Moxa-combustion byproducts improve cognitive function via olfactory-mediated modulation of the GSK-3β/CREB pathway

Objective: Olfactory dysfunction in early-stage Alzheimer's disease (AD) is associated with GSK-3β abnormalities localized in the olfactory bulb. These pathological changes not only compromise hippocampus-dependent learning and memory via synaptic impairments but also contribute to emotional disturbances such as anxiety and depression. Given that moxa-combustion byproducts (MCB), a key therapeutic component of moxibustion, enhance synaptic plasticity and improve cognition, this study aimed to investigate whether MCB ameliorates cognitive deficits by olfactory-mediated modulation of the GSK-3β/CREB pathway. Methods: Four-month-old APP/PS1 mice received 12-week MCB interventions. Behavioral assessments (Morris water maze, buried food pellet test and open field test) evaluated olfactory and cognitive functions. Pathological changes and synaptic structure in olfactory bulbs and hippocampus were analyzed via hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM). Protein levels of GSK3β, CREB, and c-Fos were quantified by Western blot (WB). Results: MCB significantly improved spatial learning, memory, and olfactory performance in AD mice. HE staining showed that MCB increased the number of olfactory mitral cells and hippocampal CA1 neurons, and could regulate synaptic plasticity. MCB downregulated GSK-3β while upregulating CREB and c-Fos in both olfactory bulb and hippocampal tissues. The effect of MCB disappeared after olfactory blockade using 3-methylindole, suggesting olfactory-mediated action. Conclusion: MCB enhances cognitive-olfactory functions and mitigates anxiety- and depression-like behaviors in AD mice, potentially via modulation of GSK-3β/CREB pathway-related proteins in the olfactory system.