Ameliorative effects of egg white hydrolysate on recognition memory impairments associated with chronic exposure to low mercury concentration

Abstract

The study aimed to investigate if the EWH is able to prevent the recognition memory disorders associated with long-term Hg exposure in rats. For this, male Wistar rats were treated for 60 days with: a) Untreated: saline solution (i.m.); b) Hydrolysate: EWH (1 g/kg/day, gavage); c) Mercury: HgCl2 (1st dose 4.6 μg/kg, subsequent doses 0.07 μg/kg/day, i.m.); d) Hydrolysate-Mercury. Object recognition memory test was performed to verify Short (STM) and Long-Term Memory (LTM) and Open Field, Plus Maze and Tail Flick tests were performed as control for behavioral experiments. Reactive Oxygen Species (ROS) in hippocampus were determined by dichlorofluorescein diacetate (DCFH-DA) method, malondialdehyde (MDA) levels by TBARS, antioxidant power by FRAP assay and total Hg concentration by atomic fluorescence spectrometry. We confirm that the STM and LTM were impaired in adult rats exposed to Hg at low concentrations, which may be related to the increased metal deposition, ROS production and subsequently the oxidative damage in hippocampus. In addition, we demonstrated for the first time that EWH treatment is able to prevent memory impairment induced by Hg exposure, reducing Hg content and ROS production in hippocampus. In conclusion, EWH ameliorates memory impairments induced by chronic exposure to low doses of Hg. These findings may represent a good public health strategy since they indicate that EWH is a promising candidate as a new natural therapy for heavy metals intoxication.