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Transduction mechanisms in vertebrate olfactory receptor cells
1Physiologisches Institut, Universität Göttingen, Germany.
Physiological Reviews
|April 30, 1998
Summary
Olfactory receptor neurons (ORNs) use G protein-coupled receptors (ORs) to detect odorants. Signal transduction involves cyclic AMP (cAMP) and calcium (Ca2+), leading to nerve impulses sent to the brain.
Area of Science:
- Neuroscience
- Molecular Biology
- Sensory Physiology
Background:
- Olfactory receptor neurons (ORNs) are crucial for smell perception.
- Odorant receptors (ORs) are G protein-coupled receptors (GPCRs) with known structures.
- Signal transduction pathways in ORNs are complex and involve second messengers.
Purpose of the Study:
- To review the biophysical and electrophysiological evidence of olfactory transduction.
- To detail signal processing and action potential generation in ORNs.
- To provide a comprehensive overview of current knowledge on smell mechanisms.
Main Methods:
- Review of existing literature on ORN transduction.
- Analysis of biophysical and electrophysiological data.
- Examination of molecular structures of ORs and signaling components.
Main Results:
- Odorant binding to ORs activates second messenger cascades, primarily involving Golf and cyclic adenosine monophosphate (cAMP).
- Increased intracellular calcium (Ca2+) activates a chloride (Cl-) current, depolarizing the ORN.
- Alternative pathways involving inositol polyphosphates and modulation of potassium (K+) and Cl- conductances exist; some odorants inhibit ORNs.
Conclusions:
- The primary olfactory transduction pathway involves cAMP and Ca2+ influx, leading to neuronal depolarization and signal transmission.
- Multiple transduction pathways and odorant-modulated conductances contribute to the complexity of smell.
- Understanding these mechanisms is key to deciphering chemosensory information processing in the olfactory bulb.