Evaluation of the Hypothalamic Kisspeptin System during the Attainment of Puberty in Gilts ()
ABSTRACT
Background: Kisspeptin has been demonstrated to
affect the attainment of puberty in multiple species, presumably through its
actions on GnRH and LH. It has previously been found there is an increase in
expression of hypothalamic in the rat and the monkey coincident with puberty. Whether
a similar phenomenon occurs in the pig remains to be determined. The objectives
of the current experiments were to determine 1) Plasma concentrations of
estradiol-17β; 2) Anterior
pituitary gland concentrations of LH, IGF-I, kisspeptin, and anterior pituitary
gland expression of LH-β and GnRH receptor; 3) Mediobasal hypothalamus expression of Kiss1 and
concentrations of kisspeptin during the
peripubertal period in the gilt. Methods: Two experiments were performed, each with
25 crossbred gilts (151 d, 105 kg). Gilts were relocated and exposed to a
mature boar beginning on d 1 and continuing throughout the experiments to
naturally induce puberty. Gilts that stood immobile within 24 hours of
slaughter were considered to have attained puberty. Plasma samples were
collected on d 1, 3, and 7 of the first experiment and d 2, 4, 6, and 8 of the
second experiment. Gilts were slaughtered on d 7 (experiment 1) or d 8
(experiment 2), when mediobasal hypothalamus (MBH), anterior pituitary glands
(AP), and blood were collected. Relative expression of MBH Kiss1 and β-actin and AP GnRH
receptor, LH-β, was determined using real-time reverse
transcriptase PCR. Fold changes in relative expression were determined using
the Relative Expression Software Tool. Hypothalamic and AP content of
kisspeptin were determined by RIA and differences were determined using the
GLIMMIX procedure of SAS. Results: Relative
expression of Kiss1 was increased (P = 0.005) 2.2 fold in the gilts that had attained puberty in the first
experiment, however, those that had attained puberty in the second were not
different (P > 0.05) from gilts
that had not. Relative expression of GnRH receptor was not different (P > 0.05) between treatments in both
experiments. Relative expression of LH-β tended
to be decreased (P = 0.09) 0.80 fold
in gilts that attained puberty in the first experiment but was not different (P > 0.05) in gilts that attained
puberty in the second experiment. AP concentrations of LH were not different (P > 0.05) between treatments in the
first experiment and were decreased (P = 0.01) in gilts that attained puberty in the second experiment. AP
concentrations of kisspeptin were not different (P > 0.05) in the first experiment but were increased (P = 0.04) in gilts that had attained
puberty in the second experiment. MBH concentrations of kisspeptin were
increased (P = 0.03) in gilts that
had attained puberty in the first experiment but were not different (P > 0.05) between treatments in the
second experiment. Conclusions: These data
further support the role that MBH expression of Kiss1 and concentrations of
kisspeptin and AP concentrations of kisspeptin fluctuate during the
peripubertal period and may play a role in the attainment of puberty in the
gilt.
Share and Cite:
Clapper, J. , Jolitz, E. , Hall, L. and Dhillo, W. (2022) Evaluation of the Hypothalamic Kisspeptin System during the Attainment of Puberty in Gilts.
Open Journal of Animal Sciences,
12, 407-427. doi:
10.4236/ojas.2022.123031.
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