Houle-Leroy P, Garland T, Swallow J G, Guderley H
Département de Biologie, Université Laval, Quebec, Quebéc, Canada G1K 7P4.
J Appl Physiol (1985). 2000 Oct;89(4):1608-16. doi: 10.1152/jappl.2000.89.4.1608.
Selective breeding is an important tool in behavioral genetics and evolutionary physiology, but it has rarely been applied to the study of exercise physiology. We are using artificial selection for increased wheel-running behavior to study the correlated evolution of locomotor activity and physiological determinants of exercise capacity in house mice. We studied enzyme activities and their response to voluntary wheel running in mixed hindlimb muscles of mice from generation 14, at which time individuals from selected lines ran more than twice as many revolutions per day as those from control (unselected) lines. Beginning at weaning and for 8 wk, we housed mice from each of four replicate selected lines and four replicate control lines with access to wheels that were free to rotate (wheel-access group) or locked (sedentary group). Among sedentary animals, mice from selected lines did not exhibit a general increase in aerobic capacities: no mitochondrial [except pyruvate dehydrogenase (PDH)] or glycolytic enzyme activity was significantly (P < 0.05) higher than in control mice. Sedentary mice from the selected lines exhibited a trend for higher muscle aerobic capacities, as indicated by higher levels of mitochondrial (cytochrome-c oxidase, carnitine palmitoyltransferase, citrate synthase, and PDH) and glycolytic (hexokinase and phosphofructokinase) enzymes, with concomitant lower anaerobic capacities, as indicated by lactate dehydrogenase (especially in male mice). Consistent with previous studies of endurance training in rats via voluntary wheel running or forced treadmill exercise, cytochrome-c oxidase, citrate synthase, and carnitine palmitoyltransferase activity increased in the wheel-access groups for both genders; hexokinase also increased in both genders. Some enzymes showed gender-specific responses: PDH and lactate dehydrogenase increased in wheel-access male but not female mice, and glycogen phosphorylase decreased in female but not in male mice. Two-way analysis of covariance revealed significant interactions between line type and activity group; for several enzymes, activities showed greater changes in mice from selected lines, presumably because such mice ran more revolutions per day and at greater velocities. Thus genetic selection for increased voluntary wheel running did not reduce the capability of muscle aerobic capacity to respond to training.
选择性育种是行为遗传学和进化生理学中的一项重要工具，但它很少被应用于运动生理学的研究。我们正在通过人工选择来增加小鼠的转轮行为，以研究家鼠运动活动的相关进化以及运动能力的生理决定因素。我们研究了第14代小鼠混合后肢肌肉中的酶活性及其对自愿转轮运动的反应，此时选择品系的个体每天的转轮圈数是对照（未选择）品系个体的两倍多。从断奶开始并持续8周，我们将四个重复选择品系和四个重复对照品系的小鼠分别饲养在可以自由转动的轮子（可转轮组）或锁定的轮子（久坐组）旁边。在久坐的动物中，选择品系的小鼠并没有表现出有氧能力的普遍提高：除丙酮酸脱氢酶（PDH）外，没有线粒体或糖酵解酶活性显著（P < 0.05）高于对照小鼠。选择品系的久坐小鼠表现出肌肉有氧能力较高的趋势，表现为线粒体（细胞色素c氧化酶、肉碱棕榈酰转移酶、柠檬酸合酶和PDH）和糖酵解（己糖激酶和磷酸果糖激酶）酶水平较高，同时厌氧能力较低，表现为乳酸脱氢酶（尤其是雄性小鼠）。与先前通过自愿转轮运动或强制跑步机运动对大鼠进行耐力训练的研究一致，细胞色素c氧化酶、柠檬酸合酶和肉碱棕榈酰转移酶活性在两个性别的可转轮组中均增加；己糖激酶在两个性别中也增加。一些酶表现出性别特异性反应：PDH和乳酸脱氢酶在可转轮的雄性小鼠中增加，但在雌性小鼠中未增加，糖原磷酸化酶在雌性小鼠中减少，但在雄性小鼠中未减少。双向协方差分析显示品系类型和活动组之间存在显著相互作用；对于几种酶，选择品系小鼠的活性变化更大，可能是因为这些小鼠每天的转轮圈数更多且速度更快。因此，对增加自愿转轮运动的基因选择并没有降低肌肉有氧能力对训练的反应能力。
