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Vascular dementia (VaD) has a serious impact on the patients' quality of life. Icariin (Ica) possesses neuroprotective potential for treating VaD, yet its oral bioavailability and blood–brain barrier (BBB) permeability remain challenges. This research introduced a PEG–PLGA-loaded chitosan hydrogel-based binary formulation tailored for intranasal delivery, enhancing the intracerebral delivery efficacy of neuroprotective agents. The formulation underwent optimization to facilitate BBB crossing, with examinations conducted on its particle size, morphology, drug-loading capacity, in vitro release, and biodistribution. Using the bilateral common carotid artery occlusion (BCCAO) rat model, the therapeutic efficacy of this binary formulation was assessed against chitosan hydrogel and PEG–PLGA nanoparticles loaded with Ica. Post-intranasal administration, enhanced cognitive function was evident in chronic cerebral hypoperfusion (CCH) rats. Further mechanistic evaluations, utilizing immunohistochemistry (IHC), RT-PCR, and ELISA, revealed augmented transcription of synaptic plasticity-associated proteins like SYP and PSD-95, and a marked reduction in hippocampal inflammatory markers such as IL-1β and TNF-α, highlighting the formulation's promise in alleviating cognitive impairment. The brain-derived neurotrophic factor (BDNF)/tropomyosin related kinase B (TrkB) pathway was activated significantly in the binary formulation compared with the other two. Our study demonstrates that the intranasal application of chitosan hydrogel loaded with Ica-encapsulated PEG–PLGA could effectively deliver Ica into the brain and enhance its neuroprotective effect. [ABSTRACT FROM AUTHOR]

Clinical and experimental data hints that prolonged and repeated epileptic seizures can lead to molecular, biochemical, metabolic, and structural changes in the brain, a continuous process of chronic brain injury that ultimately leads to neuronal death. The histological characteristics of hippocampal structure determine its high sensitivity to excitotoxicity and present different types of neuronal death, including apoptosis, necroptosis, autophagy, pyroptosis, and ferroptosis. Hippocampal neuronal death promotes the progression of epileptogenesis, seizures, and epilepsy and is closely related to the impairment of cognitive function. Massive evidence indicates that oxidative stress plays a critical role in different forms of neuronal death induced by epileptic seizures. The brain is particularly vulnerable to damage caused by oxidative stress, and an increase in oxidative stress biomarkers was found in various epilepsy types. The purpose of this review is to elucidate the molecular mechanism of neuronal death and explore the moderating effect of oxidative stress on epileptic seizure-induced neuronal death patterns so as to find potential intervention targets for neuroprotective treatment after epileptic seizures. [ABSTRACT FROM AUTHOR]