Kirkham T C, Cooper S J
Department of Psychology, University of Birmingham, England.
Physiol Behav. 1988;44(4-5):491-4. doi: 10.1016/0031-9384(88)90310-1.
The time course of sucrose (5, 10 and 20%; w/v) sham feeding was monitored in one hour tests. Intake levels increased as a function of concentration. Naloxone (1.25 mg/kg, IP) attenuated the sham feeding of 10% sucrose solution in gastric fistulated rats, without affecting initial intake rates. Furthermore, after naloxone the intake pattern of 10% sucrose was identical to that for 5% sucrose in untreated rats. In a second test, substitution of 10% sucrose by a 20% solution after 15 min of sham feeding reversed the effect of naloxone, restoring intake to 10% baseline levels. Thus naloxone's effect appeared to be behaviourally equivalent to that of sucrose dilution and was counteracted by increasing sucrose concentration. Naloxone was apparently more effective against the lower sucrose concentration, suppressing intake at an earlier stage of testing. The data confirm the importance of oropharyngeal stimulation to the suppressive action of naloxone and support opioid mediation of orosensory reward.
在一小时的测试中监测了蔗糖（5%、10%和20%；w/v）假饲的时间进程。摄入量随着浓度的增加而增加。纳洛酮（1.25毫克/千克，腹腔注射）减弱了胃瘘大鼠对10%蔗糖溶液的假饲，而不影响初始摄入率。此外，给予纳洛酮后，10%蔗糖的摄入模式与未处理大鼠中5%蔗糖的摄入模式相同。在第二项测试中，假饲15分钟后用20%的溶液替代10%的蔗糖，逆转了纳洛酮的作用，使摄入量恢复到10%的基线水平。因此，纳洛酮的作用在行为上似乎等同于蔗糖稀释的作用，并通过增加蔗糖浓度而被抵消。纳洛酮对较低蔗糖浓度的作用显然更有效，在测试的早期阶段就抑制了摄入量。这些数据证实了口咽刺激对纳洛酮抑制作用的重要性，并支持阿片类物质对口腔感觉奖赏的介导作用。
