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Fig. 18.3
Kisspeptin-ir cells in the hamster AVPV receive SCN-derived fi ber contacts expressing
AVP-ir. (
a
) Low-power photomicrographs of AVP-ir in the AVPV, in which kisspeptin cell bodies
receive extensive AVP-ir fi ber contacts. (
b
) High-power photomicrograph showing several pre-
sumptive AVP-ir terminal boutons on a kisspeptin-ir cell body at the light level. (
c
) Confocal image
(0.5 μm scan taken at ×400) confi rming AVP-ir contacts upon kisspeptin-ir cell body and pro-
cesses. In (
b
,
c
),
arrows
are indicative of close contacts. (
d
-
f
) Kisspeptin cells in the AVPV express
the V1a receptor. (
d
) Low-power photomicrographs of kisspeptin-ir cells in the AVPV, (
e
) V1a-ir
cells in the AVPV, and (
f
) the merged image showing overlap between kisspeptin-ir and V1a-ir.
From Williams WP, 3rd, Jarjisian SG, Mikkelsen JD, Kriegsfeld LJ. Circadian control of kiss-
peptin and a gated GnRH response mediate the preovulatory luteinizing hormone surge.
Endocrinology. 2011;152(2):595-606. Epub 2010/12/31. Reprinted with permission from The
Endocrine Society
a common mechanism of circadian control across species [
108
]. Additionally, these
authors established that estrogen increases the percent of GnRH cells with AVPergic
terminal appositions, providing an additional mechanism by which estrogen inte-
grates with circadian signaling to stimulate kisspeptin neurons at the time of ovula-
tion [
108
].
More recently a creative series of studies by de la Iglesia and colleagues further
established the specifi c means by which the SCN regulates
Kiss1
expression and the
LH surge [
53
]. First, to determine if the SCN communicates ipsilaterally to
Kiss1 -
expressing
neurons in the AVPV, and to assess the signifi cance of this communica-
tion for GnRH cell activation at the time of the surge, the authors lesioned one half
of this nucleus and examined AVPV
Kiss1
expression and FOS expression in GnRH
cells in female rats (Fig.
18.4
). Both
Kiss1
expression and the percentage of GnRH
cells expressing FOS were reduced on the side of the brain ipsilateral to the lesion,
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