Zagon I S, McLaughlin P J
Life Sci. 1984 Nov 12;35(20):2057-64. doi: 10.1016/0024-3205(84)90563-0.
Preweaning rats receiving daily injections of 20, 50, or 100 mg/kg naltrexone, a potent opiate antagonist, had body and brain weights that were increased 16-22% and 6-13%, respectively, from control levels on day 21 (weaning). All of these dosages of naltrexone blocked the opiate receptor for 24 hr/day as measured in opiate challenge experiments. Dosages of 0.1, 1, and 10 mg/kg naltrexone, which blocked the opiate receptor for less than 12 hr/day, inhibited growth. Repetitive administration of low dosages (3 mg/kg naltrexone, 3 times daily), which blocked the receptor 24 hr/day, increased body and brain development by 31% and 10%, respectively, whereas a cumulative dosage of 9 mg/kg naltrexone given once daily retarded growth. These results show that developmental events are dictated by the duration of opiate receptor blockade and provide compelling evidence that endogenous opioid systems play a crucial role in growth.
每日接受20、50或100毫克/千克纳曲酮（一种强效阿片拮抗剂）注射的断奶前大鼠，在第21天（断奶）时，其体重和脑重分别比对照水平增加了16% - 22%和6% - 13%。在阿片激发实验中测得，所有这些剂量的纳曲酮每天阻断阿片受体24小时。0.1、1和10毫克/千克剂量的纳曲酮每天阻断阿片受体不到12小时，会抑制生长。重复给予低剂量（3毫克/千克纳曲酮，每日3次），每天阻断受体24小时，体重和脑发育分别增加31%和10%，而每日一次给予累计剂量9毫克/千克纳曲酮则会阻碍生长。这些结果表明，发育事件由阿片受体阻断的持续时间决定，并提供了有力证据，证明内源性阿片系统在生长中起关键作用。
