Individual and Combined Effects of Nickel Oxide and Magnesium Oxide Nanoparticles on Oxidative Stress and Hepatopancreas Integrity in the Terrestrial Sentinel <scp> <i>Helix aspersa</i> </scp>

This study aimed to evaluate the toxic effects of nickel oxide (NiO) and magnesium oxide (MgO) nanoparticles (NPs), individually and in combination, on the terrestrial bio-indicator Helix aspersa. The NPs under investigation were characterized for their surface morphology and elemental composition using a scanning electron microscope (SEM) coupled to energy-dispersive X-ray spectroscopy (EDX). SEM revealed the spherical morphology of MgO-NPs and complex forms for NiO-NPs. Snails were treated with increasing doses of NPs (1 and 2 mg/g in wheat flour-based food) over 4 weeks, with a control group receiving no treatment. Oxidative stress was assessed through biochemical biomarkers such as glutathione (GSH), glutathione S-transferase (GST), glutathione peroxidase (GPx), and catalase in the hepatopancreas, alongside a histopathological examination. Our data reveal consistent trends for both NiO-NPs and MgO-NPs, with an increase in GSH levels as well as GPx and catalase activities, accompanied by a decrease in GST activities. The mixture exhibited an agonistic effect on GSH, GST, and GPx activities, which showed a decrease, while it was antagonistic for catalase activities, with an increase. At the tissue level, the signs of stress were observed through inflammation, necrosis, and cellular degeneration. Histological damage in the hepatopancreas of snails treated with NiO-NPs was pronounced, and notable alterations were observed in the sections from the MgO-NPs group compared to the control, both in a dose-dependent manner. Similarly, the group treated with the mixture showed significant tissue damage, also occurring in a dose-dependent fashion.