ABNORMAL-RAT BRAIN MONOAMINE METABOLISM IN IRON-DEFICIENCY ANEMIA

Iron deficiency in rats produces numerous alterations in brain metabolism as assessed by in vitro techniques. We used a new method of in vivo microdialysis to study the effect of acute iron deficiency anemia on rat brain monoamine metabolism. This method was used to sample extracellular fluid from an implanted microdialysis probe in the caudate puramen from freely moving animals. Method validation experiments showed that steady-state levels of dopamine, norepinephrine, and their metabolites were obtained only after 5 to 7 days of surgical recovery and with prior perfusion of the brain region. Caudate putamen dopamine was significantly increased 30% and 40% in fasted light-exposed and 2-hr-fed dark-exposed iron deficient anemic rats (hemoglobin < 6 g/dL), respectively, relative to control rats. Dihydroxyphenyl acetic acid and homovanillic acid concentrations were unaffected by iron deficiency in the fasted stare. These metabolites, along with dopamine, increased significantly (50 to 82%) in iron deficient rats with exposure to darkness and food while control rats' metabolites did not change. The present study documents that iron deficiency is associated with altered in vivo brain monoamine metabolism in the steady stare and in response to the environmental stimuli of food and darkness, While these data are supportive of the previous in vitro demonstrations of down-regulation of dopamine D-2 receptors, they also suggest that uptake and processing of monoamines is significantly perturbed by iron deficiency.