Postnatal odorant exposure induces peripheral olfactory plasticity at the cellular level.

Area of Science:

• Neuroscience
• Olfactory System Biology
• Sensory Receptor Research

Background:

• Mammalian olfactory sensory neurons (OSNs) are vital for smell and are regularly regenerated throughout life.
• The olfactory epithelium is known to be influenced by the odorant environment.
• However, the precise cellular-level impact of early olfactory exposure on OSNs remains largely unknown.

Purpose of the Study:

• To investigate the cellular-level adaptations of OSNs in response to chronic odorant exposure during early postnatal development.
• To determine if olfactory sensory neurons exhibit specific plasticity in response to distinct odorant-receptor interactions.

Main Methods:

• Exposure of MOR23-green fluorescent protein (GFP) and M71-GFP mice to specific odorant ligands (lyral for MOR23, acetophenone for M71) during early postnatal life.
• Analysis of OSN density, olfactory receptor mRNA and protein levels, and expression of key transduction pathway proteins (CNGA2, phosphodiesterase 1C) using quantitative PCR.
• Functional assessment of OSN responses to odorants via patch-clamp recordings to evaluate sensitivity, dynamic range, and response kinetics.

Main Results:

• Daily postnatal exposure to lyral led to decreased density of MOR23-expressing OSNs, while MOR23 mRNA and protein levels remained stable.
• Individual MOR23 neurons showed increased olfactory receptor transcript levels and higher expression of CNGA2 and phosphodiesterase 1C.
• Patch-clamp recordings revealed enhanced sensitivity, broader dynamic range, and faster response kinetics in lyral-exposed MOR23 neurons.
• These effects were specific to the lyral-MOR23 interaction, with no observed effects from acetophenone on MOR23 neurons or vice versa on M71 neurons.

Conclusions:

• Olfactory sensory neurons undergo specific anatomical, molecular, and functional adaptations in response to chronic odorant exposure during early life.
• This demonstrates a remarkable plasticity in the olfactory system, allowing OSNs to fine-tune their response to environmental odorants early in development.
• The findings highlight the odorant-specific nature of OSN adaptation, underscoring the intricate relationship between sensory input and neural circuitry development.