Department of Pharmacology, School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia.
Epilepsia. 2017 Jul;58(7):1172-1180. doi: 10.1111/epi.13796. Epub 2017 Jun 20.
To determine changes in glucose metabolism and the enzymes involved in the hippocampus ictally and postictally in the acute mouse flurothyl seizure model.
[U- C]-Glucose was injected (i.p.) prior to, or following a 5 min flurothyl-induced seizure. Fifteen minutes later, mice were killed and the total metabolite levels and % C enrichment were analyzed in the hippocampal formation using gas chromatography-mass spectrometry. Activities of key metabolic and antioxidant enzymes and the phosphorylation status of pyruvate dehydrogenase were measured, along with lipid peroxidation.
During seizures, total lactate levels increased 1.7-fold; however, [M + 3] enrichment of both lactate and alanine were reduced by 30% and 43%, respectively, along with a 28% decrease in phosphofructokinase activity. Postictally the % C enrichments of all measured tricarboxylic acid (TCA) cycle intermediates and the amino acids were reduced by 46-93%. At this time, pyruvate dehydrogenase (PDH) activity was 56% of that measured in controls, and there was a 1.9-fold increase in the phosphorylation of PDH at ser232. Phosphorylation of PDH is known to decrease its activity.
Here, we show that the increase of lactate levels during flurothyl seizures is from a source other than [U- C]-glucose, such as glycogen. Surprisingly, although we saw a reduction in phosphofructokinase activity during the seizure, metabolism of [U- C]-glucose into the TCA cycle seemed unaffected. Similar to our recent findings in the chronic phase of the pilocarpine model, postictally the metabolism of glucose by glycolysis and the TCA cycle was impaired along with reduced PDH activity. Although this decrease in activity may be a protective mechanism to reduce oxidative stress, which is observed in the flurothyl model, ATP is critical to the recovery of ion and neurotransmitter balance and return to normal brain function. Thus we identified promising novel strategies to enhance energy metabolism and recovery from seizures.
在急性氟烷致小鼠惊厥模型中，确定海马在发作期和发作后的葡萄糖代谢及相关酶的变化。
在氟烷诱导的 5 分钟惊厥前或后（ip）注射[U- C]-葡萄糖。15 分钟后，处死小鼠，使用气相色谱-质谱法分析海马结构中的总代谢物水平和% C 丰度。测定关键代谢和抗氧化酶的活性以及丙酮酸脱氢酶的磷酸化状态，并测定脂质过氧化。
在发作期间，总乳酸水平增加了 1.7 倍；然而，乳酸和丙氨酸的[M + 3]丰度分别降低了 30%和 43%，同时磷酸果糖激酶活性降低了 28%。发作后，所有测量的三羧酸（TCA）循环中间产物和氨基酸的% C 丰度降低了 46-93%。此时，丙酮酸脱氢酶（PDH）活性为对照的 56%，PDH 在丝氨酸 232 处的磷酸化增加了 1.9 倍。众所周知，PDH 的磷酸化降低其活性。
在这里，我们表明氟烷惊厥期间乳酸水平的增加不是来自[U- C]-葡萄糖等其他来源，而是来自糖原。令人惊讶的是，尽管我们在发作期间观察到磷酸果糖激酶活性降低，但[U- C]-葡萄糖代谢进入 TCA 循环似乎没有受到影响。与我们在匹鲁卡品模型慢性期的最近发现类似，发作后糖酵解和 TCA 循环的葡萄糖代谢受损，PDH 活性降低。尽管这种活性降低可能是减少氧化应激的保护机制，在氟烷模型中观察到，但 ATP 对恢复离子和神经递质平衡以及恢复正常大脑功能至关重要。因此，我们确定了增强能量代谢和从癫痫发作中恢复的有前途的新策略。
