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Fig. 10.2
(
a
) Representative ratemeter record (in 30 s bins) showing an increase in fi ring rate of
an oxytocin neuron (identifi ed by a transient excitation following IV CCK) in response to 25
g IV
kisspeptin-10 in a urethane-anaesthetised virgin female rat. (
b
) Representative ratemeter record (in
30 s bins) showing a dose-dependent increase in fi ring rate of an oxytocin neuron (identifi ed by a
transient excitation following IV CCK, not shown) in response to IV kisspeptin-10 in a urethane-
anaesthetised virgin female rat
μ
down-regulation of Kiss1r) is the limiting factor in the duration of the oxytocin
neuron response to a bolus IV injection of kisspeptin-10.
To further characterise the response of oxytocin neurons to IV kisspeptin, we com-
pleted dose-ranging studies that showed a clear dose-dependent increase in oxytocin
neuron fi ring rate to IV kisspeptin. Even at the lowest dose that we tested (5
g), IV
kisspeptin elicited a small but consistent increase in fi ring rate of oxytocin neurons.
Kisspeptin-10 is known to have comparable, if not greater, biological potency to
that of the full length peptide [
61
,
62
], but to eliminate the possibility that our
observed responses were specifi c to kisspeptin-10, we also completed a small num-
ber of experiments where we used kisspeptin-54 (the full length peptide). As
expected, IV kisspeptin-54 caused a similar increase in oxytocin neuron fi ring rate
to that seen with kisspeptin-10.
μ
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