The underlying mechanisms for exacerbated brain injury and poor recovery observed in patients with diabetes and ischemic stroke (IS) remain undetermined. We explored the role of microRNA-34a (miR-34a) Show more
The underlying mechanisms for exacerbated brain injury and poor recovery observed in patients with diabetes and ischemic stroke (IS) remain undetermined. We explored the role of microRNA-34a (miR-34a) in diabetic IS (DMIS) and ischemic postconditioning (IPOC)'s neuroprotective effects in tree shrews. We established a tree shrew DMIS model and exposed it to interventions, including miR-34a inhibition (antagomir), IPOC, and miR-34a overexpression (agomir). Infarct size and pathology were assessed via staining. Cellular/molecular changes (astrocytes, neurons, brain-derived neurotrophic factor [BDNF], Sine oculis homeobox 3 [SIX3], proliferation, apoptosis, axon formation) were analyzed using immunofluorescence, polymerase chain reaction (PCR), and Western blotting. In vitro, miR-34a's targeting of BDNF/SIX3 was validated, with rescue experiments testing regulation via these factors. Infarct size and neuronal damage were greater in the DMIS group than in the nondiabetic IS group. miR-34a inhibition or IPOC reduced infarcts, alleviated injury, improved cell survival, upregulated BDNF/SIX3, enhanced proliferation/axon formation, and reduced apoptosis. miR-34a overexpression reversed IPOC's benefits. In vitro, miR-34a directly targeted BDNF/SIX3, suppressing their expression; exogenous BDNF/SIX3 rescued neurotoxicity and restored function. IPOC exerts partial neuroprotection through miR-34a downregulation, highlighting miR-34a as a potential therapeutic target. Show less