Neuroglia, Volume 3, Issue 3 (September 2022) – 2 articles

Ischemic stroke is a debilitating neurological disease most commonly resulting from an occlusion within the cerebral vasculature. Ischemia/reperfusion injury is oftentimes a consequence of stroke, characterized by oxidative stress, neuroinflammation, and the activation of surrounding glial cells following restoration of blood supply. Astrocytes are regarded as the most prominent glial cell in the brain and, under pathologic conditions, display, among other pathologies, activated (GFAP) relatively proportional to the degree of reactivity. The primary objective of the study was to determine the temporal profile of astrocyte reactivity following ischemic stroke. Thirty-four Sprague-Dawley rats were assigned to surgery consisting of either 90-min middle cerebral artery occlusion (MCAo) or sham surgery. Animals were sub-grouped by postoperative euthanization day; 2 days (n = 10), 4 days (n = 11), and 7 days (n = 13). Fluorescence microscopy and densitometry were utilized to quantify GFAP immunoreactivity, which indicated a non-linear relationship following ischemia/reperfusion. Results demonstrated substantially higher GFAP levels in MCAo groups than in sham, with peak GFAP reactivity being shown in the brains of rats euthanized on day 4. These findings are applicable to future research, especially in the investigation of interventions that target reactive astrocytes following ischemic injury. Full article

Retinal pathologies have been heavily studied in response to radiation and microgravity, including spaceflight-associated neuro-ocular syndrome (SANS), which is commonly developed in space flight. SANS has been characterized in clinical studies of astronauts returning to Earth and includes a range of symptoms, such as globe flattening, optic-disc edema, retinal folds, and retinal ischemia. In cases of retinal insult, Müller glia (MG) cells respond via neuroprotective gliotic responses that may become destructive to produce glial scarring and vison loss over time. Retinal pathology is further impacted by the production of excessive reactive oxygen species (ROS) that stimulate retinal inflammation and furthers the gliosis of MG. Neuroprotectants derived from natural products (NPs) able to scavenge excess ROS and mitigate long-term, gliotic responses have garnered recent interest, especially among mature and aging adults. The natural antioxidants aloin and ginkgolide A flavonoids, derived from Aloe vera and Ginkgo biloba species, respectively, have been of particular interest due to their recent use in other nervous-system studies. The current study examined MG behaviors in response to different doses of aloin and ginkgolide A over time by measuring changes in morphology, survival, and ROS production within microscale assays. The study was further enhanced by using galactic cosmic rays (GCR) at the Brookhaven NASA Space Radiation Laboratory to simulate ionizing radiation in low- and high-radiation parameters. Changes in the survival and ROS production of radiation-treated MG were then measured in response to varying dosage of NPs. Our study used in vitro systems to evaluate the potential of NPs to reduce oxidative stress in the retina, highlighting the underexplored interplay between NP antioxidants and MG endogenous responses both in space and terrestrially. Full article