Assessment of peripheral markers and ultrasonographic parameters in pregnant mares receiving intramuscular or intrauterine cloprostenol.

The present study aimed to compare two methods of prostaglandin-induced abortion in mares by determining blood markers (progesterone, estradiol-17ß, alpha-fetoprotein, 13,14-dihydro-15-keto-prostaglandin-F2α (PGFM)), B-mode ultrasonographic parameters, and time until loss of fetal heartbeat. It was hypothesized that intrauterine infusion of cloprostenol results in earlier fetal compromise than intramuscular administration. Ovarian structures (number and sizes of follicles and corpora lutea area), fetal heartbeat, and fetal mobility of thirteen singleton pregnancies were assessed daily by transrectal ultrasonography until induction of pregnancy termination (60 ±â€¯2 days of gestation). Mares received 500 µg of cloprostenol intramuscularly every 12 h (IM, n = 7) or once transcervically (TC, n = 6). After initial cloprostenol administration, ultrasonographic examinations were repeated at 6-h intervals until loss of fetal heartbeat was detected. Plasma progesterone, estradiol-17ß, and alpha-fetoprotein were assessed for five days before and after pregnancy loss. In addition, plasma PGFM concentrations were assessed immediately before cloprostenol administration (0 min), and then 15, 30, and 45 min, and 1, 2, 3, 4, 6, 12 h after administration. Data were analyzed using the MIXED procedure with repeated measures in SAS. Significance was set at P < 0.05. All mares lost their pregnancies within 48 h after initial cloprostenol administration, with no difference in time to pregnancy loss. There were significant effects of time starting by 12 h post-induction of pregnancy termination but there was no time by group interaction for progesterone concentrations. Estradiol-17ß and alpha-fetoprotein concentrations were not altered upon impending abortion. Concentrations of PGFM increased significantly by 2 h after cloprostenol administration, but there were no differences between groups. No time effects or time by group interaction for fetal mobility and heartbeat was detected. Expectedly, the number and area of corpora lutea decreased significantly after cloprostenol administration with no significant differences between groups. In conclusion, intrauterine administration of cloprostenol was not different from repeated systemic administration to terminate the pregnancy. Both models for early fetal loss were equivalent for the endpoints assessed herein. The present study provides evidence that transcervical cloprostenol administration technique is repeatable in different settings and results in negligible side effects. While systemic administration results in colic-like signs and may result in severe reaction.

Safety assessment of DHA-rich microalgae from Schizochytrium sp.

Schizochytrium sp. (DRM) contains oil rich in highly unsaturated fatty acids (PUFAs). Docosahexaenoic acid (DHA) is the most abundant PUFA component of the oil (approx. 35% w/w). DHA-rich extracted oil from Schizochytrium sp. is intended for use as a nutritional ingredient in foods. As part of a comprehensive safety assessment program, the developmental toxicity of DRM was assessed in Sprague-Dawley derived rats [25/group, provided DRM in the diet at 0.6, 6, and 30% on gestation days (GD) 6-15] and in New Zealand White (NZW) rabbits (22/group, dosed with DRM at levels of 180, 600, and 1800 mg/kg/day by oral gavage on GD 6-19). Fish oil was used as a negative control at dose levels to provide an equivalent amount of fat to that received by the high-dose DRM rabbits. Maternal food consumption, body weights, and clinical signs were recorded at regular intervals throughout these studies. Animals were sacrificed on GD 20 (rats) and GD 29 (rabbits) and examined for implant status, fetal weight, sex, and morphologic development. No clinical signs of toxicity were observed. Maternal exposure to DRM during organogenesis did not adversely affect the frequency of postimplantation loss, mean fetal body weight/litter, or external, visceral, or skeletal malformations in either the rat or the rabbit. In the rats, neither maternal nor developmental toxicity was observed at any dietary concentration of DRM. Thus, 22 g/ kg/day(1) of DRM administered in the feed to pregnant rats during organogenesis was the NOEL (no-observed-effect level) for both maternal and developmental toxicity. In rabbits, no maternal toxicity was expressed at DRM dose levels of 180 and 600 mg/kg/day. As a possible consequence of the high-fat content of the fish oil and DRM, reductions in food consumption and body weight gain and a slight increase in abortions occurred in the fish oil control and 1800 mg/kg/day DRM groups. Developmental toxicity was not observed at any DRM dose level. Based on the results of this study, the NOEL for maternal toxicity of DRM was 600 mg/kg/day, and the NOEL for developmental toxicity was 1800 mg/kg/day in NZW rabbits.

Use of bromoergocryptine in the validation of protocols for the assessment of mechanisms of early pregnancy loss in the rat.

Validated protocols for evaluating maternally mediated mechanisms of early pregnancy failure in rodents are needed for use in the risk assessment process. To supplement previous efforts in the validation of a panel of protocols assembled for this purpose, bromoergocryptine (BEC) was used as a model compound because it is known to inhibit pituitary prolactin secretion. BEC was tested using the early pregnancy protocol (EPP), the decidual cell response technique (DCR), the pre- vs postimplantation protocol (PPP), and embryo transport rate analysis (ETRA). These protocols evaluate the effects of chemicals on multiple endpoints following exposure during (a) the first 8 days of pregnancy, (b) early pseudopregnancy accompanied by decidual induction, (c) the pre- and postimplantation intervals of early pregnancy, or (d) the period of embryo transport. In the EPP, dosing with BEC during Days 1-8 of pregnancy reduced the number of implantation sites found on Day 9 as well as serum progesterone. The DCR technique revealed a dose-dependent inhibition of decidual growth concomitant with decreased serum progesterone as a result of BEC treatment. A modified DCR technique using hormone-supplemented ovariectomized rats demonstrated that BEC did not impair decidual growth in the presence of adequate progestogenic support. Pre- vs postimplantation dosing indicated that implantation is vulnerable to BEC effects at least through Day 4. BEC had no effect on embryo transport rate. Data from these protocols identified BEC as having adverse maternal effects during early pregnancy. While the pituitary was not identified by these protocols as the site of BEC's primary action, the protocols did identify a reduction in serum progesterone and impaired uterine function as toxicological mechanisms mediating the reduced fertility seen following BEC exposure.