Key Laboratory of Tropical Island Ecology, Ministry of Education, Hainan key Laboratory of Tropical Animal and Plant Ecology, College of Life Sciences, Hainan Normal University, Haikou 571158, China.
Key Laboratory of Tropical Island Ecology, Ministry of Education, Hainan key Laboratory of Tropical Animal and Plant Ecology, College of Life Sciences, Hainan Normal University, Haikou 571158, China.
Comp Biochem Physiol C Toxicol Pharmacol. 2023 Jan;263:109491. doi: 10.1016/j.cbpc.2022.109491. Epub 2022 Oct 17.
In aquatic organisms, ammonia is one of the major factors that affect energy levels when it exceeds its optimal concentration. Numerous studies have examined the effects of ammonia on aquatic animals, but its effect on metabolism is still unknown. The effect of ammonia on carbohydrates and lipid metabolism in the Chinese striped neck turtle (Mauremys sinensis) was investigated in this study by exposing the turtle to two different ammonia concentrations (A100: 1.53 mg L) and (A200: 2.98 mg L) for 24 and 48 h, respectively. Our results showed that the mRNA expression of adenosine monophosphate-activated protein kinase α1 (AMPKα1) significantly increased only in A100 at 24 h, whereas its activity increased in both ammonia-exposed groups. The two AMPK-regulated transcription factors responsible for carbohydrate metabolism also exhibited changes in ammonia-treated groups, as hepatocyte nuclear factor-4-alpha (HNF4α) increased and forkhead box protein O1 (FoxO1) decreased. The expression of phosphofructokinase (PFK) and glucose-6-phosphatase (G-6-PAS) was subsequently downregulated. In addition, transcription factors, carbohydrate-responsive element-binding protein (ChREBP), and sterol regulatory element-binding protein 1c (SREBP-1c), which are known to be involved in lipogenesis, were suppressed. These downstream genes include fatty acid synthase, stearoyl CoA desaturase, and acetyl-CoA carboxylase (FAS, SCD-1 and ACC). Moreover, the glucose content decreased, whereas the triglyceride content increased significantly in A200 at 24 h. We concluded that AMPK signaling inhibits gluconeogenesis and lipogenesis, and promotes glycolysis to meet energy demand under stressful conditions in M. sinensis.
在水生生物中，当氨超过其最佳浓度时，氨是影响能量水平的主要因素之一。许多研究都考察了氨对水生动物的影响，但氨对代谢的影响仍不清楚。本研究通过分别将中华鳖（Mauremys sinensis）暴露于两种不同浓度的氨（A100：1.53 mg/L 和 A200：2.98 mg/L）24 和 48 h，研究了氨对中华鳖碳水化合物和脂质代谢的影响。结果表明，只有在 A100 组中，24 h 时腺苷单磷酸激活蛋白激酶α1（AMPKα1）的 mRNA 表达显著增加，而其活性在两个氨暴露组中均增加。两种 AMPK 调节的参与碳水化合物代谢的转录因子也在氨处理组中发生变化，肝细胞核因子-4-α（HNF4α）增加，叉头框蛋白 O1（FoxO1）减少。磷酸果糖激酶（PFK）和葡萄糖-6-磷酸酶（G-6-PAS）的表达随后下调。此外，参与脂肪生成的转录因子碳水化合物反应元件结合蛋白（ChREBP）和固醇调节元件结合蛋白 1c（SREBP-1c）也受到抑制。这些下游基因包括脂肪酸合酶、硬脂酰 CoA 去饱和酶和乙酰 CoA 羧化酶（FAS、SCD-1 和 ACC）。此外，在 A200 组中，24 h 时葡萄糖含量显著降低，而三酰基甘油含量显著增加。我们得出结论，AMPK 信号通路在应激条件下抑制糖异生和脂肪生成，促进糖酵解以满足中华鳖的能量需求。
