Inorganic mercury is easily absorbed by ingestion or cutaneous. However, a
relatively small amount of Hg2 + crosses the blood brain barrier or biological
membranes, and in adult rats, the retrograde axonal transport only way to Hg2+ uptake by neurons, presenting great potential neurotoxic. The aim of this
study was to determine the effects of chronic exposure to mercury chloride in
social and emotional memory in adult rats. For this we used male Wistar
rats (n= 40) with 5 months of age , divided into two groups , one of which was
exposed to mercury chloride (HgCl2) by intragastric gavage (0,375mg / kg) for
45 days. The other group, called the control group (n=20) received distilled
water by gavage. The following behavioral tests were used: the open field test,
social recognition test for the evaluation of social memory; the elevate T maze
test (LTE) was used to assess learning in the state of avoidance and short and
long - term memories. After completion of the tests, the animals were sacrificed
to evaluate the level of total mercury in the hippocampus by an Atomic
Absorption Spectrophotometer. The results showed that animals subjected to
exposure to mercury chloride did not show deficits in exploration activity. The
data from social recognition test, showed that there was no change in social
memory. In LTE test, the group exposed to HgCl2 required a greater number of
exposures for the acquisition of avoidance criteria (p<0.05) and a higher
latency in the open apparatus arm (p<0.05). After 24 hours, it was found that
treated animals spent less time in the closed arms than in the control group,
suggesting the long-term memory deficits. By just watching the HgCl2 group,
noticed an improvement in the retest, indicating preservation in the short-term
memory. The data of atomic absorption spectrometry showed greater
deposition of mercury in the hippocampus of affected animals, as compared to
control animals.
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