Why Zinc is so important?

  Dr. Jane Flinn of the Department of Psychology at George Mason University talked about the importance of metals in behavior and physiology. Her main focus was in the roles of zinc, copper, and iron in learning, memory, and Alzheimer’s.

Zinc Pills

Many of us limit our thinking that calcium is the only important metal in neuroscience, but lets talk about another equally important metal called zinc.  Zinc is heavily involved in learning and memory and are found in ca3 region of hippocampus. One of the ways zinc operates in our body is by decreasing copper level, therefore it can cause copper deficiency induced by high level of zinc, which can affect neuronal conduction. People with macular degeneration have blobs in their eyes, which are filled with zinc. Taking zinc can slow down the rate of progression of macular degeneration however it depletes the copper in the body. Hence, high level of zinc can cause copper deficiency and copper deficiency can result in anemia. Therefore, it is important to know how much of zinc is needed in our body to function properly. The role of Zinc in our body is significant because it is involved in the immune system, thus a zinc deficiency can lead to cognitive impairment. It is high in the brain, retina, and in the prostate. It is found in the brain areas in the hippocampus, the amygdala, and the prefrontal region.

Morris Water Maze (MWM)

The Morris water maze is a maze where rats can use cues to spatially learn to swim.  Mice model were compared between wild type and transgenic mice carrying the ApoE 4 gene, and human version of amyloid precursor protein (hAPP). These mice were given different level of zinc, copper, and iron in their drinking water. They experimented that zinc and iron are heavily involved in spatial memory because mice model with early onset AD showed impaired spatial memory. In addition, increased zinc diminishes the ability to learn when a cue is no longer seemed to be fearful in normal mice and rats.

Fear conditioning is when a neutral stimulus is paired with a conditioned stimulus, so the purpose in this experiment was to eliminate the fear of the neutral stimulus. Learning that a stimulus is no longer fearful is called extinction. Fair conditioning depends on the amygdala and prefrontal regions (extinction), which is highly dependent on zinc. An experiment was done to measure impairments in fear extinction. In this experiment, animals were put in a box for 6 minutes. A tone was ringed and a shock was given at the end of 3^rd minute. This was repeated three times. The next day animals were given the same environment however no tone or shock was given. Then the following day, animals were put in slightly different environments to change the appearance of the floor and bedding to see if animals believe the box is dangerous or not. The result showed that zinc enhanced mice took longer to learn fear extinction and showed memory deficit, therefore there is a negative correlation between the level of zinc and extinction rate.

Consequently, this study makes us aware about how much of zinc we should consider in our dietary supplement to avoid copper deficiency and anemia. Also, knowing that zinc is highly involved in memory, could we use zinc to slow the progression of disorders such dementia, stress, and cognitive impairment?