School of Life Sciences, Ulsan National Institute of Science and Technology, UNIST- gil 50, 44919, Eonyang-eup, Ulju, Ulsan, Republic of Korea.
National Institute of Ecology, Geumgang-ro 1210, Maseo-myeon, 33657, Seocheon, Chungnam, Republic of Korea.
BMC Ecol Evol. 2021 May 4;21(1):77. doi: 10.1186/s12862-021-01802-z.
In temperate regions many small mammals including bats hibernate during winter. During hibernation these small mammals occasionally wake up (arouse) to restore electrolyte and water balance. However, field data on water stress and concentration of bodily fluids during hibernation is scarce. Urinary creatinine concentration has long been used to calibrate urinary hormone concentration due to its close correlation with urine concentration. Therefore, by investigating urinary creatinine concentration, we can estimate bodily fluid concentration. In this study, we investigated changes in urinary creatinine from greater horseshoe bats (Rhinolophus ferrumequinum) hibernating in abandoned mineshafts in two regions in South Korea.
We collected 74 urine samples from hibernating greater horseshoe bats from 2018 to 2019. We found that urinary creatinine concentration was higher in February and March and then declined in April. There were also indications of a sex difference in the pattern of change in creatinine concentration over the three months. Bats in the warmer and less humid mineshaft had higher urinary creatinine concentrations than bats in the colder and more humid mineshaft.
These results indicate that hibernating bats face water stress as urinary concentration increases during winter and that water stress may vary depending on the microenvironment. Sex differences in behaviour during hibernation may influence arousal frequency and result in sex differences in changes in urinary creatinine concentration as hibernation progresses. Although further behavioural and endocrinal investigations are needed, our study suggests that urinary creatinine concentration can be used as a proxy to estimate the hydration status of bats and the effect of sex and environmental factors on arousal patterns during hibernation.
在温带地区，许多小型哺乳动物包括蝙蝠会在冬季冬眠。在冬眠期间，这些小型哺乳动物偶尔会醒来（唤醒）以恢复电解质和水的平衡。然而，关于冬眠期间水应激和体液浓度的野外数据却很少。由于尿肌酐浓度与尿液浓度密切相关，因此长期以来一直被用于校准尿液激素浓度。因此，通过研究尿肌酐浓度，我们可以估计体液浓度。在这项研究中，我们调查了在韩国两个地区废弃的矿井中冬眠的大马蹄蝠（Rhinolophus ferrumequinum）尿液中肌酐的变化。
我们从 2018 年到 2019 年收集了 74 份来自冬眠大马蹄蝠的尿液样本。我们发现，2 月和 3 月的尿肌酐浓度较高，然后在 4 月下降。在三个月内，肌酐浓度变化的模式也显示出性别差异。在温暖且湿度较低的矿井中蝙蝠的尿肌酐浓度高于在寒冷且湿度较高的矿井中蝙蝠的尿肌酐浓度。
这些结果表明，随着冬季尿液浓缩度的增加，冬眠蝙蝠面临水应激，而且水应激可能因微环境而异。冬眠期间行为上的性别差异可能会影响唤醒频率，并导致随着冬眠的进行，尿肌酐浓度的变化出现性别差异。尽管需要进一步的行为和内分泌学研究，但我们的研究表明，尿肌酐浓度可以作为估计蝙蝠水合状态以及性别和环境因素对冬眠期间唤醒模式影响的替代指标。
