ABSTRACT
<p><b>OBJECTIVE</b>The aims of this study were to determine the effects of heavy metals such as manganese on nicotinamideN-methyltransferase (EC 2.1.1.1) (NNMT) activity and to consider the possibility of involvement of NNMT activation in the pathogenesis of heavy metal induced Parkinson's disease.</p><p><b>METHODS</b>NNMT activity in supernatants separated from brain, liver and kidney homogenates of 5 elderly male Wistar rats by centrifugation were measured by high performance liquid chromatography system with fluorescence. NNMT activity under the conditon of 0.5 or 5.0 mM Mn(2+), Fe(2+), Cu(2+) or Cd(2+) was compared with control (no metal ion existence).</p><p><b>RESULTS</b>NNMT activities in rat brain, liver and kidneys were significantly decreased by Cu(2+), and those in the liver and kidneys were significantly decreased by Cd(2+). Mn(2+) reduced NNMT activity only in the liver. Fe(2+) had no effect on NNMT activity.</p><p><b>CONCLUSIONS</b>No metal increased NNMT activity in this study, contrary to our hypothesis. Further study is needed to clarify the reason why the effects of Mn(2+) and Fe(2+) which have a high relevance to Parkinson's disease on NNMT activity differ from those of Cu(2+) and Cd(2+).</p>
ABSTRACT
Objective: The aims of this study were to determine the effects of heavy metals such as manganese on nicotinamide N-methyltransferase (EC 2.1.1.1) (NNMT) activity and to consider the possibility of involvement of NNMT activation in the pathogenesis of heavy metal induced Parkinson’s disease. Methods: NNMT activity in supernatants separated from brain, liver and kidney homogenates of 5 elderly male Wistar rats by centrifugation were measured by high performance liquid chromatography system with fluorescence. NNMT activity under the conditon of 0.5 or 5.0 mM Mn2+, Fe2+, Cu2+ or Cd2+ was compared with control (no metal ion existence). Results: NNMT activities in rat brain, liver and kidneys were significantly decreased by Cu2+, and those in the liver and kidneys were significantly decreased by Cd2+. Mn2+ reduced NNMT activity only in the liver. Fe2+ had no effect on NNMT activity. Conclusions: No metal increased NNMT activity in this study, contrary to our hypothesis. Further study is needed to clarify the reason why the effects of Mn2+ and Fe2+ which have a high relevance to Parkinson’s disease on NNMT activity differ from those of Cu2+ and Cd2+.
Subject(s)
Metals, Heavy , LiverABSTRACT
Although it has been established that exercise is useful for health promotion, physical exercise may induce oxidative stress in humans. Our previous study showed that the concentration of plasma protein-bound sulfhydryl groups (p-SHs) was significantly decreased after strenuous exercise, i. e. full-marathon running and participation in an athletic training camp. Reactive oxygen species may cause oxidation of plasma proteins <I>in vitro</I>. To study whether moderate exercise for health promotion, e. g. jogging or walking, induces oxidative stress in human circulating blood, the authors examined the change in plasma p-SHs concentration following ergometric exercise at moderate intensity and of relatively short duration {Exercise 1: 80% ventilatory threshold (VT), 100% VT, and 110% VT; 30 min, Exercise 2 : 90% VT; 120 min} in 8 (23-28 yr; Exercise 1) and 6 males (23-28 yr; Exercise 2) respectively. The plasma p-SHs concentration did not changed significantly after Exercise 1 or 2. The data indicated that the exercise did not cause significant modification of plasma proteins, suggesting that it did not induce significant oxidative stress in the circulating blood.