Profile of miRNA in Bovine corpora lutea

The corpus luteum (CL), an ovarian transient gland, develops from the remnants of the ovulatory follicle and produces progesterone, required for maintenance of pregnancy in mammals. The development of the CL is characterized by the differentiation of granulosal and thecal cells into luteal cells, cell hypertrophy and hyperplasia. As the CL matures, growth ceases and the tissue acquires the ability to undergo regression in response to luteolytic signals (prostaglandin F2alpha). The regulators of this transition are poorly understood. MicroRNA, posttranscriptional regulators of tissue development and function, are hypothesized to play a role during these processes. The goal of this study was to profile the expression of microRNA (miRNA) in the corpus luteum (CL) of Holstein cows at two time points of the estrous cycle (early-cycle (Day4) and midcycle (D9-12); day0= day of estrus) in order to investigate their role in regulating CL development and function. Sample size = 6 animals and two time points (3 animals per time point). The aim was to compare the expression of miRNA between the early-cycle (Day4) and midcycle (days9-12) CL The three cows designated for early-cycle time point received an injection of gonadotropin releasing hormone (GnRH; Factrel; Zoetis, Florham Park, NJ) to synchronize the ovulation of a dominant follicle, and were slaughtered 4 days later to collect a day 4 CL. The three cows designated for midcycle time point were observed after CIDR removal to determine the onset of estrus, and on days 9-12 of the estrous cycle, the CL was collected by culpotomy.