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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Nutrition, Growth and Physiology » Research » Publications at this Location » Publication #326453
Title: Differences in abundance of GnRH-I and GnRH-II among bovine antral follicles

Author
item RICH, J - University Of South Dakota
item NORTHROP, EMMA - University Of South Dakota
item Cushman, Robert - Bob
item PERRY, GEORGE - University Of South Dakota

Submitted to: International Congress on Animal Reproduction
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2016
Publication Date: 6/1/2016
Citation: Rich, J.J., Northrop, E.J., Cushman, R.A., Perry, G.A. 2016. Differences in abundance of GnRH-I and GnRH-II among bovine antral follicles [abstract]. 18th International Congress on Animal Reproduction, June 26-30, 2016, Tours, France. Abstract PW1554, p. 514.

Interpretive Summary:

Technical Abstract: Estradiol plays a critical role in fertility among cattle, specifically it has been reported that preovulatory estradiol regulates uterine pH, sperm transport, and uterine secretions that impact embryo development and survival. In addition, GnRH and GnRH receptors have been reported in granulosa cells of cattle, and GnRH-like molecules have been detected in the follicular fluid of cattle. Furthermore, among other species GnRH has been reported to modulate follicular steroidogenesis. Thus, the objective of the current study was to determine changes in the relative abundance of GnRH-I and GnRH-II within granulosa cells of bovine follicles. Beef cows/heifers were synchronized using the Co-Synch protocol and artificially inseminated (d0). On day 16 after insemination animals were transported to a local abattoir. Following slaughter ovaries were collected and all follicles were classified as small (< 5 mm), medium (5 to 10 mm), or large (> 10 mm). Follicles were aspirated to collect granulosa cells, and follicles in each size group were pooled within animal (n = 16, 13, and 16 for small, medium, and large respectively). Total cellular RNA was extracted from the granulosa cells and RT-PCR was performed to determine relative abundance of mRNA for GnRH-I, GnRH-II, and GAPDH. Data were analyzed using the mixed procedure in SAS.There was no difference (P = 0.31) in abundance of GnRH-I among small, medium, or large follicles (3.8 ± 0.78, 3.37 ± 0.85, and 1.95 ± 0.94; respectively). However, relative abundance of GnRH-II tended to be influenced by follicle size. Relative abundance tended to be greater in small follicles (28.89 ± 10.13) compared to medium (2.15 ± 10.94; P = 0.08) or large (5.98 ± 10.13; P = 0.11) follicles. However, there was no difference (P = 0.80) in abundance between medium and large follicles. Thus the decreased abundance of GnRH-II among medium and large follicles compared to small follicles may play a role in the increased production of estradiol observed in medium and large follicles.