Hyperbaric Oxygen Therapy Cognitive Function in a Rat Model of Mild Cognitive Impairment Via ERK Signaling

Background: The development of novel treatment strategies to reverse or impede cognitive dysfunction associated with mild cognitive impairment (MCI) has gained attention in recent times. Meanwhile, hyperbaric oxygen (HBO) has been widely used as a neuroprotective therapy that can promote recovery of damaged neurons. The aim of this study was to investigate the effects of HBO on cognitive function in rats with MCI and to clarify the associated mechanisms. Methods: We established a D-galactose-induced MCI rat model and evaluated the role of extracellular-regulated kinase (ERK) signaling in HBO therapy for cognitive function using a specific inhibitor, U0126. All Rats were randomly assigned to four groups with 12 rats per group: normal control group; D-gal model group (group MCI); D-gal + HBO group (group HBO); D-gal + HBO + U0126 group (group U0126). We evaluated cognitive function by Morris water maze and pathological changes by hematoxylin and eosin (HE) staining of hippocampal slices. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of caspase 3, while total ERK1/2 and phospho-ERK1/2 were assessed by Western blotting. Results: Shorter escape latency was observed in the HBO group as compared to the MCI group, which was to some extent reversed by U0126. Similarly, the HBO group showed the highest number of platform crossings as compared to the MCI and U0126 groups. Pathological analysis also showed less apoptosis and better hippocampal cell morphology in the HBO group. Caspase 3 levels also differed significantly, with lowest expression in the HBO group as compared to the MCI and U0126 groups. The levels of total ERK1/2 and p-ERK1/2 were more elevated in the HBO group as compared to the MCI group. Conclusions: This study found that HBO treatment has a protective effect on early cognitive dysfunction in rats with MCI. HBO therapy may act through ERK signaling, which inhibits apoptosis and protects cognitive function.