Background: Aluminum presents in many manufactured food, tooth paste and medicines. It is also addd to the drinking water for purification purposes. However, aluminum has been proved to have toxic effects on many organs of the human body. Some studies suggested that AlCl (aluminum chloride) have detrimental effects on the histology of the lungs of Sprague Dawley rats, which was eminent in the congested blood vessels and hemorrhage. On the other hand, Propolis is a resinous wax-like bee product collected by honey bees from plant exudates and also known as bee glue. In addition, Propolis has also been found to have powerful anti-inflammatory properties and can counteract the damaging effects of aluminium. Moreover, Propolis is the focus of a large number of research projects.
Aim of work: Was to clarify the detailed histological changes in the lung resulting from aluminum toxicity and using propolis as a protective agent in albino rats.
Material and Methods: Thirty adult Sprague Dawley male albino rats, 200- 250 gm body weight were used in the study. The animals were divided into three groups, ten rats each: Group I (control group): group Ia (5 rats) received distilled water and group Ib (5 rats) received propolis 50 mg/kg. B.W. once daily. Group II (AlCl3 group): received 475mg/kg B.W., of aluminum chloride once daily. Group III (protected group): received 475mg/kg B.W., of aluminum chloride and 50 mg/kg B.W. of Propolis once daily. All the doses were given via oral gavage. After eight weeks, all rats were anaesthetized by thiopental sodium and the thoracic cage was opened and the lungs were taken out. Specimens were processed for both light and transmission electron microscopic examination.
Results: Examination of sections of lung tissue of group I (Ia and Ib) control groups showed almost the same findings, the lung had the appearance of fine lace because most of the tissue was composed of thin-walled alveoli. Examination of semithin sections revealed that the alveolar epithelium was formed of flattened squamous pneumocytes type I with its deeply stained nuclei and scanty cytoplasm. Pneumocytes type II were large irregular cuboidal cells with large rounded nuclei, prominent nucleoli and vacuolated cytoplasm. The ultrathin sections showed the pneumocyte type II with large heterochromatic nucleus and prominent nucleolus. The lungs of group II rats which received aluminum chloride showed diffuse affection. Alveoli were seen collapsed in many areas with thickening of the interalveolar septa. Congestion of the blood vessels together with extravasation of RBCs and heamosidrine granules were observed. Semithin sections showed cellular proliferation especially in pneumocytes type II was seen. Ultrathin sections revealed large areas of degeneration. Some nuclei appeared pykontic. The cytoplasm lost most of the organelles except few attenuated mitochondria. Examination of the Propolis protected group III showed that administration of propolis minimized the cellular proliferation caused by aluminium. In addition the obliteration of the alveolar lumen seemed less. Semithin sections of this group revealed some congestion of blood vessels and macrophages scattered in between the alveolar cells. Ultrathin sections showed pneumocytes type II with heterochromatic nucleus and prominent nucleoli and regular nuclear membrane and organelles rich cytoplasm. However, some residual degeneration could be detected in some pneumocytes.
Conclusion: Based on the results of the present study, it can be concluded that aluminium chloride exposure had detrimental effects on the histology of the lungs of albino rats which could in turn negatively affect respiration. Therefore, caution should be taken in its usage. Administration of propolis combined with aluminium chloride can alleviate its harmful effects.