Experimental Datasets on the Histopathological Assessment of Purkinje cells in the Cerebellum of Japanese Medaka (Oryzias latipes) Fish Exposed to Graphene Oxide

The datasets of this article present the experimental data resulted from the assessment of Purkinje cells (PKCs) in the cerebellum of Japanese medaka (Oryzias latipes) brain, considering PKCs as a potential target of graphene oxide (GO), a nanocarbon, extensively used in industries. The GO we used in these experiments was obtained either from a commercial source or synthesized in the laboratory. Before experimental use, GO was sonicated for 5 min in ice temperature. The reproductively active adult male and female fish used in the experiments were obtained from the Japanese medaka culture facilities of the Jackson State University, Jackson, MS, USA, and were maintained as a breeding pair (one male and one female) in 500 ml balanced salt solution (BSS). The fish were exposed to GO in vivo either by immersion (IMR) (20 mg/L in BSS) or by a single intraperitoneal (IP) injection (100 µg/g), injected into the peritoneal cavity of both male and female fish. Parallel controls were maintained in BSS only (IMR experiment) or injected with nanopure water (IP experiment). To avoid movement during injections, the fish were anesthetized in MS 222 (IMR), however, for IMR experiments, fish did not require anaesthesia. The injected volume (0.5µL/10 mg fish) never exceeds 50µl/fish. After injection, the injected fish were allowed for recovery in clean BSS and after recovery both partners were transferred to a 1L glass jars with 500 mL BSS (no GO). In IMR experiments, the GO was dissolved in BSS (20 mg/L) and replaced every 24 h for 96 h. During depuration, the media of the breeders refreshed once every 24h and the reproductive activity of the experimental fish were assessed by evaluating the eggs (fertilized, unfertilized, damaged) collected from the experimental fish. After 21 days of depuration, the survived fish were anaesthetized, and the head and trunk regions were preserved in 4% paraformaldehyde in PBS (20 mM) containing 0.05% Tween 20. The phenotypic sex of the fish was assessed externally by secondary sex characters (fin features) and confirmed by gonad histology (testis and ovary). The location of cerebellum in the brain was determined in paraffin sections after haematoxylin/eosin (HE) staining, and the images of cerebellum were captured using an Olympus CKX53 inverted microscope with DP22 camera and CellSens software. Using imagej software, a minimum 2 images of cerebellum/fish were assessed. The larger size, water droplet-like shape, and the distribution of the PKCs in specific regions of cerebellum (Purkinje layers), enabled us to separate them from other cellular layers (molecular and granular layers) and neurons found in the cerebellum of Japanese medaka and count them to the extent possible. The nuclear area (µm2), the cell area (soma) (µm2), and the ratio of nuclear area: cell area of the PKCs were also considered for assessment. The data were expressed as number of PKCs/mm2. Numerical data were analysed by Kruskal-Walli’s test followed by Mann-Whitney’s test as post hoc test and presented as means ± SEM. Statistically significant differences were considered for p ≤ 0.05.