Neurons and oligodendrocytes are produced in the adult brain subventricular zone (SVZ) from neural stem cells (B cells), which express GFAP and have morphological properties of astrocytes. We report here on the identification B cells expressing the PDGFRalpha in the adult SVZ. Specifically labeled PDGFRalpha expressing B cells in vivo generate neurons and oligodendrocytes. Conditional ablation of PDGFRalpha in a subpopulation of postnatal stem cells showed that this receptor is required for oligodendrogenesis, but not neurogenesis. Infusion of PDGF alone was sufficient to arrest neuroblast production and induce SVZ B cell proliferation contributing to the generation of large hyperplasias with some features of gliomas. The work demonstrates that PDGFRalpha signaling occurs early in the adult stem cell lineage and may help regulate the balance between oligodendrocyte and neuron production. Excessive PDGF activation in the SVZ in stem cells is sufficient to induce hallmarks associated with early stages of tumor formation.

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Background and Purpose: The efficiency of prehospital care chain response and the adequacy of hospital resources are challenged amid the coronavirus disease 2019 (COVID-19) outbreak, with suspected consequences for patients with ischemic stroke eligible for mechanical thrombectomy (MT). Methods: We conducted a prospective national-level data collection of patients treated with MT, ranging 45 days across epidemic containment measures instatement, and of patients treated during the same calendar period in 2019. The primary end point was the variation of patients receiving MT during the epidemic period. Secondary end points included care delays between onset, imaging, and groin puncture. To analyze the primary end point, we used a Poisson regression model. We then analyzed the correlation between the number of MTs and the number of COVID-19 cases hospitalizations, using the Pearson correlation coefficient (compared with the null value). Results: A total of 1513 patients were included at 32 centers, in all French administrative regions. There was a 21% significant decrease (0.79; [95%CI, 0.76–0.82]; P <0.001) in MT case volumes during the epidemic period, and a significant increase in delays between imaging and groin puncture, overall (mean 144.9±SD 86.8 minutes versus 126.2±70.9; P <0.001 in 2019) and in transferred patients (mean 182.6±SD 82.0 minutes versus 153.25±67; P <0.001). After the instatement of strict epidemic mitigation measures, there was a significant negative correlation between the number of hospitalizations for COVID and the number of MT cases ( R 2 −0.51; P =0.04). Patients treated during the COVID outbreak were less likely to receive intravenous thrombolysis and to have unwitnessed strokes (both P <0.05). Conclusions: Our study showed a significant decrease in patients treated with MTs during the first stages of the COVID epidemic in France and alarming indicators of lengthened care delays. These findings prompt immediate consideration of local and regional stroke networks preparedness in the varying contexts of COVID-19 pandemic evolution.

Although rats given the choice of eating high-density calories as concentrated sucrose solutions or lard exhibit reduced responsivity in the hypothalamo-pituitary-adrenal axis, rats fed high-fat diets have normal or augmented responses to stressors. To resolve this apparent discrepancy, we compared in adult male rats the effects of 7-d feeding with lard + chow (choice) to feeding a 50% lard-chow mixture (no-choice) and to chow only. Rats with choice composed diets with 50-60% total calories from lard. Rats were exposed to 30 min of restraint on d 7. In the choice group, there was a robust inhibition of ACTH and corticosterone responses to restraint compared with chow or no-choice groups. Total caloric intake was less with choice than no-choice. Fat depot weights and body weight gain were similar in the high-fat groups. Leptin concentrations were equal but insulin was higher in the choice group. We conclude the following: 1) choice of eating high-density calories strongly damps hypothalamo-pituitary-adrenal responses to stress; without choice, high-density diet is ineffective; and 2) insulin may signal metabolic well-being, and may act through hypothalamic sites to reduce caloric intake but through forebrain sites to damp stress responses.