Abstract
Early experience considerably modulates the organization and function of all sensory systems. In the mammalian olfactory system, deprivation of the sensory inputs via neonatal, unilateral naris closure has been shown to induce structural, molecular and functional changes from the olfactory epithelium to the olfactory bulb and cortex. However, it remains unknown how early experience shapes the functional properties of individual olfactory sensory neurons (OSNs), the primary odor detectors in the nose. To address this question, we examined the odorant response properties of mouse OSNs in both the closed and open nostril after 4 weeks of unilateral naris closure, with age-matched untreated animals as control. Using a patch-clamp technique on genetically tagged OSNs with defined odorant receptors (ORs), we found that sensory deprivation increased the sensitivity of MOR23 neurons in the closed side, whereas overexposure caused the opposite effect in the open side. We next analyzed the response properties, including rise time, decay time, and adaptation, induced by repeated stimulation in MOR23 and M71 neurons. Even though these two types of neuron showed distinct properties with regard to dynamic range and response kinetics, sensory deprivation significantly slowed down the decay phase of odorant-induced transduction events in both types. Using western blotting and antibody staining, we confirmed the upregulation of several signaling proteins in the closed side as compared with the open side. This study suggests that early experience modulates the functional properties of OSNs, probably by modifying the signal transduction cascade.