海洛因依赖和戒断时大鼠脑区、垂体和血浆中β-内啡肽的变化

Changes of β－endorphin contents in brain regions, pituitary and plasma in heroin dependent and abstinent rats

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 the changes of Aendorphin (β-EP) contents and heroin dependence and abstinence. Methods Thirty SD rats were divided randomly into there groups (n＝10). The rats in dependent group and abstinent group were administered with heroin. by intraperitoneal injection for 10 days, the rats in control group were injected with saline. The rats in dependent group and control group were sacrificed by decapitation 3 hours after the last injection., and those in abstinent group were sacrificed 72 hours after the last injection. Discrete brain regions (pens and medulla, hypothlamus, midbrain central gray, corpus striatum, hippocampus and frontal cortex), pituitary and plasma were collected. The contents of β－EP in all samples were measured with radioimmunoassay. Results (1)In heroin dependent group, the β－EP contents in hypothalamus, midbrain central gray, pituitary and plasma were significantly lower than those in control group (P<0.05 or 0.01), the PEP contents in other brain regions were not different from those in control group (P>0.05). (2) In heroin abstinent group, the PEP contents in hypothalamus and pituitary were not different from those in control group(P>0.05),and were significantly lower than those in control group (P<0.05 or 0.01); however, the β－EP contents in midbrain central gray and plasma were not different from those in control group(P>0.05), and were significantly higher than that in dependent group (P<0.01). Conclusion Heroin dependence can lower the level of β－EP in the body, and after heroin abstinence these changes are difficult to recover in short term, which may be involved in the neurobiological mechanisms of opioid dependence and abstinence.