The effect of chronic iron deficiency on adrenal tyrosine hydroxylase activity

Abstract
Chronic nutritional Fe deficiency of 2 to 5 wk duration reduced the blood Hb content to 30-50% of control values and resulted in an increase in rat adrenal tyrosine hydroxylase (TH) (EC 1.14.16.2) activity. Kinetic and mixing experiments indicated that this increase was due to an increase in enzyme protein. The body weight of Fe-deficient rats ranged from 60-80% of control; this factor was not responsible for the increase in adrenal TH as enzyme activity was directly proportional to final body weight. To determine whether the increase in adrenal TH in Fe-deficient rats was due to increased sympathetic activity to the adrenal medulla, the splanchnic nerve was cut. The increased TH was still observed after adrenal denervation; this indicates that the mechanism of response to Fe deficiency lies within the adrenal itself. Age of the rats is important in determining whether the increase in TH activity will occur.