6-gingerol alleviates Alzheimer's disease in rats through the Pumilio RNA binding family member 1/microRNA-340-5p/pleomorphic adenoma gene like-2/estimated glomerular filtration rate/hypoxia-inducible factor-1alpha/2alpha pathway.

This study explores the modulatory role of Pumilio RNA-binding family member 1 (circ_PUM1) in the neuroprotective mechanisms of 6-gingerol against Alzheimer's disease (AD)-related neuronal injury, providing new insights into circRNA-mediated regulation of neurodegeneration. Variations in circRNA expression indirectly influenced by 6-gingerol (6-GIN) were comprehensively assessed within AD experimental frameworks. The AD phenotype was not absent when hippocampal amyloid-β (Aβ) was introduced into rats, nor when SK-N-SH and SK-SY5Y cells were subjected to Aβ challenge, jointly constructing complementary in vivo and in vitro paradigms for mechanistic exploration. Hippocampal injury was assessed by water content measurement, histological analysis, and TUNEL staining for apoptosis. In cell models, viability, apoptosis, and inflammatory cytokines (interleukin-6, inducible nitric oxide synthase, tumor necrosis factor-α) were quantified. The expression and localization of circ_PUM1 were examined, and its direct interaction with miR-340-5p was confirmed, revealing a regulatory axis potentially mediating the neuroprotective effects of 6-GIN. We found that administration of 6-GIN effectively counteracted Aβ1-42-induced neurotoxicity by alleviating neuronal apoptosis, oxidative injury, and inflammatory responses. These protective effects were evidenced by the reduction of neuronal damage and brain edema scores, decreased secretion of proinflammatory cytokines and lipid peroxidation products malondialdehyde (MDA), as well as the restoration of endogenous antioxidant enzymes such as superoxide dismutase and glutathione peroxidase. Exposure to aβ resulted in a marked downregulation of circ_pum1 expression accompanied by elevated miR-340-5p levels; notably, 6-GIN administration reversed these molecular alterations. Mechanistic analyses further confirmed that miR-340-5p directly binds to the 3'-UTR of pleomorphic adenoma gene like-2 (PLAGL2), thereby regulating the estimated glomerular filtration rate (EGFR)/hypoxia-inducible factor-1α (HIF-1α)/hypoxia-inducible factor-2α (HIF-2α) signaling axis implicated in neuronal survival and metabolic adaptation. Collectively, these findings suggest that circ_PUM1 confers neuroprotection against Alzheimer's disease pathology by sequestering miR-340-5p and activating the PLAGL2/EGFR/HIF-1α-HIF-2α cascade, elucidating a critical pathway through which 6-GIN exerts its therapeutic potential in attenuating Aβ-associated neuronal degeneration. In conclusion: 6-GIN alleviates Aβ-induced apoptosis, oxidative stress, and neuroinflammation in AD through circ_PUM1/miR-340-5p/PLAGL2/EGFR-HIF1/2A signaling pathway.