SummaryMitochondria were prepared from liver as described previStudies were performed to determine the effects of iron deficiency on brain metabolism in rats. Concentrations of cytochrome pigments, oxidative phosphorylation, and catalase and monoamine oxidase activities in brain tissue were unaffected by iron deficiency. However, activities of aldehyde oxidase, a key enzyme in the pathway of serotonin degradation, were significantlv reduced. and concentrations of serotonin and total 5-hydroxyindole compounds were elevated in brain tissue of irondeficient animals. Aldehyde oxidase activities and concentrations of 5-hydroxyindole compounds in brain tissues returned to approximately normal values one week after treatment of iron deficient animals with iron dextran. Speculation ously (13). ~i t o c h o n d i i a were prepared from brain as follows. After removal from the calvarium the brains (4-5 g total) were placed in 20 ml of a'solution (0-5") of 0.22 M mannitol, 0,08 M sucrose, 0.2 mM EDTA, and 5 mM Tris, pH 7.4 (MSET solution).. All subsequent procedures were carried out at 0-5". The brains were rapidly minced with a sharp scissors, rinsed one time with an additional 20 ml cold MSET solution, and suspended in 6 ml MSET solution/g tissue. The' suspension was gently homogenized at low speed in a motor-driven Teflon-glass homogenizer and 0.5 ml of a solution containing 1 mg Nagase, 1 mg bovine serum albumin (fraction V), and 5 mg KHCO,/ml was added16 ml suspension. The suspension was allowed to stand for 2 min in ice and was again gently homogenized in the Teflon-glass homogenizer. An equal volume of MSET solution was then added and the sus~ension was centrifuged in a refrigStates of h n deficiency may result in reduction of important erated centrifuge for lo at g.iron containing enzymes in brain tissue and altered brain metab-solution was quickly filtered through one layer of coarse cheeseolism. cloth and was recentrifuged at 10,000 x g for 10 min. The resulting pellet was gently resuspended in the original volume of MSET ioiution and-was-centrifuged for 10 min at 5,000 X g. Previously, we have shown that a limited running ability due The pellet was again suspended in the same volume of MSET to iron deficiency in rats results from decreased levels in skeletal solution and centrifuged for 10 min at 5,000 x g . The resulting muscle mitochondria of a-glycerophosphate oxidase, an iron-mitochondrial pellet was resuspended gently in a small volume containing enzyme which is a component of the terminal electron of MSET solution (1-1.5 ml) containing 1 mg bovine serum transport systems (11). Reports of other investigators, summa-(fraction V)/ml. rized in a recent review by Pollitt and Leibel (16) suggests that Homogenates were prepared from brain by mincing the iron deficiency may in addition adversely affect behavior and tissues with a scissors, rinsing once with cold MSET solution, learning in animals and man. Since the changes observed in and then homogenizing the suspension (iced) at top speed for 5 mental function ...
1. On exposure of rats to hypobaric stress the tryptophan pyrrolase and tyrosine aminotransferase activities of the liver increased about threefold in 4h. 2. The tryptophan hydroxylase activity increased about 50% on exposure for 24h or more. 3. The increased activities reverted to the basal value on removal of the stress. 4. Treatment with cycloheximide inhibited the increase in the enzyme activities when the time of exposure was short (4h). However, the inhibitor-treated animals showed paradoxically high tyrosine aminotransferase activity on prolonged exposure (24h). 5. The pattern of haematin saturation indicated that the increase in pyrrolase activity under low pressure resembled that obtained with cortisol and not with tryptophan. 6. Repeated administration of cortisol or tryptophan did not have any effect on the activity of tryptophan hydroxylase. 7. The stress-induced increase in hydroxylase activity was not eliminated by the prior administration of 5-hydroxytryptophan to the animals.
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