van Wolfswinkel L, Seifert W F, van Ree J M
Life Sci. 1985 Jul 15;37(2):169-76. doi: 10.1016/0024-3205(85)90420-5.
To analyse the interaction between endogenous opioid systems and brain reward, the influence of repeated treatment for 3 weeks with morphine and the opioid antagonist naloxone was investigated in rats with self-stimulation electrodes in the ventral tegmental area. Changes in threshold of self-stimulation determined by a response rate insensitive two lever method were considered as changes in reward. Morphine induced a temporary decrease of the response rate which lasted 3 days, and decreased the threshold for self-stimulation. The effect on threshold remained present till morphine treatment was discontinued, indicating that tolerance does not develop to this effect of morphine. Repeated naloxone treatment gradually increased the threshold for self-stimulation. This effect persisted after discontinuation of naloxone treatment. It is concluded that blockade of opioid receptors induces long term changes in the setpoint of self-stimulation reward.
为了分析内源性阿片系统与脑奖赏之间的相互作用，我们在腹侧被盖区植入了自我刺激电极的大鼠中，研究了连续3周给予吗啡和阿片拮抗剂纳洛酮的重复治疗的影响。通过对反应率不敏感的双杠杆法测定的自我刺激阈值变化被视为奖赏变化。吗啡引起反应率暂时下降，持续3天，并降低了自我刺激阈值。对阈值的影响一直持续到停止吗啡治疗，这表明对吗啡的这种作用不会产生耐受性。重复给予纳洛酮治疗逐渐提高了自我刺激阈值。在停止纳洛酮治疗后，这种作用仍然存在。得出的结论是，阿片受体的阻断会引起自我刺激奖赏设定点的长期变化。
