Li-Li Qiu1, Wei Pan2, Dan Luo1, Guang-Fen Zhang1, Zhi-Qiang Zhou3, Xiao-Yun Sun3, Jian-Jun Yang4, Mu-Huo Ji5. 1. Department of Anesthesiology, Zhongda Hospital, School of Medicine, Southeast University, No. 87 Dingjiaqiao Road, Nanjing, 210009, China. 2. Department of Anesthesiology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China. 3. Department of Anesthesiology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, China. 4. Department of Anesthesiology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, China. yjyangjj@126.com. 5. Department of Anesthesiology, Zhongda Hospital, School of Medicine, Southeast University, No. 87 Dingjiaqiao Road, Nanjing, 210009, China. jimuhuo2019@126.com.
Abstract
BACKGROUND: Postoperative cognitive decline (POCD) is a recognized clinical phenomenon characterized by cognitive impairments in patients following anesthesia and surgery, yet its underlying mechanism remains unclear. Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal plasticity, learning, and memory via activation of TrkB-full length (TrkB-FL) receptors. It has been reported that an abnormal truncation of TrkB mediated by calpain results in dysregulation of BDNF/TrkB signaling and is associated with cognitive impairments in several neurodegenerative disorders. Calpains are Ca2+-dependent proteases, and overactivation of calpain is linked to neuronal death. Since one source of intracellular Ca2+ is N-methyl-d-aspartate receptors (NMDARs) related and the function of NMDARs can be regulated by neuroinflammation, we therefore hypothesized that dysregulation of BDNF/TrkB signaling mediated by NMDAR/Ca2+/calpain might be involved in the pathogenesis of POCD. METHODS: In the present study, 16-month-old C57BL/6 mice were subjected to exploratory laparotomy with isoflurane anesthesia to establish the POCD animal model. For the interventional study, mice were treated with either NMDAR antagonist memantine or calpain inhibitor MDL-28170. Behavioral tests were performed by open field, Y maze, and fear conditioning tests from 5 to 8 days post-surgery. The levels of Iba-1, GFAP, interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), NMDARs, calpain, BDNF, TrkB, bax, bcl-2, caspase-3, and dendritic spine density were determined in the hippocampus. RESULTS: Anesthesia and surgery-induced neuroinflammation overactivated NMDARs and then triggered overactivation of calpain, which subsequently led to the truncation of TrkB-FL, BDNF/TrkB signaling dysregulation, dendritic spine loss, and cell apoptosis, contributing to cognitive impairments in aging mice. These abnormities were prevented by memantine or MDL-28170 treatment. CONCLUSION: Collectively, our study supports the notion that NMDAR/Ca2+/calpain is mechanistically involved in anesthesia and surgery-induced BDNF/TrkB signaling disruption and cognitive impairments in aging mice, which provides one possible therapeutic target for POCD.
BACKGROUND:Postoperative cognitive decline (POCD) is a recognized clinical phenomenon characterized by cognitive impairments in patients following anesthesia and surgery, yet its underlying mechanism remains unclear. Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal plasticity, learning, and memory via activation of TrkB-full length (TrkB-FL) receptors. It has been reported that an abnormal truncation of TrkB mediated by calpain results in dysregulation of BDNF/TrkB signaling and is associated with cognitive impairments in several neurodegenerative disorders. Calpains are Ca2+-dependent proteases, and overactivation of calpain is linked to neuronal death. Since one source of intracellular Ca2+ is N-methyl-d-aspartate receptors (NMDARs) related and the function of NMDARs can be regulated by neuroinflammation, we therefore hypothesized that dysregulation of BDNF/TrkB signaling mediated by NMDAR/Ca2+/calpain might be involved in the pathogenesis of POCD. METHODS: In the present study, 16-month-old C57BL/6 mice were subjected to exploratory laparotomy with isoflurane anesthesia to establish the POCD animal model. For the interventional study, mice were treated with either NMDAR antagonist memantine or calpain inhibitor MDL-28170. Behavioral tests were performed by open field, Y maze, and fear conditioning tests from 5 to 8 days post-surgery. The levels of Iba-1, GFAP, interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), NMDARs, calpain, BDNF, TrkB, bax, bcl-2, caspase-3, and dendritic spine density were determined in the hippocampus. RESULTS: Anesthesia and surgery-induced neuroinflammation overactivated NMDARs and then triggered overactivation of calpain, which subsequently led to the truncation of TrkB-FL, BDNF/TrkB signaling dysregulation, dendritic spine loss, and cell apoptosis, contributing to cognitive impairments in aging mice. These abnormities were prevented by memantine or MDL-28170 treatment. CONCLUSION: Collectively, our study supports the notion that NMDAR/Ca2+/calpain is mechanistically involved in anesthesia and surgery-induced BDNF/TrkB signaling disruption and cognitive impairments in aging mice, which provides one possible therapeutic target for POCD.
Authors: Salima El Chehadeh; Kyung Ah Han; Dongwook Kim; Gyubin Jang; Somayeh Bakhtiari; Dongseok Lim; Hee Young Kim; Jinhu Kim; Hyeonho Kim; Julia Wynn; Wendy K Chung; Giuseppina Vitiello; Ioana Cutcutache; Matthew Page; Jozef Gecz; Kelly Harper; Ah-Reum Han; Ho Min Kim; Marja Wessels; Allan Bayat; Alberto Fernández Jaén; Angelo Selicorni; Silvia Maitz; Arjan P M de Brouwer; Anneke Vulto-van Silfhout; Martin Armstrong; Joseph Symonds; Sébastien Küry; Bertrand Isidor; Benjamin Cogné; Mathilde Nizon; Claire Feger; Jean Muller; Erin Torti; Dorothy K Grange; Marjolaine Willems; Michael C Kruer; Jaewon Ko; Amélie Piton; Ji Won Um Journal: Nat Commun Date: 2022-07-15 Impact factor: 17.694