Alzheimer’s disease (AD) is a progressively debilitating neurodegenerative disorder characterized by the
presence of proteinaceous deposits in the brain. AD often results in olfactory dysfunction and impaired olfactory
perceptual acuity may be a potential biomarker for early diagnosis of AD. Until recently, there is no Alzheimer’s
nanoscope or any other high-end microscope developed to be capable of seeing buried feature of AD clearly.
Modern neuroimaging techniques are more effective only after the occurrence of cognitive impairment. Therefore,
early detection of Alzheimer’s disease is critical in developing effective treatment of AD.
H and E (Haematoxyline and Eosin) staining is performed for examining gross morphological changes, while
TUNEL (transferase (TdT)-mediated dUTP nick end labeling) staining for monitoring neuronal death in the
olfactory epithelium (OE). Furthermore, immunohistochemistry and western blot are performed to examine β-amyloid protein expression. AD model animals were Tg2576 (transgenic mice that overexpress a mutated form of
the Aβ precursor protein), and 6 month (before onset of AD symptoms) and 14 month (after onset of AD symptoms)
old WT (wild type) and transgenic mice were compared in their olfactory system.
We found that in OE of Tg2576 mice, thickness and total number of cells were decreased, while the
numbers of TUNEL-positive neurons, caspase-3 activation were significantly increased compared with age-matched
WT. Our results demonstrate that the olfactory system may get deteriorated before onset of AD symptoms. Our
findings imply that an olfactory biopsy could be served as an early and relatively simple diagnostic tool for potential