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Fig. 14.1
MUA recording at close vicinity of kisspeptin neurons in the ARC. (
a
) A photomicro-
graph showing the placement of MUA recording electrode in a section immunostained for kiss-
peptin.
Arrowheads
indicate the area where a trace of a bundle of electrodes is observed.
ARC
arcuate nucleus;
3V
third ventricle. Scale bar: 1 mm. (
b
) Representative profi les of the MUA and
plasma LH concentrations in an OVX goat. Panel (
b
) was modifi ed from Wakabayashi Y, et al.
Neurokinin B and dynorphin A in kisspeptin neurons of the arcuate nucleus participate in genera-
tion of periodic oscillation of neural activity driving pulsatile gonadotropin-releasing hormone
secretion in the goat. J Neurosci. 2010 Feb 24;30(8):3124-32. With permission from
Journal of
Neuroscience
results are consistent with those previously demonstrated [
30
,
35
,
42
], it is reason-
able to conclude that the MUA volley observed at close vicinity of ARC kisspeptin
neurons represents the GnRH pulse generator activity. These results lead us to pro-
pose a compelling idea that the population of ARC kisspeptin neurons is the intrin-
sic source of the GnRH pulse generator [
53
-
55
]. However, the argument remains
circumstantial at this moment. Because the MUA is the summation of the electrical
activity of multiple neurons around the electrode, it is still possible that the MUA
volley originates from a population of anonymous non-kisspeptin neurons residing
in the same vicinity as kisspeptin neurons.
Anatomical Aspects of ARC Kisspeptin Neurons in Relation
to the GnRH Pulse Generator
In theory, the GnRH pulse generator should possess several neural characteristics to
perform its tasks, including the generation of rhythmic oscillations, electrophysio-
logical synchronization, transmission of the signal of rhythmic oscillation to GnRH
neurons, elicitation of a pulsatile GnRH discharge, and processing of the negative
feedback action of gonadal steroids. It appears that the functional and anatomical
characteristics of ARC kisspeptin neurons meet these requirements.
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