Radiotherapy is one of the primary modalities for oncologic treatment and has been utilized at least once in over half of newly diagnosed cancer patients. Cranial radiotherapy has significantly enhanced the long-term survival rates of patients with brain tumors. However, radiation-induced brain injury, particularly hippocampal neuronal damage along with impairment of neurogenesis, inflammation, and gliosis, adversely affects the quality of life for these patients. Astrocytes, a type of glial cell that are abundant in the brain, play essential roles in maintaining brain homeostasis and function. Despite their importance, the pathophysiological changes in astrocytes induced by radiation have not been thoroughly investigated, and no systematic or comprehensive review addressing the effects of radiation on astrocytes and related diseases has been conducted. In this paper, we review current studies on the neurophysiological roles of astrocytes following radiation exposure. We describe the pathophysiological changes in astrocytes, including astrogliosis, astrosenescence, and the associated cellular and molecular mechanisms. Additionally, we summarize the roles of astrocytes in radiation-induced impairments of neurogenesis and the blood-brain barrier (BBB). Based on current research, we propose that brain astrocytes may serve as potential therapeutic targets for treating radiation-induced brain injury (RIBI) and subsequent neurological and neuropsychiatric disorders.

Endothelial cells (ECs) constitute a monolayer that covers the interior surface of blood vessels and participates in various processes. Although vascular ECs share certain common properties, they differ in both structure and function. So far, the transcriptome profile and heterogeneity of the full repertoire of ECs in vertebrates remain poorly understood. The relatively small size of zebrafish embryos and larvae allows a feasible analysis of the broad spectrum of ECs within every tissue and organ of a whole organism. ECs have been suggested to be conditional innate immune cells. Whether ECs possess the comparable capacity of involvement in immune response is so far undetermined. Currently, through single-cell RNA sequencing analysis of total ECs of zebrafish we identified a fraction of endothelial cells expressing the marker genes of innate immune cells, named “endoimmune cells”. We found the percentage of these cells gradually increased along with the embryonic development. Then, we observed the patrolling mCherry+ cells displayed the morphology alike to the macrophages and neutrophils. Furthermore, we revealed that some of the kdrl:ras-mCherry ECs were labelled with coro1a:EGFP as well. In addition, we demonstrated that the mCherry+ EC from intersegmental vessel could gradually present the expression of GFP in Tg(kdrl:ras-mCherry∷coro1a:GFP) line, suggesting the endoimmune cells are derived from ECs. Importantly, we showed the endoimmune cells are responsive to the inflammation in zebrafish. Taken together, these data suggested the existence of endoimmune cells, a novel type of subpopulations of ECs. It will provide novel insights for understanding endothelial roles in both normal physiological function and human diseases and enable endoimmune cells-based target therapies.

Prenatal exposure to ionizing radiation is a known risk factor for neurodevelopmental deficits; however, the molecular mechanisms linking chronic embryonic insult to abnormal brain development remain poorly understood. This study investigated the long-term consequences of chronic prenatal gamma irradiation throughout gestation in C57BL/6 mice. Behavioural analysis of adult offspring revealed a specific increase in depression-like behaviours, with no significant alterations in anxiety or general exploratory activity. Immunohistochemical assessment demonstrated a significant reduction in adult hippocampal neurogenesis, marked by decreased doublecortin (DCX)-positive newborn neurons in the subgranular zone and fewer NeuN-positive mature neurons in the dentate gyrus hilus. Integrated RNA-seq, qPCR, and Western blot analyses implicated the upregulation of the Mef2c/Egr1 signalling pathway in this neurogenic deficit. Furthermore, miRNA sequencing identified a pronounced decrease in miR-1843a-3p, which was subsequently validated to directly target Mef2c. Collectively, these findings suggest that prenatal gamma irradiation disrupts neurogenic processes and adult brain function, leading to specific behavioral abnormalities. This long-term impairment is associated with, and may be at least partially mediated by, dysregulation of the miR-1843a-3p/Mef2c/Egr1 pathway.