Contreras P C, Takemori A E
Life Sci. 1984 Jun 25;34(26):2559-66. doi: 10.1016/0024-3205(84)90041-9.
Prolyl-leucyl-glycinamide (PLG) at a low dose (10 ng/mouse) administered by an intracerebroventricular (i.c.v.) injection did not affect levorphanol analgesia, but PLG at higher doses (10 and 100 micrograms/mouse) and alpha-melanocyte-stimulating hormone (alpha-MSH) (10 ng/mouse) antagonized levorphanol analgesia. Development of levorphanol tolerance was facilitated by 10 ng/mouse of PLG, unaffected by 10 micrograms/mouse of PLG, but antagonized by 100 micrograms/mouse of PLG and 10 ng/mouse of alpha-MSH. The effect of PLG on levorphanol dependence was assessed by changes in body weight and temperature during naloxone-induced withdrawal. PLG (10 ng/mouse) facilitated the development of levorphanol dependence, but 10 micrograms/mouse of PLG had no effect. PLG (100 micrograms/mouse) antagonized development of levorphanol dependence. PLG at doses of 10 and 100 micrograms/mouse precipitated withdrawal in levorphanol-dependent mice. alpha-MSH (10 ng/mouse) antagonized development of levorphanol dependence as evidenced by an increase in the ED50 of naloxone required to induce withdrawal jumping. These results indicate that PLG and alpha-MSH affected levorphanol-induced analgesia, tolerance and dependence in a qualitatively similar manner to their effect on morphine-induced analgesia, tolerance and dependence.
通过脑室内（i.c.v.）注射给予低剂量（10纳克/小鼠）的脯氨酰 - 亮氨酰 - 甘氨酰胺（PLG）不影响左啡诺镇痛，但高剂量（10和100微克/小鼠）的PLG和α - 黑素细胞刺激素（α - MSH）（10纳克/小鼠）拮抗左啡诺镇痛。10纳克/小鼠的PLG促进左啡诺耐受性的发展，10微克/小鼠的PLG对其无影响，但100微克/小鼠的PLG和10纳克/小鼠的α - MSH拮抗左啡诺耐受性。通过纳洛酮诱导戒断期间体重和体温的变化评估PLG对左啡诺依赖性的影响。PLG（10纳克/小鼠）促进左啡诺依赖性的发展，但10微克/小鼠的PLG无影响。PLG（100微克/小鼠）拮抗左啡诺依赖性的发展。10和100微克/小鼠剂量的PLG使左啡诺依赖性小鼠出现戒断反应。α - MSH（10纳克/小鼠）拮抗左啡诺依赖性的发展，这通过诱导戒断跳跃所需的纳洛酮ED50增加得到证明。这些结果表明，PLG和α - MSH对左啡诺诱导的镇痛、耐受性和依赖性的影响在质量上与其对吗啡诱导的镇痛、耐受性和依赖性的影响相似。
