Neuroprotection of Catalpol for Experimental Acute Focal Ischemic Stroke: Preclinical Evidence and Possible Mechanisms of Antioxidation, Anti-Inflammation, and Antiapoptosis

Neuroprotection is defined as using a therapy that affects the brain tissue in the still-viable ischemic penumbra to salvage or delay the infarction. Catalpol, the main active principle of the root of Radix Rehmanniae, was reported to have pleiotropic neuroprotective effects in neurodegenerative diseases including ischemic stroke. Here, we evaluated the neuroprotective effects of catalpol in experimental acute ischemic stroke. Studies on catalpol in animal models of acute ischemic stroke were identified from 6 databases. Twenty-five studies involving 805 animals were included. Twelve comparisons showed significant effects of catalpol on decreasing infarct size according to 2,3,5-triphenyltetrazolium chloride staining compared with the control (P < 0.05). One study reported significant effect of catalpol on reducing infarct size according to magnetic resonance imaging scan compared with the control (P < 0.05). Meta-analysis of these studies indicated that catalpol significantly improved the neurological function score according to Zea Longa score, Bederson score, balance beam-walking test, adhesive removal test, bar-grasping score, and corner test compared with the control (P < 0.05). In conclusion, catalpol exerted neuroprotective effects for experimental acute focal ischemic stroke, largely through reducing oxidative reactions, inhibiting apoptosis, and repressing inflammatory reactions and autophagy. However, these apparently positive findings should be interpreted with caution because of the methodological flaws.