Glucose supply from blood is mandatory for brain functioning and its interruption during acute hypoglycemia or cerebral ischemia leads to brain injury. Alternative substrates to glucose such as the ketone bodies (KB), acetoacetate (AcAc), and β-hydroxybutyrate (BHB), can be used as energy fuels in the brain during hypoglycemia and prevent neuronal death, but the mechanisms involved are still not well understood. During glucose deprivation adaptive cell responses can be activated such as autophagy, a lysosomal-dependent degradation process, to support cell survival. However, impaired or excessive autophagy can lead to cell dysfunction. We have previously shown that impaired autophagy contributes to neuronal death induced by glucose deprivation in cortical neurons and that D isomer of BHB (D-BHB) reestablishes the autophagic flux increasing viability. Here, we aimed to investigate autophagy dynamics in the brain of rats subjected to severe hypoglycemia (SH) without glucose infusion (GI), severe hypoglycemia followed by GI (SH + GI), and a brief period of hypoglycemic coma followed by GI (Coma). The effect of D-BHB administration after the coma was also tested (Coma + BHB). The transformation of LC3-I to LC3-II and the abundance of autophagy proteins, Beclin 1 (BECN1), ATG7, and ATG12–ATG5 conjugate, were analyzed as an index of autophagosome formation, and the levels of sequestrosome1/p62 (SQSTM1/p62) were determined as a hallmark of autophagic degradation. Data suggest that autophagosomes accumulate in the cortex and the hippocampus of rats after SH, likely due to impaired autophagic degradation. In the cortex, autophagosome accumulation persisted at 6 h after GI in animals exposed to SH but recovered basal levels at 24 h, while in the hippocampus no significant effect was observed. In animals subjected to coma, autophagosome accumulation was observed at 24 h after GI in both regions. D-BHB treatment reduced LC3-II and SQSTM1/p62 content and reduced ULK1 phosphorylation by AMPK, suggesting it stimulates the autophagic flux and decreases AMPK activity reducing autophagy initiation. D-BHB also reduced the number of degenerating cells. Together, data suggest different autophagy dynamics after GI in rats subjected to SH or the hypoglycemic coma and support that D-BHB treatment can modulate autophagy dynamics favoring the autophagic flux.

血液中葡萄糖的供应对于大脑功能是必不可少的，在急性低血糖或脑缺血期间，血液供应中断会导致脑损伤。葡萄糖的替代底物，例如酮体（KB），乙酰乙酸酯（AcAc）和β-羟基丁酸酯（BHB），可在低血糖症期间用作脑中的能量燃料并预防神经元死亡，但涉及的机制仍不完善了解。在葡萄糖剥夺过程中，可以激活适应性细胞反应，例如自噬，一种溶酶体依赖性降解过程，以支持细胞存活。但是，自噬受损或过度自噬会导致细胞功能障碍。先前我们已经表明，自噬受损会导致皮质神经元葡萄糖缺乏引起的神经元死亡，而BHB的D异构体（D-BHB）会重新建立自噬通量，从而提高生存能力。在这里，我们旨在研究在没有葡萄糖输注（GI）的重度低血糖（SH），重度低血糖继之为GI（SH + GI）和短暂的低血糖昏迷然后是GI（Coma）的大鼠大脑中的自噬动力学）。还测试了昏迷后施用D-BHB的效果（Coma + BHB）。分析了LC3-I向LC3-II的转化以及大量自噬蛋白Beclin 1（BECN1），ATG7和ATG12-ATG5共轭物，作为自噬小体形成的指标，以及螯合体1 / p62（SQSTM1 / p62）被确定为自噬降解的标志。数据表明，SH后大鼠的皮质和海马中自噬体积累，可能是由于自噬降解受损所致。在皮质中，自体吞噬体的积累在暴露于SH的动物中在GI后6 h持续存在，但在24 h时恢复了基础水平，而在海马体中未观察到明显的作用。在遭受昏迷的动物中，在两个区域的GI后24小时都观察到自噬体积累。D-BHB处理可降低LC3-II和SQSTM1 / p62的含量，并减少AMPK引起的ULK1磷酸化，表明其刺激自噬通量并降低AMPK活性，从而减少了自噬的发生。D-BHB还减少了退化细胞的数量。一起，