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Fig. 16.1 Gonadectomy alters the membrane properties of KNDy-GFP neurons. ( a ) Chart records
from 3 KNDy-GFP neurons show that under basal recording conditions, tonic fi ring, burst fi ring,
and quiescent ARC-KNDy neurons are present in brain slices from male mice. ( b ) Bar chart shows
that the fraction of spontaneously fi ring cells is signifi cantly higher in brain slices prepared from
adult gonad-intact mice vs. GDX mice. ( c ). Bar charts show that the resting membrane potential of
quiescent ARC-KNDy cells is indistinguishable in the intact and GDX groups. ( d , e ) Bar charts
show dramatic alterations in membrane resistance and excitability properties of KNDY cells from
GDX vs. gonad-intact male mice. The membrane resistance of ARC-KNDy neurons in the GDX
group is 50% lower than that of the gonad-intact groups, and KNDy-GDX neurons require signifi -
cantly larger currents to induce an action potential
slices with different orientations [ 20 ]. It should, however, be noted that in morpho-
logical studies, long processes were commonly observed in neurons fi lled in the
coronal slice preparation (see Sect. Morphology of ARC-KNDy Neurons and
Modulation by Sex Steroids ).
The reduced fraction of spontaneously fi ring cells in the GDX group may seem
paradoxical, since gonadectomy upregulates the expression of Kiss1 , Tac2 , and Dyn
in KNDy neurons and indirect evidence would suggest that increased kisspeptin
production drives the post-castration rise in luteinizing hormone (LH) [ 21 ]. A sim-
ple explanation might be that the sex steroid receptors on KNDy neurons drive the
transcriptional machinery, but not their fi ring activity and the subsequent release of
contained peptides. Thus, input(s) extrinsic to KNDy neurons in the slice prepa-
ration may be required for driving the sustained synchronized fi ring of KNDy neu-
rons following gonadectomy. These inputs could derive from other ER
α
-receptor
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