TITLE:
Evaluation of the Hypothalamic Kisspeptin System throughout the Estrous Cycle in Gilts
AUTHORS:
Jeffrey Clapper, Eric Jolitz, Waljit Dhillo
KEYWORDS:
Kisspeptin, Gilts, Estrous Cycle, GnRH
JOURNAL NAME:
Open Journal of Animal Sciences,
Vol.11 No.4,
September
13,
2021
ABSTRACT: Kisspeptin
has been demonstrated to affect reproductive cyclicity and the attainment of
puberty in multiple species, presumably through its actions on gonadotropin
releasing hormone and luteinizing hormone. Kisspeptin administration causes increased
plasma concentrations of LH in pigs, sheep, and rats. The objective of this
experiment was to evaluate changes in the hypothalamic kisspeptin system
throughout the estrous cycle in gilts. Estrus was synchronized in forty
crossbred gilts (191 d, 121 kg) and estrus detection was performed by exposing
gilts to a mature boar. The first day gilts stood immobile was denoted d 1 of
the estrous cycle. Blood samples were collected via jugular venipuncture on d
1, 4, 7, 9, 14, 16, and 19 of the estrous cycle. Ten animals were slaughtered
on d 1, 9, 14, and 21 of the estrous cycle when medial basal hypothalami,
anterior pituitary glands, and blood were collected. Relative expression of
hypothalamic kisspeptin (KISS1), kisspeptin receptor (KISS1R), estrogen receptors-a,
anterior pituitary gland GnRH receptor, β-actin, and GAPDH was determined
using real-time reverse transcriptase PCR. Fold changes in relative expression
were determined using the Relative Expression Software Tool. Relative
expression of KISS1 was increased (P = 0.006) 3.2 fold on d 1 versus d
21 and 2.3 fold (P = 0.003) on d 9 versus d 21 of the estrous cycle, but
was not different (P > 0.05) among the remaining days of the estrous
cycle. Relative expression of estrogen receptor-b was decreased (P =
0.05) 0.8 fold on d 9 versus d 21 and (P = 0.005) 0.7 fold on d 14
versus d 21, but was not different (P > 0.05) among the remaining
days. Relative expression of anterior pituitary gland GnRH receptor was
increased (P