Activation of CREB-BDNF Pathway in Pyramidal Neurons in the Hippocampus Improves the Neurological Outcome of Mice with Ischemic Stroke

Abstract

Cerebral ischemia is characterized by several pathological reaction evolving over time. Hyperactivation of glutamatergic neurons is the main factor leading to excitotoxicity which potentiates oxidative stress and triggers the mechanisms of neural apoptosis after cerebral ischemia. However, it is unclear whether glutamate in the ventral hippocampal Cornus Ammonis 1 (vCA1) acts a part in neurological de cits, pain perception, anxiety and depression induced by ischemic-stroke. We investigated the effects of chemogenetic inhibition or activation of vCA1 pyramidal neurons which are mainly glutamatergic neurons on sequelae induced by cerebral ischemia. Our results revealed that inhibition of vCA1 pyramidal neurons by chemogenetics alleviated neurological de cits, pain perception, anxiety and depression caused by cerebral ischemia in mice, but activation of vCA1 pyramidal neurons had limited effects. Moreover, we found that stroke was accompanied by decreased levels of cAMP-response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in vCA1, which are modulated by glutamate.In this study, overexpression of CREB protein in pyramidal neurons in vCA1 by AAV virus signi cantly upregulated the content of BDNF and ameliorated the dysfunction induced by ischemic-stroke. Our results demonstrated activation of CREB-BDNF pathway in vCA1 pyramidal neurons signi cantly improved neurological de cits, pain perception, anxiety and depression induced by ischemic-stroke.

Gene therapy of adeno‐associated virus (AAV) vectors in preclinical models of ischemic stroke

“…Inhibiting glutamatergic neurons in vCA1 through chemical genetics in the early stages (4–7 days) after MCAO in mice can reduce neural defects, pain perception, anxiety, and depressive behaviors caused by cerebral ischemia. In addition, activation of the CREB‐BDNF pathway in hippocampal pyramidal neurons of cerebral ischemic mice significantly alleviated cerebral ischemia‐induced neurological dysfunction, mechanical allodynia, anxiety, and depression 80 …”

“…The development of sequencing technology and bioinformatics has contributed to understanding the pathogenesis of ischemic stroke, selecting therapeutic targets, and establishing biomarkers, while AAV vectors have contributed to translating gene discoveries into therapeutic interventions. Genes involved in the progression of ischemic stroke include various neurotrophic factors (MANF, BDNF), 55,56,82 transcription factors (ATG7, NeuroD1, and CREB), 66,73,80 inflammasomes NLRP3, 45,47 LncRNAs (lncRNA Tug1 and lncRNA-U90926), 46,48 cytokines (CKLF1, SDF-1α, IL-10, hG-CSF, and VEGF), 49,58,64,68,71 neuroplasticity regulator (tPA, HDAC2, and Maf1), 75,78,79 circular RNAs, 59 among others.…”

“…50,52,71,79 AAV2 is currently considered the most extensively studied serotype, but AAV9 appears to be used most frequently in ischemic stroke. 59,62,70,73,80,81 When delivered intravenously, AAV9 can traverse the BBB to target newborn neurons and adult glial cells, 29 and drive axonal transport. 104 A newly engineered capsid, AAV-PHP.B, has also been used in stroke research.…”

“…[110][111][112] In stroke research, ubiquitous promoters such as the non-specific cytomegalovirus (CMV) or chickenβ-actin hybrid (CAG) are expressed in most CNS cells, primarily neurons and some scattered astrocytes. 79,103,113 Various promoters can drive specific transgene expressions, such as the hSyn promoter driving neuron-specific gene expression, 53,75,76,106,114 the GFAP promoter driving astrocyte-specific expression, 44,66,73,88 the F4/80 promoter driving microglia-specific expression, 44,66,73 the CaMK2a promoter driving glutamatergic neuronal expression, 80 and the Olig2 promoter driving oligodendrocyte-specific expression. 115 Additionally, regulatory elements such as the Tie1 promoter can drive brain endothelial cell-specific expression 57,116 and the HIF-1α…”

“…After injection, most transgenes are expressed around the injection site, with not only main neuron tropism but also transduction of astrocytes or microglia 50,52,71,79 . AAV2 is currently considered the most extensively studied serotype, but AAV9 appears to be used most frequently in ischemic stroke 59,62,70,73,80,81 . When delivered intravenously, AAV9 can traverse the BBB to target newborn neurons and adult glial cells, 29 and drive axonal transport 104 .…”