Protective effect of propolis on manganese chloride neurotoxicity of olfactory bulb in adult male albino rat.

Background: Manganese (Mn) is widely used for industrial purposes and exposure to high levels of Mn may cause an irreversible brain disease. Propolis is a natural plant product; it acts as a powerful reactive oxygen species scavenger and improves the neurodegeneration process.
Materials and Methods: In this study 40 adult male albino rats were divided randomly into four groups 10 rats each: group I (control group), group II manganese chloride (MnCl2) received 10 mg/kg/day/orally for 4 weeks by intra-gastric tube, group III (propolis group) received 50 mg/kg/day/orally for 4 weeks by intra-gastric tube, and group IV (MnCl2 + propolis group) received the same doses with the same duration and route as in groups II and III. Rats were sacrificed after 24 h of last dose. The olfactory bulbs removed, the right bulb cut to be processed for haematoxylin and eosin, immunohistochemical staining and the left cut for electron microscopic studies.
Results: Results revealed that rat olfactory bulb from MnCl2 group showed darkly stained mitral cells with dark pyknotic nuclei, some show pericellular spaces and vacuolation, dark apoptotic cells in granular cells, neuropil vacuolation and pyknotic astrocyte. Electron microscopic examination showed abnormal granular cell with irregular damaged nuclear membrane, rupture of myelin fibre. Mitral nerve cell with destructed nucleus, many cytoplasmic vacuoles, swollen rough endoplasmic reticulum, vacuolated mitochondria and neuropil were observed. Manganese chloride + propolis group showed improvement compared to MnCl2 group.
Conclusions: It was concluded that propolis can ameliorate the toxic changes of manganese chloride on rat olfactory bulb.