Edwards, Damian Andrew (1987) Nicotine as an odorant : a biochemical and electrophysiological study of receptors for nicotine in the olfactory epithelium of the rat. PhD thesis, University of Warwick.

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Abstract

The results suggest that nicotine vapour stimulates an in vitro
olfactory preparation in three strains of rat and two strains of mouse, in
a manner similar to known odorants. Preliminary experiments also suggest
that nicotine is an odorant for human subjects.
In the rat, the electro-olfactogram (EOG) produced by nicotine is
attenuated by superfusion of the olfactory mucosa with the lectin
concanavalin A. This reduction is prevented by a-methyl-D-mannoside,
suggesting. that there is a glyco-moiety associated with at least one
olfactory receptor responding to nicotine.
A concanavalin A induced change in EOG response with varying odorant
concentration for several odorants, including nicotine, can be explained by
a single concanavalin A sensitive olfactory receptor with a dissociation
constant for odorant binding in the order of 100 nM. The results also show
that hydrophilic odorants are poor stimulants for the olfactory epithelium,
supporting the hypothesis that the interaction of an odorant with the
olfactory receptors involves hydrophobic effects.
Spatial variation in response to four odorants, including nicotine, by
the rat olfactory epithelium can be explained by a mosaic of olfactory
receptors of various types in the olfactory epithelium. This observation is
consistent with current hypotheses of odour quality determination by the
olfactory mucosa.
Nicotine binding sites in olfactory and respiratory
epithelia.
Binding studies show that there are sites for 3H(-) nicotine in both
olfactory and respiratory preparations, though these sites may not be the
same in each tissue. The binding parameters for olfactory epithelium are
Ko=695 nM and Bmax=8.24 pmol/mg protein (mean of two experiments at
optimal binding conditions). The olfactory epithelium binding sites differ
from binding sites for nicotine described elsewhere for brain (e.g. Ko
values from 0.2-60 nM, Bmax values from 1-100 fmol/mg protein) and for
liver (Ko=0.2 nM, Bmax=5 fmol/mg protein).
Some of the 3H(-) nicotine binding may be to an olfactory receptor
though more conclusive evidence is required to substantiate this.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QL Zoology
Library of Congress Subject Headings (LCSH):	Rats -- Physiology, Nicotine -- Physiological effect, Olfactory receptors
Official Date:	September 1987
Dates:	Date Event September 1987 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Dodd, G. H.
Sponsors:	Science and Engineering Research Council (Great Britain) (SERC) ; Gallahers Ltd.
Extent:	190 p.
Language:	eng

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