Polystyrene Microplastics Exposure: An Insight into Multiple Organ Histological Alterations, Oxidative Stress and Neurotoxicity in Javanese Medaka Fish (Oryzias javanicus Bleeker, 1854)

Abstract

Microplastics (MPs) have become pollutants of concern due to their unknown human health effect and negative impact on terrestrial and aquatic ecosystems. There is increasing number of experimental research on MPs globally with its effects not fully understood; recent animal studies explore its effects on the intestines, yet on other vital organs. Javanese medaka fish was exposed to polystyrene microplastics (PS-MPs) beads for a period of 21 days. Histological alterations, intestinal oxidative stress, permeability and neurotoxicity were evaluated. Significant inflammatory changes and tissue damage were observed in the intestine, liver and kidney. Intestinal oxidative stress and permeability were found to be significantly increased. In the brain, neurotoxicity characterised by a significant induction of oxidative stress, lipid peroxidation and the inhibition of acetylcholinesterase enzyme were elucidated. This study provided an insight into the multiple organ effect of microplastics exposure, necessitating further exploration and identification of biomarkers to be utilised for biomonitoring population at risk in the future.

Polystyrene microplastics induce gut microbiome and metabolome changes in Javanese medaka fish (Oryzias javanicus Bleeker, 1854)

“…Polystyrene microplastics beads 5 µm size obtained from Sigma Aldrich ( Industriestrasse , Buchs (SG) , Switzerland) were used in this study. Polystyrene is a commonly used plastic in our society, and has been used by several studies [12] , [49] , [62] . In addition, MPs of size 5 µm, are of public health concern.…”

“…The PS-MPs was validated in terms of size, morphology, and chemical composition as described in our previous study using scanning electron microscopy (SEM), (JOEL JSM 6400 SEM Japan), and Fourier transform infrared spectroscopy (FTIR) (Thermo Fisher Scientific, Nicolet 6700) [62] . UV-sterilized tap water was used to prepare PS-MPs suspensions, which were sonicated to ensure even dispersion of particles before use.…”

“…Wild Javanese medaka fish of adult age (0.5–0.7 g in weight; 3–4 cm in length; both sexes), collected from Sepang estuary (2°37′15.38′ N, 101°42′38.33′ E) Malaysia were maintained in a semi-static circulating system at a temperature of 26 ± 1 °C, pH; 7.8–8.0, DO; 5.5–6.0 mg L −1 and photoperiod of 14:10 h light/dark cycle [3] , [62] . Fish were acclimatized for two weeks, the same period of which the salinity was gradually reduced by 2ppt daily from Sepang value of 14.45 ± 0.5, till it reaches a zero value, using UV-sterilised well-aerated dechlorinated tap that was used throughout the experiment to enable total adaptability [43] .…”

“…Following acclimatization, fish were randomly assigned into the control group (PS-MPs free), and 3 PS-MPs exposed groups (4 fish in 1 L glass tank), for a duration of 21 days. The water and test suspensions were refreshed every 48 h. The concentrations of the PS-MPs exposed groups of 100 µg/L (1.46 × 10 3 , MP-LOW), 500 µg/L (7.3 × 10 3 , MP-MED), and 1000 µg/L (1.46 × 10 4 , MP-HIGH), were formed by suspending the particles in UV-sterilised dechlorinated tap water, with the chosen concentrations guided by previous literature [34] , [49] , [62] , and concentrations relevant to the environment (0.2–4137.3 item/L), as detected in surface water [76] . Tanks were continuously aerated to ensure optimal dissolved oxygen, and even dispersion of PS-MPs particles.…”

“…MPs have been shown to adversely affect growth and reproduction [10] , [36] , [79] , induce oxidative stress and inflammatory changes in the gut [23] , [24] , [34] , [73] , [79] . Recently, it has been observed through histological and biochemical investigation to affect multiple organs, including the brain [62] .…”