Abstract

We studied the effects of chronic intoxication with the heavy metals lead (Pb2+) and zinc (Zn2+) on memory formation in mice. Animals were intoxicated through drinking water during the pre- and postnatal periods and then tested in the step-through inhibitory avoidance memory task. Chronic postnatal intoxication with Pb2+ did not change the step-through latency values recorded during the 4 weeks of the test (ANOVA, P>0.05). In contrast, mice intoxicated during the prenatal period showed significantly reduced latency values when compared to the control group (day 1: q = 4.62, P<0.05; day 7: q = 4.42, P<0.05; day 14: q = 5.65, P<0.05; day 21: q = 3.96, P<0.05, and day 28: q = 6.09, P<0.05). Although chronic postnatal intoxication with Zn2+ did not alter a memory retention test performed 24 h after training, we noticed a gradual decrease in latency at subsequent 4-week intervals (F = 3.07, P<0.05), an effect that was not observed in the control or in the Pb2+-treated groups. These results suggest an impairment of memory formation by Pb2+ when the animals are exposed during the critical period of neurogenesis, while Zn2+ appears to facilitate learning extinction.

Highlights

  • Forty-nine male and female Swiss mice (20-30 g) from our own colony were used

  • Given the evidence for the differential actions of Pb2+ and Zn2+ on neuronal development and their concentrations in a brain area critical to memory formation, we evaluated the effects of chronic intoxication with these heavy metals during pre- and postnatal stages of development on performance in the step-through inhibitory avoidance task

  • The inhibitory avoidance model was used to study the effects of lead and zinc on memory formation [12]

Read more

Summary

Introduction

Forty-nine male and female Swiss mice (20-30 g) from our own colony were used. The animals were distributed into 4 experimental groups and maintained at constant temperature (24.8 ± 0.2oC), with free access to food and water. Given the evidence for the differential actions of Pb2+ and Zn2+ on neuronal development and their concentrations in a brain area critical to memory formation, we evaluated the effects of chronic intoxication with these heavy metals during pre- and postnatal stages of development on performance in the step-through inhibitory avoidance task. A group of 13 mice were exposed to lead acetate at the same concentration for 60 days beginning during the second month of life (postnatal lead group, PostPb).

Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call