Abstract:
Trace metals exist in low quantities in the human body. Zinc and copper are two trace metals that are essential in the body, yet they must be balanced; otherwise, negative side effects emerge. Zinc has an antagonistic effect on copper, in that an excess amount of zinc absorbed by the body causes a copper deficiency. Furthermore, previous studies have also shown that exposing rats to zinc given both prenatally to the mother and after birth leads to cognitive impairments in adult rats and increased levels of zinc in the rat temporal cortex and hippocampus, which can be rescued in part by adding copper to the diet (Flinn et al., 2005).
This experiment examined the effect of giving zinc and zinc plus copper to adult rats in the drinking water. I raised forty-five rats on zinc (15), zinc plus copper (15), and lab water (15). Zinc and zinc plus copper were dissolved in the rats’ drinking water. The group of rats that had no metals added in the water was measured as a baseline (control). Previous experiments have shown that rats raised on zinc could not learn to extinguish a learned fear. The rats in this experiment were subjected to a fear-conditioning task, and I measured the duration of time to extinguish the learned fear. When dosed with zinc, the rats took the longest to extinguish the learned fear when a stimulus was no longer fearful. Since copper partly remediates the zinc effects, the rats dosed with zinc plus copper extinguished faster than the rats dosed solely with zinc and, in some cases, extinguished faster than the rats dosed exclusively on lab water. This experiment further elucidates the effects of zinc on cognitive abilities and the remediation of zinc’s effects when copper is present. From a larger perspective, this study emphasizes that an excess of indispensable minerals and nutrients, which are found in several food products, does not necessarily imply better human functioning.
