Minimal brain damage induced by early iron deficiency: modified dopaminergic neurotransmission

The reports that iron-deficiency anemia in human subjects induces behavioral changes was investigated in rats made nutritionally iron-deficient. The most prominent features of these animals were: the unchanged metabolism of the neurotransmitters noradrenaline, dopamine and serotonin, profound reduction of brain nonheme iron, the selective diminution of dopamine D2 receptor number (measured by Bmax), modification of dopamine-dependent behaviors and reduction of learning processes. The induction of these changes and their recovery with iron supplementation are age- and time-dependent phenomena. In newborn rats, however, the consequences of iron deficiency are irreversible, even after long-term iron supplementation. The results point to the profound effect iron metabolism can have on the long-term development and function of dopaminergic neurotransmission. These findings may not be totally unexpected, since iron distribution in the brain is highly localized in dopaminergic-peptidergic regions, such as the globus pallidus, substantia nigra, red nucleus, thalamus, caudate nucleus and nucleus accumbens. In some regions its concentration is higher than that found in the liver, the site of iron metabolism.