In recent years, evidence of the existence of cellular senescence in the central nervous system has accumulated. In ischemic stroke, cellular senescence has been suggested as an unidentified pathophysiological mechanism, prompting research into the neuroprotective potential of senolytic drugs. This study aims to provide spatio-temporal evidence of the existence of brain senescence following ischemic stroke and to elucidate the involved pathways and cell types. We focused on the most established markers of senescence: cell cycle arrest (p16, p21); lysosomal activity (senescence-associated β-galactosidase [SA-β-gal]); the senescence-associated secretory phenotype ([SASP]; Interleukin-6 [IL-6], Interleukin-1β [IL-1β], Tumor necrosis factor [TNF]); and DNA/nuclear damage (Checkpoint kinase 1 [Chk1], Checkpoint kinase 2 [Chk2], Lamin B1 [LB1]). Male Wistar rats underwent 60 min of transient middle cerebral artery occlusion, followed by 24 h and 3, 7, and 14 days of recovery. Our results show significant increases in p16 expression, particularly in neurons and microglia/macrophages; SA-β-gal accumulation in the infarcted tissue; significant increases in SASP markers as early as 24 h after reperfusion; and significant changes in Chk1, Chk2, and LB1 at 14 days. Overall, our findings lend support to the existence of senescence after ischemic stroke in neurons and microglia/macrophages. However, there is still room to gain further insight into the role of senescence in the pathophysiology of ischemic stroke and in the implementation of successful senolytic therapy.

Background/Objectives: Senescence has been recently described in brain cells following ischemic stroke. The potential of targeting senescence as an effective therapeutic approach in the treatment of ischemic stroke requires further investigation. This study evaluated the effects of the senolytic drug navitoclax after experimental ischemic stroke. Methods: Navitoclax was injected into male young Wistar rats at doses of 10 and 30 mg/kg (i.p.). to evaluate its pharmacokinetics, cerebral levels and potential to cause thrombocytopenia. Subsequently, a second group of rats underwent 60 min of transient middle cerebral artery occlusion (tMCAO). Navitoclax (10 mg/kg, i.p.) or vehicle was injected every other day between days 3 and 13 after tMCAO. Neurofunctional performance, infarct size, and senescence markers were assessed on day 14. Results: Navitoclax (10 mg/kg) administration resulted in a maximum plasma concentration of 0.702 mg/L and half-life of 11.33 h. Additionally, a brain concentration of 0.04 ± 0.02 µg/g was detected. Moderate thrombocytopenia was induced by 10 mg/kg, and to a greater extent by 30 mg/kg. Navitoclax (6 × 10 mg/kg) improved neurofunctional impairment, as indicated by significant decrease by 66% in the total time for the tape removal test, and significantly reduced infarct area by 52% when compared to vehicle. Moreover, navitoclax significantly reduced levels of SA-β-gal (by 80%), lipofuscin (by 91%), and Checkpoint kinase 2 (Chk2; by 69%) in the ischemic hemisphere. Conclusions: Navitoclax protects the brain after ischemic stroke by improving neurofunctional outcome and reducing infarct size, which is associated with reducing senescence markers. Although moderate thrombocytopenia warrants caution, targeting senescence emerges as a promising therapeutic strategy for ischemic stroke.