Conditioned medium derived from human dental pulp stem cells and photobiomodulation improves lipopolysaccharide-induced neuroinflammation, oxidative stress and cognitive impairment in rats

Abstract

Abstract Neuroinflammation has been introduced as a main player in the development of neurodegenerative disorders. Recent studies showed a promising anti-inflammatory role for conditioned medium (CM) in the nervous system. However, in order to improve the effects of CM in this study, we investigated the effect of CM and photobiomodulation (PBM) on neuroinflammation and cognitive disorders caused by it. Neuroinflammation model was induced by lipopolysaccharide (LPS) injection in male Wistar rats. Morris water maze (MWM), Passive Avoidance (PA), and probe tests were performed to assess memory and learning function. Levels of malondialdehyde (MDA), thiol, and superoxide dismutase (SOD) as well as acetylcholinesterase (AchE) enzyme activity and interleukin-6 (IL-6) were measured in the hippocampus tissue for stress oxidative and inflammation status, respectively. LPS injection induced neuroinflammation and aggrevated cognitive status. Employment of CM and PBM led to a significant increase in time and traveled distance in MWM test, duration of remaining in the dark space in PA test, and duration of presence and traveled distance in the probe test. CM and PBM treatment also improved LPS-induced stress oxidative markers status and attenuated IL-6 level and AchE enzyme activity. Our results propose a potential anti-inflammatory role for PBM, alone or in combination with CM, in LPS-induced neuroinflammation and cognitive impairment. The therapeutic capacity of PBM and CM application should be further investigated in treatment of neuroinflammation-induced major neurodegenerative disorders.