The role of astrocytic GPER in neuroprotection after transient focal cerebral ischemia: from angiogenesis to functional improvement

Abstract

With the demonstration of the protective and antioxidant effects of estrogen (E2), the female sex hormone, in several pathologies, including the central nervous system (CNS), it has become mandatory to better comprehend its actions in the body, including in males. Clinical and experimental studies show such actions of E2 in stroke, the second leading cause of death and disability worldwide, generating high costs for public health and losses for the economic sector, and currently one of the main events associated with COVID-19. E2 acts on classical nuclear receptors (ER± or ER²) or G-protein coupled estrogen receptor (GPER), whose activation stimulates rapid signaling pathways related to cell survival and angiogenesis. Recent research, including from our group, shows that glial cells (astrocytes and microglia) are essential effectors in hypoxia and cerebral ischemia, and the treatment with G1, the GPER agonist, attenuates cell death induced by glucose and oxygen deprivation (PGO) in vitro and improves motor deficits induced by the middle cerebral artery occlusion (MCAO) in male rats. We also show that the absence of GPER signaling before PGO increases cell death, suggesting that this signaling blockage would be related to the worse prognosis of ischemic lesions. Thus, this project aims to elucidate whether the manipulation of the GPER in astrocytes could attenuate motor and cognitive deficits, neuronal death and increase neurogenesis and angiogenesis in animals submitted to MCAO. We will use male Wistar rats submitted to MCAO and treated with G1 sub-chronically after insult. The animals will have the neurological and cognitive deficits evaluated and astrocytes activation, neuronal death, neurogenesis, and angiogenesis in the brain. Also, we will use viral vectors for the overexpression of GPER in astrocytes during the period of ischemia and reperfusion, in addition to the chemogenetic manipulation of this cell type. Using such approaches, we aim to elucidate the possible GPER-induced neuroprotective mechanisms and their repercussions on cellular and behavioral damage induced by MCAO. We seek to identify new signaling pathways involved in angiogenesis and which strategies can be used for a better post-stroke prognosis. The clinical and therapeutic relevance of the subject and the translational potential of this proposal are evident, and we hope that the results obtained here may guide clinical research shortly. Therefore, this project's execution will allow scientific advance in the area and enhance technological innovation's perspective with the possibility of creating new molecules with neuroprotective purposes. In quantitative terms, the execution of this project will enable the formation of nationally and internationally competitive human resources, the publication of scientific articles in indexed journals with selective editorial policy, and finally, the strengthening and expansion of the collaborative network between USP and other national and international institutions and universities and the establishment of other bilateral agreements. (AU)