Skip to main content
ARS Home » Southeast Area » Booneville, Arkansas » Dale Bumpers Small Farms Research Center » Research » Publications at this Location » Publication #137809
Title: INFLUENCE OF ESTRADIOL, PROGESTERONE, AND NUTRITION ON CONCENTRATIONS OF GONADOTROPINS AND GNRH RECEPTORS, AND ABUNDANCE OF MRNA FOR GNRH RECEPTORS AND GONADOTROPIN SUBUNITS IN PITUITARY GLANDS OF BEEF COWS

Author
item LOOPER, MICHAEL - 6227-05-00
item VIZCARRA, J - TEXAS TECH UNIV
item WETTEMANN, R - OKLA STATE UNIV
item MALAYER, J - OKLA STATE UNIV
item BRADEN, T - AUBURN UNIV
item GEISERT, R - OKLA STATE UNIV
item MORGAN, G - OKLA STATE UNIV

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2002
Publication Date: 1/1/2003
Citation: LOOPER, M.L., VIZCARRA, J.A., WETTEMANN, R.P., MALAYER, J.R., BRADEN, T.D., GEISERT, R.D., MORGAN, G.L. 2003. INFLUENCE OF ESTRADIOL, PROGESTERONE, AND NUTRITION ON CONCENTRATIONS OF GONADOTROPINS AND GNRH RECEPTORS, AND ABUNDANCE OF MRNA FOR GNRH RECEPTORS AND GONADOTROPIN SUBUNITS IN PITUITARY GLANDS OF BEEF COWS. JOURNAL OF ANIMAL SCIENCE. 81(1):269.

Interpretive Summary: Maintenance of a 12-month calving interval is important to the profitability of livestock operations. Anestrous cows were exposed to estradiol and progesterone for 7 days. Estradiol increased luteinizing hormone (LH) pulse frequency and gonadotropin-releasing hormone (GnRH) receptors in the pituitary gland. Progesterone increased synthesis of LH-beta mRNA in the pituitary gland of cows. Anestrous cows exposed to both estradiol and progesterone may resume estrous cycles sooner and be able to maintain a yearly calving interval. This is of interest to livestock producers and agricultural professionals who advise them regarding reproductive management.

Technical Abstract: Nutritionally induced anovulatory cows (n = 28) were used to determine the effect of steroids on regulation of synthesis and secretion of gonadotropins. Anovulatory cows were ovariectomized and received intravaginal inserts containing estradiol, progesterone, estradiol and progesterone, or a sham intravaginal insert (C) for 7 d. Concentrations of LH and FSH were quantified in serum and estradiol and progesterone were quantified in plasma. Cows were exsanguinated within 1-2 h after removal of intravaginal inserts and pituitary glands were collected and stored at -80 C until mRNA for GnRH receptor (GnRH-R) and gonadotropin subunits, pituitary content of GnRH-R, and LH and FSH were quantified. Pituitary glands from five proestrous cows were harvested to compare gonadotropin characteristics between ovariectomized, anovulatory cows and intact cows. Mean serum concentrations of LH and FSH were not significantly influenced by steroid treatments. However, frequency of LH pulses of ovariectomized nutritionally induced anovulatory cows was increased (P < 0.05) by treatment with estradiol, and amplitude of LH pulses was greater (P < 0.05) in cows treated with estradiol or progesterone than in cows treated with both estradiol and progesterone or sham-treated. Quantity of mRNA for LH-beta in the pituitary gland was greater when cows were treated with progesterone. Concentrations of LH in the pituitary gland were not affected by steroid treatments; however, pituitary concentrations of FSH were less (P < 0.1) in estradiol cows than in sham-treated cows. Number of GnRH-R was increased (P < 0.05) in cows treated with estradiol. Abundance of mRNA for GnRH-R, common alpha-subunit, and FSH-beta were not affected by treatments. Pituitary concentrations of LH were greater (P < 0.05) and concentrations of FSH were less (P < 0.05) in proestrous cows than in ovariectomized, anovulatory cows treated with or without steroids. Abundance of mRNA for GnRH-R, common alpha-subunit, LH-beta and FSH-beta were similar for proestrous and anovulatory cows. We conclude that treatment of nutritionally induced anovulatory cows with progesterone and estradiol may cause pulsatile secretion of LH.