Segol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
Sackler Faculty of Medicine, The Department of Vascular Surgery, Sheba Medical Center, Tel Aviv University, Tel Aviv, Israel.
PLoS One. 2022 Jan 11;17(1):e0261644. doi: 10.1371/journal.pone.0261644. eCollection 2022.
Brain reperfusion following an ischemic event is essential for tissue viability, however, it also involves processes that promote neuronal cell death. We have recently shown that local expression of the hormone leptin in cardiovascular organs drives deleterious remodeling. As cerebral ischemia-reperfusion (IR) lesions derive expression of both the leptin hormone and its receptor, we hypothesized that blocking leptin activity in the injured brain area will reduce the deleterious effects of IR injury.
C57BL6 male mice underwent bilateral common carotid artery and external carotid artery ligation. The right hemisphere was reperfused after 12 minutes, followed by intraarterial injection of either a low-dose leptin antagonist or saline solution via the ipsilateral ICA. The left common carotid artery remained ligated. Fifteen IR/leptin antagonist-injected and fourteen IR/saline-injected mice completed the experiment. Five days after surgery brains were collected and samples of the hippocampal CA1 region were analyzed for cell viability (H&E) and apoptosis (TUNEL and caspase3), for neuroinflammation (Iba1), and for signaling pathways of pSTAT3 and pSmad2.
The right hemisphere hippocampal CA1 region subjected to IR and saline injection exhibited increased apoptosis and necrosis of pyramidal cells. Also, increased density of activated microglia/macrophages was evident around the CA1 region. Comparatively, leptin antagonist treatment at reperfusion reduced apoptosis and necrosis of pyramidal cells, as indicated by increased number of viable cells (p < 0.01), and reduced TUNEL (p < 0.001) and caspase3-positive cells (p<0.05). Furthermore, this treatment reduced the density of activated microglia/macrophages (p < 0.001) in the CA1 region. Signaling pathway analysis revealed that while pSTAT3 and pSmad2-positive cells were found surrounding the stratum pyramidal in saline-treated animals, pSTAT3 signal was undetected and pSmad2 was greatly reduced in this territory following leptin antagonist treatment (p < 0.01).
Inhibition of leptin activity in hemispheric IR injury preserved the viability of ipsilateral hippocampal CA1 neurons, likely by preventing apoptosis and local inflammation. These results indicate that intraarterial anti-leptin therapy may have clinical potential in reducing hemispheric brain IR injury.
缺血事件后的脑再灌注对于组织存活至关重要，但也涉及促进神经元细胞死亡的过程。我们最近表明，心血管器官中激素瘦素的局部表达会导致有害的重塑。由于脑缺血再灌注 (IR) 损伤会导致瘦素激素及其受体的表达，我们假设在受损的脑区域阻断瘦素活性将减少 IR 损伤的有害影响。
C57BL6 雄性小鼠行双侧颈总动脉和颈外动脉结扎。12 分钟后，右侧半球再灌注，然后通过同侧颈内动脉内注射低剂量瘦素拮抗剂或生理盐水。左侧颈总动脉保持结扎。15 只 IR/瘦素拮抗剂注射和 14 只 IR/生理盐水注射的小鼠完成了实验。手术后 5 天收集大脑，分析海马 CA1 区的细胞活力 (H&E) 和细胞凋亡 (TUNEL 和 caspase3)、神经炎症 (Iba1) 以及 pSTAT3 和 pSmad2 信号通路。
接受 IR 和生理盐水注射的右侧半球海马 CA1 区表现出锥体细胞凋亡和坏死增加。此外，CA1 区周围活化的小胶质细胞/巨噬细胞密度增加。相比之下，再灌注时给予瘦素拮抗剂治疗可减少锥体细胞的凋亡和坏死，表现为存活细胞数量增加（p < 0.01），TUNEL 减少（p < 0.001）和 caspase3 阳性细胞减少（p<0.05）。此外，这种治疗还减少了 CA1 区活化的小胶质细胞/巨噬细胞的密度（p < 0.001）。信号通路分析表明，在生理盐水处理的动物中，pSTAT3 和 pSmad2 阳性细胞在锥体层周围被发现，而在接受瘦素拮抗剂治疗后，该区域的 pSTAT3 信号未被检测到，pSmad2 大大减少（p < 0.01）。
在半球性 IR 损伤中抑制瘦素活性可保护同侧海马 CA1 神经元的存活能力，可能是通过防止细胞凋亡和局部炎症来实现的。这些结果表明，动脉内抗瘦素治疗可能具有降低半球性脑 IR 损伤的临床潜力。
