Sonderegger T, O'Shea S, Zimmermann E
Pharmacol Biochem Behav. 1979;11 Suppl:29-33.
Male rat pups (Charles Rivers CD albino strain) were implanted subcutaneously with a morphine (M), placebo (P), or no pellet (NP) on Day 5 or 11 of postnatal life. Body weights of both Day 5 and 11 drug-treated males were depressed below those of controls through Day 63 (p < 0.01). On Day 72, compared to P and NP controls, M-treated males showed impaired learning in a Lashley III maze. Day 5, but not Day 11 drug-treated animals showed greater activity-wheel behavior (p < 0.01) than controls on Days 85--86, and less suppression (p < 0.025) of a conditioned emotional response on Day 145. On Day 150, Day 5 M-treated animals showed a reduced steroid response (p < 0.05) to a challenge dose of M (18 mg/kg), suggesting protracted tolerance to the pituitary-adrenal activating effects of M. Members of each treatment group were successfully bred with females on Day 90; no group differences were found in litter size, sex ratios, or birth weights of the offspring. The results of this study indicate that early exposure to M causes long-term impairment of several behaviors in male rats.
雄性幼鼠（查尔斯河CD白化病品系）在出生后第5天或第11天皮下植入吗啡（M）、安慰剂（P）或不植入药粒（NP）。到第63天时，第5天和第11天接受药物处理的雄性幼鼠的体重均低于对照组（p<0.01）。在第72天时，与P组和NP组对照组相比，接受M处理的雄性幼鼠在拉什利III型迷宫中的学习能力受损。第5天而非第11天接受药物处理的动物在第85 - 86天表现出比对照组更强的转轮活动（p<0.01），在第145天对条件性情绪反应的抑制作用更小（p<0.025）。在第150天时，第5天接受M处理的动物对挑战剂量的M（18mg/kg）的类固醇反应降低（p<0.05），表明对M的垂体 - 肾上腺激活作用产生了长期耐受性。每个处理组的雄性在第90天成功与雌性繁殖；在后代的窝仔数、性别比例或出生体重方面未发现组间差异。本研究结果表明，早期接触M会导致雄性大鼠多种行为的长期损害。
