Smith Shilo L, Rasmussen Erin B
Department of Psychology, Idaho State University, Pocatello, ID 83209, USA.
Behav Pharmacol. 2010 Jul;21(4):292-300. doi: 10.1097/FBP.0b013e32833aec4d.
The endocannabinoid system plays a role in obesity, primarily by its role in food reward. Activity, also involved in obesity, seems to be at least partially controlled by the endocannabinoid system, but the relevant behavioral and neurochemical mechanisms have not been well established. This study represents an attempt to begin elucidating these mechanisms by examining the effects of an endogenous cannabinoid ligand, 2-arachidonoylglycerol (2-AG), on the reinforcing properties of exercise reinforcement in lean and obese Zucker rats. Ten obese and 10 lean Zucker rats pressed a locked door under a progressive ratio schedule of reinforcement that, when unlocked, provided access to a running wheel for 2-min periods. After baseline breakpoints were established, doses of 2-AG (0.3-3 mg/kg) were administered before experimental sessions. Obese rats exhibited lower breakpoints for wheel activity, lower response rates, and fewer revolutions compared with lean rats. 2-AG decreased breakpoints, response rates, and revolutions for obese rats, and revolutions only for lean rats. These data suggest that 2-AG may reduce the reinforcing properties of activity, and that obese Zuckers may show a greater sensitivity to 2-AG. The data also suggest that endocannabinoids may play a role in the reinforcing properties of exercise.
内源性大麻素系统在肥胖中发挥作用，主要是通过其在食物奖赏方面的作用。身体活动也与肥胖有关，似乎至少部分受内源性大麻素系统控制，但相关的行为和神经化学机制尚未完全明确。本研究试图通过检测内源性大麻素配体2-花生四烯酸甘油酯（2-AG）对正常体重和肥胖型Zucker大鼠运动强化强化特性的影响，来开始阐明这些机制。十只肥胖型和十只正常体重的Zucker大鼠在渐进比率强化程序下按压一扇锁着的门，门打开后可进入跑步机跑步2分钟。在确定基线断点后，在实验前给予不同剂量的2-AG（0.3 - 3mg/kg）。与正常体重大鼠相比，肥胖大鼠在跑步机活动上的断点更低、反应率更低、跑步圈数更少。2-AG降低了肥胖大鼠的断点、反应率和跑步圈数，仅降低了正常体重大鼠的跑步圈数。这些数据表明，2-AG可能会降低运动的强化特性，并且肥胖型Zucker大鼠可能对2-AG更为敏感。数据还表明，内源性大麻素可能在运动的强化特性中发挥作用。
