Olfactory receptor cell function is affected by trigeminal nerve activity.

In the frog, antidromic electrical stimulation of the ophthalmic branch of the trigeminal nerve (NV-ob) evokes a slow potential in the olfactory mucosa, modifies the activity of receptor cells and modulates the responses to odour. Substance P (SP) application evokes similar electrical responses. These results imply that the functioning of the olfactory system might be controlled at the receptor cell level. It is suggested that the trigeminal system could modulate the activity of the olfactory receptor cells via a local axon reflex which may result in the release of SP.