School of Anthropology, University of Arizona, Tucson, AZ 85721, USA.
J Exp Biol. 2012 Apr 15;215(Pt 8):1331-6. doi: 10.1242/jeb.063677.
Humans report a wide range of neurobiological rewards following moderate and intense aerobic activity, popularly referred to as the 'runner's high', which may function to encourage habitual aerobic exercise. Endocannabinoids (eCBs) are endogenous neurotransmitters that appear to play a major role in generating these rewards by activating cannabinoid receptors in brain reward regions during and after exercise. Other species also regularly engage in endurance exercise (cursorial mammals), and as humans share many morphological traits with these taxa, it is possible that exercise-induced eCB signaling motivates habitual high-intensity locomotor behaviors in cursorial mammals. If true, then neurobiological rewards may explain variation in habitual locomotor activity and performance across mammals. We measured circulating eCBs in humans, dogs (a cursorial mammal) and ferrets (a non-cursorial mammal) before and after treadmill exercise to test the hypothesis that neurobiological rewards are linked to high-intensity exercise in cursorial mammals. We show that humans and dogs share significantly increased exercise-induced eCB signaling following high-intensity endurance running. eCB signaling does not significantly increase following low-intensity walking in these taxa, and eCB signaling does not significantly increase in the non-cursorial ferrets following exercise at any intensity. This study provides the first evidence that inter-specific variation in neurotransmitter signaling may explain differences in locomotor behavior among mammals. Thus, a neurobiological reward for endurance exercise may explain why humans and other cursorial mammals habitually engage in aerobic exercise despite the higher associated energy costs and injury risks, and why non-cursorial mammals avoid such locomotor behaviors.
人类在进行适度和剧烈的有氧运动后会报告一系列广泛的神经生物学奖励，通常被称为“跑步者的快感”，这可能有助于鼓励习惯性的有氧运动。内源性大麻素（eCBs）是内源性神经递质，它们似乎通过在运动中和运动后激活大脑奖励区域中的大麻素受体来产生这些奖励中发挥主要作用。其他物种也经常进行耐力运动（奔跑哺乳动物），由于人类与这些类群有许多形态特征，因此运动诱导的 eCB 信号可能会激发奔跑哺乳动物习惯性的高强度运动行为。如果这是真的，那么神经生物学奖励可能解释了哺乳动物中习惯性运动活动和性能的变化。我们在人类、狗（奔跑哺乳动物）和雪貂（非奔跑哺乳动物）进行跑步机运动前后测量了循环中的 eCBs，以测试神经生物学奖励与奔跑哺乳动物高强度运动有关的假设。我们表明，人类和狗在高强度耐力跑步后共享明显增加的运动诱导的 eCB 信号。在这些类群中，低强度行走不会导致 eCB 信号明显增加，而在任何强度下运动后，非奔跑的雪貂的 eCB 信号也不会明显增加。这项研究首次提供了证据，表明神经递质信号的种间变异可能解释了哺乳动物之间运动行为的差异。因此，耐力运动的神经生物学奖励可能解释了为什么人类和其他奔跑哺乳动物尽管与更高的相关能量成本和受伤风险有关，但仍习惯性地进行有氧运动，以及为什么非奔跑哺乳动物避免这种运动行为。
