Leptin and ghrelin prevent hippocampal dysfunction induced by Aβ oligomers

It was recently established that the stomach-derived ghrelin and the adipokine leptin promote learning and memory through actions within the hippocampus. Changes in the peripheral or brain levels of these peptides were described in Alzheimer's disease (AD) patients and were shown to correlate with the severity of cognitive decline. Furthermore, in vivo and in vitro studies demonstrated that leptin or ghrelin can ameliorate amyloid and tau pathologies as well as cognitive deficits. However, the exact role of these peptides in AD is far from being elucidated. To fill this gap, our working hypothesis was that leptin and ghrelin can exert a neuroprotective role in AD suppressing hippocampal dysfunction triggered by synapto- and neurotoxic amyloid-β oligomers (AβO). Using primary cultured hippocampal neurons, we demonstrated that both peptides reduce AβO-induced production of superoxide and mitochondrial membrane depolarization, improving cell survival, and inhibit cell death through a receptor-dependent mechanism. Furthermore, it was shown that in AβO-treated neurons both leptin and ghrelin prevent glycogen synthase kinase 3β activation. Therefore, the evidence gathered in this study revealed that leptin and ghrelin can act as neuroprotective agents able to rescue hippocampal neurons from AβO toxicity, thus highlighting their potential therapeutic role in AD.