The Notch pathway regulates autophagy after hypoxic-ischemic injury and affects synaptic plasticity.

Abstract

Following neonatal hypoxic-ischemia (HI) injury, it is crucial factor to reconstruct neural circuit and maintain neural network homeostasis for neurological recovery. A dynamic balance between the synthesis and degradation of synaptic protein is required for maintaining synaptic plasticity. Protein degradation is facilitated by autophagy. This study aimed to investigate the regulation of synaptic structural plasticity by the Notch pathway, by assessing changes in Notch pathway activation and their effects on synaptic proteins and autophagy after HI injury. The study involved 48 male newborn Yorkshire piglets, each weighing 1.0-1.5kg and 3days old. They were randomly assigned to two groups: the HI group and the Notch pathway inhibitor + HI group (n = 24 per group). Each group was further divided into six subgroups according to HI duration (n = 4 per group): a control subgroup, and 0-6, 6-12, 12-24, 24-48, and 48-72h subgroups. The expression of Notch pathway-related proteins, including Notch1, Hes1, and Notch intracellular domains, increased following HI injury. The expression of autophagy proteins increased at 0-6h and 6-12h post-HI. The expression of synaptic proteins, such as postsynaptic density protein 95 (PSD95) and synaptophysin, increased 6-12h and 12-24h after HI, respectively. Notably, the increased expression of these proteins was reversed by a Notch pathway inhibitor. Transmission electron microscopy revealed the presence of autophagosome structures in synapses. These findings shed light on the underlying mechanisms of neurological recovery after HI injury and may provide insights into potential therapeutic targets for promoting neural circuit reconstruction and maintaining neural network homeostasis.