Pellitorine protects chronic restraint stress-induced cognitive deficits via inhibiting neural inflammation and ferroptosis

Background: It has not been known that pellitorine, an active ingredient of Piper sarmentosum Roxb. with therapeutic effects against epilepsy and anxiety disorders, has the neurological effects. Our study aimed to investigate the therapeutic potential of pellitorine in addressing chronic restraint stress (CRS)-associated cognitive deficits. Methods: The CRS mouse model was treated with pellitorine and subjected to depression-like behavior assessments. Neuronal survival was evaluated through histological and Nissl staining. Immunoblotting assays were conducted to examine the expression levels of signaling pathway proteins. Immunofluorescent staining, flow cytometry, and RNA sequencing were utilized to further elucidate the pathological and molecular changes in pellitorine-treated CRS mice. Results: Behavioral experiments demonstrated that pellitorine treatment significantly alleviated depression-like behaviors and improved cognitive function in CRS mice. Histological analysis revealed a marked reduction in neuronal loss following pellitorine administration. Transcriptomic profiling indicated that pellitorine suppressed ferroptosis-associated signaling pathways and neuroinflammation. Notably, the expression of anti-ferroptosis factors, including GPX4, DHODH, and FSP1, was decreased in CRS mice but restored by pellitorine treatment. In addition, pellitorine prevented neuronal loss, preserved the expression of neuroprotective molecules such as BDNF, Nrf2, HO-1, phosphorylated-CREB, and phosphorylated-ERK1/2, and reduced the protein levels of inflammation-related markers including NLRP3, HMGB1, and NF-kappa B. Immunofluorescent staining and flow cytometry analyses further showed that pellitorine treatment reduced the number of activated microglia, as indicated by decreased Iba-1+, TREM2+, CD86+, and CX3CR1+ cell populations in the hippocampus. Importantly, pellitorine did not exhibit any observable neurotoxic effects in healthy control mice. Conclusions: Our findings demonstrate that pellitorine protects against CRS-induced cognitive deficits, neural inflammation, and ferroptosis, highlighting its promise as a therapeutic agent for mental health issues.