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Microplastics (MPs) are inevitably oxidized in the environment, and their potential toxicity to organisms has attracted wide attention. However, the neurotoxicity and mechanism of oxidized polyethylene (Ox-PE) MPs to organisms remain unclear. Herein, we prepared oxidized low-density polyethylene (Ox-LDPE) and established a model of MPs exposure by continuously orally gavage of C57BL/6 J mice with LDPE-MPs/Ox-LDPE-MPs for 28 days with or without oral administration of Lactobacillus plantarum DP189 and galactooligosaccharides (DP189&GOS). The experimental results indicated that LDPE-MPs or Ox-LDPE-MPs caused several adverse effects in mice, mainly manifested by behavioral changes, disruption of the intestinal and blood–brain barrier (BBB), and simultaneous oxidative stress, inflammatory reactions, and pathological damage in the brain and intestines. Brain transcriptomic analysis revealed that the cholinergic synaptic signaling pathways, which affect cognitive function, were significantly disrupted after exposure to LDPE-MPs or Ox-LDPE-MPs. Real-time quantitative polymerase chain reaction and Western Blotting results further demonstrated that the critical genes (Slc5a7, Chat and Slc18a3) and proteins (Chat and Slc18a3) in the cholinergic synaptic signaling pathway were significantly down-regulated after exposure to LDPE-MPs or Ox-LDPE-MPs. These alterations lead to reduced acetylcholine concentration, which causes cognitive dysfunction in mice. Importantly, the DP189&GOS interventions effectively mitigated the MPs-induced cognitive dysfunction and intestinal microbiota alteration, improved intestinal and BBB integrity, attenuated the oxidative stress and inflammatory response, and also saw a rebound in the release of acetylcholine. These results indicated that LDPE-MPs and Ox-LDPE-MPs exert neurotoxic effects on mice by inducing oxidative stress, inflammatory responses, and dysregulation of cholinergic signaling pathways in the mouse brain. That probiotic supplementation is effective in attenuating MPs-induced neurotoxicity in mice. Overall, this study reveals the potential mechanisms of neurotoxicity of LDPE-MPs and Ox-LDPE-MPs on mice and their improvement measures, necessary to assess the potential risks of plastic contaminants to human health.

Polyethylene is a plastic material that was globally produced and is well known as a non-degradable pollutant product. Plastic pollution, primarily microplastics, have been distributed to coral reef ecosystems, where these areas are ecosystems with high productivity. Karimunjawa National Park in Indonesia is one of the protected areas for coral reef ecosystem habitat in Central Java, threatened by microplastic contamination. Recent studies have shown that coral-associated bacteria have an adequate ability to degrade marine pollutant materials. No one has reported that the use of indigenous coral-associated bacteria has the potential for microplastic biodegradation, especially low-density polyethylene microplastic materials. Hence, the objective of this study was to find the potential of microplastic biodegradation agents derived from coral-associated bacteria in Karimunjawa National Park area. Various coral life-forms were isolated in July 2020 from conservation areas and areas with anthropogenic influences. Bacterial isolates were screened using tributyrin and polycaprolactone as substrates to reveal potential microplastic degradation enzymes. The total isolation results obtained 92 bacterial isolates, and then from the result of enzyme screening, there were 7 active bacteria and only 1 bacteria that potential to degrade polyethylene. LBC 1 showed that strain could degrade by 2.25±0.0684 % low-density polyethylene microplastic pellet by incubating bacterial growth until the stationary phase. Identification of LBC 1 strain was carried out by extracting DNA and bacterial 16S rRNA sequences. Bacterial gene identification refers to Bacillus paramycoides with a similarity level in the National Center Biotechnology Information database of 99.44%. These results prove that hard coral association bacteria can degrade low-density polyethylene microplastics. [ABSTRACT FROM AUTHOR]