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Fig. 8.15
Effects of Peptide 271 in vitro and in vivo. (
a
) Peptide 271 can still bind with an IC
50
of
15 nM. (
b
) Peptide 271 has no intrinsic IP stimulation but can antagonise KP-10 stimulated IP
production by 62% with an IC50 of 1
M. (
c
) LH and FSH secretory profi les are shown from adult
male rats receiving three consecutive i.p. injections (5 nmol/each) of the antagonist of KP, peptide
271 (
denoted by arrows
); the last injection was associated with an i.c.v. bolus of KP-10 (100
pmol). Integrated secretory responses following KP-10 administration, calculated as area under the
curve (AUC), are also depicted as bar graphs. (
d
,
e
) Bar graphs show AUC for LH pulse amplitude
(
d
) and pulse interval (
e
) during 2-h time periods before infusion, during infusion, and after infu-
sion in OVX ewes (
n
= 5 per group). A signifi cantly prolonged pulse interval during peptide 271
infusion was detected. (
f
) Mean LH surges in OVX ewes treated with Peptide 271 or aCSF. The
x
-axis is time (hours) from the peak of the LH surge. (
g
) AUC analysis revealed a signifi cant
decrease in the LH surge in ewes treated with Peptide 271. Data are the mean ± SEM. *
P
< 0.05,
**
P
< 0.01 vs. corresponding control group. (From Pineda, R., et al., Critical roles of kisspeptins
in female puberty and preovulatory gonadotropin surges as revealed by a novel antagonist.
Endocrinology. 151(2):722-30. Reprinted with permission from The Endocrine Society. And from
Smith, J.T., et al., Kisspeptin is essential for the full preovulatory LH surge and stimulates GnRH
release from the isolated ovine median eminence. Endocrinology. 2011. 152(3):1001-12. Reprinted
with permission from The Endocrine Society)
μ
GnRH antagonist. Collectively, the studies indicate that there is an element of
GnRH secretion which is independent of KP. These fi ndings have important thera-
peutic implications, as they indicate that KP antagonists may be utilised to partially
suppress gonadal function and steroid hormone secretion. However, as GnRH and
LH are not known to have any continuous basal mode of secretion, this may be an
artefact of the assays utilised.
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