Author
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Hunt, Janet |
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Zito, Carol |
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Submitted to: North Dakota Academy of Science Proceedings
Publication Type: Other Publication Acceptance Date: 9/15/1997 Publication Date: N/A Citation: N/A Interpretive Summary: One type of blood cells known as platelets have been proposed to model the central nervous system in neurotransmitter (substance involved in sending signals through nerves) uptake and binding. Uptake of the neurotransmitter serotonin by blood platelets is consistently reduced in depressed patients. We investigated platelet serotonin uptake as a possible functional marker relating iron deficiency to mood and behavior. The effects of deficient or marginal dietary iron on platelet serotonin uptake were tested in three animal experiments. Growing rats consumed experimental diets with deficient, marginal, or adequate amounts of iron fed for 7-10 weeks. Iron deficient diets resulted in severe anemia, depleted liver iron, and reduced growth. With this severe iron deficiency, serotonin transport into platelets was decreased. Diets with marginal iron n content resulted in low liver iron and slightly lower hematocrit without overt anemia, but did not affect growth. The platelet serotonin uptake was unaffected by this marginal iron deficiency. The results suggest that both the number and affinity of serotonin receptors in platelets are reduced by severe iron deficiency, but are unaffected by marginal iron status. These results may be useful in further investigation of the effects of severe iron deficiency. However, platelet serotonin uptake measurements apparently are not useful in the investigation of the possible psychological effects of marginal iron deficiency. Technical Abstract: Blood platelets have been proposed to model the central nervous system in neurotransmitter uptake and binding. Platelet serotonin uptake is consistently reduced in depressed patients. We investigated platelet serotonin uptake as a possible functional marker relating iron deficiency to mood and behavior. The effects of deficient or marginal dietary iron on n the kinetics of platelet serotonin uptake were tested in three animal experiments. Experimental diets (AIN-93G) that were modified in iron content, were fed for 7-10 wk to growing male Sprague-Dawley rats. Platelet serotonin uptake kinetics were determined by incubating 0.05 to 1.0 uM 14**C-labeled 5-hydroxytryptamine (serotonin) with 8x10**7 platelets/mL, at 37 deg C with and without imipramine inhibition of active transport, for 2.25 m in an automated cell harvester. Diets containing less than 5 mg iron/kg produced severe iron deficiency characterized by anemia, depleted liver iron, and lower body weight. With this severe iron deficiency, both the Kt and Jmax of serotonin transport into platelets were decreased. Diets containing 15-20 mg iron/kg resulted in marginal iron deficiency with low liver iron and slightly lower hematocrit without overt anemia, but did not affect body weight. The kinetics of platelet serotonin uptake were unaffected by this marginal iron deficiency. The results suggest that both the number and affinity of serotonin receptors in platelets are reduced by severe iron deficiency, but are unaffected by marginal iron status. These results may be useful in further investigation of the effects of severe iron deficiency. However, platelet serotonin uptake measurements apparently are not useful in the investigation of the possible psychological effects of marginal iron deficiency. |
