Lifespan of mature olfactory sensory neurons varies with location in the mouse olfactory epithelium and age of the animal

Abstract

The olfactory sensory neurons (OSNs) of the olfactory epithelium (OE) exhibit a remarkable regenerative capability, which protects the population against environmental insult and enables adjustment to new odors. The lifespan of OSNs is still open to question, with estimates ranging from 1 month to at least 1 year. However, the estimates come with some caveats, including low labeling efficiency and a focus solely on newborn neurons. We revisited the issue via the use of OMP-tTA; TetO-Cre; Rosa26fl(stop)-Tdtomato (OMP-tTA;TdT) mice, which allowed us to selectively label ∼95% of the OMP(+) OSN population that reach maturity by a given time and, by switching to doxycycline chow, to "chase" this preexisting OSN population. Two loading protocols were used: conception to 2 months old and conception to 4.5 months old. Surviving OSNs were common up to 6 months chase time in both groups, but more neurons survived when loading for 4.5 months as compared with 2 months. A spatial difference was evident: higher percentages of OSNs survived in the dorsomedial OE as compared with ventrolateral and in posterior versus anterior OE regions. Finally, proliferation rates anticorrelated with the spatial differences in OSN survival; higher proliferation rates were observed ventrally. Together, these results demonstrate spatial and temporal differences in OSN survival, highlighting it as a dynamic system that can be studied for factors affecting neuronal survival.

Characterization of human oxidoreductases involved in aldehyde odorant metabolism

“…Bathing of the neuron's cilia in the mucus allows for the first step of odorant perception due to the interaction of odorant molecules with receptors located on the membrane of these neurons. Aldehydes are highly toxic to neurons 55 and need to be particularly protected and continuously renewed for less than one month for rodent olfactory neurons 56,57 . In this context, to safeguard an acute sense of smell, metabolization of aldehyde compounds, including aldehyde odorants, appears essential within the mucus.…”

The Role of the Stimulus in Olfactory Plasticity

“…Meanwhile, these inchoate OSNs grow axons that migrate to the olfactory bulb glomeruli where they form functional connections with 2nd-order neurons [76]. This lifelong process underlies the replacement of mature neurons with newborn neurons in cycles with periods of perhaps two months [5,77].…”