Melittin - A Main Component of Bee Venom: A Promising Therapeutic Agent for Neuroprotection through Nrf2/HO-1 Pathway Activation

Abstract

The Nrf2/HO-1 pathway, known for its significant role in regulating innate antioxidant defense mechanisms, is increasingly being recognized for its potential in neuroprotection studies. Derived from bee venom, melittin's neuroprotective effects are raising interest. This study confirms that melittin specificity upregulated the weaken Nrf2/HO-1 signaling in mice brain. Interestingly, we also revealed melittin’s efficient tactic, as the restored redox balance alone gradually stabilized other regulations of the mouse hippocampus. Using a scopolamine-induced, a common and effective neurodegeneration model in mice, chemical analysis revealed that melittin crosses the compromised blood-brain barrier, accumulates in the hippocampus, and significantly enhances neurogenesis and cognitive function in scopolamine-induced mice. Careful observation in mice showed: first signs of changes within 5 hours after melittin administration were the restoration of the Nrf2/HO-1 system and suppresses oxidative stress. After this event, from 7 to 12.5 hours after administration were the rebalancing of inflammation, apoptosis, neurotrophic factors, cholinergic function, and mitochondrial performance. This chain reaction underscores the redox balance's role in reviving multiple neuronal functions. Evidence of enhancement in mouse hippocampus led to further exploration with hippocampal cell line HT22. Immunofluorescence analysis showed melittin-induced Nrf2 translocation to the nucleus, which would initiating the translation of antioxidant genes like HO-1. Pathway inhibitors pinpointed melittin's direct influence on the Nrf2/HO-1 pathway. 3D docking models and pull-down assays suggested melittin's direct interaction with Keap1, Nrf2/HO-1’s activator. Overall, this study not only highlighted melittin specifically effect on Nrf2/HO-1, thus, rebalancing cellular redox, but also showed that this is a effective multi-effect therapeutic strategy against neurodegeneration.