Human olfactory receptor neurons express heat shock protein 70: age-related trends

Immunocytochemical methods were used to investigate the cellular distribution and age-related trends in the expression of constitutive and/or inducible forms of heat shock protein (hsp) 70 in the human nasal mucosa of 22 subjects who ranged in age from 16 weeks prenatal to 90 years, including 3 subjects with Alzheimer's disease. The olfactory mucosa was characterized by the presence of olfactory marker protein-immunoreactive olfactory receptor neurons. The hsp 70 immunoreactivity was localized in olfactory receptor neurons and the supranuclear region of sustentacular cells in the olfactory epithelium, and in the acinar cells of the Bowman's glands in the lamina propria. A systematic age-related decrement in the expression of hsp 70 immunoreactivity was observed in the olfactory receptor neurons. This trend was not apparent in sustentacular cells and Bowman's glands. A marked decrement in hsp 70 immunoreactivity was also noted in the olfactory receptor neurons of subjects with Alzheimer's disease when compared to age-matched controls. These results suggest that the age-dependent decrease in hsp 70 in olfactory receptor neurons of older subjects and those with Alzheimer's disease may be attributable to their greater susceptibility to stress.