Neuromodulatory Effects of Gonadotropin Releasing Hormone on Olfactory Receptor Neurons

The terminal nerve is an anterior cranial nerve that innervates the lamina propria of the chemosensory epithelia of the nasal cavity. The function of the terminal nerve is ambiguous, but it has been suggested to serve a neuromodulatory role. We tested this hypothesis by exposing olfactory receptor n...

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Bibliographic Details
Published in:The Journal of neuroscience 2000-06, Vol.20 (11), p.3947-3955
Main Authors: Eisthen, Heather L, Delay, Rona J, Wirsig-Wiechmann, Celeste R, Dionne, Vincent E
Format: Article
Language:English
Subjects:
Animals
Electrophysiology
Female
Gonadotropin-Releasing Hormone - pharmacology
Immunohistochemistry
Male
Necturus
Necturus maculosus
Neurotransmitter Agents - pharmacology
Olfactory Receptor Neurons - drug effects
Patch-Clamp Techniques
Presynaptic Terminals - drug effects
Receptors, LHRH - metabolism
Sex Characteristics
Tetrodotoxin - pharmacology
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Summary:The terminal nerve is an anterior cranial nerve that innervates the lamina propria of the chemosensory epithelia of the nasal cavity. The function of the terminal nerve is ambiguous, but it has been suggested to serve a neuromodulatory role. We tested this hypothesis by exposing olfactory receptor neurons from mudpuppies (Necturus maculosus) to a peptide, gonadotropin releasing hormone (GnRH), that is found in cells and fibers of the terminal nerve. We used voltage-clamped whole-cell recordings to examine the effects of 0. 5-50 micrometer GnRH on voltage-activated currents in olfactory receptor neurons from epithelial slices. We found that GnRH increases the magnitude, but does not alter the kinetics, of a tetrodotoxin-sensitive inward current. This increase in magnitude generally begins 5-10 min after initial exposure to GnRH, is sustained for at least 60 min during GnRH exposure, and recovers to baseline within 5 min after GnRH is washed off. This effect occurred in almost 60% of the total number of olfactory receptor neurons examined and appeared to be seasonal: approximately 67% of neurons responded to GnRH during the courtship and mating season, compared with approximately 33% during the summer, when the sexes separate. GnRH also appears to alter an outward current in the same cells. Taken together, these data suggest that GnRH increases the excitability of olfactory receptor neurons and that the terminal nerve functions to modulate the odorant sensitivity of olfactory receptor neurons.
ISSN:0270-6474
1529-2401
DOI:10.1523/jneurosci.20-11-03947.2000