Chronic exposure to low mercury chloride concentration induces object recognition and aversive memories deficits in rats

•Chronic low mercury chloride doses exposure in adult rats.•Chronic mercury exposure in adulthood impairs object recognition memory.•Chronic mercury exposure in adulthood impairs inhibitory avoidance memory.

This work examines the effects of chronic exposure to low inorganic mercury (mercury chloride, HgCl2) concentration on the recognition and aversive memories. Forty male Wistar rats were divided into 4 groups treated during 30 or 60 days with saline (control) or HgCl2 doses. After treated the animals were tested considering object recognition and inhibitory avoidance behavioral memory paradigms. Elevated plus maze, open field and tail flick tests were used to assess anxiety, locomotor and exploratory activity and pain thresholds. Only exposure for 60 days to HgCl2 induced in memory deficits quantified in the object recognition task. In the inhibitory avoidance all the animals exposed to mercury (for 30 or 60 days) presented worst performance than control animals. Our results suggest that chronic exposure to low mercury chloride concentrations impairs memory formation.