Changes in equine endometrial retinol-binding protein RNA during the estrous cycle and early pregnancy and with exogenous steroids.

The research studies changes in equine endometrial retinol-binding protein (RBP) RNA during different periods of a horse’s reproduction cycle and early pregnancy, as well as with the introduction of external steroids.

Research Methodology

• The researchers constructed a cDNA library using poly(A) RNA obtained from Day 14 nonbred equine endometrium.
• They used a cDNA probe for porcine retinol-binding protein (RBP) to screen this library, and extracted a full cDNA sequence.
• Endometrial biopsies were collected from cycling, nonbred mares on various days of the estrous cycle and from pregnant mares at specific days after ovulation.
• Same procedures were followed with noncycling, anestrous mares, following different hormonal treatments. These included treatment with control vehicle (C), estradiol-17 valerate (E), progesterone (P), estradiol + progesterone (ESP), and extended estradiol + progesterone (ELP).
• Northern blot analyses were performed on total RNA using cDNA probes to equine retinol-binding protein and human glyceraldehyde-3 phosphate dehydrogenase (G3PDH).

Research Findings

• RBP RNA levels from nonbred mares were low during early diestrus and increased after Day 10.
• RBP RNA levels from pregnant mares were similar to those of nonbred mares for corresponding days, indicating consistency between nonbred and pregnant mares at specific periods of their reproductive cycle.
• Research findings showed estradiol treatment tended to decrease the endometrial RBP RNA level while progesterone and its combinations (ESP and ELP) increased it when compared to the control group. However, there were no significant differences among RBP RNA levels in the progesterone, ESP, and ELP treated groups.

This research offers valuable insight into the impact of various hormones and states of the reproductive cycle on retinol-binding protein RNA in horses, which contributes to the understanding of equine reproductive biology.