Histological study on effect of Nigella sativa on aged olfactory system of female albino rat

Nigella sativa (NS) has wide-ranging healing properties, neuroprotective and antioxidant effects. Aging process is commonly associated with a decline in the chemical senses including smell. To detect a possible improvement effect of NS on the aging of the olfactory system we used 15 female albino rats that equally divided into three groups: group I (control adult), group II (control aged), group III (treated aged) received 40 mg/kg/day NS orally for two months. Specimens from the olfactory epithelium (OE), main olfactory bulb (MOB) and piriform cortex (PC) were processed for light and electron microscopy. Aging in OE revealed reduction in thickness, vacuolations, an increase in PAS reaction and lipofuscin autofluorescence. Aged MOB and PC exhibited a reduction in basophilia and accumulation of neurofibrillary tangles (NFTs) in mitral and pyramidal cells respectively. NS treatment improved the structure and the thickness of the OE and reduced the lipofuscin autofluorescence. It also attenuated the reduction in cytoplasmic basophilia and the accumulation of lipofuscin pigment and the NFTs in both mitral and pyramidal cells and the lipofuscin autofluorescence. These observations indicate that use of NS, could be of value in improving the structural changes of the peripheral and central main olfactory organs, which occurred in association with aging.