease of the splenic pulp volume density and significant increase of the connective tissue volume density. Reducing the presence of splenic pulp was mainly due to the decrease in the volume density of all structural components of the white pulp. Changes were observed in all drug treated groups of rats. Our results have shown that the MPA provoked changes suggested atrophy of the spleen lymphoid tissue. Although the atrophic changes of the spleen were significant after the application of both dexamethasone and MPA, the white pulp was significantly more sensitive substrate for dexamethasone than for the MPA.