Iron deficiency alters dopamine uptake and response to L-DOPA injection in Sprague–Dawley rats


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Iron deficiency (ID) disrupts brain dopamine (DA) and norepinephrine (NE) metabolism including functioning of monoamine transporters and receptors. We employed caudate microdialysis and no net flux (NNF) in post-weaning rats to determine if ID decreased the extraction fraction (Ed). Five micromolar quinpirole, a dopamine D2 receptor agonist, resulted in 80% decrease in extracellular DA and 45% higher Ed in control animals. The D2 agonist had no effect on Ed in ID animals despite a reduction in basal DA. DAT mRNA levels were reduced by 58% with ID, while DAT protein in ventral midbrain and caudate and membrane associated DAT were also reduced by ID. Carbidopa/l-DOPA was administered to determine if elevated extracellular DA in ID was due to increased release. The DA response to l-DOPA in ID rats was 50% smaller and delayed, whereas the NE response was threefold higher. The caudate concentration of NE was also elevated in ID. Elevated dopamine-β-hydroxylase activity in ID provides a tentative explanation for the increased NE response to l-DOPA. These experiments provide new evidence that ID results in altered synthesis and functioning of DAT and perhaps suggests some compensatory changes in NE metabolism.