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目的研究海洛因依赖和戒断与β－内啡肽（β－ＥＰ）含量变化的关系。方法３０只ＳＤ大鼠随机分为海洛因依赖组、海洛因戒断组和对照组，各１０只。依赖组和戒断组大鼠腹腔内注射海洛因１０天建立海洛因依赖模型，对照组注射生理盐水。于第１０天未次用药３小时后（对照组和依赖组）或７２小时后（戒断组），将大鼠断头，收集躯干血、垂体和各脑区（包括桥延脑、下丘脑、中脑中央灰质、纹状体、海马和额叶皮质）标本，用放射免疫法测定所有标本的β－ＥＰ含量。结果（１）依赖组大鼠下丘脑、中脑中央灰质、垂体和血浆中的β－ＥＰ含量较对照组显著下降（Ｐ＜０．０５或０．０１），其余脑区的β－ＥＰ含量无显著变化（Ｐ＞０．０５）；（２）戒断组大鼠垂体和下丘脑的β－ＥＰ含量与依赖组比较无显著差异（Ｐ＞０．０５），仍显著低于对照组水平（Ｐ＜０．０５或０．０１）；而血浆、中脑中央灰质的β－ＥＰ含量较依赖组显著升高（Ｐ＜０．０１），至与对照组比较无明显不同（Ｐ＞０．０５）。结论海洛因依赖导致机体内β－ＥＰ水平明显下降，戒断后降低的β－ＥＰ水平短期内难以恢复正常，这可能是阿片类依赖和戒断的重要神经生物学机理之一。
Objective To study the relationship between heroin dependence and withdrawal and the changes of β-endorphin (β-EP) content. Methods Thirty SD rats were randomly divided into heroin dependence group, heroin withdrawal group and control group, 10 in each. The heroin dependence model was established in the dependent group and the withdrawal group by intraperitoneal injection of heroin for 10 days, and the control group was injected with normal saline. The rats were decapitated and the trunk blood, pituitary gland, and brain regions (including bridging brain, hypothalamus) were collected 3 hours after the last administration (control group and dependence group) or 72 hours later (withdrawal group) , Midbrain central gray matter, striatum, hippocampus and frontal cortex) were measured by radioimmunoassay in all specimens of β-EP content. Results (1) The content of β-EP in hypothalamus, midbrain gray matter, pituitary and plasma in dependent group was significantly lower than that in control group (P <0.05 or 0.01), and the content of β-EP in other brain regions (2) The content of β-EP in the pituitary and hypothalamus of the withdrawal group was not significantly different from the dependence group (P> 0.05), but still significantly lower than that of the control group (P <0.05 or 0.01). The levels of β-EP in plasma and midbrain central gray matter were significantly higher than those in the dependent group (P <0.01), but not significantly different from those in the control group .05). CONCLUSION: Heroin dependence causes a significant decrease of β-EP in the body. The decreased level of β-EP after withdrawal is hard to recover in the short term, which may be one of the important neurobiological mechanisms of opioid dependence and withdrawal.