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

A cDNA library was constructed from poly(A) RNA obtained from Day 14 nonbred equine endometrium. A cDNA probe for porcine retinol-binding protein (RBP) was used to screen the library, and a complete cDNA sequence (1133 bp, excluding the poly(A) tail) was obtained. Endometrial biopsies were obtained from cycling, nonbred mares at Days 0, 1, 4, 8, 10, 11, 13, and 15 and from pregnant mares at Days 11, 13, 15, and 17 after ovulation (n = 2 mares each day). Endometrial biopsies were also taken from 18 noncycling anestrous mares after the following treatments: C (vehicle control for 1 day, n = 3), E (estradiol-17 valerate, 5 mg/day for 6 days, n = 3), P (progesterone, 250 mg/day for 6 days, n = 4), ESP (E for 6 days followed by, P for 6 days, n = 4), and ELP (E for 6 days followed by P for 12 days, n = 4). Northern blot analyses were performed on total RNA (30 micrograms) using cDNA probes to equine (e) RBP and human glyceraldehyde-3 phosphate dehydrogenase (G3PDH). The RBP RNA levels (normalized to G3PDH) from nonbred mares were low during early diestrus and increased after Day 10, and RBP RNA levels from pregnant mares were similar to those of nonbred mares for corresponding days. E tended to decrease endometrial RBP RNA; and P, ESP, and ELP increased it compared to C. There were no significant differences among P, ESP, and ELP RBP RNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)