Neuromodulatory Effects of Gonadotropin Releasing Hormone on Olfactory Receptor Neurons

• DOI: 10.1523/jneurosci.20-11-03947.2000
• Publication Date: 2018-04-04T19:25:29Z
• Authors: Heather L. Eisthen; Rona J. Delay; Celeste R. Wirsig...; Vincent E. Dionne
• Keywords: Male; Neurotransmitter Agents; Sex Characteristics; 0303 health sciences; Patch-Clamp Techniques; Necturus; Presynaptic Terminals; Tetrodotoxin; Immunohistochemistry; Olfactory Receptor Neurons; Electrophysiology; Gonadotropin-Releasing Hormone; 03 medical and health sciences; Animals; Female; Receptors, LHRH

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 μmGnRH 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: ∼67% of neurons responded to GnRH during the courtship and mating season, compared with ∼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.