101 Effects of Active Immunization Against GnRH in Oocyte Donors with Cystic Ovarian Disease

Abstract

Cows intensively used as oocyte donors for in vitro embryo production (IVEP) are usually kept nonpregnant for prolonged intervals, exposed to successive hormonal treatments, and frequently become overweight. These are all risk factors for the development of endocrine unbalance and, consequently, cystic ovarian disease (COD). The aim of this study was to evaluate the effect of active immunization against gonadotropin-releasing hormone (GnRH) on (1) ovarian follicular population, and (2) development potential of oocytes used for IVEP. Nelore (Bos indicus) cows (n = 14), previously diagnosed with chronic COD (Faria et al. 2017 Anim. Reprod., in press), weighing 620.0 ± 12.8 kg and with body condition score of 4.1 ± 0.2, were assigned to control (n = 6) or treatment (n = 8) group. Cows in the treatment group received 2 SC injections of 1.0 mL of anti-GnRH vaccine (Bopriva, Zoetis, Brazil), 28 days apart (weeks 0 and 4), whereas cows in the control group received placebo on the same schedule. Transrectal ultrasonography was performed weekly from week 0 to evaluate the number and distribution of follicles among size classes, endometrial thickness, and clinical presence of mucometra. Immunization was considered effective (E-IM) when no follicles ≥5.0 mm were observed on the ovaries during a given examination. Cows having E-IM were then used as oocyte donors for IVEP. Cumulus-oocyte complexes (COC) were collected in 5 consecutive ovum pick-up weekly sessions. As a control for IVEP, oocytes from a slaughterhouse were used, with similar procedures performed on the same days and using the same semen batch. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC, USA) with repeated-measures statement was used to evaluate the effects of treatment, time, and interactions on ovarian endpoints; and the GLM procedure was used to analyse embryo production data. Results are shown as mean ± SEM. There were time and time × treatment effects on ovarian parameters. Treated cows had a decrease (P < 0.05) in the average diameter of the largest follicle and in the number of follicles ≥8 mm, and an increase (P < 0.05) in follicular population after week 6. Nonetheless, individual response to treatment was variable: only 50% of the cows (4 of 8) were E-IM at week 8, whereas 25% (2 of 8) still had COD (largest follicle ≥18.0 mm) at this timepoint. Overall, a negative correlation was detected between follicular population and the diameter of the largest follicle (r = –0.60, P < 0.0001) or the number of follicles ≥8 mm (r = –0.47, P < 0.0001). There was no effect (P > 0.05) of treatment on endometrial thickness or mucometra score. Cows with E-IM produced 22.2 ± 3.6 total and 12.9 ± 2.3 viable COC. Cleavage rate did not differ between E-IM and control (slaughterhouse) oocytes (70.8 ± 7.0 v. 75.1 ± 3.0%, respectively; P > 0.05); however, blastocyst rate was greater in the E-IM group compared with controls (39.7 ± 5.5 v. 20.5 ± 4.7%, respectively; P < 0.02). In summary, our results suggest that active immunization against GnRH leads to variable results in the distribution of the follicular population in cows with COD, but it does not negatively affect IVEP efficiency. This research was supported by Zoetis, CNPq, and CAPES.

Intraovarian injection of mesenchymal stem cells improves oocyte yield and in vitro embryo production in a bovine model of fertility loss

“…In Experiment 2, most donors had varied records of chronic COD and refractoriness to conventional GnRH or P4 treatments, so they were treated with an anti-GnRH vaccine. Previous studies have shown that cows receiving either GnRH immunization or GnRH agonist, despite having suppressed follicle growth, can be used as oocyte donors and produce embryos in vitro 14,48 . Therefore, we decided to include a group with FSH priming, and thus we could not use the same experimental model as in Experiment 1.…”

“…The cows underwent a gynecological exam by B-mode and color Doppler ultrasonography to characterize ovarian status. To control for the potential detrimental effects of COD, cows were treated with two injections of an anti-GnRH vaccine (Bopriva, Zoetis Saúde Animal, São Paulo, Brazil), given 30 days apart, as previously described 14 . Twenty days later, cows were re-evaluated and were distributed in a balanced manner according to ovarian antral follicle count (AFC) into one of the following experimental groups: a) control group (CG), intraovarian injection of saline; b) intraovarian injection of MSC (treatment in both ovaries); or c) injection of MSC after priming with 150 IU FSH (Pluset, Hertape Calier Saúde Animal, Juatuba, Brazil).…”

“…Few studies have evaluated ovarian damage caused by OPU, and these reported abnormalities such as tunica albuginea thickening, inflammation, stromal fibrosis, and adhesions [10][11][12] . Repeated OPU procedures have also been associated with endocrine abnormalities including increased plasma FSH/LH concentrations, follicle growth rate, and incidence of codominance 13 , and it is also a risk factor for the development of cystic ovarian disease 14 .…”