Coping with extremes: lowered myocardial phosphofructokinase activities and glucose content but increased fatty acids content in highland Eurasian Tree Sparrows

Abstract

Background Efficient and selective utilization of metabolic substrates is one of the key strategies in high-altitude animals to cope with hypoxia and hypothermia. Previous findings have shown that the energy substrate utilization of highland animals varies with evolutionary history and phylogeny. The heart is a proxy for the cardiopulmonary system, and the metabolic substrate utilization in the myocardium is also under the strong selective pressure of chronically hypoxic and hypothermic environments. However, little information is available on the physiological adjustments in relation to metabolic substrate utilization in the myocardium for coping with high-altitude environments. Methods We compared the metabolic enzyme activities, including hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), citrate synthase (CS), carnitine palmitoyl transferase 1 (CPT-1), lactic dehydrogenase (LDH), and creatine kinase (CK), and metabolic substrate contents including glucose (Glu), triglyceride (TG), and free fatty acid (FFA) in the myocardium of a typical human commensal species, Eurasian Tree Sparrows (Passermontanus) between the Qinghai-Tibet Plateau (the QTP, 3230 m) and low altitude population (Shijiazhuang, 80 m), and between sexes. Results Among the seven metabolic enzymes and three substrates investigated, we identified no significant differences in PK, CPT-1, HK, CS, LDH, and CK activities and TG content of the myocardium between high and low altitude populations. However, the QTP sparrows had significantly lower Glu content and PFK activities but higher FFA content relative to their lowland counterparts. In addition, male sparrows had higher myocardial HK and CS activities relative to females, independent of altitude. Conclusions Our results showed that the QTP sparrows elevated fatty acid utilization rather than glucose preference in the myocardium relative to lowland counterpart, which contributes to uncovering both the physiological adjustments for adapting to the extreme conditions of the QTP, intraspecifically.

Birds and plastic pollution: recent advances

“…As birds have a great number of specific groups, different groups can be used to assess the plastic pollution burden, long-term effects of MPs exposure in various environments, and toxicological effects in the laboratory. For instance, human commensal species, such as the Eurasian Tree Sparrow (Sun et al 2016 ; Li et al 2019 ; Yang et al 2019 ; Ding et al 2021 ), House Sparrow ( P. domesticus ) (Hanson et al 2020 ) and House Wren ( Troglodytes aedon ) (Juárez et al 2020 ) utilize human resources in rural and urban areas and have a remarkably broad distribution range. These species could be used as bioindicators to evaluate the plastic pollution burden in different environments because they have been well studied in the past two decades.…”

Physiological but not morphological adjustments along latitudinal gradients in a human commensal species, the Eurasian tree sparrow

“…The Eurasian tree sparrow (Passer montanus; ETS) is a typical human commensal species widely distributed across Eurasia. Morphological and physiological features of the ETS have been shown to vary with altitude (Sun et al 2016 ;Ding et al 2021;Nabi et al 2021 ), lifehistory stage (Li et al 2016;Wang et al 2022), urbanization (Zhang et al 2011), and captivity stress (Li et al 2019). Notably, unlike other avian species, ETSs neither increase their body mass at a higher latitude (Zheng et al 2014) nor decrease baseline and stressinduced CORT levels during their breeding season at higher altitudes (Li et al 2011).…”