Odorant-regulated Ca2+ gradients in rat olfactory neurons

Area of Science:

• Neuroscience
• Olfactory System Biology
• Cellular Physiology

Background:

• Olfactory neurons detect odors via cation influx, leading to increased intracellular calcium ([Cai]).
• Elevated [Cai] is hypothesized to mediate adaptation to sustained odorant stimulation.
• Previous studies suggest a role for [Cai] in olfactory adaptation.

Purpose of the Study:

• To image and analyze the spatial distribution of [Cai] in rat olfactory neurons (RON) during odorant stimulation.
• To investigate the relationship between odorant-induced [Cai] changes and cellular location.
• To explore the implications of spatially inhomogeneous [Cai] increases for olfactory adaptation.

Main Methods:

• Utilized the Ca2+ indicator fura-2 for calcium imaging in rat olfactory neurons (RON).
• Applied odorant stimulation to observe changes in intracellular calcium ([Cai]) distribution.
• Compared odorant-induced [Cai] changes with those induced by K(+)-depolarization.

Main Results:

• A significant percentage (42%) of RON responded to odorants with increased [Cai].
• Approximately half of responding neurons showed an apical [Cai] increase, distinct from the soma.
• Odorant-induced [Cai] gradients were sustained during continuous stimulation, unlike homogeneous K(+)-induced increases.

Conclusions:

• Odorant stimulation elicits spatially inhomogeneous increases in [Cai] in a subset of rat olfactory neurons.
• The location-dependent nature of odorant-induced [Cai] changes suggests differential effects on cellular components.
• These findings have significant implications for understanding the role of calcium in olfactory adaptation processes.