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Title: Ontogeny of gene expression in the hypothalamic-pitutitary axis and luteinizing hormone secretion during pubertal development in the gilt

Author
item Barb, Claude
item Hausman, Gary
item REKAYA, ROMDHANE - UGA

Submitted to: Reproduction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2005
Publication Date: 1/20/2006
Citation: Barb, C.R., Hausman, G.J., Rekaya, R. 2006. Ontogeny of gene expression in the hypothalamic-pitutitary axis and luteinizing hormone secretion during pubertal development in the gilt. Reproduction. (Suppl)62:33-44.

Interpretive Summary: Identifying brain and pituitary genes associated with changes in luteinizing hormone (LH), pituitary hormone necessary for reproduction, secretion and growth is of great relevance during pubertal development in the pig. Evidence supports the idea that specific genes regulate brain hormone secretion which regulates LH release by acting directly on the pituitary gland. Thus, understanding these interactions is necessary in order to develop new methods to promote maximal growth and enhance onset of puberty and reproductive function in the pig.

Technical Abstract: The occurrence of puberty in the female is due to the interplay of central and peripheral mechanisms in which the hypothalamic-pituitary-ovarian axis regulates growth, gonadal function, as well as, adipocyte hormone secretion. Hypothalamic GnRH mRNA expression did not change. Concomitant with the age related reduction in the oestrogen negative feed back on LH secretion was an increased expression of repressor of ER activity gene (REA) at 210 days of age. Hypothalamic M'-opioid receptor expression decreased at 210 days of age followed by increased expression of progesterone receptor (PR) membrane compliment-1 and steroid membrane binding protein gene at 210 days of age. This represents development of the endogenous opioid peptide (EOP)-progesterone dependent LH inhibitory pathway. Adipose tissue leptin and insulin like growth factor –I (IGF-I) gene expression increased with age and adiposity. Pituitary LH', estrogen receptor-alpha, IGF-I-receptor, and growth hormone releasing hormone-receptor (GHRHR) gene expression increased with age. These results identify key hypothalamic and pituitary genes associated with changes in LH secretion and growth during pubertal development and adipose tissue genes and secreted proteins related to maturation of the neuroendocrine axis and puberty.