Oocytes recovered from cows treated with retinol become unviable as blastocysts produced in vitro

Abstract

Retinoids have been shown to enhance developmental competence of the oocyte in cattle, sheep and pigs. In this study we investigated whether exogenous retinol stimulates the bovine oocyte during its intrafollicular growth and the time limits of exposure to exogenous retinol. In addition, we also determined the efficiency of ovum pick-up techniques in combination with retinol treatment and the viability of embryos after transfer to recipients. In Experiment 1, heifers were injected with retinol or vehicle, and concentrations of retinol in the blood were analysed on Day 0 (prior to injection), Day 1 and, together with follicular fluid, Day 4. Blood retinol increased by Day 1 and cleared on Day 4, but retinol remained higher within the follicle. In Experiment 2, oocyte donors were injected weekly with retinol or vehicle four times during a twice-per-week cycle of eight recovery sessions (starting 4 days before the first session), followed by a second eight-session cycle without treatment. Oocytes recovered were fertilized and culturedin vitro.Retinol treatment yielded higher numbers of low-quality oocytes throughout, although retinol measured during cycles did not change. Total oocytes, and morulae and blastocyst rates, increased during the first five sessions following treatment with retinol. As previously shown with oocytes from slaughterhouse ovaries, retinoic acid stimulated blastocyst development. Following transfer to recipients, blastocysts from oocytes exposed to retinol were unable to establish pregnancy. Our study confirms the existence of an effect of retinol on the intrafollicular oocyte in the cow and provides evidence regarding the teratogenic effect of retinol.

Retinoic acid‐metabolizing enzyme cytochrome P450 26a1 (cyp26a1) is essential for implantation: Functional study of its role in early pregnancy

“…Indeed, excessive RA decreases the viability of mouse blastocysts in vitro, because RA induces cell death and inhibits cell proliferation of blastocysts (Huang et al, 2003;Huang et al, 2005). In addition, blastocysts developed from cow oocytes exposed to retinol were unable to establish pregnancy (Hidalgo et al, 2005).…”

Bovine Early Embryonic Development and Vitamin A

“…1984; Schweigert and Zucker 1988; Haliloglu et al. 2002; Hidalgo et al. 2005; our unpublished results) in proportion to the respective blood contents (Chew et al.…”

“…The above challenges can be tested in part by treating oocyte donor cows with ROH, as those oocytes aspirated from the follicle would develop free from the effects of tissular ROH when cultured in vitro up to the blastocyst stage. Recent work from our group (Hidalgo et al. 2005) analysed the effects of ROH directly on the oocyte during its intrafollicular growth, the time limits of exposure to exogenous ROH and the viability of these oocytes.…”

Analysis of Follicular Fluid Retinoids in Women Undergoing In Vitro Fertilization: Retinoic Acid Influences Embryo Quality and Is Reduced in Women With Endometriosis

“…10,[34][35][36][37][38][39][40] To this end, in cattle, sheep, and pigs, retinoids have been shown to enhance competence of oocyte development. 36 Although concentrations of ROL in the FF of women and animals have previously been quantified, 13,16,41 direct determination of the active metabolic products including ATRA has not, to our knowledge, been reported. Our results indicate that the ratio of plasma to FF concentrations of ROL and the ATRA isomers ranged from 1.6 to 2.3 while that of the REs showed a ratio of 4.2.…”