Ambroxol Attenuates Detrimental Effect of LPS-Induced Glia-Mediated Neuroinflammation, Oxidative Stress and Cognitive Dysfunction in Mice Brain

Safi Ullah ^1* Tae Ju Park ^2* Jun Sung Park ^1* Abubakar Atiq ^1* Jawad Ali ¹ Min Hwa Kang ^1* Waqar Ali ^1* Kyonghwan Choe ^1,3* Myeong Ok Kim ^1,4*

• ¹ Gyeongsang National University, Jinju, Republic of Korea
• ² Paul O'Gorman Leukaemia Research Centre, Institute of Cancer Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
• ³ Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, Netherlands, Netherlands
• ⁴ Alz-Dementia Korea Co., Jinju 52828, Republic of Korea., Jinju, South Gyeongsang, Republic of Korea

Neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are multifactorial. Among various factors, lipopolysaccharides (LPS) from Gram-negative bacteria, such as E. coli, are considered potential causative agents. Despite significant advancements in the field, there is still no cure. In this study, we investigated the neuroprotective effects of ambroxol against lipopolysaccharide (LPS)-induced neuroinflammation, oxidative stress, neurodegeneration, and the associated cognitive dysfunction. Intraperitoneal injection of LPS (250 µg/kg every alternative day for a total of seven doses over 14 days) triggered glial cell activation, neuroinflammation, oxidative stress, and neurodegeneration in the mouse brain. Ambroxol treatment (30 mg/kg/day for 14 days) significantly reduced neuroinflammation and oxidative stress compared to LPS-treated mice.Immunoblotting and immunofluorescence results showed that ambroxol reduced levels of Toll-like receptor 4 (TLR4) and oxidative stress kinase phospho-c-Jun N-terminal Kinase 1 (p-JNK). It also decreased astrocyte and microglia activation in the cortex and hippocampus of LPS+Amb-treated 2 mice, as indicated by the downregulation of GFAP and Iba-1. Furthermore, ambroxol reversed LPSinduced neuroinflammation by inhibiting inflammatory mediators, such as IL-1β and TNF-α, through regulation of the transcription factor p-NFkB. Persistent neuroinflammation disrupted the natural antioxidant mechanisms, leading to oxidative stress. Ambroxol treatment upregulated antioxidant markers, including Nrf-2, HO-1, and SOD, which were downregulated in the LPS-treated group.Additionally, ambroxol inhibited lipid peroxidation, maintaining MDA levels in the mouse brain.Ambroxol also improves synaptic integrity by upregulating synaptic biomarkers, including PSD-95 and SNAP-23. Overall, ambroxol demonstrated anti-inflammatory, antioxidant, and neuroprotective effects in LPS-treated mice, highlighting its potential benefits in neurological disorders.