Humanin, a Mitochondrial-Derived Peptide Released by Astrocytes, Prevents Synapse Loss in Hippocampal Neurons

This study investigated the neuroprotective role of humanin, a 24-amino acid peptide encoded by mitochondrial DNA, focusing specifically on its release by astrocytes and its effects on hippocampal neurons. The researchers used primary cultures of rat neurons and astrocytes to assess the impact of humanin on glutamate-induced toxicity.

The results demonstrated that astrocytes release humanin constitutively and that this release is increased under stress conditions. Exogenous humanin prevented dendritic atrophy and synapse loss caused by glutamatergic excitotoxicity in cultured hippocampal neurons. These effects were mediated by mechanisms involving the preservation of dendritic spine integrity.

A particularly relevant aspect of the work is the demonstration that astrocytes function as a paracrine source of humanin, suggesting a glial-neuronal communication mechanism that had been little explored until then. This interaction may be crucial for maintaining synaptic homeostasis during aging.

The implications of this study are significant for understanding neurodegenerative diseases such as Alzheimer's, where synaptic loss is an early and critical event. Humanin emerges as a potential therapeutic candidate for protecting hippocampal circuits vulnerable to aging and neurodegeneration.