Getchell, T. (1986) Functional Properties of Vertebrate Olfactory Receptor Neurons. Physiological Reviews, Vol. 66, No. 3 

Functional Properties of Vertebrate Olfactory Receptor Neurons

The experiment on mice showed that an inverse agonist triggers the olfactory receptor to reduce its basal activity. Consequently, the olfactory receptors will induce the inhibitory responses, which include blockage of the CNG channel. But the above phenomenon was only observed in olfactory receptors which display basal activity.

The connection between basal activity, inhibitory responses, and inverse agonist

Of the 302 neurons in the C. elegans nervous system, 14 have been characterized as chemosensory, or olfactory, neurons that detect volatile odorants. Each type of chemosensory neuron is tuned to a specific odorant or set of odorants. For example, the AWA olfactory neurons are activated in reaction to diacetyl, thiazoles, and pyrazine. A single olfactory neuron expresses multiple types of olfactory receptors. Researchers test C. elegans via a chemotaxis assay to characterize the different olfactory receptors and their respective odorants. As an example, Sengupta et al (1996) matched the olfactory receptor gene “odr-10” specifically to diacetyl, and therefore to the AWA olfactory neuron.

C. elegans and olfaction

The olfactory receptor neurons are the major component in the olfactory sensory system. The olfactory receptor neuron is a bipolar neuron, the cell body is embedded in the nasal chamber and within the olfactory epithelium. Its nonmyelinated axon transduces the signal to the olfactory bulb without discontinuity.

University of California, Berkeley

In the nose, there are three types of cells in the olfactory epithelium. 

- Olfactory receptor neurons
- Basal cells 
- Supporting cells 

Receptors in the nose 

These are cells in the olfactory epithelium that detect chemicals in the air called odorants using specialized receptors. These neurons can be replaced in adults (Costanzo, 1991). 

The olfactory receptor neurons consist of multiple structures that assist in detecting odorants. 

- cilia
- dendritic knob

Olfactory receptor neurons

This is the layer of cells that lines the nasal cavity.

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