Adell A, Trullas R, Gelpi E
Departament de Neuroquímica, C.S.I.C., Jordi Girona Salgado, Barcelona, Spain.
Brain Res. 1988 Aug 30;459(1):54-9. doi: 10.1016/0006-8993(88)90285-5.
The effects of predictable and unpredictable shock on concentrations of serotonin (5-hydroxytryptamine, 5-HT), 5-hydroxyindoleacetic acid (5-HIAA), tryptophan (TP) and noradrenaline (NA) have been studied in 7 regions of rat brain. Two separate experiments have been carried out determining these substances both at 30 min and 2 h after the stress session. Unpredictable shock depleted NA levels in all brain regions except the striatum. However, at 2 h poststress NA in these regions increased significantly in comparison with both controls and predictably shocked rats. Predictable shock also decreased NA in locus coeruleus, brainstem and hypothalamus, which was not observed 2 h later. Both predictable and unpredictable shock decreased 5-HT in brainstem and hypothalamus. At 2 h poststress, 5-HT levels in these regions were still decreased in predictably shocked rats, but had attained control values in unpredictably shocked rats. 5-HT metabolism expressed as the 5-HIAA/5-HT ratio, was significantly increased 30 min after predictable shock in all regions except the locus coeruleus and hippocampus. Unpredictable shock produced a much more marked increase in 5-HIAA/5-HT ratio. At 2 h poststress 5-HT metabolism returned to control values in most of the brain regions of predictably shocked animals, but it remained high after unpredictable shock. The activation of serotonergic metabolism following each type of shock is different according to the nucleus in which the 5-HT nerve endings originate. Only slight increases in tryptophan were observed after both types of shock. Our results suggest that unpredictable shock is perceived as a more anxiogenic situation and that under this condition both 5-HT and NA levels are more effectively normalized with time.
研究了可预测和不可预测电击对大鼠脑7个区域中血清素（5-羟色胺，5-HT）、5-羟吲哚乙酸（5-HIAA）、色氨酸（TP）和去甲肾上腺素（NA）浓度的影响。进行了两项独立实验，在应激期后30分钟和2小时测定这些物质。不可预测电击使除纹状体外的所有脑区NA水平降低。然而，应激后2小时，这些区域的NA与对照组和可预测电击的大鼠相比显著增加。可预测电击也使蓝斑、脑干和下丘脑的NA降低，但2小时后未观察到这种情况。可预测和不可预测电击均使脑干和下丘脑的5-HT降低。应激后2小时，可预测电击大鼠这些区域的5-HT水平仍降低，但不可预测电击大鼠已达到对照值。以5-HIAA/5-HT比值表示的5-HT代谢在可预测电击后30分钟在除蓝斑和海马体之外的所有区域均显著增加。不可预测电击使5-HIAA/5-HT比值有更明显的增加。应激后2小时，可预测电击动物大多数脑区的5-HT代谢恢复到对照值，但不可预测电击后仍保持较高水平。每种类型电击后5-羟色胺能代谢的激活根据5-HT神经末梢起源的核不同而不同。两种类型电击后仅观察到色氨酸略有增加。我们的结果表明，不可预测电击被视为更具焦虑性的情况，并且在此条件下，5-HT和NA水平随时间更有效地恢复正常。
