Histological and immunohistochemical study on the effect of doxorubicin on the heart of adult albino rat and the possible protective role of an antioxidant

Doxorubicin is one of the first anthracyclines in clinical use and has a broad anti-tumor spectrum. With the increasing use of anthracycline antibiotic, acute and cumulative dose-related cardiotoxicity have been recognized. This work was undertaken with the aim of studying the histological, Ultrastructural and immunohistochemical changes in the myocardium of albino rats following doxorubicin administration and the possible protective role of an antioxidant [probucol]. Sixty adult albino rats of both sexes weighing 200 - 250 gms, were used in this study. They were divided into four groups: a control group [group I] composed of 30 rats and three treated groups [10 rats for each]. Probucol treated group [group II], were injected intraperitoneally [IP] with probucol in a dose of 10 mg / kg b. w every other day for four weeks. Doxorubicin treated group [group III], were injected [IP] with doxorubicin in a dose of 2.5 mg / kg b. w. every other day for two weeks. Probucol and doxorubicin treated group [group IV], were injected [IP] with probucol for two weeks followed by probucl plus doxorubicin for another two weeks with the same doses and ways mentioned before. The control animals were divided into three subgroups [10 rats for each], [group la], were injected [IP] with 1ml corn oil [solvent for probucol]. [group Ib] were injected [IP] with 1ml physiological saline [solvent for doxorubicin]. [group Ic] were injected [IP] with 1ml physiological saline and 1 ml corn oil by the same ways and durations mentioned before with treated animals. Heart specimens were taken two and four weeks after the last injection and processed for histological, Ultrastructural and immunohistochemical studies. Light microscopic studies revealed many degenerative changes that were time-dependent varying from vacuolation to myocytolysis and loss of myofibrils. Evidences of apoptosis were detected in the form of cytoplasmic eosinophilia and the nuclei varying from peripheral margination of chromatin up to pyknosis, confirmed immunohistochemically with positive reaction for caspase-3 activity that was increased in a time-dependent manner to reach up to four times of the control level four weeks after doxorubicin treatment, as detected by image analysis. Ultrastructural examination showed extensive degeneration of the muscle fibers with marked loss and even complete disappearance of myofibrils, there was dilatation of smooth endoplasmic reticulum, increased amount of glycogen granules and mitochondriosis, with degeneration and moth-eaten appearance of many mitochondria. The nucleus appeared hyperchromatic with peripherally clumped chromatin. The above mentioned toxic effects of doxorubicin on the myocardium were markedly attenuated by probucol administration before and in combination with doxorubicin injections. From this study, it was concluded that, probucol markedly attenuated doxorubicin induced cardiomyopathic changes which is time- dependent

Histological and genetic studies on the effect of dexamethasone on the thymus gland of adult male albino rat

Despite of Glucocorticoids have a well known immunosuppressive action, a little is known about its induction of lymphoid cell death through activation of programmed-cell death known as apoptosis. This work was undertaken with the aim of studying the histological and genetic changes in the thymus gland of albino rats following dexamethasone administration and withdrawal using different doses. Thirty-six adult male albino rats weighting 180-200 gm were used in the present study. The rats were divided into three equal groups [12 animals for each]. Group I [control], injected daily intraperitoneally [IP] with 1ml distilled water. Group H, injected daily [IP] with low dose of dexamathazone [1 gm / Kg b.w.] for seven days and group III, injected daily [IP] with high dose of dexamathazon [2 gm / Kg b.w.] for seven days. Specimens were taken one day after the 1st, 3[rd] and 7[th] injection and three animals from each group were left for recovery and sacrificed seven days after stoppage of treatment. From each specimen, a part was taken for histological, and immunohistochemical studies under light microscopy and the other part was processed for gel electrophoresis. Histological results demonstrated apoptotic changes in thymocytes after a single dose of dexamethasone, more pronounced with the high dose. Aggregation of apoptotic lymphocytes and many large macrophages engulfing apoptotic materials were seen in the cortex. The apoptotic changes were confirmed with positive reaction for Fas-ligand immune activity after a single dose of dexamethasone injection. Severe atrophy of the gland was seen more with high dose where the cortex appeared depleted from lymphocytes. Withdrawal of the drug revealed considerable degree of resolution. The lymphocytes appeared morphologically normal with dispersion of their nuclear chromatin. Our results were confirmed by the results obtained by gel electrophoresis which showed DNA ladders after one day of injection in both low and high doses and complete disappearance of ladders after seven days of medication and in recovered animals. From this study, it was concluded that dexamethasone induced apoptotic changes in thymocytes early after a short period of adminestratione and these changes were timed and dose-dependant with recovery periods proportional to the dose