Belahsen R, Deshaies Y
Department of Physiology, School of Medicine, Laval University, Québec, Canada.
Can J Physiol Pharmacol. 1992 Dec;70(12):1555-62. doi: 10.1139/y92-223.
This study evaluated the effects of beta 2-adrenoceptor stimulation on some determinants of triglyceride metabolism. Male Sprague-Dawley rats were injected twice daily with clenbuterol (30 micrograms.kg-1) for 7 days, or with an equivalent volume of vehicle. Serum triglycerides, hepatic triglyceride secretion rate, and lipoprotein lipase activity in white and brown adipose tissues as well as in red vastus lateralis muscle and heart were evaluated in the fasting state and following a fat-free, high-sucrose meal, 3 h after the last agonist injection. In rats killed in the fasting and postprandial states, clenbuterol reduced the mass of white adipose tissue (-25 and -12%, respectively; p < 0.02), whereas it increased the mass of vastus lateralis muscle (+11 and +7%; p < 0.002) and heart (+13 and %; p < 0.0001). In vehicle-injected animals, the fasting state was associated with lower lipoprotein lipase activity in white and brown adipose tissues, and higher enzyme activity in vastus lateralis and heart, compared with the postprandial state. Postprandially, treatment with clenbuterol reduced lipoprotein lipase activity in white adipose (-24%), whereas it increased enzyme activity in brown adipose (+107%) as well as in vastus lateralis (+35%). In fasted animals, no significant variation of enzyme activity in these tissues was observed following clenbuterol treatment, whereas in the heart, a decrease of lipoprotein lipase activity was observed (-22%). Clenbuterol lowered serum triglycerides significantly (-23%), but not their rate of secretion, whereas the agonist decreased the insulin to glucagon ratio only in the postprandial state.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究评估了β2-肾上腺素能受体刺激对甘油三酯代谢某些决定因素的影响。将雄性斯普拉格-道利大鼠每日注射两次克伦特罗（30微克·千克-1），持续7天，或注射等量的赋形剂。在禁食状态以及在最后一次注射激动剂3小时后给予无脂肪、高蔗糖餐之后，评估血清甘油三酯、肝脏甘油三酯分泌率以及白色和棕色脂肪组织以及股外侧肌和心脏中的脂蛋白脂肪酶活性。在禁食和餐后状态处死的大鼠中，克伦特罗降低了白色脂肪组织的质量（分别降低25%和12%；p<0.02），而增加了股外侧肌的质量（分别增加11%和7%；p<0.002）和心脏的质量（分别增加13%和%；p<0.0001）。在注射赋形剂的动物中，与餐后状态相比，禁食状态下白色和棕色脂肪组织中的脂蛋白脂肪酶活性较低，而股外侧肌和心脏中的酶活性较高。餐后，用克伦特罗治疗降低了白色脂肪中的脂蛋白脂肪酶活性（降低24%），而增加了棕色脂肪（增加107%）以及股外侧肌（增加35%）中的酶活性。在禁食动物中，克伦特罗治疗后这些组织中的酶活性未观察到显著变化，而在心脏中，观察到脂蛋白脂肪酶活性降低（降低22%）。克伦特罗显著降低了血清甘油三酯（降低23%），但未降低其分泌率，而该激动剂仅在餐后状态下降低了胰岛素与胰高血糖素的比值。（摘要截短至250字）
