Sprengell Marie, Kubera Britta, Peters Achim
Medical Clinic 1, Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany.
Front Neurosci. 2021 Jun 24;15:685031. doi: 10.3389/fnins.2021.685031. eCollection 2021.
This work joins a series that methodically tests the predictions of the Selfish-Brain theory. The theory postulates a vital ability of the mammalian brain, namely to give priority to its own energy metabolism. The brain behaves "selfishly" in this respect. For the cerebral artery occlusion studied here, the theory predicts an increase in blood glucose concentration, what becomes the hypothesis to be tested. We conducted a systematic review of cerebral-artery-occlusion papers to test whether or not the included studies could confirm this hypothesis. We identified 239 records, screened 231 works by title or abstract, and analyzed 89 by full text. According to strict selection criteria (set out in our PROSPERO preregistration, complying with PRISMA guidelines), 7 papers provided enough information to decide on the hypothesis. Our hypothesis could be fully confirmed for the 3 to 24 h after the onset of a transient 2 h or permanent occlusion. As for the mechanism, the theory predicts that the energy-deprived brain suppresses insulin secretion via the sympathoadrenal system, thereby preventing insulin-mediated glucose uptake into muscle and fat and, as a result, enhancing insulin-independent glucose uptake via the blood-brain barrier. Evidence from our included studies actually demonstrated cerebral insulin suppression. In all, the current work confirms the second major prediction of the Selfish-Brain theory that relates to a proximal bottleneck of the cerebral supply chain, cerebral artery occlusion. Its first major prediction relates to a distal supply bottleneck, caloric restriction, and is fulfilled as shown by our previous work, whereas the prediction of the long held gluco-lipostatic theory, which sees the brain as only passively supplied, is violated (Sprengell et al., 2021). The crucial point was that caloric restriction elicits smaller changes in mass (energy) in the brain than in the body. Taken together, the evidence from the current and previous work clearly shows that the most accurate predictions are possible with a theory that views the brain as an independently self-regulating energy compartment occupying a primary position in energy metabolism.
这项研究是一系列系统检验“自私大脑”理论预测的研究之一。该理论假定哺乳动物大脑具有一种至关重要的能力，即优先考虑自身的能量代谢。在这方面，大脑表现得“自私”。对于此处研究的脑动脉闭塞情况，该理论预测血糖浓度会升高，这就成为了待检验的假设。我们对脑动脉闭塞相关论文进行了系统综述，以检验纳入的研究是否能证实这一假设。我们识别出239条记录，通过标题或摘要筛选了231篇论文，并对89篇进行了全文分析。根据严格的选择标准（在我们的PROSPERO预注册中列出，符合PRISMA指南），7篇论文提供了足够信息来判定该假设。在短暂性2小时或永久性闭塞发作后的3至24小时内，我们的假设得到了充分证实。至于机制，该理论预测能量匮乏的大脑会通过交感肾上腺系统抑制胰岛素分泌，从而阻止胰岛素介导的葡萄糖进入肌肉和脂肪，结果是增强通过血脑屏障的非胰岛素依赖性葡萄糖摄取。我们纳入研究的证据实际上证明了大脑胰岛素受到抑制。总体而言，当前研究证实了“自私大脑”理论的第二个主要预测，该预测与脑供应链的近端瓶颈——脑动脉闭塞有关。其第一个主要预测与远端供应瓶颈——热量限制有关，正如我们之前的研究所示已得到证实，而长期以来将大脑视为仅被动获取营养的糖脂稳态理论的预测则被推翻（Sprengell等人，2021年）。关键在于热量限制引起的大脑质量（能量）变化小于身体。综合来看，当前和之前研究的证据清楚地表明，将大脑视为能量代谢中占据首要位置的独立自我调节能量单元的理论能够做出最准确的预测。
