Animal Science Group, School of Agriculture and Environment, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand.
School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand.
Theriogenology. 2023 Sep 15;208:77-87. doi: 10.1016/j.theriogenology.2023.05.024. Epub 2023 Jun 4.
While captivity-related stress and the associated rise in baseline glucocorticoid (GC) concentrations have been linked to ovarian quiescence in some felid species, no study has examined the effects of elevated GC on oocyte quality. This study examined the effects of exogenous GC administration on the ovarian response and oocyte quality of domestic cats after an ovarian stimulation protocol. Entire mature female cats were divided into treatment (n = 6) and control (n = 6) groups. Cats in the GC treatment (GCT) group were given 1 mg kg oral prednisolone daily from Day 0-45. All cats (n = 12) were given 0.088 mg kg day progesterone orally from Day 0-37, before treatment with 75 IU eCG im to induce follicular growth on Day 40, followed by 50 IU hCG im 80 h later to induce ovulation. Cats were ovariohysterectomised 30 h after the hCG treatment. Blood samples were collected on Days 0, 10, 30 and 40 (prior to eCG treatment), 80 h after eCG treatment, and on Day 45 for cortisol, glucose, prednisolone, oestradiol, and progesterone analysis. Cortisol concentrations did not differ between treatment groups throughout the study. Mean glucose concentrations were higher in the GCT cats (P = 0.004). Prednisolone was undetectable in all samples. Oestradiol and progesterone concentrations confirmed that the eCG treatment stimulated follicular activity and ovulation in all cats. Following ovariohysterectomy, the ovarian responses were graded (1 = excellent, 4 = poor) and oocytes retrieved from the oviducts. Each oocyte was given a total oocyte score (TOS: using an 9-point scale, 8 = best) based on four parameters: oocyte morphology, size, ooplasm uniformity and granularity, and zona pellucida (ZP) thickness and variation. Ovulation was confirmed in all cats, with a mean of 10.5 ± 1.1 ovulations per cat. Ovarian mass, ovarian response, number of ovulations, and oocyte recovery did not differ between groups. Oocyte diameter did not differ between the groups, but the ZP was thinner in the GCT group (3.1 ± 0.3 μm vs. 4.1 ± 0.3 μm, P = 0.03). The TOS was similar between treatment and control cats, but the ooplasm grade was lower (1.5 ± 0.1 vs. 1.9 ± 0.1, P = 0.01) and there was a tendency for ZP grade to be poorer (0.8 ± 0.1 vs. 1.2 ± 0.2; P = 0.08) in the treatment group. In conclusion, the GC treatment resulted in morphological changes to oocytes collected following ovarian stimulation. Whether these changes would affect fertility warrants further investigation.
虽然与圈养相关的应激和相关的基础糖皮质激素 (GC) 浓度升高与一些猫科动物的卵巢静止有关，但尚无研究检查升高的 GC 对卵母细胞质量的影响。本研究检查了外源性 GC 给药对卵巢刺激方案后家猫卵巢反应和卵母细胞质量的影响。整个成熟雌性猫被分为治疗（n = 6）和对照组（n = 6）。GC 治疗（GCT）组的猫每天口服 1mg/kg 泼尼松龙，从第 0-45 天。所有猫（n = 12）从第 0-37 天每天口服 0.088mg/kg 孕酮，然后在第 40 天用 75IU eCG 肌内注射诱导卵泡生长，然后在 80 小时后用 50IU hCG 肌内注射诱导排卵。在 hCG 治疗后 30 小时，猫被卵巢子宫切除术。在第 0、10、30 和 40 天（在 eCG 治疗前）、eCG 治疗后 80 小时以及第 45 天采集血液样本，用于皮质醇、葡萄糖、泼尼松龙、雌二醇和孕酮分析。在整个研究过程中，治疗组之间的皮质醇浓度没有差异。GCT 猫的平均葡萄糖浓度较高（P = 0.004）。所有样本中均未检测到泼尼松龙。雌二醇和孕酮浓度证实 eCG 治疗刺激了所有猫的卵泡活动和排卵。卵巢子宫切除术后，对卵巢反应进行分级（1=优秀，4=差），并从输卵管中取出卵母细胞。根据四个参数对每个卵母细胞进行总卵母细胞评分（TOS：使用 9 分制，8=最佳）：卵母细胞形态、大小、卵质均匀性和颗粒度以及透明带（ZP）厚度和变化。所有猫均确认排卵，平均每只猫排卵 10.5±1.1 个。卵巢质量、卵巢反应、排卵数和卵母细胞回收率在组间无差异。卵母细胞直径在组间无差异，但 GCT 组的 ZP 较薄（3.1±0.3μm 与 4.1±0.3μm，P=0.03）。治疗组和对照组猫的 TOS 相似，但卵质等级较低（1.5±0.1 与 1.9±0.1，P=0.01），ZP 等级较差的趋势（0.8±0.1 与 1.2±0.2；P=0.08）。总之，GC 治疗导致卵巢刺激后采集的卵母细胞发生形态变化。这些变化是否会影响生育能力需要进一步研究。
