Karvinen Sira M, Silvennoinen Mika, Ma Hongqiang, Törmäkangas Timo, Rantalainen Timo, Rinnankoski-Tuikka Rita, Lensu Sanna, Koch Lauren G, Britton Steven L, Kainulainen Heikki
Department of Biology of Physical Activity, Neuromuscular Research Center, University of Jyväskylä Jyväskylä, Finland.
Department of Health Sciences, University of Jyväskylä Jyväskylä, Finland.
Front Physiol. 2016 Jul 25;7:311. doi: 10.3389/fphys.2016.00311. eCollection 2016.
The production of heat, i.e., thermogenesis, is a significant component of the metabolic rate, which in turn affects weight gain and health. Thermogenesis is linked to physical activity (PA) level. However, it is not known whether intrinsic exercise capacity, aging, and long-term voluntary running affect core body temperature. Here we use rat models selectively bred to differ in maximal treadmill endurance running capacity (Low capacity runners, LCR and High capacity Runners, HCR), that as adults are divergent for aerobic exercise capacity, aging, and metabolic disease risk to study the connection between PA and body temperature. Ten high capacity runner (HCR) and ten low capacity runner (LCR) female rats were studied between 9 and 21 months of age. Rectal body temperature of HCR and LCR rats was measured before and after 1-year voluntary running/control intervention to explore the effects of aging and PA. Also, we determined whether injected glucose and spontaneous activity affect the body temperature differently between LCR and HCR rats at 9 vs. 21 months of age. HCRs had on average 1.3°C higher body temperature than LCRs (p < 0.001). Aging decreased the body temperature level of HCRs to similar levels with LCRs. The opportunity to run voluntarily had a significant impact on the body temperature of HCRs (p < 0.001) allowing them to maintain body temperature at a similar level as when at younger age. Compared to LCRs, HCRs were spontaneously more active, had higher relative gastrocnemius muscle mass and higher UCP2, PGC-1α, cyt c, and OXPHOS levels in the skeletal muscle (p < 0.050). These results suggest that higher PA level together with greater relative muscle mass and higher mitochondrial content/function contribute to the accumulation of heat in the HCRs. Interestingly, neither aging nor voluntary training had a significant impact on core body temperature of LCRs. However, glucose injection resulted in a lowering of the body temperature of LCRs (p < 0.050), but not that of HCRs. In conclusion, rats born with high intrinsic capacity for aerobic exercise and better health have higher body temperature compared to rats born with low exercise capacity and disease risk. Voluntary running allowed HCRs to maintain high body temperature during aging, which suggests that high PA level was crucial in maintaining the high body temperature of HCRs.
产热，即生热作用，是代谢率的一个重要组成部分，而代谢率又会影响体重增加和健康状况。生热作用与身体活动（PA）水平相关。然而，目前尚不清楚内在运动能力、衰老和长期自愿跑步是否会影响核心体温。在此，我们使用经过选择性培育的大鼠模型，这些大鼠在跑步机上的最大耐力跑能力有所不同（低能力跑步者，LCR和高能力跑步者，HCR），成年后在有氧运动能力、衰老和代谢疾病风险方面存在差异，以此来研究身体活动与体温之间的联系。对10只高能力跑步者（HCR）和10只低能力跑步者（LCR）雌性大鼠在9至21月龄期间进行了研究。在1年的自愿跑步/对照干预前后，测量了HCR和LCR大鼠的直肠体温，以探究衰老和身体活动的影响。此外，我们还确定了在9月龄和21月龄时，注射葡萄糖和自发活动对LCR和HCR大鼠体温的影响是否不同。HCR的平均体温比LCR高1.3°C（p < 0.001）。衰老使HCR的体温水平降至与LCR相似的水平。自愿跑步的机会对HCR的体温有显著影响（p < 0.001），使它们能够将体温维持在与年轻时相似的水平。与LCR相比，HCR自发活动更频繁，腓肠肌相对质量更高，骨骼肌中UCP2、PGC - 1α、细胞色素c和氧化磷酸化水平更高（p < 0.050）。这些结果表明，较高的身体活动水平以及更大的相对肌肉质量和更高的线粒体含量/功能，有助于HCR产热。有趣的是，衰老和自愿训练对LCR的核心体温均无显著影响。然而，注射葡萄糖会使LCR的体温降低（p < 0.050），但对HCR则无此影响。总之，与天生运动能力低且有疾病风险的大鼠相比，天生有氧运动能力高且健康状况更好的大鼠体温更高。自愿跑步使HCR在衰老过程中能够维持较高体温，这表明高身体活动水平对于维持HCR的高体温至关重要。
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