Inhibitory activity of ingested microplastics on gut lactic acid bacteria and neuronal maintenance in Sprague-Dawley Ras

Abstract

Throughout the years, the number of plastics in the ocean which breakdown into microplastic fragments as they are exposed to different modes of degradation have exponentially increased. As most studies focus on the prevalence of these particles in aquatic systems, evidence-based information regarding their effects in terrestrial organisms, especially in mammals, need to be established. In this study, 8-to-9-week old male Sprague-Dawley rats were orally gavaged with 0.2 mg of polyethylene microplastic for 14 days with fecal and blood samples from the control and treatment groups collected pre- and post-treatment. Rats fed with microplastics showed a near significant decrease (P = 0.063) in lactic acid bacteria populations from 7.82 ± 0.196 log cfu/g to 5.96 ± 0.149 log cfu/g and a highly significant decrease (P = 0.031) in peripheral BDNF concentrations from 684.9 ± 17.12 pg/mL to 387.0 ± 9.68 pg/mL. Excised brains from representative control rats depicted healthy neurons and neuropil while the treatment rats underwent vascular congestion, cytoplasmic eosinophilia, loss of nuclei and cytoplasm, pyknosis, and neuropilar microvacuolation. Logistic analysis of the lactic acid bacteria populations and BDNF concentrations indicate that their interaction were jointly responsible for the presence of lesions in the treatment rat brains (X2 = 8.393, P = 0.039).