Cadmium (Cd) is an environmental endocrine-disrupting pollutant which mainly occurs in pulsed manner in natural waters, while traditional toxicology experiments have less examined the effects of pulsed exposure. Here, we studied the effects of short-term (7 days) continuous and pulse exposure to 100 μg/L Cd on gut morphology and microbiota of frogs (Pelophylax nigromaculatus) during pre-hibernation. Compared to continuous exposure, Cd pulse exposure significantly increased individual mortality and decreased the villi height and the ratio of villi height to crypt depth of the gut. Cd continuous and pulse exposure both changed the community structure and relative abundance of intestinal microbiota. Compared to continuous exposure, Cd pulse exposure significantly decreased the relative abundance of beneficial bacteria (e.g., Cetobacterium and Aeromonas genus), and significantly increased the relative abundance of harmful bacteria (e.g., Parabacteroides, Odoribacter, and Acinetobacter genus). This study shows that the gut histology and microbiota of amphibians during pre-hibernation are more susceptible to Cd pulse exposure than continuous exposure.

镉（Cd）是一种环境内分泌干扰污染物，主要以脉冲方式出现在天然水中，而传统的毒理学实验较少研究脉冲暴露的影响。在这里，我们研究了短期（7 天）连续和脉冲暴露于 100 μg/L Cd 对青蛙肠道形态和微生物群的影响（Pelophylax nigromaculatus) 在冬眠前。与连续暴露相比，Cd 脉冲暴露显着增加了个体死亡率并降低了肠道的绒毛高度和绒毛高度与隐窝深度的比率。Cd 连续和脉冲暴露都改变了肠道微生物群的群落结构和相对丰度。与连续暴露相比，Cd 脉冲暴露显着降低了有益细菌（例如，鲸蜡杆菌和气单胞菌属）的相对丰度，并显着增加了有害细菌（例如，副杆菌属、臭杆菌属和不动杆菌属）的相对丰度。属）。这项研究表明，两栖动物在冬眠前的肠道组织学和微生物群比持续暴露更容易受到镉脉冲的影响。