Effects of genetic selection for early puberty on the hypothalamic-pituitaryovarian axis in gilts

• Published in: Journal of animal science 2020-11, Vol.98, p.212-212
• Main Authors: Harlow, KaLynn, Renwick, Allison, Shuping, Sydney, Sommer, Jeff, Knauer, Mark, Nestor, Casey
• Format: Article
• Language: English
• Subjects: 17β-Estradiol; Animal sciences; Genetics; Gonadotropins; Hogs; Hypothalamus; Immunohistochemistry; Kiss1 protein; Negative feedback; Neurokinin; Neurokinin B; Ovaries; Pituitary (anterior); Pituitary gland; Puberty; Sex hormones; Sucrose; Sugar
• ISSN: 0021-8812; 1525-3163

Puberty onset in gilts is an awakening of the hypothalamic-pituitary-ovarian axis that is the result of reduced estradiol-negative feedback at the level of the hypothalamus which yields elevated gonadotropin secretion from the anterior pituitary. Given the importance of hypothalamic kisspeptin and neurokinin B (NKB) signaling for the onset of puberty in other species, the objective of this study was to determine if gilts selected for early pubertal onset (SELECT) would display measurable differences within the hypothalamus (i.e. increased expression of kisspeptin and NKB) and within the ovary (i.e. increased ovarian mass) compared to age-matched and weight-matched gilts (CONTROL) that achieve puberty 20 days later than SELECT gilts. Gilts were sacrificed at three timepoints: Timepoint A, both groups were determined to be prepubertal (n=6/group), Timepoint B, SELECT gilts were determined to be pubertal and CONTROL gilts were determined to be prepubertal (n=6/group), and Timepoint C, both groups were determined to be pubertal (n=6/group). All animals were euthanized, heads were perfused with 8 L of 4% paraformaldehyde, and ovaries were harvested. Brain tissue was removed post-fixation, submerged in fixative for 24 hrs followed by 20% sucrose until sectioned for immunohistochemistry. Ovarian mass tended (p