Implication of metabolomic profiles to wide thermoneutral zone in Mongolian gerbils (Meriones unguiculatus)

Abstract

Mongolian gerbils (Meriones unguiculatus) have evolved a wide thermoneutral zone (26.5-38.9 °C) and high upper critical temperature, and appear to have a high tolerance for heat exposure. Here, we use a metabolomic approach to measure global metabolite profiles for gerbils between lower (27 °C) and upper critical temperatures (38 °C) to investigate the role of metabolomic characterization in maintaining basal metabolic rates within a wide thermoneutral zone. We found that in serum and liver, 14 and 19 metabolites were significantly altered, respectively. In the aerobic respiration-related tricarboxylic cycle (TCA), 5 intermediates (isocitric acid, cis-aconitic acid, α-ketoglutaric acid, fumaric acid and malic acid) were increased in serum in 38 °C animals; however, no such increase was found in the liver. A stable level of hepatic TCA cycle intermediates may be related to the steady state of aerobic respiration at 38 °C. Metabolomic results also revealed that acute heat exposure caused increased oxidative stress and low molecular weight antioxidants in Mongolian gerbils. Increased methionine and 2-hydroxybutyrate suggest an accelerated synthesis of glutathione. Increased urate and its precursors, inosine and hypoxanthine, were detected at 38 °C. Glucuronate, threonate and oxalate involved in ascorbate synthesis and degradation were increased in serum at 38 °C. In conclusion, although dramatic metabolomic variation was found, a stable hepatic TCA cycle may contribute to maintaining a constant basal metabolic rate within a wide thermoneutral zone in Mongolian gerbils.

Metabolomics Profiling of Serum and Urine in Three Beef Cattle Breeds Revealed Different Levels of Tolerance to Heat Stress

“…In previous studies, heat stress led to upregulation of the TCA cycle, which increased levels of TCA cycle intermediates, such as citric acid, cis-aconitic acid, αketoglutaric acid, succinic acid, fumaric acid, and malic acid. 38,43 In the present study, we found that serum and urine levels of citric acid, aconitic acid, and fumaric acid were significantly higher in the SXC group in comparison with the JMY and XHC groups. Moreover, levels of citric acid, aconitic acid, and succinic acid were significantly higher in the XHC group in comparison with the JMY group.…”

High Ambient Temperature Aggravates Experimental Autoimmune Uveitis Symptoms

“…Previous studies have suggested that the intermediates α-ketoglutaric acid, fumaric acid and succinic acid of the aerobic respiration-related TCA cycle were increased in plasma from animals kept at a high ambient temperature (Shi and Wang, 2016;Nonaka et al, 2018). Succinic acid can induce higher frequencies of helper T cells by amplifying the antigen presentation of monocytes through succinate receptor 1, but failed to activate T cells by itself (Rubic et al, 2008;Saraiva et al, 2018).…”

Higher Concentration of Dietary Selenium, Zinc, and Copper Complex Reduces Heat Stress-Associated Oxidative Stress and Metabolic Alteration in the Blood of Holstein and Jersey Steers

“…In contrast, mineral supplementation did not affect the metabolic intermediates of glycolysis in Holstein steers, which might have caused breed-specific metabolic adaptation. HS upregulates the TCA cycle, leading to higher levels of metabolic intermediates, such as citric acid, α-ketoglutaric acid, succinic acid, fumaric acid, and malic acid [ 13 , 70 ]. In this study, decreasing patterns of succinic acid and malic acid, along with increased mineral supplementation, were observed in both breeds.…”