Schulteis G, Martinez J L
Department of Psychology, University of California, Berkeley 94720.
Peptides. 1993 Mar-Apr;14(2):161-7. doi: 10.1016/0196-9781(93)90024-b.
We examined experience-dependent alterations in the production of individual enkephalin metabolites during Leu-enkephalin hydrolysis in rat plasma in vitro. High performance liquid chromatography separation and electrochemical detection were used to quantify accumulation of the primary N-terminal products of enkephalin hydrolysis, Tyr and Tyr-Gly-Gly. Blood was sampled from rats through indwelling femoral artery catheters before, during, and after active avoidance training or appropriate control treatments. Avoidance training increased Tyr production, as did handling and exposing animals to the novel avoidance chamber without foot-shock training. On the other hand, Tyr-Gly-Gly production was elevated by blood sampling alone, by handling/novelty, and by training, but the effect of training was significantly greater than the effects of either of the other treatments. Interestingly, Tyr-Gly-Gly production was highly correlated (r = -0.885) with a measure of escape performance. Since the enzymes that participate in enkephalin hydrolysis act upon a number of peptides, regulation of enzyme activity may be one mechanism whereby an organism can modulate levels of circulating peptides in response to environmental experiences; this may contribute to the expression of appropriate behavioral responses to those environmental experiences.
我们在体外研究了大鼠血浆中亮氨酸脑啡肽水解过程中，个体脑啡肽代谢产物生成的经验依赖性变化。采用高效液相色谱分离和电化学检测法，对脑啡肽水解的主要N端产物酪氨酸（Tyr）和酪氨酸-甘氨酸-甘氨酸（Tyr-Gly-Gly）的积累进行定量分析。在主动回避训练或适当的对照处理之前、期间和之后，通过留置的股动脉导管从大鼠采集血液样本。回避训练增加了酪氨酸的生成，处理动物以及将动物置于新的回避箱但不进行电击训练也会增加酪氨酸的生成。另一方面，单独采血、处理/新奇刺激以及训练都会使酪氨酸-甘氨酸-甘氨酸的生成增加，但训练的影响明显大于其他任何一种处理的影响。有趣的是，酪氨酸-甘氨酸-甘氨酸的生成与逃避表现的一项指标高度相关（r = -0.885）。由于参与脑啡肽水解的酶作用于多种肽类，酶活性的调节可能是生物体能够根据环境经验调节循环肽水平的一种机制；这可能有助于对这些环境经验表达适当的行为反应。
