Morfeld Kari A, Brown Janine L
Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA 22630, USA.
Reprod Fertil Dev. 2016 Apr;28(5):640-7. doi: 10.1071/RD14140.
The purpose of the present study was to determine whether excessive body fat and altered metabolic hormone concentrations in the circulation were associated with ovarian acyclicity in the world's largest land mammal, the African elephant. We compared body condition, glucose, insulin and leptin concentrations and the glucose-to-insulin ratio (G:I) between cycling (n=23; normal 14-16 week cycles based on serum progestagens for at least 2 years) and non-cycling (n=23; consistent baseline progestagen concentrations for at least 2 years) females. A validated body condition score (BCS) index (five-point scale; 1=thinnest, 5=fattest) was used to assess the degree of fatness of the study elephants. The mean BCS of non-cycling elephants was higher than that of their cycling counterparts. There were differences in concentrations of serum metabolic biomarkers, with non-cycling elephants in the BCS 5 category having higher leptin and insulin concentrations and a lower G:I ratio than cycling BCS 5 females. Using 'non-cycling' as the outcome variable in regression models, high BCS was a strong predictor of a non-cycling status. This study provides the first evidence that ovarian acyclicity in zoo African elephants is associated with body condition indicative of obesity, as well as elevated, perturbed biomarkers of metabolic status.
本研究的目的是确定在世界上最大的陆地哺乳动物非洲象中，体内脂肪过多和循环中代谢激素浓度的改变是否与卵巢无周期性有关。我们比较了处于发情周期（n = 23；基于血清孕激素，正常的14 - 16周周期至少持续2年）和非发情周期（n = 23；至少2年孕激素浓度持续处于基线水平）的雌性非洲象的身体状况、葡萄糖、胰岛素和瘦素浓度以及葡萄糖与胰岛素的比值（G:I）。使用经过验证的身体状况评分（BCS）指数（五分制；1 = 最瘦，5 = 最胖）来评估研究对象大象的肥胖程度。非发情周期大象的平均BCS高于处于发情周期的大象。血清代谢生物标志物的浓度存在差异，BCS为5级的非发情周期大象比处于发情周期的BCS为5级的雌性大象具有更高的瘦素和胰岛素浓度以及更低的G:I比值。在回归模型中，以“非发情周期”作为结果变量，高BCS是无发情周期状态的有力预测指标。本研究首次提供证据表明，动物园中的非洲象卵巢无周期性与表明肥胖的身体状况以及代谢状态的生物标志物升高和紊乱有关。
